CN116495782A - High-stability nano cesium tungsten bronze transparent heat-insulating powder and preparation method and application thereof - Google Patents

Abstract

The invention belongs to the field of nano materials, and relates to high-stability transparent heat-insulating powder of cesium tungsten bronze, and a preparation method and application thereof. Reducing the tungsten-containing compound into low-valence tungsten atoms by using a solid phase method and using a metal simple substance as a reducing agent, and oxidizing to obtain a small-size high-valence tungsten compound; mixing the powder with cesium salt, and calcining to obtain high-stability small-size nano cesium tungsten bronze powder, wherein the particle size is 0.1-50 nm. Or directly mixing metal salt with cesium salt and tungsten-containing compound, and calcining in a certain atmosphere to obtain cesium tungsten bronze powder with a primary particle size of nanometer grade and a particle size of 50-200 nm. The introduction of metal elements in the method ensures that metal is easily oxidized to generate metal oxide in the solid phase method preparation, powder grinding and use process of the cesium tungsten bronze material as a transparent heat-insulating coating or film, can be used as a passivation layer of cesium tungsten bronze, can stabilize cesium tungsten bronze nano-particles and improves weather resistance of the cesium tungsten bronze in the use process.

Description

A kind of highly stable nano-cesium tungsten bronze transparent heat-insulating powder and its preparation method and application

technical field

The invention belongs to the technical field of nanomaterials, and relates to a highly stable nano-cesium tungsten bronze transparent heat-insulating powder and a preparation method and application thereof.

Background technique

Cesium tungsten bronze material (Cs _x WO ₃ (0<x≤0.33)) is a non-stoichiometric compound with high visible light transmittance and excellent near-infrared shielding performance (it can shield near-infrared wavelengths greater than 1000 nm light) characteristics. However, cesium tungsten bronze is not stable in actual use, and the main reasons for its instability are: On the one hand, due to the characteristics of cesium tungsten bronze, Cs ⁺ contributes a large number of electrons, and the oxygen vacancies generated in the system will lead to a part of + The 6-valent W atom is reduced to +5 valence, resulting in a reduced chemical environment on the surface of the material, and the reduced chemical environment is easily destroyed by light and heat under actual working conditions, making cesium tungsten bronze It is oxidized during use [Chem., 2006, 12(29), 7717-7723.], and causes the Cs ⁺ ions in the crystal lattice to precipitate from tungsten bronze, resulting in poor crystallinity of tungsten bronze, material instability and poor weather resistance And other problems, eventually make cesium tungsten bronze lose the near-infrared light shielding performance. On the other hand, the particle size of cesium tungsten bronze prepared by the solid phase method is generally large. In order to improve the visible light transmittance, it is often necessary to carry out secondary crushing through grinding, and mechanical grinding will cause the surface of the material to be amorphized, affecting the cesium tungsten. Optical stability of bronze [Cryst. Eng. Comm.,2018, 20, 1509–1519.].

Therefore, in view of the problem that the tungsten element in cesium tungsten bronze is easily oxidized and cesium ions are precipitated, resulting in unstable optical properties of the material, researchers have mainly explored the following solutions: (1) Use element doping to improve the stability of the material sex. Introducing foreign atoms into cesium tungsten bronze lattice to tune its stability and optical properties. Mo-doped small-sized tungsten bronze was synthesized by hydrothermal method, which greatly improved the infrared light blocking rate [Appl. Surf. Sci., 2017, 399, 41–47. ]; (2) in the outer layer of cesium tungsten bronze Coated with an inert oxide composite layer. The main method is to mix the ground cesium tungsten bronze slurry with SiO ₂ [J.Mater. Chem. C, 2015, 3 (31), 8050–8060.], Al ₂ O ₃ , ZnO [Ceram. Int., 2018 , 44,2738-2744.] or gC ₃ N ₄ complex [Appl. Catal. B: Environ., 2018, 229, 218–226.], making amorphous WO ₃ sandwiched between cesium tungsten bronze and an inert layer , limit the WO ₃ reaction area, and can stabilize cesium tungsten bronze to a certain extent. Although the above method slows down the oxidation of cesium tungsten bronze to a certain extent, the preparation method is complicated, and there are problems such as washing, drying, and difficult disposal of waste liquid. Therefore, the low-cost and high-efficiency preparation of small-sized and highly stable cesium tungsten bronze nano-powder materials has always been a hot research topic.

Since the solid-phase method is recognized in the field as the easiest method for industrialization, but the preparation of high-stability and small-sized cesium tungsten bronze nano-powders by the solid-phase method still lacks the preparation technology of nanoparticles, so the development of new methods based on the solid-phase method The method for large-scale preparation of high-stability cesium tungsten bronze nano-powders is a bottleneck problem in this field.

Contents of the invention

Aiming at the technical problem that the particle size of cesium tungsten bronze prepared by the existing solid-state method is large, unstable, and easily causes unstable optical properties of the material, the present invention proposes a highly stable nano-cesium tungsten bronze transparent heat-insulating powder and its preparation method and application . The invention has the advantages of simple preparation process, low cost, less agglomeration, high purity and good repeatability. The solid-phase method is used for reaction, and there is no discharge of other "three wastes" except a small amount of water and carbon dioxide, which is beneficial to industrialization. And the metal element and the tungsten-containing compound raw materials are successively reduced and oxidized to obtain a small-sized tungsten-containing compound, and then mixed with cesium salt and calcined, the prepared high-stable nano-cesium tungsten bronze transparent heat-insulating powder has a particle size of 0.1~50 nm; In the present invention, the metal salt is directly mixed with cesium salt and tungsten salt, and then calcined in a certain atmosphere to obtain a pure-phase cesium tungsten bronze with a primary particle size of nanometer. When applied to heat insulation materials for automobiles and building glass, while ensuring the visible light transmittance is above 70%, the near-infrared light blocking rate can be as high as 95%, and the ultraviolet light blocking rate can be above 99%. Development and application prospects.

In order to achieve the above object, the technical solution of the present invention is achieved in that:

A high-stable nano-cesium tungsten bronze transparent heat-insulating powder is obtained by using a solid-phase method to uniformly mix a metal element or a metal salt with a tungsten-containing compound and a cesium salt, and then calcined. When the metal element is used as a raw material, the high-stable nanometer The particle size of the cesium tungsten bronze transparent heat-insulating powder is 0.1-50 nm; when metal salt is used as the raw material, the particle size of the highly stable nano-cesium tungsten bronze transparent heat-insulating powder is 50-200 nm.

Further, the metal element is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the metal in the metal salt is magnesium, aluminum, iron, nickel, copper, zinc , zirconium, tin, antimony, tungsten or bismuth, the metal salt is carbonate, citrate, isopropoxide, acetate, oxalate, isooctanoate, acetylacetonate , methanesulfonate or meta-acid in any one.

The preparation method of the highly stable nano-cesium tungsten bronze transparent heat-insulating powder, when the raw material is a simple metal, the steps are as follows:

(1) Mix the elemental metal with the tungsten-containing compound raw materials, and then undergo a reduction reaction and an oxidation reaction in turn to obtain a small-sized tungsten-containing compound;

(2) After uniformly mixing the small-sized tungsten-containing compound obtained in step (1) with cesium salt, calcining to obtain a highly stable nano-cesium tungsten bronze transparent heat-insulating powder with a particle size of 0.1-50 nm.

Further, the metal element in the step (1) is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the raw material of the tungsten-containing compound is tungstic acid, ammonium tungstate , ammonium paratungstate, ammonium metatungstate or tungsten trioxide; the molar ratio of the metal element to the tungsten atom in the tungsten-containing compound raw material is (0.001~1.5):1.

Further, the reduction reaction in the step (1) is a ball milling process at room temperature, the ball milling time is 0.5~24 h, and the ball milling speed is 50~1000r/min; the oxidation reaction is a calcination process in a certain atmosphere, and the atmosphere is nitrogen, argon, ammonia , Oxygen, ammonia-argon mixed gas, hydrogen-argon mixed gas or any one of air, the calcination temperature is 200~1000℃, the calcination time is 1~12 h, and the particle size of the small-sized tungsten-containing compound is 0.1~50nm .

Preferably, the oxidation reaction is calcined in an oxygen or air atmosphere, the calcining temperature is 300-1000° C., and the calcining time is 1-6 h.

Further, the cesium salt in the step (2) is any one of cesium carbonate, cesium bicarbonate, cesium sulfate, cesium nitrate, cesium formate, cesium acetate, cesium oxalate, cesium hydroxide or cesium oxide, cesium salt and small Size The molar ratio of tungsten atoms in the tungsten-containing compound is (0.1~0.5):1; the calcination atmosphere is nitrogen, argon or vacuum, the calcination temperature is 200~1000°C, and the heating rate is 1~50°C/min , the calcination time is 1~12 h.

Further, in the preparation method of the highly stable nano-cesium tungsten bronze transparent heat-insulating powder, when the raw material is a metal salt, the metal salt is directly mixed with the tungsten-containing compound raw material and the cesium salt, and then calcined to obtain a particle size of 50 ~200 nm highly stable nano-cesium tungsten bronze transparent heat-insulating powder.

Further, the metal in the metal salt is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the metal salt is carbonate, citrate, iso Any one of propoxide, acetate, oxalate, isooctanoate, acetylacetonate, methanesulfonate or metasalt; the difference between the metal element in the metal salt and the tungsten atom in the raw material of the tungsten-containing compound The molar ratio is (0.001~1.5):1.

Preferably, the metal salt is an easily decomposed metal salt, such as magnesium carbonate, magnesium citrate, aluminum carbonate, aluminum acetylacetonate, aluminum isopropoxide, iron acetate, ferrous citrate, nickel oxalate, copper acetate, isooctanoic acid Any one of zinc, zinc acetylacetonate, zirconium acetate, zirconium citrate, tin methanesulfonate, tin acetate, antimony acetate, metatungstic acid, or bismuth oxalate.

Further, the cesium salt is any one of cesium carbonate, cesium bicarbonate, cesium sulfate, cesium nitrate, cesium formate, cesium acetate, cesium oxalate, cesium hydroxide or cesium oxide, cesium salt and tungsten in the tungsten-containing compound raw material The molar ratio of atoms is (0.1~0.5):1; the calcination atmosphere is nitrogen, argon or vacuum, the calcination temperature is 200~1000°C, the heating rate is 1~50°C/min, and the calcination time is 1 ~12 h.

Preferably, the calcination atmosphere is nitrogen, argon or vacuum condition, and the calcination temperature is 300-1000°C.

Further, the preparation method of the above-mentioned highly stable nano-cesium tungsten bronze transparent heat-insulating powder can be understood as:

A. Mix the metal element with the tungsten-containing compound raw material, and then undergo reduction reaction and oxidation reaction in turn to obtain a small-sized tungsten-containing compound;

B. After uniformly mixing the small-sized tungsten-containing compound obtained in step A with cesium salt, calcining to obtain a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the particle size of which is 0.1-50 nm.

Or C. After directly mixing the metal salt with the tungsten-containing compound raw material and cesium salt, calcining in a certain atmosphere, the primary particle can be obtained as a nano-scale highly stable cesium tungsten bronze transparent heat-insulating powder, and its particle size is 50~200 nm.

Further, the highly stable nano-cesium tungsten bronze transparent heat-insulating powder prepared by the above method has a molecular formula of Cs _x WO ₃ , where 0.2≤x≤0.33.

Further, the highly stable nano-cesium tungsten bronze transparent heat-insulating powder has a visible light transmittance greater than 70%, an ultraviolet light absorption rate of more than 99%, and a near-infrared light blocking rate of more than 95%.

The application of the highly stable nano-cesium tungsten bronze transparent heat-insulating powder in transparent heat-insulating coatings and films is as follows: the nano-cesium tungsten bronze transparent heat-insulating powder is ground to obtain a high-stable cesium tungsten bronze nanometer The dispersion slurry is used as a coating, and the cesium tungsten bronze nano-dispersion slurry is compounded with polyvinyl butyral (PVB) to prepare a transparent heat-insulating film.

Furthermore, after compounding it with polyvinyl butyral to prepare a transparent heat-insulating film, in the "Double 85" test box (temperature 85 ° C, humidity 85%) accelerated aging for 60 days, the near-infrared light rejection rate only decreased 3.8%.

The present invention has the following beneficial effects:

1. The present invention utilizes the solid-phase method to reduce tungsten-containing compounds to low-valence tungsten atoms, and then oxidize them to obtain small-sized high-valent tungsten compounds by using simple metals as reducing agents. After mixing the small-sized tungsten compound obtained by reduction and oxidation with cesium salt, it is calcined in a certain atmosphere to obtain a highly stable nano-cesium tungsten bronze transparent heat-insulating powder (particle size 0.1~50 nm), with high purity, Transparent heat insulation performance is good, compared with non-metal-doped cesium tungsten bronze, it has more excellent moisture and heat resistance performance. In addition, the present invention directly mixes the metal salt with cesium salt and tungsten salt evenly, and then calcines in a certain atmosphere to obtain pure-phase cesium tungsten bronze with a primary particle size of nanoscale (particle size 50-200nm). The solid-phase method of the invention has a simple preparation process route, high efficiency, easy-to-obtain raw materials, no industrial "three wastes" discharge, and is beneficial to industrialization.

2. The introduction of metal elements in this method makes the metal easily oxidized to form metal oxides during the solid-phase preparation of cesium tungsten bronze materials, powder grinding, and use as transparent heat-insulating coatings or films, which can be used as cesium tungsten bronze materials. The passivation layer of tungsten bronze can stabilize cesium tungsten bronze nanoparticles and improve the weather resistance of cesium tungsten bronze during use. Moreover, the present invention further researches and finds that after mixing the elemental metal with the tungsten-containing compound raw material and carrying out the reduction and oxidation reactions in sequence, the introduction of the metal element provides the interface between the metal and the tungsten compound particles, which limits the growth of the particles, and obtains Tungsten compounds with a smaller size (particle size 0.1-50 nm) can be used as raw materials to obtain nano-scale cesium tungsten bronze powder (particle size 0.1-50 nm) with uniform particle size distribution and small particle size.

3. The highly stable nano-cesium tungsten bronze powder prepared by the present invention is suitable for heat insulation of automobiles and architectural glass. While ensuring that the visible light transmittance (T _{λ=550 nm} ) is above 70%, the near-infrared light rejection rate (T _{λ=950 nm} ) can be as high as more than 95%, and the ultraviolet light blocking rate (T _{λ=320 nm} ) is more than 99%, which has broad development and application prospects. The results of the "Double 85" aging resistance test carried out by the present invention show that the aging resistance of metal-doped cesium tungsten bronze is significantly better than that of non-metal-doped samples. After 60 days, the near-infrared light rejection rate of the metal-doped sample decreased by only 3.8% at a wavelength of 950 nm; while the rejection rate of the undoped sample decreased by 7.7% under the same conditions, which was the same as that of the commercially available cesium tungsten bronze nanopowder. Under these conditions, the barrier rate decreased by 8.9%. The invention solves the problem that the particle size of the cesium tungsten bronze prepared by the existing solid state method is large, and the optical properties of the material are easily unstable during use.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work.

Figure 1 is an SEM image of small-sized tungsten trioxide prepared in Example 1 of the present invention.

FIG. 2 is an SEM image of the cesium tungsten bronze nanomaterial prepared in Example 2 of the present invention.

FIG. 3 is a TEM image of the cesium tungsten bronze nanomaterial prepared in Example 2 of the present invention.

FIG. 4 is an XRD pattern of the cesium tungsten bronze nanomaterial prepared in Example 2 of the present invention.

Fig. 5 is the spectrograms of cesium tungsten bronze nanomaterials and PVB composite film prepared in Example 2 of the present invention aged in a "double 85" test chamber for 4 days and 60 days.

FIG. 6 is an SEM image of the cesium tungsten bronze nanomaterial prepared in Example 3 of the present invention.

FIG. 7 is an XRD pattern of the cesium tungsten bronze nanomaterial prepared in Example 3 of the present invention.

Fig. 8 is an SEM image of cesium tungsten bronze nanomaterials prepared directly using cesium source and tungsten oxide prepared in the comparative example of the present invention.

Fig. 9 is a spectrogram of the cesium tungsten bronze nanomaterial and PVB composite film prepared in the comparative example of the present invention aged in a "double 85" test chamber for 60 days.

Figure 10 is the spectrogram of the PVB composite film made of commercially available cesium tungsten bronze nanopowder aged in the "Double 85" test chamber for 60 days.

Detailed ways

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The raw materials used in each embodiment of the present invention are commercially available commodities.

Example 1

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 150 g of tungsten trioxide, place it in a vacuum ball mill jar, weigh 1 g of magnesium and mix it evenly. Filled with nitrogen protection, ball milled at 100 r/min for 24 h to complete the reduction reaction, and then the ball milled powder was oxidized in a tube furnace at 300 °C for 6 h in an air atmosphere to obtain small-sized trioxide Tungsten, the morphology is shown in Figure 1, and the particle size is ≤50 nm.

Take 110 g of the obtained small-sized tungsten trioxide, add 40 g of cesium carbonate and mix evenly, and react at 800 °C for 2 h at a heating rate of 1 °C/min under nitrogen atmosphere to obtain the pure phase Cs _0.32 WO ₃ highly stable cesium tungsten bronze nanoparticles.

Example 2

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 200 g of tungsten trioxide, place it in a vacuum ball mill jar, and add 1.0 g of metal aluminum powder. After the ball mill tank was air-washed three times, the ball mill was carried out after vacuuming, and the ball mill was mechanically milled at a speed of 200 r/min for 10 h. Small-sized tungsten trioxide can be obtained by oxidation of the ball-milled powder at 600 °C for 2 h in an air atmosphere.

Take 145 g of reduced and oxidized tungsten trioxide powder, add 40 g of cesium bicarbonate, place it in a mortar and mix evenly, and react at 700 °C for 2 h under an argon atmosphere at a heating rate of 3 °C/min , until the temperature is lowered to room temperature and taken out, the highly stable cesium tungsten bronze Cs _0.32 WO ₃ nanoparticles can be prepared.

The morphology of the cesium tungsten bronze prepared in this example is shown in Figure 2, and the particle size is below 50 nm. Figure 3 is the elemental distribution diagram of cesium tungsten bronze powder observed by transmission electron microscope, in which it can be seen that metal aluminum is doped in cesium tungsten bronze.

The XRD of the prepared cesium tungsten bronze is shown in Figure 4, and the pure phase cesium tungsten bronze Cs _0.32 WO ₃ nanopowder (PDF#:83-1334) was obtained. The invention utilizes a solid-phase method and uses simple metal as a reducing agent to reduce tungsten-containing compounds to low-valence tungsten atoms, and then oxidize to obtain small-sized high-valence tungsten compounds. After mixing the small-sized tungsten compound obtained by reduction and oxidation with cesium salt, it is calcined in a certain atmosphere to obtain a highly stable nano-cesium tungsten bronze transparent heat-insulating powder (particle size 0.1~50 nm), with high purity, Transparent heat insulation performance is good, compared with non-metal-doped cesium tungsten bronze, it has more excellent moisture and heat resistance performance. In addition, the present invention directly mixes the metal salt with cesium salt and tungsten salt evenly, and then calcines in a certain atmosphere to obtain pure-phase cesium tungsten bronze with a primary particle size of nanoscale (particle size 50-200nm). The solid-phase method of the invention has a simple preparation process route, high efficiency, easy-to-obtain raw materials, no industrial "three wastes" discharge, and is beneficial to industrialization.

The introduction of metal elements in this method makes the metal easily oxidized to form metal oxides during the solid-phase preparation of cesium tungsten bronze materials, powder grinding, and use as transparent heat-shielding coatings or films, which can be used as cesium tungsten bronze The passivation layer can stabilize cesium tungsten bronze nanoparticles and improve the weather resistance of cesium tungsten bronze during use. Moreover, the present invention further researches and finds that after mixing the elemental metal with the tungsten-containing compound raw material and carrying out the reduction and oxidation reactions in sequence, the introduction of the metal element provides the interface between the metal and the tungsten compound particles, which limits the growth of the particles, and obtains Smaller size (0.1~50nm) tungsten compounds can be used as raw materials to obtain nano-scale cesium tungsten bronze powder (0.1~50nm) with uniform particle size distribution and small particle size.

comparative example

A preparation method of cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 145 g of tungsten trioxide and 40 g of cesium bicarbonate, place them in a mortar and mix them evenly, and react at 700°C for 2 h at a heating rate of 3°C/min under a nitrogen atmosphere until the temperature drops to room temperature, then take them out. Cesium tungsten bronze Cs _0.32 WO ₃ nanoparticles can be prepared.

The morphology of the prepared cesium tungsten bronze is shown in Figure 8, and the particle size is about 200 nm.

Example 3

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 400 g of tungsten trioxide, add 10 g of aluminum acetylacetonate, add 100 g of cesium bicarbonate, react at 700 °C for 2 h at a heating rate of 3 °C/min under nitrogen atmosphere, and naturally cool to room temperature to prepare Highly stable pure-phase cesium tungsten bronze Cs _0.30 WO ₃ nanoparticles were obtained. The morphology of the prepared cesium tungsten bronze is shown in Figure 6, the particle size is below 200 nm, and the crystal structure is shown in Figure 7, which is a hexagonal crystal structure (PDF#81-1244). The difference is mainly due to the amount of cesium ion doping.

Example 4

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 200 g of tungstic acid, place it in a vacuum ball mill jar, and add 65 g of iron powder into it. After vacuuming and washing, under the protection of nitrogen, the ball milled at a speed of 200 r/min for 8 h, and the ball-milled powder was oxidized in an air atmosphere at a heating rate of 5 °C/min at 700 °C for 1 h to obtain a small Dimensions Tungsten Oxide.

Take 150 g of reduced and oxidized tungsten trioxide powder, add 23 g of cesium acetate and mix well, then react at 400°C for 12 hours at a heating rate of 20°C/min under an argon atmosphere to obtain Cesium tungsten bronze Cs _0.33 WO ₃ nanometer powder.

Example 5

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 360 g of ammonium tungstate, weigh 0.2 g of nickel oxalate, add 30 g of cesium formate and mix well, then react at 400 °C for 12 h at a heating rate of 5 °C/min under nitrogen atmosphere to obtain Cesium tungsten bronze Cs _x WO ₃ (x=0.2) nanoparticles.

Example 6

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 100 g of tungsten trioxide, place it in a vacuum ball mill jar, weigh 0.1 g of copper powder and mix evenly. Ball milled at 200 r/min for 12 h, and the ball milled powder was oxidized in a tube furnace at 200 °C for 6 h at a heating rate of 5 °C/min in an air atmosphere to obtain small-sized tungsten trioxide.

Take 50 g of reduced and oxidized tungsten trioxide powder, add 9 g of cesium hydroxide and mix well, then carry out the reduction reaction at 600 °C for 2 h at a heating rate of 5 °C/min under a nitrogen atmosphere to obtain Cesium Tungsten Bronze Cs _0.30 WO ₃ Nanoparticles.

Example 7

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 1000 g of tungsten trioxide, place it in a vacuum ball mill jar, and add 300 g of zinc powder into it. Ball mill for 2 h at a speed of 300 r/min, place the ball milled powder in an air atmosphere in a tube furnace, and carry out an oxidation reaction at 800 °C for 1 h at a heating rate of 5 °C/min to obtain small-sized trioxide tungsten.

Take 500 g of reduced and oxidized tungsten trioxide powder, add 210 g of cesium acetate, place it in a mortar and mix evenly, then carry out the reduction reaction at 400 °C at a heating rate of 50 °C/min under an argon atmosphere for 12 h, cesium tungsten bronze Cs _0.33 WO ₃ nanoparticles can be prepared.

Example 8

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 64 g of tungstic acid, 15 g of zirconium acetate, and 15 g of cesium oxalate and mix them evenly, then carry out a reduction reaction at 700°C for 2 hours at a heating rate of 3°C/min under an argon atmosphere to obtain cesium tungsten Bronze Cs _0.33 WO ₃ nanoparticles.

Example 9

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 500 g of tungsten trioxide, place it in a vacuum ball mill jar, weigh 10 g of tin powder and mix evenly. Ball milled for 24 h at a speed of 200 r/min, and the ball-milled powder was oxidized in a tube furnace at 600 °C for 2 h at a heating rate of 2 °C/min in an air atmosphere to obtain small-sized tungsten trioxide.

Take 100 g of reduced and oxidized tungsten trioxide powder, add 25 g of cesium bicarbonate and mix well, then carry out the reduction reaction at 700 °C for 2 h at a heating rate of 10 °C/min under an argon atmosphere, and the product can be prepared Cesium tungsten bronze Cs _0.30 WO ₃ nanoparticles were obtained.

Example 10

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 50 g of tungsten trioxide, 1 g of metatungstic acid, and 10 g of cesium hydroxide and mix them evenly, then carry out a reduction reaction at 800°C for 1 h at a heating rate of 5°C/min under an argon atmosphere to produce Cesium tungsten bronze Cs _0.30 WO ₃ nanoparticles were obtained.

Example 11

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 100 g of tungsten trioxide, weigh 2 g of bismuth oxalate and 90 g of cesium oxalate, mix them evenly, and carry out a reduction reaction at 400 °C for 6 h at a heating rate of 5 °C/min in a nitrogen atmosphere to obtain Cesium Tungsten Bronze Cs _0.30 WO ₃ Nanoparticles.

Example 12

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 200 g of tungsten trioxide, place it in a vacuum ball mill jar, weigh 35 g of aluminum powder and mix evenly. Filled with nitrogen protection, ball milled at a speed of 1000 r/min for 0.5 h, and the ball milled powder was oxidized in a tube furnace at 400 °C for 2 h at a heating rate of 4 °C/min under a nitrogen atmosphere, and then repeated Reduction and oxidation process, that is, the oxidized tungsten trioxide is put into a vacuum ball mill tank, filled with nitrogen, ball milled at a speed of 1000 r/min for 0.5 h, and then put into a tube furnace. ℃ for 2 h to obtain small-sized tungsten trioxide.

Take 100 g of reduced and oxidized tungsten trioxide powder, add 85 g of cesium carbonate and mix evenly, and react at 800 °C for 3 h at a heating rate of 4 °C/min under nitrogen atmosphere to obtain high Stabilized cesium tungsten bronze Cs _0.30 WO ₃ nanoparticles.

Example 13

A preparation method of a highly stable nano-cesium tungsten bronze transparent heat-insulating powder, the steps are as follows:

Weigh 50 g of tungsten trioxide, weigh 75 g of antimony acetate, add 45 g of cesium carbonate and mix evenly, and react at 200 °C for 12 h at a heating rate of 4 °C/min under nitrogen atmosphere to obtain high Stabilized cesium tungsten bronze Cs _0.30 WO ₃ nanoparticles.

Application example

The preparation of transparent thermal insulation composite film is as follows:

Take 5 g of the cesium tungsten bronze nanopowder prepared in Example 2, put it in a beaker, add 4 g of dispersant and 50 g of absolute ethanol, and after ultrasonic treatment for 10 min, pour it into a nano grinder for ball mill dispersion treatment (ball milling medium: zirconia beads, size: 0.1 mm, rotation speed: 4980 rpm), and then filter out the zirconia beads with a 200-mesh sieve to obtain a cesium tungsten bronze dispersion. Take 2.5 g of polyvinyl butyral powder and 15 g of absolute ethanol, stir and mix, seal, then place in an oven and heat at 60°C for 3 h to obtain a uniformly mixed PVB colloid. Put the PVB colloid prepared above into the defoaming box, and then add 0.11 g of plasticizer (triethylene glycol diisocaprylate), 0.145 g of antioxidant (2,6-di-tert-butyl-4- methyl phenol (BHT for short) and 0.2 g of the above-prepared cesium tungsten bronze dispersion were put into a defoamer for degassing for 10 min. The coated glass bottom plate is dried in an electric heating constant temperature blast drying oven to obtain a cesium tungsten bronze transparent heat-insulating composite film.

Evaluate the transparent heat insulation performance of the transparent heat insulation composite film prepared in this application example. The method is: put the prepared transparent heat-insulating composite film into the "Double 85" test box (temperature 85 ℃, humidity 85%) to evaluate its resistance to humidity and heat, and measure the ultraviolet-visible-near-infrared spectrum of the composite film. Evaluate its thermal insulation performance (shown in Figure 5). The results show that the transmittance of the prepared transparent heat-insulating composite film at 950 nm is 7.2% when not aged, which corresponds to its near-infrared light rejection rate of 92.8%. After aging for 4 days, the response characteristics of the material to light are basically No change, after aging for 60 days, the spectral change is not obvious (as shown in Figure 5), the transmittance of near-infrared light at 950 nm is 11%, and the corresponding rejection rate is 89%. The cesium tungsten bronze prepared by this method, The blocking rate of near-infrared light at 950 nm is only decreased by 3.8%.

Figure 10 is the spectrogram of the commercially available cesium tungsten bronze nanopowder compounded with PVB in the same way, and the transparent heat-insulating composite film prepared after aging in the "Double 85" test chamber for 60 days. When not aged, the transmittance of the transparent heat-insulating composite film at a wavelength of 950nm is 5.2%, corresponding to its barrier rate of 94.8%. After 60 days of aging in a high-humidity environment, the near-infrared light transmittance at 950 nm 14.1%, corresponding to its rejection rate of 85.9%, the near-infrared light rejection rate of commercially available cesium tungsten bronze at 950 nm has dropped by about 8.9%.

The highly stable nano-cesium tungsten bronze powder prepared by the present invention is suitable for heat insulation and heat preservation of automobiles and building glass. While ensuring that the visible light transmittance (T _{λ=550 nm} ) is above 70%, the near-infrared light rejection rate (T _{λ=950 nm} ) can be as high as more than 95%, and the ultraviolet light blocking rate (T _{λ=320 nm} ) is more than 99%, which has broad development and application prospects.

Application example comparison example

The only difference between the preparation of the transparent heat-insulating composite film and the application example is that the cesium tungsten bronze nanopowder prepared in the comparative example is used, as follows:

Take 5 g of the cesium tungsten bronze nanopowder prepared in the comparative example, put it in a beaker, add 4 g of dispersant and 50 g of absolute ethanol, and after ultrasonic treatment for 10 min, pour it into a nano grinder for ball milling dispersion treatment (Ball milling medium: zirconia beads, size: 0.1 mm, rotational speed: 4980 rpm), and then filter the zirconia beads with a 200-mesh sieve to obtain the cesium tungsten bronze dispersion. Take 2.5 g of polyvinyl butyral powder and 15 g of absolute ethanol, stir and mix, seal, then place in an oven and heat at 60°C for 3 h to obtain a uniformly mixed PVB colloid. The above prepared PVB colloid was placed in a defoaming box, and then, 0.11 g of plasticizer (triethylene glycol diisocaprylate), 0.145 g of antioxidant (2,6-di-tert-butyl-4-methyl phenol, referred to as BHT) and 0.2 g of the cesium tungsten bronze dispersion prepared above, degassing treatment for 10 min, and the evenly mixed coating was coated on the glass bottom plate with a scraper, and then the glass bottom plate covered with the coating was placed on the The cesium tungsten bronze transparent heat-insulating composite film is obtained by drying in an electric heating constant temperature blast drying oven.

Figure 9 shows the cesium tungsten bronze transparent heat-insulating powder prepared by using the comparative example. According to the same method of compounding with PVB as in Example 2, the transparent heat-insulating composite film prepared in the "Double 85" test box (temperature 85 ° C, humidity 85%) after aging for 60 days, the response characteristics of the material to light. The results show that the cesium tungsten bronze transparent heat-insulating composite film, when not aged, has a transmittance of 6.0% at a wavelength of 950 nm, corresponding to a barrier rate of 94%. After aging in a high temperature and high humidity environment for 60 days, the transmittance of 950 The transmittance at nm is 13.7%, corresponding to its rejection rate of 86.3%, and the near-infrared light rejection rate at 950 nm of the cesium tungsten bronze nanomaterial prepared in the comparative example is reduced by 7.7%.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A high-stability transparent heat-insulating powder of nano cesium tungsten bronze is characterized in that: the high-stability nano cesium tungsten bronze transparent heat-insulating powder is obtained by uniformly mixing a metal simple substance or metal salt, a tungsten-containing compound and cesium salt by a solid phase method and calcining, wherein the particle size of the high-stability nano cesium tungsten bronze transparent heat-insulating powder is 0.1-50 nm when the metal simple substance is used as a raw material; when the metal salt is used as a raw material, the particle size of the high-stability nano cesium tungsten bronze transparent heat insulation powder is 50-200 nm.

2. The high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 1, wherein the powder is characterized in that: the metal simple substance is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the metal in the metal salt is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth, and the metal salt is any one of carbonate, citrate, isopropoxide, acetate, oxalate, isooctanoate, acetylacetonate, methylsulfonate or metaacid salt of the metal.

3. The method for preparing the high-stability nano cesium tungsten bronze transparent heat-insulating powder according to claim 1 or 2, wherein when the raw material is a metal simple substance, the method comprises the following steps:

(1) Mixing a metal simple substance with a tungsten-containing compound raw material, and sequentially carrying out reduction reaction and oxidation reaction to obtain a small-size tungsten-containing compound;

(2) And (3) uniformly mixing the small-size tungsten-containing compound obtained in the step (1) with cesium salt, and calcining to obtain the high-stability nano cesium tungsten bronze transparent heat-insulating powder with the particle size of 0.1-50 nm.

4. The method for preparing the high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 3, which is characterized in that: the metal simple substance in the step (1) is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the tungsten-containing compound raw material is any one of tungstic acid, ammonium tungstate, ammonium paratungstate, ammonium metatungstate or tungsten trioxide; the molar ratio of the metal simple substance to tungsten atoms in the tungsten-containing compound raw material is (0.001-1.5): 1.

5. The method for preparing the high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 4, which is characterized in that: the reduction reaction in the step (1) is a room temperature ball milling process, the ball milling time is 0.5-24 h, and the ball milling rotating speed is 50-1000 r/min; the oxidation reaction is a calcination process in a certain atmosphere, the atmosphere is any one of nitrogen, argon, ammonia, oxygen, ammonia-argon mixture, hydrogen-argon mixture or air, the calcination temperature is 200-1000 ℃, the calcination time is 1-12 h, and the particle size of the small-size tungsten-containing compound is 0.1-50 nm.

6. The method for preparing the high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 5, which is characterized in that: the cesium salt in the step (2) is any one of cesium carbonate, cesium bicarbonate, cesium sulfate, cesium nitrate, cesium formate, cesium acetate, cesium oxalate, cesium hydroxide or cesium oxide, and the molar ratio of the cesium salt to tungsten atoms in the small-size tungsten-containing compound is (0.1-0.5): 1; the calcination atmosphere is nitrogen, argon or vacuum, the calcination temperature is 200-1000 ℃, the heating rate is 1-50 ℃/min, and the calcination time is 1-12 h.

7. The method for preparing the high-stability nano cesium tungsten bronze transparent heat-insulating powder according to claim 1 or 2, which is characterized in that: when the raw material is metal salt, the tungsten compound raw material and cesium salt are directly and uniformly mixed and calcined to obtain the high-stability nano cesium tungsten bronze transparent heat-insulating powder with the particle size of 50-200 nm.

8. The method for preparing the high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 7, which is characterized in that: the metal in the metal salt is any one of magnesium, aluminum, iron, nickel, copper, zinc, zirconium, tin, antimony, tungsten or bismuth; the metal salt is any one of carbonate, citrate, isopropoxide, acetate, oxalate, isooctanoate, acetylacetonate, methylsulfonate or metaacid salt of metal; the molar ratio of the metal element in the metal salt to the tungsten atom in the tungsten-containing compound raw material is (0.001-1.5): 1.

9. The method for preparing the high-stability nano cesium tungsten bronze transparent heat insulation powder according to claim 8, which is characterized in that: the cesium salt is any one of cesium carbonate, cesium bicarbonate, cesium sulfate, cesium nitrate, cesium formate, cesium acetate, cesium oxalate, cesium hydroxide or cesium oxide, and the molar ratio of the cesium salt to tungsten atoms in the tungsten-containing compound raw material is (0.1-0.5): 1; the calcination atmosphere is nitrogen, argon or vacuum, the calcination temperature is 200-1000 ℃, the heating rate is 1-50 ℃/min, and the calcination time is 1-12 h.

10. The application of the high-stability nano cesium tungsten bronze transparent heat insulation powder in transparent heat insulation paint and film as claimed in claim 1 or 2, which is characterized in that: the transparent heat-insulating powder of nano cesium tungsten bronze is ground to obtain high-stability nano cesium tungsten bronze dispersion slurry which is used as a coating, and the nano cesium tungsten bronze dispersion slurry is compounded with polyvinyl butyral to prepare the transparent heat-insulating film.