Infrared reflective pigment and preparation method thereof

Abstract

The invention discloses an infrared reflection pigment and a preparation method thereof, and the preparation method comprises the following steps: weighing a Y source, a Ce source, an Al source and a Mn source according to a chemical general formula of a product, x is less than or equal to 0.02, 0lt; y < = 0.2; stirring and mixing a Y source, a Ce source, an Al source, a Mn source, a complexing agent and a solvent to obtain a mixed solution, and adding the mixed solution into the precipitant solution for reaction to obtain an insoluble substance; and mixing the insoluble substance with a mineralizing agent, and calcining to obtain the infrared reflection pigment. According to the invention, based on the basic configuration of YAlO3, Ce with variable valence and an ion radius similar to that of Y is introduced to reduce chemical defects on the surface of a material, and Mn is introduced to bring certain lattice defects, so that the concentration of free carriers in crystals is reduced, and the near-infrared reflectivity of the pigment is improved.

Description

Technical Field

[0001] This invention relates to the field of infrared reflective pigment technology, and in particular to an infrared reflective pigment and its preparation method. Background Technology

[0002] Pigments are coloring substances that can stain the surface of objects. They can be applied to surfaces through brushing, spraying, or mixing to create various colors and effects. With rapid economic and scientific development, pigments, merely as decorative substances, can no longer meet the simplified needs of modern people and the demands of social development. Multifunctional pigments with vibrant colors, high durability, and high reflectivity and heat insulation have become the focus of application, research, and development. Therefore, functional pigments that can efficiently reflect near-infrared light from sunlight while displaying the desired color—infrared reflective pigments—have emerged.

[0003] Compared to organic pigments, inorganic infrared reflective pigments exhibit better resistance to acids and alkalis, high temperatures, and weathering, making them more popular in the industry. To improve the performance of inorganic infrared reflective pigments, methods such as designing specific microstructures, introducing functional ion doping, compounding with other substances, and surface coating modification have been widely applied. For example, CN116445008A discloses a method for preparing a near-infrared reflective pigment, including cooling molten antimony oxide to a semi-molten state, adding Pigment Red 254 under stirring, followed by adding zinc oxide and a near-infrared additive to obtain a composite pigment; mixing tetrabutyl titanate, acetic acid, and ethanol, then adding the composite pigment to obtain a composite sol; ball milling the composite sol, adding a stabilizer, and then performing a hydrothermal reaction to obtain titanium dioxide. Antimony oxide Pigment Red 254 is a composite pigment. This pigment possesses stable color, good acid and alkali resistance, and high near-infrared spectral reflectance. However, the preparation method is relatively complex and involves a large amount of stabilizer. CN114958033A discloses a high near-infrared reflectance colored pigment, the preparation method of which includes... The raw materials are weighed according to the stoichiometric ratio of each element, ground into powder, and then dried and calcined to obtain a high near-infrared reflectance colored pigment. This method allows for the control of pigment color and reflectivity by changing the doping concentration. However, it does not address improving the pigment's heat insulation properties. Summary of the Invention

[0004] Traditional infrared reflective pigments often contain toxic heavy metals such as cadmium, selenium, mercury, and lead, limiting their applications. Rare earth (Y) aluminates possess the functional properties of rare earth elements and rich spectral characteristics, making them suitable for preparation as highly reflective and environmentally friendly inorganic pigments. YAlO3 oxide has a stable structure and advantages such as low thermal conductivity (resulting in scattering during transport), high melting point, good high-temperature stability, and weak anisotropy. However, related studies have shown that traditional solid-state methods require high-temperature calcination above 1600℃ to obtain single-phase perovskite YAlO3 oxide; otherwise, Y3Al5O is easily introduced into the product. 12 Impurity phases such as Al2Y4O9 will directly affect the color of the pigment.

[0005] The purpose of this invention is to reduce chemical defects on the material surface by introducing Ce with a variable valence and an ionic radius similar to Y, based on the basic configuration of YAlO3, and to introduce Mn to introduce certain lattice defects, thereby reducing the concentration of free carriers in the crystal and improving the near-infrared reflectivity of the pigment; in addition, by introducing a mineralizer, the formation of YAlO3 is promoted at a lower temperature, thereby reducing the high temperature conditions required for the reaction.

[0006] To achieve the above objectives, the present invention provides an infrared reflective pigment, comprising, According to the general chemical formula of the product Weigh out the Y source, Ce source, Al source and Mn source, where 0 <x≤0.02,0<y≤0.2; A mixed solution is obtained by stirring and mixing a Y source, a Ce source, an Al source, a Mn source, a complexing agent, and a solvent. The mixed solution is then added to a precipitant solution to react and obtain an insoluble substance. Insoluble substances are mixed with mineralizing agents and then calcined to obtain infrared reflective pigments.

[0007] Furthermore, the concentration of the Y source in the mixed solution is 0.5~2 mol / L.

[0008] Furthermore, the complexing agent is a mixture of glutamic acid and aspartic acid; The total concentration of the complexing agent in the mixed solution is 0.1~0.5 mol / L.

[0009] Furthermore, the concentration of the precipitant solution is 1~3 mol / L; The precipitant in the precipitant solution includes at least one of ammonium bicarbonate and ammonium carbonate. The volume ratio of the mixed solution to the precipitant solution is 1:8~15.

[0010] Furthermore, the mass ratio of the insoluble matter to the mineralizing agent is 100:0.5~2.

[0011] Mineralizing agents are substances used in the synthesis process to accelerate physicochemical reactions. They are typically compounds based on F, Cl, and boron salts. The chemical composition of the mineralizing agent has a significant impact on the color properties and phase structure of the prepared pigment. In this invention, the selection of the mineralizing agent must not introduce other metal ions.

[0012] Furthermore, the mineralizing agent includes at least one of boric acid, ammonium fluoride, ammonium chloride, and ammonium carbonate.

[0013] Furthermore, the insoluble material and the mineralizer are mixed by wet ball milling, which is carried out at a ball milling speed of 200-500 rpm for 5-30 minutes.

[0014] Furthermore, the calcination is carried out at a temperature of 1300~1400℃ for 1~6 hours.

[0015] It should be noted that the Y, Ce, Al, and Mn sources used in this invention are selected from soluble salts of Y, Ce, Al, and Mn, respectively, preferably nitrates of these metals. The solvents for the mixed solution and the precipitant solution are not strictly limited, as long as they can dissolve the Y, Ce, Al, Mn sources and the precipitant. Preferably, for safety and cost-effectiveness, water is selected as the solvent.

[0016] The present invention also provides an infrared reflective pigment, which is obtained by the above preparation method.

[0017] The present invention also provides the application of the above-mentioned infrared reflective pigment in heat reflective coatings.

[0018] Compared with the prior art, the present invention has the following beneficial effects: This invention is based on the basic configuration of YAlO3. It introduces Ce with variable valence and ionic radius similar to Y to reduce chemical defects on the material surface, and introduces Mn to bring certain lattice defects, thereby reducing the concentration of free carriers in the crystal and improving the near-infrared reflectivity of the pigment.

[0019] This invention regulates the precipitation process by adding a complexing agent during the preparation of the precursor. The microstructure improves the infrared absorption performance of infrared reflective pigments. Attached Figure Description

[0020] Figure 1 A flowchart illustrating the preparation method of the infrared reflective pigment of the present invention is shown; Figure 2 A scanning electron microscope image of the infrared reflective pigment prepared in Example 2 is shown; Figure 3 A scanning electron microscope image of the infrared reflective pigment prepared in Comparative Example 4 is shown. Figure 4A scanning electron microscope image of the infrared reflective pigment prepared in Comparative Example 5 is shown; Figure 5 A scanning electron microscope image of the infrared reflective pigment prepared in Comparative Example 6 is shown. Figure 6 The ultraviolet-visible diffuse reflectance spectra of the infrared reflective pigments prepared in the examples and comparative examples are shown. Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0022] In this invention, unless otherwise specified, all equipment and raw materials are commercially available or commonly used in the industry. The methods described in the following embodiments are conventional methods in the art, unless otherwise specified.

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 like Figure 1 As shown, a method for preparing an infrared reflective pigment includes the following steps: S1, according to the general chemical formula of the product Weigh ; S2, will and Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0025] Example 2 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh ; S2, will and Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0026] Example 3 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh and ; S2, will and Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0027] Comparative Example 1 A method for preparing an infrared reflective pigment, comprising the following steps: S1. Weigh out according to the general chemical formula YAlO3 of the product. ; S2, will Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0028] Comparative Example 2 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh , ; S2, will Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0029] Comparative Example 3 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh , ; S2, will Glutamic acid, aspartic acid, and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentrations of α-amino acids were 0.99 mol / L, glutamic acid was 0.4 mol / L, and aspartic acid was 0.1 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0030] Comparative Example 4 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh ; S2, will The mixture was stirred with water at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentration was 0.99 mol / L; S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0031] Comparative Example 5 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh ; S2, will and Glutamic acid and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentration of [unspecified substance] was 0.99 mol / L, and the concentration of glutamic acid was 0.5 mol / L. S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0032] Comparative Example 6 A method for preparing an infrared reflective pigment, comprising the following steps: S1, according to the general chemical formula of the product Weigh ; S2, will and Aspartic acid and water were stirred at 350 rpm for 20 minutes to obtain a mixed solution. The mixed solution contained Y... 3+ The concentration of is 0.99 mol / L, and the concentration of aspartic acid is 0.5 mol / L; S3. Add 1L of the mixed solution to a constant pressure funnel and add it to 10L of 2.5mol / L ammonium carbonate aqueous solution at a dropping rate of 2mL / s and continuously stirred at 200rpm. After the addition is complete, continue stirring and reacting for 2h. Filter the suspension, wash it several times with deionized water, and then place the filter cake in a constant temperature oven at 120℃ to dry for 3h. After cooling, the insoluble matter is obtained. S4. Add 1 kg of insoluble matter and 0.01 kg of boric acid to a ball mill and wet ball mill with ethanol as the medium. Continue ball milling at 350 rpm for 20 min to obtain the precursor. Transfer the precursor to an air atmosphere muffle furnace and heat it to 1350℃ at a heating rate of 5℃ / min. Hold the temperature for 2 h and then cool it naturally to obtain the infrared reflective pigment.

[0033] Test case The microstructure of the infrared reflective pigments prepared in Example 2 and Comparative Examples 4-6 was observed using scanning electron microscopy, and the results are as follows: Figures 2-5 As shown in the figure, compared to Comparative Example 4 without the addition of a chelating agent, the introduction of the chelating agents glutamic acid and / or aspartic acid can enrich the... The abundant porosity of the coating facilitates the dispersion of infrared-reflective pigments within the coating, thereby enhancing the performance of the coated product.

[0034] The UV-Vis diffuse reflectance spectra of the infrared reflective pigments prepared in the examples and comparative examples were measured using a UV-Vis-NIR spectrophotometer. The results are as follows: Figure 6 As shown in the figure, a, b, and c represent Examples 1, 3, and 2, respectively. It can be seen that Comparative Examples 1 and 2, without Mn doping, have a reflectivity of over 90% in the visible light region, indicating that this pigment reflects almost all sunlight in the 380-780 nm range, and the pigment is white. In contrast, the reflectivity of the other comparative examples and examples decreases significantly at this wavelength, and the pigment color changes from white to blue. This may be due to manganese ions replacing aluminum ions, causing dd orbital transitions within the manganese ions, in the O... 2- 2p orbital and Y 3+ Introducing Mn between 3d orbitals 3+ The 3d orbital charge transfer transitions cause changes in the band gap energy.

[0035] The reflectance spectrum in the near-infrared band (780~2526nm) was also measured using a UV-Vis-NIR spectrophotometer, and the near-infrared reflectance (R0) was obtained from the near-infrared reflectance spectrum. NIR ) and solar reflectance (R sol These results are shown in Table 1.

[0036] Table 1 Near-infrared reflectance results

[0037] As can be seen from the test results in Table 1, compared with Comparative Examples 1 and 2, the other embodiments introducing Mn and the R of the comparative examples... NIR and R sol The reflectivity decreased significantly because Mn substitution introduces lattice defects, attracting free carriers to repair them, thus reducing the free carrier concentration in the crystal and consequently lowering the reflectivity. Furthermore, the results of Examples 2 and 3 also indicate that higher Mn doping levels further reduce reflectivity.

[0038] To evaluate the heat insulation effect of near-infrared reflective pigments, the infrared reflective pigments prepared in the examples and comparative examples were mixed with alkyd resin at a mass ratio of 0.2:1 to form coatings. These coatings were then applied to a 10cm × 8cm galvanized sheet and allowed to dry naturally to form a 100μm thick coating. The coated galvanized sheet was kept 25cm away from a 100W infrared lamp and irradiated for 30 minutes. The temperature changes during the process were recorded, and the average surface temperature of the galvanized sheet at the end is shown in Table 2.

[0039] Table 2 Termination Temperature Results

[0040] As can be seen from the test results in Table 2, the coating formed by the infrared reflective pigment of Example 2 of the present invention has the lowest average temperature, which indicates that it has the best heat insulation performance. This is due to the porous structure that allows it to be well dispersed, as well as the high near-infrared reflectivity and solar reflectivity.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an infrared reflective pigment, characterized in that, include, According to the general chemical formula of the product Weigh out the Y source, Ce source, Al source and Mn source, where 0 <x≤0.02,0<y≤0.2; A mixed solution is obtained by stirring and mixing a Y source, a Ce source, an Al source, a Mn source, a complexing agent, and a solvent. The mixed solution is then added to a precipitant solution to react and obtain an insoluble substance. Insoluble substances are mixed with mineralizing agents and then calcined to obtain infrared reflective pigments.

2. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The concentration of the Y source in the mixed solution is 0.5~2 mol / L.

3. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The complexing agent is a mixture of glutamic acid and aspartic acid; The total concentration of the complexing agent in the mixed solution is 0.1~0.5 mol / L.

4. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The concentration of the precipitant solution is 1~3 mol / L; The precipitant in the precipitant solution includes at least one of ammonium bicarbonate and ammonium carbonate. The volume ratio of the mixed solution to the precipitant solution is 1:8~15.

5. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The mass ratio of the insoluble matter to the mineralizing agent is 100:0.5~2.

6. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The mineralizing agent includes at least one of boric acid, ammonium fluoride, ammonium chloride, and ammonium carbonate.

7. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The insoluble matter and the mineralizer are mixed by wet ball milling, which is carried out at a ball milling speed of 200-500 rpm for 5-30 minutes.

8. The method for preparing the infrared reflective pigment according to claim 1, characterized in that, The calcination is carried out at a temperature of 1300~1400℃ for 1~6 hours.

9. An infrared reflective pigment, characterized in that, It is obtained by the preparation method described in any one of claims 1 to 8.

10. The application of the infrared reflective pigment as described in claim 9 in a heat reflective coating.

Images