High near-infrared reflection inorganic pigment based on non-coloring ion doping as well as preparation method and application of high near-infrared reflection inorganic pigment

Abstract

The invention relates to a high near infrared reflection inorganic pigment based on non-coloring ion doping and a preparation method and application thereof, the chemical general formula of the pigment is Ba (Mg, B, C, Ti) 12O19, the element B is a coloring ion, and the element C is a non-coloring ion. The method is mainly based on doping of non-coloring ions, the structure and the refractive index of the pigment are changed, and the near-infrared reflection pigment can be prepared by adopting three different methods as required, namely a solid phase method, a combustion synthesis method and a coprecipitation method. Compared with the prior art, the inorganic pigment powder which is low in toxic element content, deep in color, high in near-infrared reflectivity and excellent in heat insulation performance is obtained through a preparation technology which is low in cost, simple in technology and adjustable in color, and the inorganic pigment powder can be widely applied to the fields of building outer wall heat insulation coatings, paint and the like.

Description

Technical Field

[0001] The invention relates to the technical field of inorganic pigment preparation, and in particular to a high near-infrared reflective inorganic pigment based on non-coloring ion doping, and a preparation method and application thereof. Background Art

[0002] The acceleration of urbanization has brought great challenges to the energy management of urban buildings. In particular, with the impact of climate change, high temperatures in summer have occurred frequently, causing heat accumulation inside cities and causing serious urban heat island effects. This phenomenon not only reduces the living comfort of urban residents, but also greatly increases the energy demand for building cooling, exacerbating overall energy consumption and carbon emissions. In response to this problem, high near-infrared reflective pigments have emerged as an effective solution. This pigment has the characteristic of reflecting most near-infrared radiation, which can effectively reduce the heat absorbed inside buildings, thereby reducing the cooling demand of buildings, improving energy efficiency, and achieving energy conservation and emission reduction.

[0003] Compared with white pigments, colored near-infrared reflective pigments can better meet people's demand for architectural color diversity, and will not affect its thermal insulation performance, because the near-infrared band in solar radiation is the main heat source. However, at present, inorganic near-infrared reflective pigments are mainly based on composite metal oxides, and there are still some problems to be solved. On the one hand, traditional pigments contain a large amount of toxic elements, and their scope of use is limited; on the other hand, although the new rare earth-based inorganic near-infrared reflective pigments have solved the toxicity problem, the use of rare earths has led to expensive pigments, which is not conducive to large-scale promotion and application. In addition, the color variety of traditional near-infrared reflective pigments is relatively limited, and it is difficult to meet the diverse needs of building exterior design. At the same time, its preparation process is usually complicated, which requires a lot of time and cost, resulting in generally high prices, which is not conducive to large-scale promotion and application.

[0004] The current solution to reduce toxic elements in traditional pigments mainly includes coating, which is to apply a non-toxic protective layer on the surface of the pigment to isolate the toxic elements from the external environment. This method can effectively reduce the content of toxic elements in the pigment, but it may affect the color and hiding power of the pigment.

[0005] Chinese patent CN 115594227 A discloses an inorganic yellow high entropy pigment with high near-infrared reflection performance and a preparation method thereof. The molecular formula of the yellow pigment is Ti 1-x M xO2, wherein x=0.02-0.18, M is 4-6 elements from Ce, Cr, Ni, Nb, Bi, Sb, Zn, and Ta, the L* value, a* value, and b* value of the pigment are 60-80, 15-25, and 60-73, respectively, and the near-infrared reflection reaches more than 88%. However, the pigment is bright yellow and there is an obvious light pollution problem. At the same time, its simple structure is not conducive to the expansion of color.

[0006] Therefore, developing new pigments with low development cost, simple process, good color rendering and environmental friendliness has become a key topic in current pigment research. Summary of the invention

[0007] The purpose of the present invention is to provide a high near-infrared reflective inorganic pigment based on non-coloring ion doping and its preparation method and application, so as to provide a high near-infrared reflective inorganic pigment based on non-coloring ion doping with low toxic element content and high color intensity.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] In one aspect, the present invention provides a non-coloring ion-doped high near-infrared reflective inorganic pigment, the general chemical formula of which is AM 12 O 19 , specifically Ba(Mg,B,C,Ti) 12 O 19 , wherein element B is a coloring ion and element C is a non-coloring ion, and both replace the M site, and the near-infrared reflectivity of the pigment is 67-84%.

[0010] Preferably, the element B is selected from one or more of Co, Ni, Cu and Cr.

[0011] Preferably, the element C is a metal element having an ion radius close to that of Mg or Ti.

[0012] More preferably, the element C is selected from one or more of Ca, Zr and Zn.

[0013] Preferably, the pigment has a chemical formula of Ba(Mg,Cr,Zn,Ti) 12 O 19 .

[0014] Further preferably, the general chemical formula of the pigment is BaMg x Cr y Zn z Ti 12-x-y-z O 19 , the value range of x is 2.5~5.4, the value range of y is 0.2~2.0, and the value range of z is 0.5~2.5.

[0015] Further preferably, the type and dosage of the coloring element are selected according to the color of the pigment. For example, when the pigment is yellow-green, the coloring ion is Cr, and y is 0.2-2.0.

[0016] In a second aspect, the present invention also provides a method for preparing the above-mentioned high near-infrared reflective inorganic pigment based on non-coloring ion doping.

[0017] Preferably, when the solid phase method is used for preparation, the steps are as follows: according to the chemical formula Ba(Mg, Cr, Zn, Ti) 12 O 19 BaCO3, MgO, TiO2, Cr2O3 and ZnO are weighed as raw materials in the stoichiometric ratio of each element, the raw materials are mixed evenly to obtain mixed raw material powder and calcined to obtain yellow-green near-infrared reflective pigment powder.

[0018] Further preferably, the raw material mixing includes a simple mixing method or a wet high-energy ball milling mixing method; when the raw material mixing method is a wet high-energy ball milling mixing method, ethanol is used as the mobile phase, the ball milling is performed at a ball milling speed of 200 to 500 rpm for 5 to 15 minutes, and then filtered and dried.

[0019] More preferably, the calcination temperature in the solid phase method is 1100-1300° C., and the calcination time is 1-6 hours.

[0020] Preferably, when the combustion synthesis method is used, the steps are as follows: according to the chemical formula Ba(Mg, Cr, Zn, Ti) 12 O 19 The stoichiometric ratio of each element in the reaction mixture is as follows: Ba(NO3)2, Mg(NO3)2·6H2O, Cr(NO3)3·9H2O and Zn(NO3)2·6H2O are weighed as raw materials and dissolved in deionized water; butyl titanate Ti(OC4H9)4 is added to an ethylene glycol solution, stirred and heated to a temperature of 70-90°C, and citric acid is added to completely dissolve the solution; the two solutions are mixed and evaporated to dryness to obtain a precursor, which is subjected to a combustion reaction to obtain a yellow-green near-infrared reflective pigment powder.

[0021] Preferably, titanate Ti(OC4H9)4 is measured with a measuring cylinder and slowly added to the ethylene glycol solution, more preferably, added to the ethylene glycol solution at a speed of 5 ml per minute.

[0022] Preferably, the combustion reaction in the combustion synthesis method is carried out in an open heating device, the ignition temperature of the combustion reaction is 200-300°C, and the duration of the combustion reaction is completed within 1 minute after ignition.

[0023] Preferably, when the coprecipitation method is used, the steps are as follows: according to the chemical formula Ba(Mg, Cr, Zn, Ti) 12 O 19 BaCl2·2H2O, MgCl2·6H2O, CrCl3·6H2O, ZnCl2 and Ti(SO4)2 are weighed as raw materials in the stoichiometric ratio of each element, dissolved in deionized water, stirred and ammonia water is added dropwise to the mixed solution until the pH value is 10-11, and the yellow-green near-infrared reflective pigment powder can be obtained by continuing stirring, aging, filtering, drying, grinding and calcining.

[0024] Preferably, the calcination temperature in the coprecipitation method is 1100-1300° C., and the calcination time is 1-3 hours.

[0025] In a third aspect, the present invention also provides an application of the above-mentioned high near-infrared reflective inorganic pigment based on non-coloring ion doping, including application in heat-reflective coatings, preferably application in thermal insulation coatings for building exterior walls, to reduce the surface temperature of the building.

[0026] More preferably, the invention also includes application in paint.

[0027] More preferably, the invention also includes application in automobile surface paint.

[0028] The present invention adopts an ion substitution method to reduce the content of toxic elements in the pigment by replacing toxic metal ions such as cobalt and cadmium with harmless ions such as zinc. This method is mainly based on the doping of non-coloring ions to change the structure and refractive index of the pigment and improve the heat insulation and energy saving performance of the pigment.

[0029] The present invention utilizes the complex calcite crystal structure to prepare a yellow-green near-infrared reflective pigment, and can prepare a dark-hued pigment with lower brightness by doping with coloring ions to meet different application requirements.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) The high near-infrared reflective inorganic pigment based on non-coloring ion doping provided by the present invention can improve the near-infrared reflectivity of the pigment by adding non-coloring ions without changing the color intensity of the pigment, thereby significantly improving the heat insulation and energy-saving performance of the pigment.

[0032] (2) The high near-infrared reflective inorganic pigment provided by the present invention has a low content of toxic elements. Even at a low coloring ion doping concentration, the doping of non-coloring ions will not reduce the color intensity of the pigment. The solid phase method is used to prepare Ba(Mg, Cr, Zn, Ti) 12 O 19When the doping amount of coloring ion chromium in the pigment is 3wt.% and 10wt.%, the doping of non-coloring ion Zn does not change the color intensity of the pigment, but instead increases its near-infrared reflectivity by 4% and 9% respectively, which means that the thermal insulation and energy-saving performance of the pigment has been significantly improved.

[0033] (3) In the process of preparing the high near-infrared reflective inorganic pigment, the present invention can prepare near-infrared reflective inorganic pigments of different colors by selecting different coloring elements.

[0034] (4) The present invention can prepare dark-hued pigments with lower brightness by doping with coloring ions. The prepared yellow-green near-infrared reflective pigment can overcome the problem of light pollution and is conducive to the expansion of colors.

[0035] (5) The calcination temperature of the pigment prepared by the present invention is above 1000° C. and can withstand high temperatures without affecting the color or near-infrared reflectivity. Therefore, the pigment prepared by the present invention has excellent stability.

[0036] (6) The preparation method of the non-coloring ion-doped high near-infrared reflective inorganic pigment provided by the present invention has a simple process and low cost, and different preparation methods can be adopted according to actual needs and conditions, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The XRD patterns of the pigments prepared in Experimental Examples 1-6 ((A) is the XRD pattern, and (B) is a partial enlarged view);

[0038] Figure 2 Lattice constant diagram of the pigments prepared in Experimental Examples 1-6;

[0039] Figure 3 UV-Vis-NIR diffuse reflectance spectra of the pigments prepared in Examples 1-2, 2-2, 3-2 and Comparative Examples 1-1, 2-1, 3-1;

[0040] Figure 4 Optical photographs of the pigments prepared in Examples 1-2, 2-2, 3-2 and Comparative Examples 1-1, 2-1, and 3-1;

[0041] Figure 5 Energyplus simulation results of the pigment coating prepared from Example 3-2 and green commercial Cr2O3 pigment ((A) is the annual refrigeration energy consumption diagram, (B) is the annual refrigeration energy saving efficiency diagram, (C) is the annual energy consumption diagram, and (D) is the annual energy saving efficiency diagram). DETAILED DESCRIPTION

[0042] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0043] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0044] The commercial Cr2O3 used in the examples was purchased from Hengshui Friendship New Materials chromium oxide green pigment PT5396.

[0045] Preparation of BaMg by solid phase method 5-y Zn y Ti5Cr2O 19 High near infrared reflective inorganic pigment

[0046] Test Example 1 y = 0

[0047] According to the chemical formula BaMg5Ti5Cr2O 19 The stoichiometric ratio of each element is 0.986 g of barium carbonate, 1.007 g of magnesium oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then placed in a muffle furnace and calcined at 1300°C for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0048] Test Example 2 y = 0.5

[0049] According to the chemical formula BaMg 4.5 Zn 0.5 Ti5Cr2O 19 The stoichiometric ratio of each element in the mixture is 0.986 g of barium carbonate, 0.906 g of magnesium oxide, 0.203 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0050] Test Example 3 y = 1.0

[0051] According to the chemical formula BaMg4ZnTi5Cr2O 19 The stoichiometric ratio of each element is 0.986 g of barium carbonate, 0.806 g of magnesium oxide, 0.406 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then placed in a muffle furnace and calcined at 1300°C for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0052] Test Example 4 y = 1.5

[0053] According to the chemical formula BaMg 3.5 Zn 1.5 Ti5Cr2O 19 The stoichiometric ratio of each element in the mixture is 0.986 g of barium carbonate, 0.706 g of magnesium oxide, 0.609 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0054] Test Example 5 y = 2

[0055] According to the chemical formula BaMg3Zn2Ti5Cr2O 19 The stoichiometric ratio of each element in the mixture is 0.986 g of barium carbonate, 0.606 g of magnesium oxide, 0.812 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0056] Test Example 6 y = 2.5

[0057] According to the chemical formula BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The stoichiometric ratio of each element in the mixture is 0.986 g of barium carbonate, 0.506 g of magnesium oxide, 1.015 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0058] The XRD patterns of the pigments prepared in Test Examples 1-6 are as follows: Figure 1 As shown in the figure, it can be seen that the diffraction peaks in the XRD spectrum are sharp and dense, indicating that all pigments have a high degree of crystallinity. In addition, the diffraction peaks of Test Examples 1-6 match well with the standard peaks of the hexagonal structure and space group (P63 / mmc), indicating that even in the case of high Zn doping concentration, the doping of non-coloring ions Zn will not cause changes in the crystal structure. At the same time, there are no other peaks in the XRD spectrum, indicating that Zn has been successfully incorporated into the crystal lattice. It can be seen from the enlarged image that with the increase of Zn doping concentration, the diffraction peak of the (107) crystal plane moves toward the low angle direction, while the diffraction peak of the (114) crystal plane remains basically unchanged. Due to the Zn 2+(ion radius = 0.070nm) and Mg 2+ The ion radius of (ion radius = 0.072nm) is slightly different. According to the Bragg equation, when the ions in the crystal structure are replaced by ions with smaller radius, the interplanar spacing decreases and the diffraction peak should shift to a higher angle. However, the diffraction peak of the (107) crystal plane shifts to a lower angle, which is inconsistent with the theory. The XRD data was refined by Rietveld to obtain the unit cell parameters and unit cell volume, such as Figure 2 As shown in the figure, Zn doping causes obvious changes in the lattice parameters a and c. As the Zn doping content increases, the crystal axis a gradually decreases, while the crystal axis c gradually increases. This is the reason why the (107) crystal plane shifts to a low angle. However, due to Zn 2+ The ionic radius is slightly smaller than that of Mg 2+ , the unit cell volume gradually decreases. Based on the change of the local structure of the crystal after Zn doping, this may lead to the change of its optical properties.

[0059] Preparation of BaMg by solid phase method 6-x-y Zn y Ti 6-x Cr 2x O 19 High near infrared reflective inorganic pigment

[0060] Comparative Example 1-1 x = 0.25, y = 0

[0061] According to the chemical formula BaMg 5.75 Ti 5.75 Cr 0.5 O 19 The chemical measurements of the elements are as follows: 0.986 g of barium carbonate, 1.158 g of magnesium oxide, 2.295 g of titanium dioxide and 0.190 g of chromium trioxide are weighed respectively, the raw materials are mixed evenly after high-energy ball milling, and then the mixed raw materials are placed in a muffle furnace and calcined at 1300°C for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0062] Example 1-2 x = 0.25, y = 2.5

[0063] According to the chemical formula BaMg 3.25 Zn 2.5 Ti 5.75 Cr 0.5 O 19 The stoichiometric ratio of each element in the mixture is 0.986 g of barium carbonate, 0.654 g of magnesium oxide, 1.017 g of zinc oxide, 2.295 g of titanium dioxide and 0.190 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0064] Comparative Example 2-1 x = 0.5, y = 0

[0065] According to the chemical formula BaMg 5.5 Ti 5.5 CrO 19 The chemical measurements of the elements are as follows: 0.986 g of barium carbonate, 1.107 g of magnesium oxide, 2.195 g of titanium dioxide and 0.380 g of chromium trioxide are weighed respectively, the raw materials are mixed evenly after high-energy ball milling, and then the mixed raw materials are placed in a muffle furnace and calcined at 1300°C for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0066] Example 2 - 2x = 0.5, y = 2.5

[0067] According to the chemical formula BaMg3Zn 2.5 Ti 5.5 CrO 19 The chemical measurements of the elements are as follows: 0.986 g of barium carbonate, 0.604 g of magnesium oxide, 1.017 g of zinc oxide, 2.195 g of titanium dioxide and 0.380 g of chromium trioxide are weighed respectively, the raw materials are mixed evenly after high-energy ball milling, and then the mixed raw materials are calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0068] Comparative Example 3-1x=1,y=0

[0069] BaMg5Ti5Cr2O 19

[0070] According to the chemical formula BaMg5Ti5Cr2O 19 The stoichiometric ratio of each element is 0.986 g of barium carbonate, 1.007 g of magnesium oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide. The raw materials are mixed evenly after high-energy ball milling. The mixed raw materials are then placed in a muffle furnace and calcined at 1300°C for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0071] Example 3-2x=1,y=2.5

[0072] According to the chemical formula BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The chemical measurements of the elements are as follows: 0.986 g of barium carbonate, 0.503 g of magnesium oxide, 1.017 g of zinc oxide, 1.995 g of titanium dioxide and 0.759 g of chromium trioxide are weighed respectively, the raw materials are mixed evenly after high-energy ball milling, and then the mixed raw materials are calcined at 1300°C in a muffle furnace for 3 hours to obtain a yellow-green near-infrared reflective pigment powder.

[0073] Performance Testing

[0074] Hitachi UH4150 UV-visible near-infrared spectrophotometer was used to test the diffuse reflectance spectrum of heat reflective pigments. The near-infrared reflectance ratio of heat reflective pigments at 700-2500nm was calculated according to the standard relative spectral distribution data of solar radiation in ASTM G173-03. The calculation formula is:

[0075]

[0076] In the formula, λ represents the wavelength of light, and i(λ) is the solar spectral irradiance (W·m -2 ·nm -1 ), r(λ) is the spectral reflectance obtained from the experiment, and d(λ) is the wavelength interval. The product color coordinates are characterized by the CIE1976L*a*b* color space defined by the International Commission on Illumination. The L* axis represents the brightness from 0 to 100. The smaller the L* value, the darker the color of the pigment; the a* axis represents the color from green (-) to red (+); the b* axis represents the color from blue (-) to yellow (+); C* is the color saturation, and h is the hue.

[0077] The UV-Vis-NIR diffuse reflectance spectra of the pigments prepared in Examples 1-2, 2-2, 3-2 and Comparative Examples 1-1, 2-1, 3-1 are as follows: Figure 3 As shown in the optical photograph Figure 4 As shown. Figure 3-4 It can be seen that the chromium ions doped into BaMg6Ti6O 19 After the lattice is formed, an obvious spectral valley appears in the visible light region, indicating that the sample partially absorbs visible light, making it appear yellow-green; at the same time, as the Cr doping concentration increases, the reflectivity of the entire visible light region gradually decreases, and the absorption gradually increases, causing the sample color to gradually darken. Table 1 summarizes the L*a*b* values ​​and C*, R* values ​​of the pigments prepared in Examples 1-2, 2-2, 3-2, Comparative Examples 1-1, 2-1, and 3-1. In Comparative Example 3-1, when x=1, y=0, that is, Cr is in BaMg5Ti5Cr2O 19 When the sample accounts for 11.5wt.%, its color parameters L*, a*, b* are 60.58, -16.25, 20.88 respectively, with a high color saturation (C*=26.45), showing a yellow-green color. At the same time, the sample has a broad absorption centered at 1250nm in the near-infrared region, and the absorption intensity increases with the Cr 3+ The increase of doping concentration significantly affects the near-infrared reflectivity of the sample. The TSR (solar reflectivity) and R* value (near-infrared light reflectivity) drop significantly from 60% and 80% to 41% and 57%, the heat gain coefficient increases, and the cooling effect decreases.

[0078] Table 1. CIE 1976 L*a*b* values ​​and C*, R*, TSR values ​​of pigments

[0079]

[0080] At the same time, from Figure 3 It can be seen that the addition of Zn has a significant improvement in the near-infrared reflectivity of samples at various Cr doping concentrations. 3.25 Zn 2.5 Ti 5.75 Cr 0.5 O 19 The chromium content is only 2.64wt.%, but it has excellent color performance (L*=72.51, a*=-20.24, b*=23.51) and reflective performance (R*=84%, TSR=60%). Increasing the Cr doping concentration of the sample will reduce the brightness of the sample, thereby improving its color performance. For example, in Example 3-2, the high doping concentration of BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The chromium content in it is increased to 10.31wt.%, with excellent color properties (L*=61.98, a*=-18.72, b*=22.23). At the same time, due to the addition of Zn, its reflective properties are significantly improved (R*=67%, TSR=47%).

[0081] In summary, compared to similar green pigments: Bi 0.6 Cr 0.4 PO4 pigment (8.63wt.%, C*=7.91, R*=85%), Y3Al 4.7 Cr 0.3 O 12 Pigment (2.58 wt.%, C*=11.7, R*=76%), Co 0.25 Zn 0.75 Cr2O4 pigment (44.87wt.%, C*=24.6, R*=52%), etc. The pigment synthesized by the present invention has low chromium content, high color intensity and high near-infrared reflectivity.

[0082] In order to reduce the energy consumption caused by buildings absorbing solar radiation, it is imperative to prepare pigments into coatings and apply them to building coatings. Therefore, the high near-infrared reflective inorganic pigment prepared in Example 3-2 of the present invention is further used to prepare building coatings. The specific method is as follows:

[0083] (1) Pigment, pure acrylic emulsion, water and film-forming aid are mixed in a certain proportion, magnetically stirred at room temperature for 3 hours, and then a defoamer and a thickener are added thereto to obtain a coating with a certain viscosity and stability;

[0084] (2) Pour the paint onto an aluminum plate and use a 1 mm scraper to evenly spread the paint on the aluminum plate. After drying at room temperature for 12 hours, a coating with a specific color can be obtained.

[0085] BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The TSR and R* values ​​of the coating are 11% and 12% lower than those of the powder, respectively, while the difference between the commercial Cr2O3 coating and the powder is 8%, indicating that the sample has a greater loss of reflectivity after being made into a coating, which may be determined by the basic properties of the pigment. 2.5 Zn 2.5 Ti5Cr2O 19 The coating’s TSR and R* values ​​are 5% higher than commercial Cr2O3 coatings, which means it reflects more energy and reduces heat buildup.

[0086] Table 2. CIE 1976 L*a*b* values ​​and C*, R*, TSR values ​​of pigments and coatings

[0087]

[0088] BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The solar reflectance and visible light reflectance of commercial Cr2O3 coatings are 0.36, 0.18 and 0.31, 0.13 respectively. In comparison, the corresponding values ​​of ordinary concrete are 0.30 and 0.30, and the heat absorption rate is 0.9 as the set value. Figure 5 Energyplus simulation results for the pigment coating prepared from Example 3-2 and the green commercial pigment Cr2O3. Figure 5 As shown in (A), in all simulated cities, BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The annual cooling energy consumption of the exterior walls and roofs of the model houses with or commercial Cr2O3 coatings was generally lower than that of the untreated houses. Compared with ordinary concrete, such as Figure 5 As shown in (B), the refrigeration energy saving efficiency of commercial Cr2O3 coating is 1-2%, while BaMg 2.5 Zn 2.5 Ti5Cr2O 19 The refrigeration energy saving efficiency of the coating is 5-8%, which is significantly improved. Figure 5As shown in (D), compared with the refrigeration energy efficiency, the energy efficiency throughout the year generally decreased, especially in Shanghai, Wuhan and Nanchang, which are located in high latitudes. 2.5 Zn 2.5 Ti5Cr2O 19 The coating's year-round energy-saving efficiency is less than 2%. These cities have lower external ambient temperatures in winter, and near-infrared reflective coatings reduce heat accumulation in buildings, which increases building heating energy consumption. However, the use of near-infrared reflective coatings can improve the building's year-round energy-saving efficiency, especially in warmer regions. The model house in Haikou uses BaMg 2.5 Zn 2.5 Ti5Cr2O 19 Coating can reduce annual energy consumption by 5.2%. Therefore, near-infrared reflective pigments are more suitable for southern Chinese cities.

[0089] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A high near-infrared reflective inorganic pigment based on non-coloring ion doping, characterized in that: The general chemical formula of the pigment is Ba(Mg, B, C, Ti) 12 O 19 , where element B is the colored ion and element C is the non-colored ion.

2. A non-coloring ion-doped high near-infrared reflective inorganic pigment according to claim 1, characterized in that: The element B is selected from one or more of Co, Ni, Cu, and Cr, and the element C is selected from one or more of Ca, Zr, and Zn.

3. The high near-infrared reflective inorganic pigment based on non-coloring ion doping according to claim 1, characterized in that: The general chemical formula of the pigment is Ba(Mg,Cr,Zn,Ti) 12 O 19 .

4. A method for preparing a highly near-infrared reflective inorganic pigment based on non-coloring ion doping according to any one of claims 1 to 3, characterized in that: When using the solid phase method, the steps are as follows: According to the chemical formula Ba(Mg,Cr,Zn,Ti) 12 O 19 BaCO3, MgO, TiO2, Cr2O3 and ZnO are weighed as raw materials in the stoichiometric ratio of each element, the raw materials are mixed evenly to obtain mixed raw material powder and calcined to obtain yellow-green near-infrared reflective pigment powder.

5. The method for preparing a high near-infrared reflective inorganic pigment based on non-coloring ion doping according to claim 4, characterized in that: The raw material mixing includes simple mixing or wet high-energy ball milling mixing. When the raw material mixing is wet high-energy ball milling mixing, ethanol is used as the mobile phase, the raw materials are ball milled at a ball milling speed of 200 to 500 rpm for 5 to 15 minutes, and filtered and dried.

6. The method for preparing a high near-infrared reflective inorganic pigment based on non-coloring ion doping according to claim 4, characterized in that: The calcination temperature is 1100-1300° C., and the calcination time is 1-6 hours.

7. A method for preparing a highly near-infrared reflective inorganic pigment based on non-coloring ion doping according to any one of claims 1 to 3, characterized in that: When using the combustion synthesis method, the steps are as follows: According to the chemical formula Ba(Mg,Cr,Zn,Ti) 12 O 19 The stoichiometric ratio of each element in the mixture is as follows: Ba(NO3)2, Mg(NO3)2·6H2O, Cr(NO3)3·9H2O and Zn(NO3)2·6H2O are weighed as raw materials and dissolved in deionized water; butyl titanate Ti(OC4H9)4 is added to an ethylene glycol solution, stirred and heated, and then citric acid is added to completely dissolve it; the two solutions are mixed and evaporated to obtain a precursor, which is subjected to a combustion reaction to obtain a yellow-green near-infrared reflective pigment powder.

8. The method for preparing a high near-infrared reflective inorganic pigment based on non-coloring ion doping according to claim 7, characterized in that: The stirring and heating is performed until the temperature reaches 70-90° C., and then citric acid is added.

9. A method for preparing a highly near-infrared reflective inorganic pigment based on non-coloring ion doping according to any one of claims 1 to 3, characterized in that: When the coprecipitation method is used, the steps are as follows: According to the chemical formula Ba(Mg, Cr, Zn, Ti) 12 O 19 BaCl2·2H2O, MgCl2·6H2O, CrCl3·6H2O, ZnCl2 and Ti(SO4)2 are weighed as raw materials in the stoichiometric ratio of each element, dissolved in deionized water, stirred and ammonia water is added dropwise until the pH value is 10-11, and the yellow-green near-infrared reflective pigment powder can be obtained by continuing stirring, aging, filtering, drying, grinding and calcining.

10. Use of the non-coloring ion-doped high near-infrared reflective inorganic pigment according to any one of claims 1 to 3, including use in heat reflective coatings.

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