High near-infrared reflection pigment based on structural regulation and control as well as preparation method and application of high near-infrared reflection pigment

Abstract

The invention relates to a high near-infrared reflection pigment based on structure regulation and control as well as a preparation method and application of the high near-infrared reflection pigment. The general chemical formula of the pigment is (Ca, A) (Al, B, Ti) 12O19, the element A is an element for replacing Ca, the element B is an element for replacing Al, and the element B is a coloring element. The method is mainly based on structural regulation and control, and the near-infrared reflective 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 present invention relates to the technical field of pigment preparation, and in particular to a high near-infrared reflective pigment based on structural regulation, and a preparation method and application thereof. Background Art

[0002] As urbanization accelerates, the environmental and energy problems caused by it are increasing day by day. Traditional pigments are commonly used in urban buildings, which absorb solar radiation and gather heat. In summer, this effect causes the urban heat island effect, which not only reduces the comfort of urban living, but also increases the energy consumption of building cooling. In order to alleviate the urban heat island effect and improve the energy efficiency of urban buildings, high near-infrared reflective coatings are one of the conventional solutions. Its characteristics are to reflect the near-infrared band of solar radiation as much as possible, reduce the heat collection effect of the building surface, and thus reduce the energy consumption for air conditioning and refrigeration in hot weather.

[0003] Generally, white pigments have high solar reflectivity, but they have problems such as light pollution and poor stain resistance. At the same time, they cannot meet people's requirements for architectural color diversity. Therefore, colored near-infrared reflective pigments are more in line with market demand. At the same time, the near-infrared band in solar radiation is the main heat source. In terms of functionality, the diversity of colors does not affect its thermal insulation performance. At present, inorganic near-infrared reflective pigments are mainly composite metal oxides, among which the main problems are two points: first, traditional pigments contain a large amount of toxic elements such as cobalt and cadmium, and their scope of use is greatly limited; second, although the new rare earth-based inorganic near-infrared reflective pigments have solved the toxicity problem of pigments, the use of rare earths makes the pigments expensive, which is not conducive to large-scale promotion.

[0004] The current solution to reduce toxic elements in traditional pigments includes preparing traditional pigments on carriers. This solution can effectively reduce the content of toxic elements in pigments, but there are some disadvantages, such as many restrictions on the pigment preparation process and the particle size of the obtained pigment. Therefore, the development of new pigments with low cost, simple process, good color rendering and environmental friendliness has become a key topic in current pigment research. Summary of the invention

[0005] The purpose of the present invention is to provide a high near-infrared reflective pigment based on structure regulation and its preparation method and application, so as to provide a high near-infrared reflective pigment with low toxic element content and high color intensity.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] In one aspect, the present invention provides a high near-infrared reflective pigment based on structural regulation, wherein the general chemical formula of the pigment is (Ca, A)(Al, B, Ti) 12 O 19, wherein element A is an element replacing Ca, element A is an alkaline earth metal or a rare earth metal element, element B is an element replacing Al, and element B is a coloring element.

[0008] The present invention changes the doping concentration of Ti to cause distortion of the local structure of colored ions in the crystal, thereby preparing a high near-infrared reflective pigment based on structural regulation.

[0009] Preferably, the element A is any metal element having an ion radius close to that of the Ca element.

[0010] More preferably, the element A is selected from one or more of Sr, La and Y.

[0011] Preferably, the element B is selected from one or more of Co, Ni, and Cu, and the doping amount of the element B in the pigment is less than the doping amount of Ti.

[0012] Preferably, the pigment has the general chemical formula of Ca(Al,Co,Ti) 12 O 19 .

[0013] Preferably, the pigment has the general chemical formula of Ca(Al,Ni,Ti) 12 O 19 .

[0014] Preferably, the pigment has the general chemical formula (Ca, La)(Al, Ni, Ti) 12 O 19 .

[0015] Preferably, the pigment has the general chemical formula of Ca a A b Al c B x Ti y O 19 , where the value range of a is 1.0~0.7, the value range of b is 0~0.3, the value range of c is 11.7~10.7, the value range of x is 0.1~0.5, and the value range of y is 0.2~0.8.

[0016] Further preferably, the type and dosage of the coloring element are selected according to the color of the pigment. For example, when the coloring element is Co and y is 0.1 to 0.5, the pigment is a blue near-infrared reflective pigment.

[0017] In a second aspect, the present invention also provides a method for preparing the above-mentioned high near-infrared reflective pigment based on structure regulation.

[0018] Preferably, when the pigment is prepared by a solid phase method, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O19 The stoichiometric ratios of the elements in the 3 、Al 2 O 3 、Co 2 O 3 and TiO 2 The raw materials are mixed evenly and calcined to obtain blue near-infrared reflective pigment powder.

[0019] Preferably, the raw material mixing comprises a simple mixing method or a wet high-energy ball milling mixing method.

[0020] Further preferably, when the raw materials are mixed by wet high-energy ball milling, 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 then filtered and dried.

[0021] More preferably, the calcination temperature is 1300-1500° C., and the calcination time is 1-6 hours.

[0022] Preferably, when the pigment is prepared by combustion synthesis, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O 19 The stoichiometric ratios of the elements in the 3 ) 2 ·4H 2 O、Al(NO 3 ) 2 9H 2 O and Co(NO 3 ) 2 6H 2 O, dissolved in deionized water; titanate butyl ester Ti(OC 4 H 9 ) 4 Add it to the ethylene glycol solution, stir and heat, and add citric acid to make it completely dissolved; mix the two solutions and evaporate to dryness to obtain a precursor, which is subjected to a combustion reaction to obtain a blue near-infrared reflective pigment powder.

[0023] Preferably, after the stirring and heating to a temperature of 65 to 85° C., citric acid is added.

[0024] Preferably, titanate Ti(OC 4 H 9 ) 4 , slowly add it into the ethylene glycol solution, and more preferably add it into the ethylene glycol solution at a speed of 5 ml per minute.

[0025] Further preferably, the combustion reaction 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.

[0026] Preferably, when the pigment is prepared by coprecipitation, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O 19 The stoichiometric ratios of the elements in the 2 ·2H 2 O、AlCl 3 6H 2 O、CoCl 2 6H 2 O and Ti(SO 4 ) 2 , dissolve it in deionized water, stir and add ammonia water drop by drop until the pH value is 10-11, continue stirring, aging, filtering, drying, grinding, and calcining to obtain blue near-infrared reflective pigment powder.

[0027] Preferably, the calcination temperature in the coprecipitation method is 1300-1500° C., and the calcination time is 1-3 hours.

[0028] In a third aspect, the present invention further provides an application of the above-mentioned high near-infrared reflective pigment based on structural regulation, including application in heat reflective coatings, preferably application in building coatings, to reduce the surface temperature of buildings.

[0029] The present invention uses a low-cost, simple process, and color-adjustable preparation process to obtain an inorganic pigment powder with low toxic element content, darker color, higher near-infrared reflectivity, and excellent thermal insulation performance. The inorganic pigment powder can be widely used in the fields of building exterior wall thermal insulation coatings, paints, and the like.

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

[0031] (1) (Ca, A)(Al, B, Ti) prepared by the present invention 12 O 19 In inorganic pigments, the amount of titanium doped is greater than the amount of coloring elements doped, so that pigments with low content of coloring elements still have high color intensity and good heat reflection performance.

[0032] (2) The present invention uses a solid phase method to prepare Ca(Al, Co, Ti) 12 O 19 When the cobalt doping content in the pigment is less than 1%, the color intensity can reach 40, which means that the pigment color can be guaranteed not to be affected while minimizing the toxic elements.

[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 calcination temperature of the pigment prepared by the present invention is above 1300°C, which means that the prepared pigment can withstand high temperatures without affecting the color or near-infrared reflectivity. Therefore, the (Ca, A)(Al, B, Ti) prepared by the present invention 12 O 19 Inorganic pigments have good thermal stability.

[0035] (5) 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

[0036] Figure 1 For example 2, CaAl 12 O 19 With CaAl 11.8-y Co 0.2 Ti y O 19 XRD pattern of

[0037] Figure 2 For example 2, CaAl 12 O 19 With CaAl 11.8-y Co 0.2 Ti y O 19 Lattice parameter diagram of ;

[0038] Figure 3 For example 2, CaAl 12 O 19 With CaAl 11.8-y Co 0.2 Ti y O 19 UV-Vis-NIR diffuse reflectance spectrum;

[0039] Figure 4 For example 4, CaAl 11.9-y Ni 0.1 Ti y O 19 UV-Vis-NIR diffuse reflectance spectrum;

[0040] Figure 5 For example, Ca 0.9 La 0.1 Al 11.9-y Ni 0.1 Ti y O19 UV-Vis-NIR diffuse reflectance spectrum;

[0041] Figure 6 Optical photographs of the pigments prepared in Comparative Example 2-2, Example 2-4, Example 2-5, Comparative Example 4-1, Example 4-2, Example, Comparative Example 5-1, Example 5-2, and Example 5-3 (A is Comparative Example 2-2, Example 2-4, and Example 2-5, and B is Comparative Example 4-1, Example 4-2, Example, Comparative Example 5-1, Example 5-2, and Example 5-3);

[0042] Figure 7 The variation curves of the inner surface temperature of the coatings prepared with the pigments prepared in Examples 1-3 and the blue commercial pigment as a function of the irradiation time with infrared light and the final temperature of the outer surface after irradiation (the curves in the figure are the inner layer temperatures of each coating, and the photos are the outer layer temperatures). DETAILED DESCRIPTION

[0043] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0044] 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.

[0045] 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.

[0046] The commercial blue pigment used in the examples was purchased from Fenglin New Materials Cobalt Blue FU-554.

[0047] Preparation of CaAl by solid phase method 11.9-y Co 0.1 Ti y O 19 Blue near infrared reflective pigment powder

[0048] Comparative Example 1-1, y=0, the comparative sample is CaAl 11.9 Co 0.1 O 19

[0049] Weigh 0.500 g of calcium carbonate, 3.031 g of aluminum oxide, and 0.041 g of cobalt trioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0050] Example 1-2, y=0.1, comparative sample is CaAl 11.8 Co 0.1 Ti 0.1 O 19

[0051] Weigh 0.500 g of calcium carbonate, 3.005 g of aluminum oxide, 0.041 g of cobalt trioxide, and 0.040 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0052] Example 1-3, y=0.2, sample is CaAl 11.7 Co 0.1 Ti 0.2 O 19

[0053] Weigh 0.500 g of calcium carbonate, 2.980 g of aluminum oxide, 0.041 g of cobalt trioxide, and 0.080 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0054] Preparation of CaAl by solid phase method 11.8-y Co 0.2 Ti y O 19 Blue near infrared reflective pigment powder

[0055] Comparative Example 2-1, the comparative sample is CaAl 12 O 19

[0056] Weigh 0.500 g of calcium carbonate and 3.056 g of aluminum oxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450°C in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0057] Comparative Example 2-2, y=0, the comparative sample is CaAl 11.8 Co 0.2 O 19

[0058] Weigh 0.500 g of calcium carbonate, 3.005 g of aluminum oxide, and 0.083 g of cobalt trioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0059] Comparative Example 2-3, y=0.1, comparative sample is CaAl 11.7 Co 0.2Ti 0.1 O 19

[0060] Weigh 0.500 g of calcium carbonate, 2.980 g of aluminum oxide, 0.083 g of cobalt trioxide, and 0.040 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0061] Comparative Example 2-4, y=0.2, comparative sample is CaAl 11.6 Co 0.2 Ti 0.2 O 19

[0062] Weigh 0.500 g of calcium carbonate, 2.954 g of aluminum oxide, 0.083 g of cobalt trioxide, and 0.080 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0063] Example 2-5, y=0.3, sample is CaAl 11.5 Co 0.2 Ti 0.3 O 19

[0064] Weigh 0.500 g of calcium carbonate, 2.929 g of aluminum oxide, 0.083 g of cobalt trioxide, and 0.120 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0065] Example 2-6, y=0.4, sample is CaAl 11.4 Co 0.2 Ti 0.4 O 19

[0066] Weigh 0.500 g of calcium carbonate, 2.903 g of aluminum oxide, 0.083 g of cobalt trioxide, and 0.160 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0067] Example 2-7, y=0.5, sample is CaAl 11.3 Co 0.2 Ti 0.5 O 19

[0068] Weigh 0.500 g of calcium carbonate, 2.878 g of aluminum oxide, 0.083 g of cobalt trioxide, and 0.199 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0069] Preparation of CaAl by solid phase method 11.7-y Co 0.3 Ti y O 19 Blue near infrared reflective pigment powder

[0070] Comparative Example 3-1, y=0, the comparative sample is CaAl 11.7 Co 0.3 O 19

[0071] Weigh 0.500 g of calcium carbonate, 2.980 g of aluminum oxide, and 0.124 g of cobalt trioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0072] Comparative Example 3-2, y=0.3, the comparative sample is CaAl 11.4 Co 0.3 Ti 0.3 O 19

[0073] Weigh 0.500 g of calcium carbonate, 2.903 g of aluminum oxide, 0.124 g of cobalt trioxide, and 0.120 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0074] Example 3-3, y=0.4, sample is CaAl 11.3 Co 0.3 Ti 0.4 O 19

[0075] Weigh 0.500 g of calcium carbonate, 2.878 g of aluminum oxide, 0.124 g of cobalt trioxide, and 0.160 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0076] Preparation of CaAl by solid phase method 11.9-y Ni 0.1 Ti y O 19 Blue near infrared reflective pigment powder

[0077] Comparative Example 4-1, y=0, the comparative sample is CaAl 11.9 Ni 0.1 O 19

[0078] Weigh 0.500 g of calcium carbonate, 3.031 g of aluminum oxide, and 0.037 g of nickel oxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0079] Example 4-2, y=0.1, comparative sample is CaAl 11.8 Ni 0.1 Ti 0.1 O 19

[0080] Weigh 0.500 g of calcium carbonate, 3.005 g of aluminum oxide, 0.037 g of nickel oxide, and 0.040 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0081] Example 4-3, y=0.2, sample is CaAl 11.7 Ni 0.1 Ti 0.2 O 19

[0082] Weigh 0.500 g of calcium carbonate, 2.980 g of aluminum oxide, 0.037 g of nickel oxide, and 0.080 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0083] Example 4-4, y=0.3, sample is CaAl 11.6 Ni 0.1 Ti 0.3 O 19

[0084] Weigh 0.500 g of calcium carbonate, 2.954 g of aluminum oxide, 0.037 g of nickel oxide, and 0.120 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0085] Example 4-5, y=0.4, sample is CaAl 11.5 Ni 0.1 Ti 0.4 O 19

[0086] Weigh 0.500 g of calcium carbonate, 2.929 g of aluminum oxide, 0.037 g of nickel oxide, and 0.160 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0087] Solid phase method was used to prepare Ca 0.9 La 0.1 Al 11.9-y Ni 0.1 Ti y O 19 Blue near infrared reflective pigment powder

[0088] Comparative Example 5-1, y=0, comparative sample is Ca 0.9 La 0.1 Al 11.9 Ni 0.1 O 19

[0089] Weigh 0.450 g of calcium carbonate, 0.081 g of lanthanum oxide, 3.031 g of aluminum oxide, and 0.037 g of nickel oxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450° C. in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0090] Example 5-2, y=0.1, comparative sample is Ca 0.9 La 0.1 Al 11.8 Ni 0.1 Ti 0.1 O 19

[0091] Weigh 0.450 g of calcium carbonate, 0.081 g of lanthanum oxide, 3.005 g of aluminum oxide, 0.037 g of nickel oxide, and 0.040 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450°C in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0092] Example 5-3, y=0.2, sample is Ca 0.9 La 0.1 Al 11.7 Ni 0.1 Ti 0.2 O 19

[0093] Weigh 0.450 g of calcium carbonate, 0.081 g of lanthanum oxide, 2.980 g of aluminum oxide, 0.037 g of nickel oxide, and 0.080 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450°C in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0094] Example 5-4, y=0.3, sample is Ca 0.9 La 0.1 Al 11.6 Ni 0.1 Ti 0.3 O 19

[0095] Weigh 0.450 g of calcium carbonate, 0.081 g of lanthanum oxide, 2.954 g of aluminum oxide, 0.037 g of nickel oxide, and 0.120 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450°C in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0096] Example 5-5, y=0.4, sample is Ca 0.9 La 0.1 Al 11.5 Ni 0.1 Ti 0.4 O 19

[0097] Weigh 0.450 g of calcium carbonate, 0.081 g of lanthanum oxide, 2.929 g of aluminum oxide, 0.037 g of nickel oxide, and 0.160 g of titanium dioxide respectively, mix the raw materials evenly after high-energy ball milling, and then calcine the mixed raw materials at 1450°C in a muffle furnace for 3 hours to obtain blue near-infrared reflective pigment powder.

[0098] Performance Testing

[0099] Comparative Example 2-1 CaAl 12 O 19 Pigment, CaAl prepared in Comparative Example 2-2 and Examples 2-3, 4, 5, 6, 7 11.8-y Co 0.2 Ti y O 19 The XRD pattern of the pigment is as follows Figure 1 The diffraction peaks in the XRD spectrum are sharp and dense, indicating that all pigments have a high degree of crystallinity. 11.8-y Co 0.2 Ti y O 19 The diffraction peaks of the hexagonal CaO(Al 2 O 3 )6 (JCPDS card number 76-0665) and they have the same space group (P63 / mmc), indicating that with the increase of CaO(Al 2 O 3 ) 6 The increase of Ti doping concentration in the phase usually does not change the initial crystal structure and has been successfully incorporated into CaO (Al 2 O 3 ) 6 The CaAl prepared in Comparative Examples 2-1, 2-2, Examples 2-3, 4, 5, 6, and 7 11.8-y Co 0.2 Ti y O 19 The lattice parameters of the pigment are Figure 2 As shown in the figure, as the amount of Ti doping increases, due to the different ionic radii of Ti and Al, it can be observed that the incorporation of Ti causes changes in the lattice parameters (a and c), especially the change in the lattice parameter c. As shown in the shaded area in the figure, the lattice parameters mutate and the lattice is distorted accordingly.

[0100] Comparative Example 2-1 CaAl 12 O 19 Pigment, CaAl prepared in Comparative Example 2-2 and Examples 2-3, 4, 5, 6, 7 11.8-y Co 0.2 Ti y O 19 The UV-Vis-NIR diffuse reflectance spectrum of the pigment is as follows: Figure 3 As shown. Figure 3 In the 12 O 19 It can reflect almost all sunlight in the visible light region, indicating that CaAl 12 O 19 The color is white. 12 O 19 After the lattice, a clear spectral valley appears, indicating that part of the visible light has been absorbed. Figure 6 As shown in A, different amounts of titanium ions are doped into CaAl 12 O 19 When the amount of titanium ions is greater than that of cobalt ions, the color of the pigment becomes darker, which is probably because the excessive titanium ion doping causes CaAl 12 O 19 The crystal lattice is distorted, which in turn deepens the color intensity of the prepared pigment. Figure 3It can also be seen that CaAl 12 O 19 The near-infrared reflectivity is the highest when cobalt ions replace Al 3+ After the addition of ions, the near-infrared reflectivity in the 1200-1600nm wavelength range decreases due to the absorption of this wave by the cobalt ions located in the tetrahedral gaps. When a small amount or an equal amount of titanium ions is doped, the near-infrared reflectivity remains basically unchanged; and after excessive titanium ions are doped, the corresponding absorption of cobalt ions in the 1200-1600nm range is aggravated. However, the near-infrared energy of solar radiation is mainly concentrated in the 700-1200nm range. The high reflectivity of the pigment in this range indicates that the pigment has a higher reflectivity. Compared with the generally reported near-infrared spectra, such as similar blue pigments: NiAl 2 O 4 Pigment (R*=53%), MgAl-LDH@SiO 2 @CoAl 2 O 4 Pigment (R*=59%), etc. The pigment prepared by the present invention still maintains a relatively high near-infrared reflectivity (R) reflective pigment.

[0101] Figure 4 , Figure 5 Wherein CaAl 11.9-y Ni 0.1 Ti y O 19 , Ca 0.9 La 0.1 Al 11.9-y Ni 0.1 Ti y O 19 UV-Vis-NIR diffuse reflectance spectrum, Figure 6 The optical photographs of the pigments prepared by B all showed the same results.

[0102] In the present invention, a Hitachi UH4150 ultraviolet-visible near-infrared spectrophotometer is used to test the diffuse reflectance spectrum of the heat reflective pigment. The near-infrared light reflectance ratio of the heat reflective pigment at 700 to 2500 nm is calculated according to the standard relative spectral distribution data of solar radiation of ASTM G173-03, and the calculation formula is:

[0103]

[0104] 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 in the present invention use the CIE system L*, a* and b*, and C* is the color saturation, which is defined by the International Illumination Commission.

[0105] The color coordinates of the pigments prepared in each comparative example and embodiment are characterized by the CIE1976L*a*b* color space, and the results are shown in Table 1. The L* axis represents the brightness from 0 to 100. The smaller the L* value is, the darker the color of the pigment is. The a* axis represents the colors from green (-) to red (+), and the b* axis represents the colors from blue (-) to yellow (+). In each embodiment and comparative example, the color intensity of the pigment doped with only cobalt ions or nickel ions is relatively low. The color saturation of cobalt ions is 22.67-29.15, while the color saturation of nickel ions is only 7.69, and its brightness is relatively high; after doping with an equal amount of titanium ions, the color intensity is slightly improved; and after doping with excessive titanium ions, the color intensity of the pigment is significantly improved. The color saturation of cobalt ions can reach 40.49-46.45, and that of nickel ions can reach 32.02. This shows that doping with excessive titanium ions significantly enhances the color intensity of the pigment, which is consistent with the above results. Figure 6 The pigment is consistent with the photo.

[0106] Table 1. CIE 1976 L*a*b* values ​​and C*, R* values ​​of pigments

[0107]

[0108]

[0109] 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 architectural coatings. At the same time, the high near-infrared solar reflectivity of these pigments indicates that these pigments used in coatings can reflect a large amount of heat. Therefore, the CaAl prepared in Examples 1-3 of the present invention 11.7 Co 0.1 Ti 0.2 O 19 The pigment is compared with the commercial blue pigment as a coating. The specific steps are as follows:

[0110] (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;

[0111] (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.

[0112] Irradiate the coating under near-infrared light for the same time and record the temperature difference between the inner and outer surfaces of the temperature coating. Figure 7 As shown, it was found that CaAl 11.7 Co 0.1 Ti 0.2 O 19 The inner and outer surface temperatures of the pigment coating are lower than those of commercial pigments by 9°C and 12°C respectively. 11.7 Co 0.1 Ti 0.2 O 19 The pigments can be used as potential blue heat-reflecting thermal insulation coatings. All of these pigments are promising candidates for cool pigments to save energy.

[0113] 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 pigment based on structural regulation, characterized in that: The general chemical formula of the pigment is (Ca, A)(Al, B, Ti) 12 O 19 , wherein element A is an element replacing Ca, element A is an alkaline earth metal or a rare earth metal element, element B is an element replacing Al, and element B is a coloring element.

2. The high near-infrared reflective pigment based on structure regulation according to claim 1, characterized in that: The element A is selected from one or more of Sr, La, and Y, and the element B is selected from one or more of Co, Ni, and Cu.

3. The high near-infrared reflective pigment based on structure regulation according to claim 1, characterized in that: The doping amount of the element B in the pigment is smaller than the doping amount of Ti.

4. A method for preparing a high near-infrared reflective pigment based on structure regulation according to any one of claims 1 to 3, characterized in that: When the pigment is prepared by solid phase method, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O 19 The stoichiometric ratio of each element in the mixture is respectively taken as raw materials: CaCO3, Al2O3, Co2O3 and TiO2, the raw materials are mixed evenly, and calcined to obtain blue near-infrared reflective pigment powder.

5. The method for preparing a high near-infrared reflective pigment based on structure regulation 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 pigment based on structure regulation according to claim 4, characterized in that: The calcination temperature is 1300-1500° C., and the calcination time is 1-6 hours.

7. A method for preparing a high near-infrared reflective pigment based on structure regulation according to any one of claims 1 to 3, characterized in that: When the pigment is prepared by combustion synthesis, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O 19 The stoichiometric ratios of the elements in the mixture are respectively weighed Ca(NO3)2·4H2O, Al(NO3)2·9H2O and Co(NO3)2·6H2O, and dissolved in deionized water; titanate butyl ester Ti(OC4H9)4 is measured and added to an ethylene glycol solution, stirred and heated, and citric acid is added to completely dissolve the solution; the two solutions are mixed and evaporated to obtain a precursor, which is subjected to a combustion reaction to obtain a blue near-infrared reflective pigment powder.

8. The method for preparing a high near-infrared reflective pigment based on structure regulation according to claim 7, characterized in that: The stirring and heating is performed until the temperature reaches 65-85°C and then citric acid is added.

9. A method for preparing a high near-infrared reflective pigment based on structure regulation according to any one of claims 1 to 3, characterized in that: When the pigment is prepared by coprecipitation method, the steps are as follows: according to the chemical formula Ca(Al, Co, Ti) 12 O 19 The stoichiometric ratios of the elements in the mixture are respectively weighed: CaCl2·2H2O, AlCl3·6H2O, CoCl2·6H2O and Ti(SO4)2, dissolved in deionized water, stirred and ammonia water is added dropwise until the pH value is 10-11, and the mixture is stirred, aged, filtered, dried, ground and calcined to obtain a blue near-infrared reflective pigment powder.

10. An application of the high near-infrared reflective pigment based on structural regulation as claimed in any one of claims 1 to 3, including application in heat reflective coatings.

Images