Rare earth red pigment with high near-infrared reflection performance, preparation method and application thereof

Abstract

The present invention belongs to the technical field of inorganic infrared reflective pigments, and specifically relates to a rare earth red pigment with high near-infrared reflective performance, a preparation method thereof and an application thereof. The rare earth red pigment is a composite oxide containing Ce, Pr, Mo and Si, and its chemical formula is Ce 0.95‑x‑ y Pr 0.05 Mo x Si y O2, wherein x=0.01-0.05, y=0.01-0.05. The beneficial effects of the present invention are as follows: the rare earth red pigment provided by the present invention does not contain heavy metal ions such as lead and chromium and their oxides, is environmentally friendly and non-toxic, has bright colors and has high near-infrared reflection performance, and its near-infrared reflectivity is as high as 95% or more, which is much higher than commercial iron oxide red pigment. It is used in architectural coatings, meets the pollution reduction requirements of the architectural coatings industry, and is of great significance to improving the urban heat island effect and saving energy.

Description

Technical Field

[0001] The invention belongs to the technical field of inorganic infrared reflective pigments, and in particular relates to a rare earth red pigment with high near-infrared reflective performance, a preparation method and application thereof. Background Art

[0002] Solar radiation has a significant impact on the earth, and the solar energy received by the earth contains 52% near-infrared radiation. "Cold" pigments with high near-infrared reflectivity can reduce heat accumulation on the surface of buildings, reduce energy consumption, and improve comfort. The use of near-infrared reflective pigments helps to improve economic benefits and environmental safety, is conducive to solving urgent resource and environmental problems, and is of great significance to the sustainable development of society. Traditional inorganic near-infrared pigments contain heavy metal elements such as chromium, lead, cobalt, cadmium, antimony, selenium, etc. When the heavy metal content exceeds a certain level, it will pose a serious threat to the environment and human health. Many countries have imposed strict restrictions on their use. Therefore, inorganic pigments with high near-infrared reflectivity, color and non-toxicity have become the development trend of reflective pigments in the future.

[0003] The application and research of near-infrared reflective pigments are divided into two parts: white pigments and color pigments. At present, rutile titanium dioxide is the most widely used in my country. White pigments have always been the preferred near-infrared reflective pigments due to their low absorbance and high non-selective scattering in the visible light range. Common white near-infrared reflective pigments include zinc white (ZnO), titanium dioxide (TiO2), zinc sulfide (ZnS) and lead powder (zinc sulfate mixed with barium sulfate). However, since the color of white near-infrared pigments is too single, large-scale use in urban agglomerations will cause "white pollution" and damage vision. The improvement method is to mix other color pigments into white pigments and develop color pigments. And with the development of society, people have higher demands for pigment coatings, and people are more inclined to choose colored pigments. Therefore, the development of color pigments is also one of the recent research hotspots.

[0004] The most difficult inorganic pigments to synthesize are red pigments, and currently the industrial and commercial inorganic red pigments are lead red, cadmium red and iron oxide red. Lead red and cadmium red directly endanger human health and are prohibited by law from being used in environments and decorations that humans come into contact with in daily life. Although iron oxide red is non-toxic, its chromaticity cannot be adjusted and its color is single, which makes it difficult to meet human needs. In addition, the near-infrared reflectivity of commercial red pigments is low, which cannot meet the needs of the high-end market and the development trend of high near-infrared reflective pigments. Summary of the invention

[0005] The purpose of the present invention is to provide a rare earth red pigment with bright color, environmental protection, non-toxicity and high near-infrared reflection performance, and its preparation method and application in view of the above problems existing in the prior art.

[0006] In order to achieve the above-mentioned purpose of the present invention, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, a rare earth red pigment having high near-infrared reflectivity is provided. The rare earth red pigment is a composite oxide containing Ce, Pr, Mo and Si, and has a chemical formula of Ce 0.95-x-y Pr 0.05 Mo x Si y O2, wherein x = 0.01-0.05, y = 0.01-0.05.

[0008] The second aspect of the present invention provides a method for preparing the rare earth red pigment having high near-infrared reflectivity, comprising the following steps:

[0009] (1) According to the chemical formula Ce 0.95-x-y Pr 0.05 Mo x Si y The stoichiometric ratio of each element in O2 is obtained by taking a compound containing Ce, a compound containing Pr, a compound containing Mo and a compound containing Si respectively, mixing and grinding each compound with a mineralizer, wherein the added mass of the mineralizer accounts for 1-3% of the total mass of the raw materials, to obtain a mixed material;

[0010] (2) calcining the mixture at high temperature to obtain a semi-finished product;

[0011] (3) Grinding, washing and drying the semi-finished product in sequence to obtain the rare earth red pigment with high near-infrared reflection performance.

[0012] Preferably, in step (1), the Ce-containing compound is at least one of Ce-containing carbonates, oxides, chlorides, nitrates and sulfates.

[0013] Preferably, in step (1), the Pr-containing compound is at least one of a carbonate, an oxide, a chloride, a nitrate and a sulfate containing Pr.

[0014] Preferably, in step (1), the Si-containing compound is a Si-containing oxide or silicate.

[0015] Preferably, in step (1), the Mo-containing compound is a Mo-containing oxide or a water-soluble molybdenum salt.

[0016] Preferably, in step (1), the mineralizer is one or more of barium fluoride, magnesium fluoride, calcium chloride, magnesium chloride, sodium chloride and calcium carbonate.

[0017] Preferably, in step (2), the grinding is ball milling, the material-ball ratio is 1:3, and the ball milling time is 4 hours.

[0018] Preferably, in step (3), the calcination temperature is 900-1400° C. and the calcination time is 60-240 min.

[0019] The third aspect of the present invention provides the use of the above-mentioned rare earth red pigment with high near-infrared reflection performance in architectural coatings.

[0020] The beneficial effects of the present invention are:

[0021] The rare earth red pigment provided by the present invention does not contain heavy metal ions such as lead and chromium and their oxides, is environmentally friendly and non-toxic, has bright colors and has high near-infrared reflection performance, and its near-infrared reflectivity is as high as 95% or more, which is much higher than commercial iron oxide red pigment. It is used in architectural coatings, meets the pollution reduction requirements of the architectural coatings industry, and is of great significance to improving the urban heat island effect and saving energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a photo of the rare earth red pigment of the present invention;

[0023] Figure 2 is the XRD spectrum of the rare earth red pigment of the present invention;

[0024] Figure 3 The SEM spectrum of the rare earth red pigment of the present invention;

[0025] Figure 4 The near-infrared reflection spectra of the rare earth red pigments of Example 2 and various comparative examples are shown. DETAILED DESCRIPTION

[0026] To make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described in detail below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0027] Example 1

[0028] 28g of cerium carbonate, 1.8g of praseodymium chloride, 1.6g of magnesium silicate, 1.8g of sodium molybdate and 0.8g of magnesium fluoride are placed in a ball mill together, and zirconium oxide balls three times the weight of the raw materials are added. The mixture is ground for 4 hours, and then placed in an alumina crucible, calcined at 900°C in a muffle furnace for 240 minutes, washed with deionized water and ethanol, filtered under reduced pressure, and dried in vacuum to obtain a rare earth red pigment with high near-infrared reflectivity.

[0029] Example 2

[0030] 30g of cerium oxide, 1.7g of praseodymium oxide, 1.4g of silicon dioxide, 1.4g of molybdenum oxide and 0.6g of barium fluoride are placed in a ball mill together, and zirconium oxide balls three times the weight of the raw materials are added. Grind for 4 hours, then put it into an alumina crucible, calcine it at 1400°C in a muffle furnace for 60 minutes, wash it with deionized water and ethanol, filter it under reduced pressure, and dry it in vacuum to obtain a rare earth red pigment with high near-infrared reflection performance.

[0031] Example 3

[0032] 33g of cerium nitrate, 1.7g of praseodymium oxide, 1.0g of silicon dioxide, 1.0g of molybdenum oxide and 0.5g of calcium chloride are placed in a ball mill together, and zirconium oxide balls three times the weight of the raw materials are added. The mixture is ground for 4h, and then placed in an alumina crucible, calcined at 1000°C in a muffle furnace for 120min, washed with deionized water and ethanol, filtered under reduced pressure, and dried in vacuum to obtain a rare earth red pigment with high near-infrared reflectivity.

[0033] Example 4

[0034] 38g of cerium sulfate, 1.9g of praseodymium carbonate, 0.8g of silicon dioxide, 0.8g of molybdenum oxide and 0.3g of magnesium chloride are placed in a ball mill together, and zirconium oxide balls three times the weight of the raw materials are added, and the mixture is ground for 4 hours to obtain a mixture; then it is placed in an alumina crucible, calcined at 1100°C in a muffle furnace for 100 minutes, washed with deionized water and ethanol, filtered under reduced pressure, and vacuum dried to obtain a rare earth red pigment with high near-infrared reflection performance.

[0035] Example 5

[0036] 40g of cerium chloride, 1.7g of praseodymium oxide, 0.5g of silicon dioxide, 0.5g of molybdenum oxide and 0.2g of calcium carbonate are placed in a ball mill together, and zirconium oxide balls three times the weight of the raw materials are added. The mixture is ground for 4 hours, and then placed in an alumina crucible, calcined at 1200°C in a muffle furnace for 80 minutes, washed with deionized water and ethanol, filtered under reduced pressure, and dried in vacuum to obtain a rare earth red pigment with high near-infrared reflectivity.

[0037] Comparative Example 1

[0038] The only difference from Example 2 is that silicon dioxide, molybdenum oxide and barium fluoride are removed.

[0039] Comparative Example 2

[0040] The only difference from Example 2 is that molybdenum oxide and barium fluoride are removed.

[0041] Comparative Example 3

[0042] The only difference from Example 2 is that silicon dioxide and barium fluoride are removed.

[0043] Comparative Example 4

[0044] The only difference from Example 2 is that the barium fluoride is removed.

[0045] The rare earth red pigments prepared in the examples of the present invention and the comparative examples were tested, and the results were as follows:

[0046] (i) Figure 1 This is a sample picture of the rare earth red pigment of the present invention. The rare earth red pigment has bright color, small particle size of 5-8 microns, good tinting power, and excellent temperature resistance and acid and alkali resistance.

[0047] (ii) Figure 2 The XRD spectrum of the rare earth red pigment of the present invention shows that the positions of its main characteristic peaks (2θ is 28.8°, 33.1°, 48.1° and 56.8°) are consistent with the characteristic peak positions of the standard card (JCPDS 34-0394) of CeO2, which conforms to the crystal phase characteristics of CeO2. Therefore, the prepared rare earth red pigment presents a fluorite structure by forming a solid solution after doping rare earth oxides and other metals and non-metal oxides. Under high-temperature calcination conditions, the rare earth oxides and other metals and non-metal oxides are dissolved in the CeO2 lattice to form a solid solution.

[0048] (ⅲ) Figure 3 This is the SEM spectrum of the rare earth red pigment of the present invention. The figure shows neatly arranged nearly circular grains, but most of them are agglomerated into blocks. This may be because the sample is calcined at high temperature, the solid phases react and grow with each other, and the sample's morphology is eventually destroyed due to rapid cooling and repeated grinding during post-processing.

[0049] (iv) Table 1 shows the chromaticity comparison results of the embodiments and comparative examples. Figure 4 The near-infrared reflectance spectra of the rare earth red pigments of Example 2 and Comparative Examples 1, 2, and 3 are shown. It can be seen from the figure that the reflectance of the sample of Example 2 in the near-infrared region of 700-2500nm is as high as 95% or more, which is significantly higher than that of the samples of the comparative examples, and significantly higher than the near-infrared reflectance of the currently commercialized iron oxide pigments; the redness value a* of the rare earth red pigment of Example 2 is 32.01, while the redness value a* of iron oxide is 28.90, and the L* of the rare earth red pigment of Example 2 is 43.92, which is brighter and more vivid than the iron oxide pigment. Comparative Example 4 removes the mineralizer on the basis of Example 2, and although it does not affect the near-infrared reflectance, the redness values ​​a* and L* are reduced to a certain extent compared with Example 2.

[0050] See Table 1 for details.

[0051] Table 1 Comparison of the chromaticity values ​​of the pigments of each embodiment and comparative example

[0052]

[0053] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A rare earth red pigment with high near-infrared reflection performance, characterized in that: The rare earth red pigment is a composite oxide containing Ce, Pr, Mo and Si, and its chemical formula is Ce 0.95-x-y Pr 0.05 Mo x Si y O2, where x = 0.01-0.05, y = 0.01-0.05; The method for preparing the rare earth red pigment with high near-infrared reflection performance comprises the following steps: (1) According to the chemical formula Ce 0.95-x-y Pr 0.05 Mo x Si y The stoichiometric ratio of each element in O2 is obtained by taking a compound containing Ce, a compound containing Pr, a compound containing Mo and a compound containing Si respectively, mixing and grinding each compound with a mineralizer, wherein the added mass of the mineralizer accounts for 1-3% of the total mass of the raw materials, to obtain a mixed material; wherein: The Ce-containing compound is at least one of Ce-containing carbonates, oxides, chlorides, nitrates and sulfates; The Pr-containing compound is at least one of a carbonate, an oxide, a chloride, a nitrate and a sulfate containing Pr; The Si-containing compound is an oxide or a silicate containing Si; The Mo-containing compound is a Mo-containing oxide or a water-soluble molybdenum salt; The mineralizer is one or more of barium fluoride, magnesium fluoride, calcium chloride, magnesium chloride, sodium chloride and calcium carbonate; (2) calcining the mixture at high temperature to obtain a semi-finished product; wherein the calcination temperature is 900-1400° C. and the calcination time is 60-240 min; (3) Grinding, washing and drying the semi-finished product in sequence to obtain the rare earth red pigment with high near-infrared reflectivity; wherein the grinding is ball milling, the material-to-ball ratio is 1:3, and the ball milling time is 4 hours.

2. The method for preparing the rare earth red pigment with high near-infrared reflection performance according to claim 1, characterized in that: The following steps are involved: (1) According to the chemical formula Ce 0.95-x-y Pr 0.05 Mo x Si y The stoichiometric ratio of each element in O2 is obtained by taking a compound containing Ce, a compound containing Pr, a compound containing Mo and a compound containing Si respectively, mixing and grinding each compound with a mineralizer, wherein the added mass of the mineralizer accounts for 1-3% of the total mass of the raw materials, to obtain a mixed material; wherein: The Ce-containing compound is at least one of Ce-containing carbonates, oxides, chlorides, nitrates and sulfates; The Pr-containing compound is at least one of a carbonate, an oxide, a chloride, a nitrate and a sulfate containing Pr; The Si-containing compound is an oxide or a silicate containing Si; The Mo-containing compound is a Mo-containing oxide or a water-soluble molybdenum salt; The mineralizer is one or more of barium fluoride, magnesium fluoride, calcium chloride, magnesium chloride, sodium chloride and calcium carbonate; (2) calcining the mixture at high temperature to obtain a semi-finished product; wherein the calcination temperature is 900-1400° C. and the calcination time is 60-240 min; (3) Grinding, washing and drying the semi-finished product in sequence to obtain the rare earth red pigment with high near-infrared reflectivity; wherein the grinding is ball milling, the material-to-ball ratio is 1:3, and the ball milling time is 4 hours.

3. Use of the rare earth red pigment with high near-infrared reflection performance as claimed in claim 1 in architectural coatings.

Images