An orange-red inorganic pigment with both near-infrared high reflection and infrared selective radiation characteristics, and its preparation method and application

Abstract

The present invention discloses an orange-red inorganic pigment that combines high near-infrared reflectivity with selective infrared radiation. The pigment contains the elements Li, Mn, and Re, wherein the Re element is any one of Ti, Zr, or Hf. This invention avoids the use of toxic heavy metals, making it more environmentally friendly. Through the synergistic effect of Li, Mn, and Re, the pigment achieves high reflectivity, high emissivity, and ideal color. Compared to traditional single-component pigments, this combination exhibits superior optical properties.

Description

Technical Field

[0001] The present invention relates to the field of pigments, and in particular to a synergistic cooling orange-red pigment with near-infrared high reflection and infrared selective radiation characteristics and a preparation method thereof. Background Art

[0002] With the increasing severity of global climate change and the urban heat island effect, demand for cooling materials in areas such as building energy conservation and military equipment is increasing. Traditional cooling materials primarily consist of white and light-colored paints, which reduce surface temperatures through high reflectivity. However, these materials often lack aesthetic appeal and diversity, making it difficult to meet the color requirements of different scenarios. Therefore, the development of pigments with excellent cooling effects and rich colors has become a research hotspot. Currently, the common colored cooling pigments on the market mainly include the following categories: 1) Chromium pigments, such as chrome yellow (PbCrO4) described in patent CN108559280A, have bright colors but contain heavy metals, posing environmental and health risks; 2) Iron pigments, such as iron oxide red (Fe2O3) described in patent CN108713000A, are environmentally friendly but have low near-infrared reflectivity and limited cooling effect; 3) Composite oxide pigments, such as doped and modified TiO2 described in patent CN1756805A, have some cooling effects but often lack color saturation. In addition, some studies have attempted to improve pigment performance by doping with rare earth elements, but this typically requires high preparation temperatures and high energy consumption. Against this backdrop, developing an orange-red pigment that combines excellent cooling performance with desirable color and environmental friendliness is of great significance. In particular, achieving high near-infrared reflectivity while maintaining high far-infrared emissivity and good color performance is a major technical challenge. Simultaneously, simplifying the preparation process and reducing production costs are also pressing issues. Summary of the Invention

[0003] Purpose of the invention: The present invention aims to develop a new type of orange-red inorganic pigment with both near-infrared high reflectivity and infrared selective radiation properties through innovative material design and optimized preparation methods to meet the growing demand for high-performance colored cooling materials.

[0004] The technical problem that the present invention also aims to solve is to provide a preparation method and application of the above orange-red inorganic pigment.

[0005] In order to solve the above technical problems, the present invention discloses an orange-red inorganic pigment having both near-infrared high reflectivity and infrared selective radiation characteristics, wherein the orange-red inorganic pigment contains Li, Mn and Re elements, wherein the Re element is any one of Ti, Zr or Hf.

[0006] Specifically, when Re is Ti, the molar ratio range of Ti / (Mn + Ti) is 0.1 < x ≤ 0.8; when Re is Zr, the molar ratio range of Zr / (Mn + Zr) is 0.1 ≤ y ≤ 0.8; when Re is Hf, the molar ratio range of Hf / (Mn + Hf) is 0.1 ≤ z ≤ 0.8; wherein, the molar ratio of Li to (Mn + Re) is 1.5:1 to 2.5:1, preferably 2:1.

[0007] The present invention further provides a method for preparing the above orange-red inorganic pigment, which is characterized by comprising the following steps:

[0008] (1) Weigh the raw materials containing Li source, Mn source and Re source according to the stoichiometric ratio;

[0009] (2) Mix and ball-mill the above raw materials;

[0010] (3) Dry and grind the ball-milled mixture; preferably, place the ball-milled mixture at 80 °C for drying and grinding;

[0011] (4) Calcinate the ground powder at 800 - 1000 °C for 8 - 12 hours;

[0012] (5) Cool, grind and sieve the calcined product to obtain the orange-red inorganic pigment with both near-infrared high reflectivity and infrared selective radiation characteristics.

[0013] Preferably, in step (2), anhydrous ethanol is used as the ball-milling medium, the ball-milling time is 6 - 8 hours, and the ball-milling speed is 300 - 400 rpm.

[0014] In step (5), a 200-mesh sieve is used for sieving.

[0015] Among them, the Li source is lithium carbonate, the Mn source is manganese carbonate, and the Re source is selected from any one of titanium dioxide, zirconium dioxide, and hafnium dioxide.

[0016] The orange-red inorganic pigment prepared by the present invention can be adjusted within the range from red to orange-red. [[ID=第31]]

[0017] When Re is Ti: (a) the near-infrared solar reflectance R of the pigment ≥ 64.5%; (b) the emissivity ε(λ) of the pigment in the 8 - 14 μm band ≥ 0.84; (c) in the CIE Lab color coordinates of the pigment, the range of L* is 59 - 68, the range of a* is 21 - 30, and the range of b* is 11 - 22.

[0018] When Re is Zr: (a) the near-infrared solar reflectivity R of the pigment is ≥77%; (b) the emissivity ε(λ) of the pigment in the 8-14 μm band is ≥0.84; (c) in the CIE Lab color coordinates of the pigment, L* is in the range of 64-74, a* is in the range of 22-31, and b* is in the range of 18-25.

[0019] When Re is Hf: (a) the near-infrared solar reflectivity R of the pigment is ≥79%; (b) the emissivity ε(λ) of the pigment in the 8-14 μm band is ≥0.84; (c) in the CIE Lab color coordinates of the pigment, L* is in the range of 66-77, a* is in the range of 21-26, and b* is in the range of 16-22.

[0020] The orange-red inorganic pigment prepared by the invention has a primary particle size within the range of 100-500 nm and a secondary particle size within the range of 0.5-5 μm.

[0021] The present invention further proposes the use of the orange-red inorganic pigment in the preparation of exterior building paint, automobile paint or roof paint.

[0022] The present invention also provides a coating composition, which contains the above orange-red inorganic pigment.

[0023] Furthermore, the coating composition also includes a resin base and a solvent

[0024] The present invention aims to develop a new type of orange-red inorganic pigment with both near-infrared high reflectivity and infrared selective radiation properties through innovative material design and optimized preparation methods to meet the growing demand for high-performance colored cooling materials.

[0025] The orange-red inorganic pigment of the present invention, which has both near-infrared high reflectivity and infrared selective radiation properties, demonstrates significant technological advancement, mainly reflected in its innovative material composition, excellent optical properties, excellent color expression, multi-element synergistic effect, flexible component control, and simple and efficient preparation method.

[0026] Beneficial effects: This application adopts a novel combination of lithium (Li), manganese (Mn) and Re elements (Re is at least one of Ti, Zr or Hf), which avoids the use of toxic heavy metals and is more environmentally friendly. Through the synergistic effect of Li, Mn and Re elements, the unity of high reflectivity, high emissivity and ideal color is achieved. Compared with traditional pigments with a single component, this combination has better optical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, and the above and / or other advantages of the present invention will become more apparent.

[0028] Figure 1 Reflectance spectra of a series of samples in Example 1: (a) 0.2-2.5 μm; (b) 2.5-25 μm;

[0029] Figure 2 Reflection spectra of the samples in Example 2: (a) 0.2-2.5 μm; (b) 2.5-25 μm;

[0030] Figure 3 Reflection spectra of the series of samples in Example 3: (a) 0.2-2.5 μm; (b) 2.5-25 μm;

[0031] Figure 4 Reflection spectra of the samples of Example 4: (a) 0.2-2.5 μm; (b) 2.5-25 μm;

[0032] Figure 5 Reflection spectra of the series of samples in Example 5: (a) 0.2-2.5 μm; (b) 2.5-25 μm;

[0033] Figure 6 Reflection spectra of a series of samples in Example 6: (a) 0.2-2.5 μm; (b) 2.5-25 μm. DETAILED DESCRIPTION

[0034] Example 1:

[0035] Li2CO3, MnO2, and TiO2 powders were weighed according to the stoichiometric ratio of 1:1-x:x (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8) and placed in a polytetrafluoroethylene ball mill. Zirconia balls of varying particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added, with a ball-to-material ratio of 5:1. An appropriate amount of anhydrous ethanol was added as a ball milling medium and the mixture was ball milled at 300 rpm for 6 hours. The resulting mixture was filtered and the filtered mixed sample was placed in an 80°C oven to dry. The dried block sample was ground into powder. The mixed powder was placed in a muffle furnace and sintered at 900°C for 10 hours. The sample was cooled in the furnace to below 100°C and then removed. The sintered powder was ground and sieved (200 mesh) to obtain orange-red powder Li2Mn 1-x Ti xO3 (abbreviated as LMT-x, x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, and pure Li2MnO3 abbreviated as LMO). The performance parameters of the products involved in Example 1 are shown in Table 1. All pigments exhibit high infrared emissivity (ε(λ) > 83.70%), which is higher than that of commercially available iron red pigment (ε(λ) = 83.19%). The highest emissivity, LMT-0.6, reaches 85.77%.

[0036] Table 1: Product performance parameters of Example 1

[0037]

[0038] Example 2

[0039] Li2CO3, MnO2 and ZrO2 powders were weighed according to the stoichiometric ratio of 1:1-y:y (y = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8), placed in a polytetrafluoroethylene ball mill, and zirconia balls of different particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added with a ball-to-material ratio of 5:1. Anhydrous ethanol was added as the ball milling medium, and the mixture was ball milled at a speed of 300 rpm for 6 h. The obtained mixture was filtered, and the mixed sample obtained by filtration was placed in an oven at 80°C for drying, and the dried block sample was ground into powder; the mixed powder was placed in a muffle furnace and sintered at 900°C for 10 hours. The sample was cooled to below 100°C with the furnace and then taken out. The sintered powder was ground and sieved (200 mesh) to obtain Zr-doped Li2MnO3 mixed phase orange-red powder pigment (abbreviated as Mn 1-y Zr y , y=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8). The product performance parameters involved in Example 2 are shown in Table 2.

[0040] Table 2: Product performance parameters of Example 2

[0041]

[0042] Example 3:

[0043] Li2CO3, MnO2 and HfO2 powders were weighed according to the stoichiometric ratio of 1:1-z:z (z==0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8), placed in a polytetrafluoroethylene ball mill, and zirconia balls of different particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added, with a ball-to-material ratio of 5:1. Anhydrous ethanol was added as a ball milling medium and ball milled at 300 rpm for 6 hours. The resulting mixture was filtered, and the filtered mixed sample was placed in an oven at 80°C to dry, and the dried block sample was ground into powder; the mixed powder was placed in a muffle furnace and sintered at 900°C for 10 hours. The sample was cooled in the furnace to below 100°C and then taken out. The sintered powder was ground and sieved (200 mesh) to obtain Hf-doped Li2MnO3 mixed phase orange-red powder pigment (abbreviated as Mn 1-z Hf z , z=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8). The product performance parameters involved in Example 3 are shown in Table 3.

[0044] Table 3: Product performance parameters of Example 3

[0045]

[0046]

[0047] Example 4:

[0048] The ground LMT-x (x = 0.2, 0.4, 0.6, 0.8) pigments and fluorocarbon resin were placed in a polytetrafluoroethylene ball mill in a mass ratio of (1:10), and zirconium oxide balls of different particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added. The ball-to-material ratio was 5:1. The ball milling was carried out at a speed of 300 rpm for 3 hours to ensure that the pigment was completely dispersed in the resin. Then, the coating was applied to an aluminum plate (4cm*4cm*1mm) using a 200μm coating rod and dried at room temperature for 12 hours. Its cooling performance was tested.

[0049] The cooling performance of the composite material was tested using a thermal measurement method using a self-designed apparatus. Depending on the experimental environment, thermal measurements can be performed indoors or at room temperature. Indoor thermal measurements were conducted using a solar simulator at an ambient temperature of 26°C. The composite coating was evenly coated on an aluminum alloy sheet measuring 4 cm x 4 cm x 1 mm. This sheet was then covered with a polytetrafluoroethylene mold (7.5 cm x 7.5 cm x 5 cm) with a 2.5 cm x 2.5 cm circular groove cut out from the top. A 94043A infrared lamp from Newport, Germany, was used to simulate sunlight. The coating was exposed to simulated sunlight for 4 hours. A K-type thermocouple was fixed 1.5 cm below the center of the aluminum sheet to measure the temperature change caused by infrared absorption within the cavity. The temperature change was recorded every 1 minute. Outdoor thermal measurements were conducted in Shenzhen, China (22°N, 114°E; November 21–24, 2023) using the same test apparatus as for the indoor thermal measurements, exposing the coating directly to sunlight and air. The coating samples involved in Example 4 are recorded as LMT-0.2, LMT-0.4, LMT-0.6, and LMT-0.8, and their performance parameters are shown in Table 4.

[0050] Table 4: Product performance parameters of Example 4

[0051]

[0052] Example 5:

[0053] The ground Mn 1-y Zr y Pigments (y = 0.2, 0.4, 0.6, 0.8) and fluorocarbon resin were placed in a polytetrafluoroethylene ball mill in a mass ratio of (1:10), and zirconium oxide balls of different particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added. The ball-to-material ratio was 5:1, and the ball milling was carried out at a speed of 300 rpm for 3 hours to ensure that the pigment was completely dispersed in the resin. Then, the coating was applied to an aluminum plate (4 cm * 4 cm * 1 mm) using a 200 μm coating rod and dried at room temperature for 12 hours. Its cooling performance was tested.

[0054] The cooling performance of the composite material was tested using a thermal measurement method using a self-designed apparatus. Depending on the experimental environment, thermal measurements can be performed indoors or at room temperature. Indoor thermal measurements were conducted using a solar simulator at an ambient temperature of 26°C. The composite coating was evenly coated on an aluminum alloy sheet measuring 4 cm x 4 cm x 1 mm. This sheet was then covered with a polytetrafluoroethylene mold (7.5 cm x 7.5 cm x 5 cm) with a 2.5 cm x 2.5 cm circular groove cut out from the top. A 94043A infrared lamp from Newport, Germany, was used to simulate sunlight. The coating was exposed to simulated sunlight for 4 hours. A K-type thermocouple was fixed 1.5 cm below the center of the aluminum sheet to measure the temperature change caused by infrared absorption within the cavity. The temperature change was recorded every 1 minute. Outdoor thermal measurements were conducted in Shenzhen, China (22°N, 114°E; November 21–24, 2023) using the same test apparatus as for the indoor thermal measurements, exposing the coating directly to sunlight and air. The samples involved in Example 5 are denoted as LMZ-0.2, LMZ-0.4, LMZ-0.6, and LMZ-0.8, and their performance parameters are shown in Table 5.

[0055] Table 5: Product performance parameters of Example 5

[0056]

[0057]

[0058] Example 6:

[0059] The ground Mn 1-z Hf z Pigments (z = 0.2, 0.4, 0.6, 0.8) and fluorocarbon resin were placed in a polytetrafluoroethylene ball mill in a mass ratio of (1:10), and zirconium oxide balls of different particle sizes (small particle size: medium particle size: large particle size = 1:1:5) were added. The ball-to-material ratio was 5:1, and the ball milling was carried out at a speed of 300 rpm for 3 hours to ensure that the pigment was completely dispersed in the resin. Then, the coating was applied on an aluminum plate (4 cm * 4 cm * 1 mm) using a 200 μm coating rod and dried at room temperature for 12 hours. Its cooling performance was tested.

[0060] The cooling performance of the composite material was tested using a thermal measurement method using a self-designed apparatus. Depending on the experimental environment, thermal measurements can be performed indoors or at room temperature. Indoor thermal measurements were conducted using a solar simulator at an ambient temperature of 26°C. The composite coating was evenly coated on an aluminum alloy sheet measuring 4 cm x 4 cm x 1 mm. This sheet was then covered with a polytetrafluoroethylene mold (7.5 cm x 7.5 cm x 5 cm) with a 2.5 cm x 2.5 cm circular groove cut out from the top. A 94043A infrared lamp from Newport, Germany, was used to simulate sunlight. The coating was exposed to simulated sunlight for 4 hours. A K-type thermocouple was fixed 1.5 cm below the center of the aluminum sheet to measure the temperature change caused by infrared absorption within the cavity. The temperature change was recorded every 1 minute. Outdoor thermal measurements were conducted in Shenzhen, China (22°N, 114°E; November 21–24, 2023) using the same test apparatus as for the indoor thermal measurements, exposing the coating directly to sunlight and air. The samples involved in Example 6 are denoted as LMH-0.2, LMH-0.4, LMH-0.6, and LMH-0.8, and their performance parameters are shown in Table 6.

[0061] Table 6: Product performance parameters of Example 6

[0062]

[0063]

[0064] In summary,

[0065] When Re is Ti: (a) the near-infrared solar reflectivity R of the pigment is ≥64.5%; (b) the emissivity ε(λ) of the pigment in the 8-14 μm band is ≥0.84; (c) in the CIE Lab color coordinates of the pigment, L* is in the range of 59-68, a* is in the range of 21-30, and b* is in the range of 11-22.

[0066] When Re is Zr: (a) the near-infrared solar reflectivity R of the pigment is ≥77%; (b) the emissivity ε(λ) of the pigment in the 8-14 μm band is ≥0.84; (c) in the CIE Lab color coordinates of the pigment, L* is in the range of 64-74, a* is in the range of 22-31, and b* is in the range of 18-25.

[0067] When Re is Hf: (a) the near-infrared solar reflectivity R of the pigment is ≥79%; (b) the emissivity ε(λ) of the pigment in the 8-14 μm band is ≥0.84; (c) in the CIE Lab color coordinates of the pigment, L* is in the range of 66-77, a* is in the range of 21-26, and b* is in the range of 16-22.

[0068] The orange-red inorganic pigment prepared by the invention has a primary particle size within the range of 100-500 nm and a secondary particle size within the range of 0.5-5 μm.

[0069] The present invention provides a method and concept for preparing an orange-red inorganic pigment that combines high near-infrared reflectivity with selective infrared radiation. While numerous methods and approaches exist for implementing this technical solution, the foregoing merely represents a preferred embodiment of the present invention. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications are also within the scope of the present invention. Any components not specified in this embodiment may be implemented using existing technologies.

Claims

1. An application of an orange-red inorganic pigment having both near-infrared high reflectivity and infrared selective radiation properties in the preparation of exterior building coatings, automotive coatings or roof coatings, characterized in that: The coating material contains the orange-red inorganic pigment and a fluorocarbon resin base material. The orange-red inorganic pigment contains Li, Mn, and Re elements, where the Re element is any one of Ti, Zr, or Hf. When Re is Ti, the molar ratio of Ti / (Mn + Ti) ranges from 0.1 < x ≤ 0.8; when Re is Zr, the molar ratio of Zr / (Mn + Zr) ranges from 0.1 ≤ y ≤ 0.8; when Re is Hf, the molar ratio of Hf / (Mn + Hf) ranges from 0.1 ≤ z ≤ 0.

8. Wherein, the molar ratio of Li to (Mn + Re) is 1.5:1 to 2.5:1; The orange-red inorganic pigment is prepared through the following steps: (1) Weigh the raw materials containing Li source, Mn source, and Re source according to the stoichiometric ratio; (2) Mix and ball-mill the above raw materials; (3) Dry and grind the ball-milled mixture; (4) Calcinate the ground powder at 800 - 1000 °C for 8 - 12 hours; (5) Cool, grind, and sieve the calcined product to obtain the orange-red inorganic pigment with both near-infrared high reflection and infrared selective radiation characteristics; Wherein, the Li source is lithium carbonate, the Mn source is manganese carbonate, and the Re source is any one selected from titanium dioxide, zirconium dioxide, and hafnium dioxide.

2. The use according to claim 1, characterized in that In step (2), anhydrous ethanol is used as the ball-milling medium, the ball-milling time is 6 - 8 hours, and the ball-milling speed is 300 - 400 rpm.

3. The use according to claim 1, characterized in that In step (5), a 200-mesh sieve is used for sieving.

4. The use according to claim 1, characterized in that The molar ratio of Li to (Mn + Re) is 2:

1.

5. The use according to claim 1, characterized in that The mass ratio of the orange-red inorganic pigment to the fluorocarbon resin base material is 1:10.

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