CN115196678B - Chromium (III) -doped high near infrared reflection inorganic pigment and preparation method and application thereof - Google Patents

Abstract

The invention discloses a chromium (III) doped high near infrared reflection inorganic pigment, a preparation method and application thereof, wherein the chemical general formula of the pigment is Bi ₃Y_1‑xCr_xO₆ (x is more than 0 and less than or equal to 0.5). The pigment prepared by the invention can be widely used in the fields of cosmetics, building outer walls, ship decks, aerospace, oil tank storage tanks and the like (such as preparation of chemical product storage tank coating, vehicle and ship heat insulation coating, metal plate heat insulation coating, communication base station heat insulation coating, building outer wall coating and the like) so as to meet the color requirements of people and be used as a cooling material. Meanwhile, the pigment preparation process is simple, the equipment requirement is low, and the industrial production can be realized.

Description

A chromium (III) doped high near-infrared reflective inorganic pigment and its preparation method and application

Technical Field

The invention belongs to the field of inorganic oxide pigments, and in particular relates to a high near-infrared reflective inorganic pigment (Bi ₃ Y _{1- x} Cr _x O ₆ inorganic pigment) and a preparation method and application thereof.

Background technique

At present, human resources are scarce, which has inspired many researchers to develop and utilize solar energy. However, sunlight will also generate energy radiation to buildings, and excessive heat accumulated on the surface of buildings may even cause the "heat island effect", which brings many inconveniences to human life. In order to balance the unhealthy cycle caused by the "heat island effect", additional energy will inevitably be added for cooling, such as the use of a large number of central air conditioners and cooling equipment, thus promoting a new wave of energy conservation concepts. One of the directions is the preparation of special near-infrared reflective inorganic pigments, which are a new type of energy-saving and environmentally friendly material that can reflect most of the near-infrared radiation and thus have a high solar reflectivity. Applying it to the surface of an object can achieve a significant heat insulation and cooling effect. Therefore, the above-mentioned coating can be used for the interior and exterior walls of buildings in hot summer and cold winter areas to make the building warm in winter and cool in summer, thereby reducing the accumulation of building energy and the load of the cooling system, and then reducing the use of cooling equipment such as air conditioners, so as to alleviate the urban "heat island effect" and save energy, thereby realizing a sustainable development strategy for energy.

In recent years, the research and development of high near-infrared reflective materials has attracted extensive attention from a large number of scholars. At the same time, under the guidance of the green environmental protection concept, high solar reflective pigments are developing rapidly. Compared with organic pigments, inorganic pigments show greater advantages in chemical corrosion resistance, hiding power and weather resistance.

TiO ₂ with high near-infrared reflection performance is considered to be the best and most important white pigment in the world. However, it is limited by its single color and cannot meet people's visual enjoyment and color performance requirements. Various color pigments have also emerged. At present, yellow pigment is the most reported inorganic pigment. For example, Indian experts have reported a series of bismuth vanadate-based (BiVO ₄ -CaMoO ₄ , (LiLaZn) _1/3 MoO ₄ -BiVO ₄ , Li _0.1 RE _0.1 Bi _0.8 Mo _0.2 V _0.8 O ₄ ) yellow pigments. The above yellow pigments generally have good color performance and high near-infrared reflection performance. Chinese researchers have also developed a series of color pigments. For example, Han Aijun's research group has developed bright red mica/γ-Ce _2-x Y _x S ₃ , orange-yellow Fe-doped LaAlO ₃ and other high-reflectivity color pigments. However, research on red-like inorganic pigments is relatively rare. At present, red inorganic pigments mainly include red iron oxide, cadmium red and cerium sulfide. However, the near-infrared reflectivity of iron oxide red pigment is relatively low; cadmium red pigment contains highly toxic elements, which is harmful to human health; and cerium sulfide pigment has good color performance, but it is mostly used in high-end cosmetics due to its complex preparation process and high cost. Therefore, how to develop red-like pigments with good color performance, low cost and simple preparation process has become a technical problem that needs to be solved urgently.

Summary of the invention

In order to improve the above technical problems, the present invention provides a near-infrared reflective pigment, the general chemical formula of the pigment is: Bi ₃ Y _1-x Cr _x O ₆ , wherein:

Cr(III) is a doping element, x represents the doping molar amount of Cr(III), and 0＜x≤0.5.

For example, 0＜x≤0.05 or 0.05＜x≤0.5; illustratively, x is 0.01, 0.02, 0.03, 0.04, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5.

The invention can change the color of the pigment from light yellow to brick red by changing the doping molar amount of Cr(III).

According to an embodiment of the present invention, when 0＜x≤0.05, the color of the near-infrared reflective pigment is yellow; when 0.05＜x≤0.5, the color of the pigment is brick red.

According to an embodiment of the present invention, the average particle size of the near-infrared reflective pigment is 2 to 10 μm, preferably 3 to 8 μm, and exemplified by 2 μm, 3 μm, 5 μm, 8 μm, and 10 μm.

According to an embodiment of the present invention, the average near-infrared reflectivity of the near-infrared reflective pigment is greater than 90%, for example, 91-98%, exemplified by 92%, 93%, 95%, 98%.

According to an embodiment of the present invention, the near-infrared reflective pigment is prepared from raw materials including a Bi source, a Y source, and a Cr source through a solid phase sintering method.

According to an embodiment of the present invention, the Bi source is provided by a compound containing Bi, for example, provided by at least one of carbonates, oxides, chlorides, nitrates and sulfates containing Bi, preferably provided by oxides containing Bi (such as Bi ₂ O ₃ ).

According to an embodiment of the present invention, the Y source is provided by a compound containing the Y element; for example, provided by at least one of carbonates, oxides, chlorides, nitrates and sulfates containing the Y element; preferably provided by oxides containing the Y element (such as Y ₂ O ₃ ).

According to an embodiment of the present invention, the Cr source is provided by a compound containing Cr; for example, provided by at least one of carbonates, oxides, chlorides, nitrates and sulfates containing Cr; preferably provided by oxides containing Cr (such as Cr ₂ O ₃ ).

According to an embodiment of the present invention, the near-infrared reflective pigment may be Bi ₃ Y _0.95 Cr _0.05 O ₆ , Bi ₃ Y _0.7 Cr _0.3 O ₆ , or Bi ₃ Y _0.5 Cr _0.5 O ₆ . Preferably, the colors of Bi ₃ Y _0.7 Cr _0.3 O ₆ and Bi ₃ Y _0.5 Cr _0.5 O ₆ are both brick red. Preferably, the color of Bi ₃ Y _0.95 Cr _0.05 O ₆ is orange-yellow.

The present invention also provides a method for preparing the above-mentioned near-infrared reflective pigment, comprising the following steps:

The near-infrared reflective pigment is obtained by using Bi source, Y source and Cr source as raw materials, mixing them according to the stoichiometric ratio of each element in the chemical formula Bi ₃ Y _1-x Cr _x O ₆ (0＜x≤0.5) and adopting solid phase sintering.

According to an embodiment of the present invention, the Bi source, Y source and Cr source have the meanings as described above.

According to an embodiment of the present invention, the temperature of the solid phase sintering is 700°C to 1000°C, exemplarily 700°C, 800°C, 900°C, 1000°C, preferably 900°C.

According to an embodiment of the present invention, the solid phase sintering time is 240 to 600 min, exemplified by 240 min, 360 min, 480 min, 600 min, and preferably 480 min.

According to an embodiment of the present invention, the heating rate of the solid phase sintering is 1 to 10°C/min, exemplified by 1°C/min, 5°C/min, 10°C/min, and preferably 10°C/min.

According to an embodiment of the present invention, before the solid phase sintering treatment, the step of grinding the raw material is also included. For example, the grinding can be wet grinding or ball milling; preferably, the medium used for grinding can be at least one of acetone, water and ethanol, preferably acetone. Preferably, the grinding time is 2 to 6 hours, such as 2 hours, 4 hours, 6 hours. Furthermore, the grinding speed is 200 to 600 rpn/min.

According to an embodiment of the present invention, the preparation method further comprises the step of drying the ground raw material. For example, the drying temperature is 40 to 60°C, exemplified by 40°C, 50°C, 60°C, and preferably 50°C. Further, the drying time can be 0.5 to 2 hours, exemplified by 0.5 hours, 1.5 hours, 2 hours, and preferably 1 hour.

According to an embodiment of the present invention, the preparation method further comprises, after solid phase sintering is completed, grinding the obtained calcined sample. Preferably, the average particle size of the calcined sample after grinding is 2 to 10 μm, preferably 3 to 8 μm, exemplified by 2 μm, 3 μm, 5 μm, 8 μm, 10 μm.

According to an exemplary embodiment of the present invention, the preparation method comprises the following steps: according to the stoichiometric ratio of each element in the chemical formula _{Bi3Y1 - xCrxO6} (0＜x≤0.5), weighing Bi source, Y source and Cr source in _sequence , adding grinding media (such as acetone) for grinding, then drying the ground mixture and solid-phase sintering it, _and grinding the obtained calcined sample again to obtain a near-infrared reflective pigment with uniform particle size.

The present invention also provides the application of the near-infrared reflective pigment in the fields of cosmetics, building materials, coatings, plastics, vehicles, ship decks, aerospace, oil tanks or inks.

Preferably, the near-infrared reflective pigment can be used in high-reflectivity coatings, such as for preparing chemical product storage tank coatings, vehicle and ship thermal insulation coatings, metal sheet thermal insulation coatings, communication base station thermal insulation coatings or building exterior wall coatings.

Beneficial effects of the present invention

The present invention prepares a _{Bi3Y1 - xCrxO6 inorganic} pigment with high near-infrared reflection. By changing the doping molar amount of Cr(III), the color of the pigment can be changed from light yellow to brick red. When the color of the pigment becomes darker, the near-infrared reflectivity of the pigment can still reach more than 90%. The pigment prepared by the present invention can be widely used in the fields of cosmetics, building exterior walls, ship decks, aviation and aerospace, oil tank storage tanks, etc., which can not only meet people's demand for color, but also be used as a cooling material. At the same time, the process of preparing the pigment by the present invention is simple, the equipment requirement is low, and industrial production can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an XRD spectrum of Bi ₃ Y _0.7 Cr _0.3 O ₆ prepared in Example 1 and Bi ₃ Y _0.5 Cr _0.5 O ₆ prepared in Example 2. FIG.

FIG. 2 is a near-infrared reflectivity spectra of Bi ₃ Y _0.7 Cr _0.3 O ₆ prepared in Example 1 and Bi ₃ Y _0.5 Cr _0.5 O ₆ prepared in Example 2. FIG.

Detailed ways

The technical scheme of the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that the following embodiments are only exemplary descriptions and explanations of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope that the present invention is intended to protect.

Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

In the following examples of the present invention, the purity of bismuth oxide and chromium oxide are both 99%, and both are purchased from Aladdin Reagent Co., Ltd. Yttrium oxide (99.99%) was purchased from Ganzhou Zhanhai New Material Technology Co., Ltd.

The structural characteristics of the synthesized samples were analyzed using a Rigaku X-ray diffractometer with a scanning range of 10°-80°, a scanning speed of 10°/min, a step length of 0.02°/s, and an operating voltage and current of 40 kV and 15 mA, respectively.

The near-infrared reflectivity of the pigment was measured using an Agilent 5000 UV-visible-near-infrared spectrophotometer from the United States. The reference white board was polytetrafluoroethylene (PTFE). The powder sample was placed in a transparent container for testing and measured in 1nm steps within the range of 200nm-2500nm. The solar reflectivity (R*) was calculated according to the G173-03 standard established by the American Society for Testing Materials and Chemicals (ASTM). The calculation formula is:

Where r(λ) and i(λ) represent the reflectivity and standard radiation intensity (W·m ^-2 ·nm ^-1 ) of the sample at wavelength λ, respectively.

The Hangzhou CS-580A spectrophotometer was used to record the color coordinates of the pigment samples. The light source was CLEDs. According to the CIE1976-L*a*b* colorimetric system of the International Commission on Illumination (CIE), the L* value represents the brightness of the sample, ranging from 0 (black) to 100 (white), where a* represents the red-green nature of the pigment, ranging from -128 to 128, with negative a* representing green and positive red; the b* value represents the blue-yellow nature of the pigment, ranging from -128 to 128, with negative b* representing blue and positive yellow. In addition to the Lab value, the parameter C* is also used to represent the color saturation of the pigment. The calculation formula for C* is: C*＝[(a*) ² +(b*) ² ] ^1/2 .

Example 1-2

Examples 1-2 use a solid phase sintering method to synthesize pigments. The difference between the examples lies in the amount of raw materials used. Table 1 lists the types and amounts of raw materials used in each example.

The high near-infrared reflective inorganic pigment has a chemical structural formula of Bi ₃ Y _1-x Cr _x O ₆ (x=0.3 or 0.5), and the specific preparation steps are as follows:

1) According to the stoichiometric ratio of each element in the chemical formula Bi ₃ Y _1-x Cr _x O ₆ (x=0.3 or 0.5), weigh a compound containing Bi element, a compound containing Y element and a compound containing Cr element respectively;

2) adding the mixed powder weighed in step 1) into a mortar, adding acetone and grinding until most of the acetone evaporates (the powder is not wet);

3) The powder in step 2) was transferred into a crucible, and then placed in an oven and dried at 50° C. for 1 h;

4) The powder in step 3) is transferred into a muffle furnace and heated to 900°C at a heating rate of 10°C/min, and then kept warm for 6 hours. The calcined sample finally obtained is taken out and ground evenly to obtain a pigment sample, and the average particle size of the pigment sample is 3 to 8 μm.

Table 1 Preparation parameters of Example 1-2

Example Pigment chemical formula Bi ₂ O ₃ (g) _{Y2O3 (} g) Cr ₂ O ₃ (g) Example 1 Bi ₃ Y _0.7 Cr _0.3 O ₆ 5 0.5653 0.1631 Example 2 Bi ₃ Y _0.5 Cr _0.5 O ₆ 5 0.4038 0.2718

Figures 1 and 2 show the structural properties and near-infrared reflectivity of the Bi ₃ Y _1-x Cr _x O ₆ pigment samples prepared in Example 1-2. As can be seen from Figure 1, a complete solid solution is formed after the pigment sample is calcined. As can be seen from Figure 2, the average near-infrared reflectivity of the pigment is higher than 90%. The color properties of the pigment tested by the colorimeter are Bi ₃ Y _0.7 Cr _0.3 O ₆ (L*＝48.21, a*＝34.31, b*＝31.75); Bi ₃ Y _0.5 Cr _0.5 O ₆ (L*＝49.13, a*＝37.92, b*＝30.47), indicating that the color of the pigment is brick red.

Example 3

The preparation method is the same as that of Example 1, except that: Bi ₂ O ₃ (5 g), Y ₂ O ₃ (0.7673 g), and Cr ₂ O ₃ (0.0272 g) are weighed according to the stoichiometric ratio, and a Bi ₃ Y _0.95 Cr _0.05 O ₆ pigment sample is prepared according to the method of Example 1. The near-infrared reflectivity thereof is measured to be 93%; the color performance test thereof is performed, and the result shows orange-yellow (L*=60.50, a*=31.37, b*=47.19), indicating that the color of the pigment is yellow.

The above is an explanation of the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (10)

1. The preparation method of the near infrared reflection pigment is characterized in that a Bi source, a Y source and a Cr source are used as raw materials, the raw materials are mixed according to the stoichiometric ratio of each element in a chemical formula Bi ₃Y_1-xCr_xO₆, and solid phase sintering is adopted to obtain the near infrared reflection pigment; the temperature of the solid phase sintering is 900-1000 ℃, and the time of the solid phase sintering is 480-600 min;

the chemical general formula of the pigment is as follows: bi ₃Y_1-xCr_xO₆, wherein:

Cr (III) is a doping element, and x represents the doping molar quantity of Cr (III), wherein x is more than 0 and less than or equal to 0.5;

When x is more than 0 and less than or equal to 0.05, the color of the near infrared reflecting pigment is a yellow color system; when x is more than 0.05 and less than or equal to 0.5, the color of the pigment is a brick red color system.

2. The method of claim 1, wherein the near infrared reflective pigment has an average particle diameter of 2 to 10 μm;

And/or, the near infrared reflective pigment has an average near infrared reflectance of greater than 90%.

3. The production method according to claim 1, wherein the Bi source is provided by at least one of a Bi element-containing carbonate, oxide, chloride, nitrate and sulfate;

the Y source is provided by at least one of carbonate, oxide, chloride, nitrate and sulfate containing Y element;

The Cr source is provided by at least one of a Cr element-containing carbonate, oxide, chloride, nitrate, and sulfate.

4. The preparation method of claim 2, wherein the near infrared reflective pigment has an average near infrared reflectance of 91-98%;

The near infrared reflective pigment is Bi₃Y_0.95Cr_0.05O₆、Bi₃Y_0.7Cr_0.3O₆、Bi₃Y_0.5Cr_0.5O₆.

5. The preparation method of claim 1, wherein the temperature rise rate of the solid phase sintering is 1-10 ℃/min.

6. The method of claim 1, further comprising the step of grinding the raw materials prior to the solid phase sintering process;

and/or the preparation method further comprises the step of drying the ground raw materials, wherein the drying temperature is 40-60 ℃, and the drying time is 0.5-2 hours;

And/or, the preparation method further comprises the step of grinding the prepared calcined sample after the solid-phase sintering is completed, wherein the average particle size of the ground calcined sample is 2-10 mu m.

7. The preparation method according to claim 6, wherein the preparation method comprises the steps of: sequentially weighing a Bi source, a Y source and a Cr source according to the stoichiometric ratio of each element in the chemical formula Bi ₃Y_1-xCr_xO₆, adding a grinding medium for grinding, then drying the ground mixture, performing solid-phase sintering treatment, and grinding the obtained calcined sample again to obtain the near infrared reflection pigment with uniform particle size.

8. Use of the near infrared reflective pigments produced by the production process of any of claims 1 to 7 in the fields of cosmetics, construction materials, paints, plastics, vehicles, ship decks, aerospace, tank storages or inks.

9. The use according to claim 8, wherein the near infrared reflective pigments are used in high reflectivity coatings.

10. The use according to claim 9, wherein the near infrared reflective pigment is used for the preparation of a chemical storage tank coating, a car and vessel insulation coating, a metal sheet insulation coating, a communication base station insulation coating or a building exterior wall coating.