CN115196678A - A kind of chromium (III) doped high near-infrared reflection inorganic pigment and its preparation method and application - Google Patents

Abstract

The invention discloses a chromium (III)-doped inorganic pigment with high near-infrared reflection and a preparation method and application thereof. The chemical formula of the pigment is Bi ₃ Y _1-x Cr _x O ₆ (0<x≤0.5), and the The invention can change the color of the pigment from light yellow to brick red by changing the doping amount of Cr(III), and still have a high near-infrared reflectance (higher than 90 when the color of the pigment becomes darker to dark brick red). %) to effectively reflect solar radiation energy. The pigment prepared by the invention can be widely used in cosmetics, building exterior walls, ship decks, aerospace, oil tank storage tanks and other fields (for example, for the preparation of chemical product storage tank coatings, vehicle and ship thermal insulation coatings, metal plate thermal insulation coatings, Communication base station thermal insulation coating, building exterior wall coating, etc.) to meet people's demand for color, and as a cool material. At the same time, the process for preparing the pigment is simple, the equipment requirement is low, and the industrialized production can be realized.

Description

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

technical field

The invention belongs to the field of inorganic oxide pigments, in particular to a high near-infrared reflection 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 in short supply, which has inspired many researchers to develop and utilize solar energy. However, sunlight can also generate energy radiation to buildings, and the excessive heat accumulated on the surface of buildings can even cause a "heat island effect", which brings a lot of inconvenience to human life. In order to balance the bad cycle caused by the "heat island effect", additional energy is bound to 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 saving concepts. One of the directions is the preparation of special near-infrared reflective inorganic pigments. This kind of pigment is a new type of energy-saving and environmentally friendly material, which can reflect most of the near-infrared radiation, so it has a high solar reflectance. The finished coating can be applied on the surface of the object to achieve obvious heat insulation and cooling effect. Therefore, the above coatings can be used for the interior and exterior walls of buildings in areas that are hot in summer and cold in winter, so as 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, thereby reducing the use of cooling equipment such as air conditioners. In order to alleviate the urban "heat island effect" and save energy, so as to realize the sustainable development strategy of energy.

In recent years, the research and development of high near-infrared reflective materials has attracted extensive attention of a large number of scholars. At the same time, under the guidance of the concept of green environmental protection, high solar reflective pigments are developing rapidly. Compared with organic pigments, inorganic pigments show greater advantages in chemical 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 at present, but it is limited by a single color, so it cannot meet people's requirements for visual enjoyment and color performance. Various color pigments have also emerged. At present, yellow pigments are the most reported inorganic pigments. For example, Indian experts reported a series of bismuth vanadate-based (BiVO ₄ -CaMoO ₄ , (LiLaZn) 1/3 MoO 4 -BiVO 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 better color properties and higher near-infrared reflection properties. Chinese researchers have also developed a series of color pigments. For example, Han Aijun's research group developed high-reflection color pigments such as bright red mica/γ-Ce _2-x Y _x S ₃ and orange-yellow Fe-doped LaAlO ₃ . However, studies on red-like inorganic pigments are rare. At present, red inorganic pigments mainly include iron oxide red, 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 will cause harm to human health; and cerium sulfide pigment has good color performance, but its preparation process is complicated and the cost is high. It is mostly used in high-end cosmetics. Therefore, how to develop a red-like pigment with good color performance, low cost and simple preparation process has become an urgent technical problem to be solved.

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), 0<x≤0.5.

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

In the present invention, the color of the pigment can be changed 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 near-infrared reflective pigment has an average particle size of 2-10 μm, preferably 3-8 μm, exemplarily 2 μm, 3 μm, 5 μm, 8 μm, 10 μm.

According to an embodiment of the present invention, the average near-infrared reflectance of the near-infrared reflective pigment is greater than 90%, such as 91-98%, exemplarily 92%, 93%, 95%, 98%.

According to an embodiment of the present invention, the near-infrared reflective pigment is prepared from raw materials including Bi source, Y source, and 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 element. For example, it is provided by at least one of carbonates, oxides, chlorides, nitrates, and sulfates containing Bi elements; preferably, it is provided by oxides containing Bi elements (eg, Bi ₂ O ₃ ).

According to an embodiment of the present invention, the Y source is provided by a compound containing Y element; for example, provided by at least one of carbonate, oxide, chloride, nitrate and sulfate containing Y element; preferably by Oxides containing Y element (eg Y ₂ O ₃ ) are provided.

According to an embodiment of the present invention, the Cr source is provided by a Cr-containing compound; for example, by at least one of a Cr-containing carbonate, oxide, chloride, nitrate and sulfate; preferably by Oxides containing Cr element (eg Cr ₂ O ₃ ) are provided.

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 , 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 preparation method of the above-mentioned near-infrared reflective pigment, comprising the following steps:

Using Bi source, Y source and Cr source as raw materials, mixing 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 to obtain the near-infrared Reflective paint.

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 240-600 min, exemplarily 240 min, 360 min, 480 min, 600 min, preferably 480 min.

According to an embodiment of the present invention, the heating rate of the solid phase sintering is 1-10°C/min, exemplarily 1°C/min, 5°C/min, 10°C/min, 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 further included. For example, the grinding can be wet grinding or ball grinding; preferably, the medium used for grinding can be at least one of acetone, water and ethanol, preferably acetone. Preferably, the grinding time is 2-6h, for example, 2h, 4h, 6h. Further, the rotational speed of the grinding is 200-600 rpn/min.

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

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

According to an exemplary embodiment of the present invention, the preparation method includes the steps _of : _{sequentially weighing} the _{Bi source} , Y source and Cr source are added with grinding media (eg acetone) for grinding, then the ground mixture is dried and solid-phase sintered, and the obtained calcined sample is ground again to obtain near-infrared reflective pigments with uniform particle size.

The present invention also provides applications of the above-mentioned near-infrared reflective pigments in the fields of cosmetics, building materials, coatings, plastics, vehicles, ship decks, aerospace, oil storage tanks or inks and the like.

Preferably, the near-infrared reflective pigment can be used for coatings with high reflectivity, for example, for the preparation of 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, etc. .

The beneficial effects of the present invention

The invention prepares a Bi ₃ Y _1-x Cr _x O ₆ 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. And when the color of the pigment becomes darker, the near-infrared reflectance of the pigment can still reach more than 90%. The pigment prepared by the invention can be widely used in the fields of cosmetics, building exterior walls, ship decks, aerospace, oil tank storage tanks, etc., and can not only meet people's demand for color, but also be used as a cool material. At the same time, the process for preparing the pigment is simple, the equipment requirement is low, and the industrialized production can be realized.

Description of drawings

1 is the XRD patterns of the Bi ₃ Y _0.7 Cr _0.3 O ₆ prepared in Example 1 and the Bi ₃ Y _0.5 Cr _0.5 O ₆ pigment prepared in Example 2.

2 is a near-infrared reflectance spectrum of the Bi ₃ Y _0.7 Cr _0.3 O ₆ prepared in Example 1 and the Bi ₃ Y _0.5 Cr _0.5 O ₆ pigment prepared in Example 2.

Detailed ways

The technical solutions of the present invention will be described in further detail below with reference to specific embodiments. It should be understood that the following examples are only for illustrating and explaining the present invention, and should not be construed as limiting the protection scope of the present invention. All technologies implemented based on the above content of the present invention are covered within the intended protection scope of the present invention.

Unless otherwise stated, the starting 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 by Japanese Rigaku X-ray diffractometer, scanning range: 10°-80°, scanning speed: 10°/min, step size: 0.02°/s, operating voltage and current were 40kV and 15mA, respectively.

The near-infrared reflection properties of the pigments were measured using an Agilent 5000 UV-Vis-NIR spectrophotometer. The reference white plate was polytetrafluoroethylene (PTFE). The powder samples were placed in a transparent container for testing at 200nm-2500nm. Measured in steps of 1 nm. The solar reflectance (R*) is calculated according to the G173-03 standard formulated by the American Society for Testing and Materials (ASTM), and the calculation formula is:

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

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* chromaticity system regulations of the International Commission on Illumination (CIE), the L* value represents the sample. The brightness ranges from 0 (black) to 100 (white), where a* represents the red-green nature of the pigment, ranging from -128 to 128, a negative value a* represents green, a positive value represents red; b* The value represents the blue-yellow property of the pigment, and the value ranges from -128 to 128. The negative value b* represents blue, and the positive value represents yellow. In addition to the Lab value, the parameter C* is also used to represent the color saturation of the pigment. The calculation formula is: C*=[(a*) ² +(b*) ² ] ^1/2 .

Example 1-2

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

High near-infrared reflection inorganic pigment, its chemical structural formula is 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), respectively weigh the compound containing Bi element, the compound containing Y element and the compound containing Cr element;

2) Add the mixed powder weighed in step 1) into a mortar, add acetone and grind until most of the acetone is volatilized (the powder is not wet);

3) Transfer the powder in step 2) into a crucible, then put it into an oven, and dry it at 50°C for 1 hour;

4) Move the powder in step 3) into a muffle furnace and heat it up to 900°C at a heating rate of 10°C/min, and then keep the temperature for 6 hours. The final calcined sample is taken out and ground evenly to obtain a pigment sample. The average particle size of the pigment sample is 3～8μm.

Table 1 Example 1-2 Preparation Parameters

Example Pigment chemical formula Bi₂O₃(g) Y₂O₃(g) Cr₂O₃(g) Example 1 Bi₃Y_0.7Cr_0.3O₆ 5 0.5653 0.1631 Example 2 Bi₃Y_0.5Cr_0.5O₆ 5 0.4038 0.2718

Figures 1 and 2 show the structural properties and near-infrared reflection properties of the Bi ₃ Y _1-x Cr _x O ₆ pigment samples prepared in Examples 1-2. As can be seen in Figure 1, the pigment sample formed a complete solid solution after calcination. As can be seen in Figure 2, the average NIR reflectance of the pigment is higher than 90%. The color properties of the pigments 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 pigment color is brick red.

Example 3

The preparation method is the same as that of Example 1, except that Bi ₂ O ₃ (5g), Y ₂ O ₃ (0.7673g), Cr ₂ O ₃ (0.0272g) were weighed by stoichiometric ratio, and the same method was used in Example 1. The method of preparing Bi ₃ Y _0.95 Cr _0.05 O ₆ pigment samples. The near-infrared reflectance was measured to be 93%; the color property test was carried out, and the result was orange-yellow (L*=60.50, a*=31.37, b*=47.19), indicating that the color of the pigment is yellow.

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

Claims (10)

1. A near-infrared reflective pigment, characterized in that said pigment has the general chemical formula: bi ₃ Y _1-x Cr _x O ₆ Wherein:

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

For example, 0 < x.ltoreq.0.05 or 0.05 < x.ltoreq.0.5.

Preferably, when the near-infrared reflection pigment has x of more than 0 and less than or equal to 0.05, the color of the pigment is yellow; when x is more than 0.05 and less than or equal to 0.5, the color of the pigment is brick red.

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

Preferably, the near infrared reflective pigment has an average near infrared reflectance of greater than 90%, such as from 91 to 98%.

3. The near-infrared reflective pigment according to claim 1 or 2, wherein the near-infrared reflective pigment is prepared from raw materials comprising a Bi source, a Y source, and a Cr source by a solid-phase sintering method.

4. The near-infrared reflective pigment of claim 3, wherein the source of Bi is provided by a compound comprising a Bi element. For example, by at least one of a carbonate, an oxide, a chloride, a nitrate and a sulfate of the Bi-containing element.

Preferably, the Y source is provided by a compound containing the Y element; for example, by at least one of a carbonate, an oxide, a chloride, a nitrate, and a sulfate containing the element Y.

Preferably, the source of Cr is provided by a compound containing a Cr element; for example, by at least one of a carbonate, an oxide, a chloride, a nitrate, and a sulfate of a Cr-containing element.

5. The near-infrared reflective pigment according to any one of claims 1 to 4, wherein the near-infrared reflective pigment is Bi ₃ Y _0.95 Cr _0.05 O ₆ 、Bi ₃ Y _0.7 Cr _0.3 O ₆ 、Bi ₃ Y _0.5 Cr _0.5 O ₆ 。

6. The process for preparing a near-infrared reflective pigment according to any one of claims 1 to 5, characterized in that the process comprises the steps of:

bi source, Y source and Cr source are used as raw materials, and Bi is expressed by a chemical formula ₃ Y _1-x Cr _x O ₆ And (x is more than 0 and less than or equal to 0.5), and the near-infrared reflection pigment is obtained by solid-phase sintering.

Preferably, the Bi, Y and Cr sources all have the meaning as defined in claim 4.

7. The method of claim 6, wherein the temperature of the solid phase sintering is 700 ℃ to 1000 ℃.

Preferably, the time for solid phase sintering is 240-600 min.

Preferably, the temperature rise rate of the solid-phase sintering is 1-10 ℃/min.

8. The method according to claim 6 or 7, further comprising a step of grinding the raw material before the solid-phase sintering treatment.

Preferably, the preparation method further comprises a step of drying the ground raw material. For example, the drying temperature is 40 to 60 ℃, and the drying time can be 0.5 to 2 hours.

Preferably, the preparation method further comprises the step of grinding the prepared calcined sample after the solid-phase sintering is completed. Preferably, the average particle size of the calcined sample after grinding is 2 to 10 μm.

9. The method of any one of claims 6 to 8, comprising the steps of: according to the formula Bi ₃ Y _1-x Cr _x O ₆ (x is more than 0 and less than or equal to 0.5), sequentially weighing a Bi source, a Y source and a Cr source, adding a grinding medium for grinding, 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.

10. Use of the near-infrared reflective pigment according to any one of claims 1 to 5 and/or the near-infrared reflective pigment produced by the production process according to any one of claims 6 to 9 in the fields of cosmetics, building materials, coatings, plastics, vehicles, ship decks, aerospace, tank tanks or inks, and the like.

Preferably, the near-infrared reflection pigment can be used for high-reflectivity coatings, such as coatings for preparing chemical storage tanks, thermal insulation coatings for vehicles and ships, thermal insulation coatings for metal plates, thermal insulation coatings for communication base stations or coatings for building exterior walls.

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