Cobalt-free and nickel-free medium-temperature black pigment with high saturation chromatic value and preparation method of cobalt-free and nickel-free medium-temperature black pigment

Abstract

The invention discloses a cobalt-free nickel-free medium-temperature high-saturation black pigment based on an iron doping strategy and a preparation method thereof. The chemical general formula of the material is Na < 0.67 > Fe < x > Mn < 1-x > O < 2 >. Aiming at the problems of high cost and prominent environmental risk of the traditional cobalt-nickel-based black pigment, the technology initiates the preparation of the high-purity black pigment by taking cheap and harmless metal oxides such as sodium, iron and manganese as raw materials, accurately regulating and controlling the doping proportion (x = 0-0.5) of Fe < 3 + > and combining a solid-phase method process, and the material synthesis temperature is low. The pigment is mixed with ground color transparent slurry to prepare glaze, and the glaze slurry is coated on a sample made of high-whiteness clay by using a dipping technology. And air-drying the sample for 12 hours. And finally calcining at 1200 DEG C for 2 hours. After being calcined at a medium temperature (1200 DEG C), the pigment shows pure bright black with a high saturation chromatic value, and has excellent heat-resistant stability and chemical stability. The preparation process is simple, the energy consumption is low, the raw material cost is lower than that of a traditional cobalt-nickel-based pigment, and meanwhile heavy metal pollution is avoided. The pigment is particularly suitable for the fields of ceramic glazes, glass coloring, high-temperature coatings and the like, and can meet the requirements of environmental protection laws and regulations and remarkably reduce the production cost.

Description

Technical Field

[0001] The invention belongs to the technical field of material science and relates to a cobalt-free and nickel-free black pigment with a medium-temperature and high-saturation chromaticity value and a preparation method thereof. Background Art

[0002] As a basic functional material, black pigments are widely used in ceramic glazes, glass coloring, industrial coatings, plastic products and other fields. Their performance directly affects the color stability, durability and environmental adaptability of the final product. The core coloring components of traditional black pigments mostly rely on transition metal oxides such as cobalt (Co) and nickel (Ni) (such as Co3O4, NiO, etc.), such as classic spinel black pigments (CoFe2O4, NiFe2O4) or cobalt black (CoCr2O4). Cobalt is a commonly used colorant in black pigments. It is produced by Co 3+ / Co 2+ Cobalt absorbs visible light through electron transitions. However, cobalt resources are highly concentrated globally (primarily in regions like the Democratic Republic of the Congo), and the mining and refining process is energy-intensive and highly polluting. Furthermore, cobalt prices fluctuate widely, contributing to the high production costs of black ceramics. While nickel-based black pigments are slightly less expensive, nickel easily volatilizes at high temperatures and produces harmful gases (such as NiO), posing a potential threat to the environment and human health. Traditional black pigments typically require temperatures exceeding 1200°C to ensure sufficient reaction between the cobalt or nickel oxides and the matrix. However, high temperatures can lead to abnormal pigment particle growth, reducing light scattering efficiency and resulting in a dull, dark appearance. Furthermore, high-temperature sintering can increase the number of lattice oxygen vacancies, weakening the material's ability to absorb visible light and ultimately reducing color saturation. As global environmental regulations tighten, ceramic pigments containing cobalt and nickel face increasingly stringent restrictions in markets such as the EU and North America. For example, if cobalt migration exceeds 0.01% (by mass), it may be classified as a hazardous substance, leading to export restrictions. Therefore, the development of cobalt-free and nickel-free environmentally friendly black pigments with high saturation has become an urgent need in the industry. As a transition metal abundant in the earth's crust, iron has the advantages of low cost (only 1 / 10 of cobalt) and renewable resources. 3+ / Fe 2 + ) can form a synergistic effect with manganese (Mn), providing a new idea for replacing cobalt and nickel. 3+ d electrons (3d 5 ) and the d electrons (3d 4 / 3d 3) can significantly enhance the material's ability to absorb visible light through charge transfer interactions. Iron is non-toxic and naturally degradable, and its oxides (such as Fe2O3) are widely used in food, medicine and other fields, which is in line with the concept of green manufacturing. In addition, the supply chain of iron raw materials is stable, and the global annual output exceeds 1.5 billion tons, which can guarantee large-scale production needs. Therefore, this research and development result can not only effectively alleviate the cost pressure caused by resource shortages and reduce the production costs of pigment manufacturers, but also fundamentally reduce pollution to the environment and promote the industry to develop in a green and sustainable direction. At the same time, it meets the market demand for high-quality pigments, provides strong support for product upgrades in many fields such as construction and industrial equipment, and has huge economic value and social significance. Summary of the Invention

[0003] Aiming at the problem that cobalt and nickel metals exist in black pigments and the chromaticity value is insufficient, the present invention provides a cobalt-free and nickel-free black pigment with medium temperature and high saturation chromaticity value and a preparation method thereof.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A cobalt-free and nickel-free black pigment material with high saturation chromaticity value at medium temperature, with the chemical formula of Na 0.67 Fe x Mn 1-x O2, x=0-0.5. The method for preparing a cobalt-free and nickel-free black pigment with a medium temperature and high saturation chromaticity value comprises the following steps:

[0006] (1) Raw material mixing: The raw materials are corresponding oxides or carbonates. The valence of iron in the iron source must be trivalent, and the valence of manganese in the manganese source must be tetravalent. The raw materials are mixed in an agate mortar.

[0007] (2) Grinding and mixing: Add 3-5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 30-60 minutes to mix evenly.

[0008] (3) Calcination: The mixed powder obtained in step (2) is calcined. The calcination temperature is 500-700°C, the heating rate is 5-10°C / min below 700°C, the holding time is 4-8 hours, the atmosphere is air, and the cooling rate is 2-5°C / min above 200°C and below 200°C.

[0009] The present invention aims to solve the problems of high cost and prominent environmental risks of traditional cobalt-nickel based black pigments. This technology is the first to use cheap and harmless metal oxides such as sodium, iron and manganese as raw materials. By precisely controlling Fe 3+The doping ratio is combined with the solid-phase process to prepare a high-purity black pigment, and the material synthesis temperature is low. The pigment is mixed with a base color transparent slurry to prepare a glaze, and the glaze slurry is applied to a sample made of high-white clay using an impregnation technique. The sample is air-dried for 12 hours. Finally, it is calcined at 1200°C for 2 hours. After calcination at medium temperature (1200°C), the pigment exhibits a pure bright black color with a high saturation chromaticity value and has excellent heat resistance and chemical stability. Its preparation process is simple, energy consumption is low, and the raw material cost is lower than that of traditional cobalt-nickel based pigments, while avoiding heavy metal pollution. The pigment of the present invention is particularly suitable for ceramic glazes, glass coloring, high-temperature coatings and other fields, can meet the requirements of environmental protection regulations and significantly reduce production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is Na prepared in Example 1 of the present invention 0.67 UV absorption spectrum of MnO2 pigment.

[0011] Figure 2 It is Na prepared in Example 1 of the present invention 0.67 UV absorption spectrum of MnO2 pigment after glazing.

[0012] Figure 3 It is Na prepared in Example 1 of the present invention 0.67 Appearance of MnO2 pigment.

[0013] Figure 4 It is Na prepared in Example 1 of the present invention 0.67 The appearance of MnO2 pigment after glazing.

[0014] Figure 5 It is Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 XRD pattern of O2 pigment.

[0015] Figure 6 It is Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 UV absorption spectrum of O2 pigment.

[0016] Figure 7 It is Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 UV absorption spectrum of O2 pigment after glazing.

[0017] Figure 8 It is Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 Appearance of O2 pigment.

[0018] Figure 9 It is Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 The appearance of O2 color after glazing.

[0019] Figure 10 It is Na prepared in Example 3 of the present invention 0.67 Fe 0.5 Mn 0.5 UV absorption spectrum of O2 pigment.

[0020] Figure 11 It is Na prepared in Example 3 of the present invention 0.67 Fe 0.5 Mn 0.5 UV absorption spectrum of O2 pigment after glazing. DETAILED DESCRIPTION

[0021] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0022] The chemical reagents used in the examples of the present invention are all analytical grade products; the examples are analyzed using a RINT2200V / PC X-ray diffractometer from Rigaku, Japan;

[0023] Example 1

[0024] (1) Weighing of raw materials: Na2CO3 and MnO2. Mix all weighed raw materials in an agate mortar.

[0025] (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly.

[0026] (3) Calcination: The mixed powder obtained in step (2) is calcined. The calcination temperature is 500°C, the heating rate is 6°C / min below 700°C, the holding time is 8 hours, the atmosphere is air, the cooling rate is 2°C / min above 200°C, and the temperature below 200°C is cooled to room temperature in the furnace to obtain Na 0.67 MnO2 sample. The UV absorption and appearance of the obtained sample are shown in the attached Figure 1-4 The chromaticity values of the samples are shown in Table 1.

[0027] Table 1 is the Na prepared in Example 1 of the present invention 0.67 Chromaticity value of MnO2 pigment.

[0028]

[0029] from Figure 1-2 You can see Na 0.67The MnO2 sample has strong absorption in the entire visible light range, which also explains why the sample appears bright black. Figure 3-4 Shows Na 0.67 The MnO2 pigment and glaze exhibit a bright black color. The chromaticity parameter L* in Table 1 is 17.07, which is significantly superior to other black pigments available on the market and reported in the literature.

[0030] Example 2

[0031] (1) Weighing of raw materials: Na2CO3, Fe2O3, and MnO2. Mix all weighed raw materials in an agate mortar.

[0032] (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly.

[0033] (3) Calcination: The mixed powder obtained in step (2) is calcined. The calcination temperature is 600°C, the heating rate is 6°C / min below 700°C, the holding time is 6 hours, the atmosphere is air, the cooling rate is 2°C / min above 200°C, and the temperature below 200°C is cooled to room temperature in the furnace to obtain Na 0.67 Fe 0.1 Mn 0.9 O2 sample. The sample's phase structure, UV-visible absorption characteristics and macroscopic morphology are shown in the attached Figure 5-9 The chromaticity parameters are shown in Table 2.

[0034] Table 2 is the Na prepared in Example 2 of the present invention 0.67 Fe 0.1 Mn 0.9 Chromaticity value of O2 colorant.

[0035]

[0036] XRD patterns ( Figure 5 ) confirmed that the product was a single phase without interference from other peaks; UV-visible absorption spectrum ( Figure 6-7 ) shows that the sample has a strong absorption characteristic in the entire visible light region of 400-700nm, and the absorption intensity of the glaze is higher than that of the pigment itself. Figure 8-9 Shows Na 0.67 Fe 0.1 Mn 0.9 Photos of the O2 pigment and its glaze show a uniform, bright black hue. According to the data in Table 2, the pigment's CIE Lab chromaticity values are L* = 14.66, a* = 1.95, and b* = -0.79. Its overall blackness index (L* = 14.66) significantly outperforms most black pigments reported in the literature (such as CoFe2O4, which has an L* of ≈ 22.3), reaching internationally leading levels.

[0037] Example 3

[0038] (1) Weighing of raw materials: Na2CO3, Fe2O3, and MnO2. Mix all weighed raw materials in an agate mortar.

[0039] (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly.

[0040] (3) Calcination: The mixed powder obtained in step (2) is calcined. The calcination temperature is 700°C, the heating rate is 6°C / min below 700°C, the holding time is 4 hours, the atmosphere is air, the cooling rate is 2°C / min above 200°C, and the temperature below 200°C is cooled to room temperature in the furnace to obtain Na 0.67 Fe 0.5 Mn 0.5 O2 sample. The UV absorption of the obtained sample is as shown in the attached Figure 10-11 The chromaticity values of the samples are shown in Table 3.

[0041] Table 3 is the Na prepared in Example 3 of the present invention 0.67 Fe 0.5 Mn 0.5 Chromaticity value of O2 colorant.

[0042]

[0043] UV-visible absorption spectrum ( Figure 10-11 ) shows that the samples have strong absorption in the visible light region of 400-700nm. The chromaticity parameters are shown in Table 3. Its comprehensive blackness index L*=18.40 is still better than most black pigments.

Claims

1. A cobalt-free and nickel-free black pigment with a medium temperature and high saturation chromaticity value, characterized in that: The expression of the black pigment is Na 0.67 Fe x Mn 1-x O2, the value of x is 0~0.

5.

2. The method for preparing the cobalt-free and nickel-free medium-temperature high-saturation chromaticity black pigment according to claim 1, comprising the following steps: (1) Mixing raw materials: The raw materials are corresponding oxides or carbonates, the valence of iron in the iron source must be positive trivalent, and the valence of manganese in the manganese source must be positive tetravalent. The raw materials are mixed in an agate mortar according to the proportions described in claim 1; (2) Grinding and mixing: Add 3-5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 30-60 minutes to mix evenly; (3) Calcination: Calcinate the mixed powder obtained in step (2); the calcination temperature is 500-700°C, the heating rate is 5-10°C / min below 700°C, the holding time is 4-8h, the atmosphere is air, and the cooling rate is 2-5°C / min above 200°C and furnace cooling below 200°C.

3. The preparation method according to claim 2, characterized in that step: (1) Raw material mixing: x is 0, and the raw materials used are Na2CO3 and MnO2; the raw materials are mixed in an agate mortar; (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly. (3) Calcination: The mixed powder obtained in step (2) was calcined at a temperature of 500°C to obtain Na 0.67 MnO2 samples; During calcination, the heating rate was 6°C / min below 700°C, the holding time was 8h, and the atmosphere was air; During calcination, the cooling rate is: 2℃ / min above 200℃, and cool to room temperature with the furnace below 200℃.

4. The preparation method according to claim 2, wherein: (1) Raw material mixing: x is greater than 0 and less than 0.5, and the raw materials used are Na2CO3, Fe2O3 and MnO2; all weighed raw materials are mixed in an agate mortar; (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly; (3) Calcination: The mixed powder obtained in step (2) was calcined at a temperature of 600°C to obtain Na 0.67 Fe 0.1 Mn 0.9 O2 sample; Heating rate during calcination: below 700°C, 6°C / min, holding time is 6h, atmosphere is air; During calcination, the cooling rate is: 2℃ / min above 200℃, and cool to room temperature with the furnace below 200℃.

5. The preparation method according to claim 2, characterized in that , follow these steps: (1) Raw material mixing: x is greater than 0 and less than 0.5, and the raw materials used are Na2CO3, Fe2O3 and MnO2; all weighed raw materials are mixed in an agate mortar; (2) Grinding and mixing: Add 5 ml of alcohol to the powdered raw materials mixed in step (1) and grind for 60 minutes to mix evenly; (3) Calcination: The mixed powder obtained in step (2) was calcined at a temperature of 700°C to obtain Na 0.67 Fe 0.5 Mn 0.5 O2 sample; During calcination, the heating rate is 6°C / min below 700°C, the holding time is 4h, and the atmosphere is air; During calcination, the cooling rate is: 2℃ / min above 200℃, and cool to room temperature with the furnace below 200℃.

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