Kaolinite-based cobalt blue inorganic composite pigment and preparation method thereof

Abstract

The invention provides a kaolinite-based cobalt blue inorganic composite pigment and a preparation method thereof, and the kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate, the preparation method of the kaolinite-based cobalt blue inorganic composite pigment specifically comprises the following steps: (1) preparing a precursor through wet mechanical ball milling: mixing a cobalt source, an aluminum source, kaolinite and an alkaline regulator, adding the mixture into a ball milling tank, and then adding grinding balls and a grinding aid into the ball milling tank for ball milling; (2) centrifuging, washing and drying a precursor obtained after ball milling; and (3) grinding and dispersing the precursor, and calcining in a muffle furnace to obtain the kaolinite-based cobalt blue inorganic composite pigment. According to the technical scheme, alkaline wastewater is basically not generated, the method is green and environment-friendly, the consumption of a cobalt source is reduced, the production cost is reduced, the dispersity of CoAl2O4 particles is improved, the chromatic value of the cobalt blue pigment is improved, and meanwhile, the material dispersion degree and the grinding efficiency are improved by adding the grinding aid.

Description

Technical Field

[0001] The invention relates to the technical field of nano-spinel composite pigments, and in particular to a kaolinite-based cobalt blue inorganic composite pigment and a preparation method thereof. Background Art

[0002] Synthetic cobalt blue (CoAl2O4) is a metal oxide mixed-phase pigment with a spinel structure. Compared with other blue inorganic pigments, cobalt blue pigment has better color performance and physical and chemical stability. Therefore, it is widely used as a colorant in coatings, glass, ceramics, papermaking, plastics and other fields. However, due to the scarcity of cobalt resources, the manufacturing cost of high-end cobalt blue pigments has remained high. In addition, the main production methods of cobalt blue are currently solid-phase method and liquid-phase method. Among them, the solid-phase method has problems such as high calcination temperature (>1300℃), high energy consumption, and serious agglomeration of particles in the product, while the liquid-phase method has shortcomings such as complex process flow, low product output, and the generation of a large amount of alkaline wastewater causing environmental pollution. Summary of the invention

[0003] According to the technical problems existing in the existing production methods of cobalt blue pigments mentioned above, a kaolinite-based cobalt blue inorganic composite pigment and a preparation method thereof are provided. The kaolinite-based cobalt blue inorganic composite pigment is prepared by wet mechanical ball milling combined with a calcination process. The kaolinite-based cobalt blue inorganic composite pigment has the advantages of simple and efficient preparation process, basically no alkaline wastewater generation, and green environmental protection. At the same time, the addition of a grinding aid helps to improve the dispersion degree of the material and improve the grinding efficiency. In addition, since kaolinite has abundant reserves, low prices, and the characteristics of large specific surface area, good stability and strong adsorption capacity, the cobalt blue inorganic composite pigment prepared by the present invention using kaolinite as a base material reduces the amount of cobalt source required for the preparation of high-end cobalt blue pigments, reduces the preparation and production costs, and improves the dispersibility of CoAl2O4 particles, thereby improving the chromaticity value of the cobalt blue pigment.

[0004] The technical means adopted by the present invention are as follows:

[0005] A method for preparing a kaolinite-based cobalt blue inorganic composite pigment, wherein the kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate, and the method for preparing the kaolinite-based cobalt blue inorganic composite pigment specifically comprises the following steps:

[0006] (1) Preparing the precursor by wet mechanical ball milling: a cobalt source, an aluminum source, kaolinite and an alkaline adjuster are mixed and added to a ball mill, and then grinding balls and a grinding aid are added to the ball mill, and the ball mill is placed in a ball mill for ball milling;

[0007] (2) centrifuging, washing and drying the precursor obtained after ball milling;

[0008] (3) Grinding and dispersing the dried precursor, and calcining it in a muffle furnace for a certain period of time to obtain the kaolinite-based cobalt blue inorganic composite pigment.

[0009] Furthermore, the cobalt source is at least one of cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate and cobalt oxalate; the aluminum source is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; 2+ With Al 3+ The molar ratio of the alkaline regulator to the cobalt source is 0.08 to 0.56; the alkaline regulator is sodium carbonate; the alkaline regulator and the sodium carbonate in the cobalt source and the Co 2+ The molar ratio is 3 to 4.75; the mass ratio of the added amount of kaolinite to the theoretically generated CoAl2O4 particles is 0.2 to 1.2.

[0010] Furthermore, the grinding aid is anhydrous ethanol.

[0011] Furthermore, the ball mill is one of a vertical planetary ball mill, a horizontal planetary ball mill and an omnidirectional planetary ball mill.

[0012] Furthermore, the calcination temperature is 800-1100° C., and the calcination time is 2 hours.

[0013] Further, step (1) specifically comprises: mixing cobalt nitrate, aluminum nitrate, kaolinite and sodium carbonate and adding the mixture into a zirconia ball mill, then adding zirconia balls and anhydrous ethanol into the zirconia ball mill at a ball-to-material ratio of 10:1 to 30:1, placing the zirconia ball mill in a ball mill and grinding at 1000 rpm for 4 hours to obtain a precursor;

[0014] Step (2) specifically comprises: adding 8 mL of deionized water to the zirconia ball mill after the reaction is completed, stirring and taking out the precursor in the zirconia ball mill, repeating three times; then centrifuging the taken out precursor, washing it three times with deionized water, and drying it in a forced air drying oven at 60° C. for 18 hours;

[0015] Step (3) specifically comprises: grinding and dispersing the dried precursor in an agate mortar, and then calcining it in a muffle furnace to finally obtain the kaolinite-based cobalt blue inorganic composite pigment.

[0016] The present invention also provides a kaolinite-based cobalt blue inorganic composite pigment, which is prepared by the above-mentioned preparation method. The kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate, wherein the CoAl2O4 particles are prepared by mixing Co in a cobalt source and an aluminum source. 2+ and Al 3+The precursor precipitated during the wet mechanical ball milling process is calcined and crystallized, and is uniformly loaded on the surface of the kaolinite substrate. The kaolinite substrate is in the form of amorphous agglomerates formed after wet mechanical ball milling and calcination. The chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is b * The value can reach -49.92 to -42.74.

[0017] Furthermore, the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is * The value can reach -49.92.

[0018] Furthermore, the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment can reach: L * :54.98~58.64、C * :42.74~50.12、a * :0.63~4.5.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] 1. The preparation method of the kaolinite-based cobalt blue inorganic composite pigment provided by the present invention adopts wet mechanical ball milling combined with calcination process to prepare the kaolinite-based cobalt blue inorganic composite pigment. The process flow is simple and efficient, and does not produce a large amount of alkaline wastewater, which is green and environmentally friendly. At the same time, the addition of grinding aids helps to improve the dispersion degree of materials and improve grinding efficiency.

[0021] 2. The kaolinite-based cobalt blue inorganic composite pigment and preparation method thereof provided by the present invention use cheap and abundant kaolinite as the base material to load CoAl2O4 particles, which can effectively reduce the required amount of cobalt source, reduce the preparation and production costs, improve the dispersibility of CoAl2O4 particles, improve the chromaticity value of the product, and realize the high-value and efficient utilization of kaolinite.

[0022] Based on the above reasons, the present invention can be widely promoted in the field of cobalt blue pigment production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1 This is a comparison chart of the chromaticity values ​​of the single CoAl2O4 cobalt blue pigment obtained in Comparative Example 1 and the kaolinite-based cobalt blue inorganic composite pigments obtained in Examples 1-5.

[0025] Figure 2 This is the XRD spectrum of the kaolinite-based cobalt blue inorganic composite pigment obtained in Example 1-5.

[0026] Figure 3 This is a SEM photograph of the single CoAl2O4 cobalt blue pigment obtained in Comparative Example 1.

[0027] Figure 4 This is a SEM photograph of the kaolinite-based cobalt blue inorganic composite pigment obtained in Example 4.

[0028] Figure 5 This is a reflection spectrum diagram of the kaolinite-based cobalt blue inorganic composite pigment obtained in Examples 1-5 in the visible light range. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] The present invention provides a method for preparing a kaolinite-based cobalt blue inorganic composite pigment. The kaolinite-based cobalt blue inorganic composite pigment consists of spinel CoAl2O4 particles and a kaolinite substrate. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment specifically comprises the following steps:

[0031] (1) Preparing the precursor by wet mechanical ball milling: a cobalt source, an aluminum source, kaolinite and an alkaline adjuster are mixed and added to a ball mill, and then grinding balls and a grinding aid are added to the ball mill, and the ball mill is placed in a ball mill for ball milling;

[0032] (2) centrifuging, washing and drying the precursor obtained after ball milling;

[0033] (3) Grinding and dispersing the dried precursor, and calcining it in a muffle furnace for a certain period of time to obtain the kaolinite-based cobalt blue inorganic composite pigment.

[0034] Furthermore, the cobalt source is at least one of cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate and cobalt oxalate; the aluminum source is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; 2+ With Al 3+ The molar ratio is 0.08 to 0.56.

[0035] Furthermore, the alkaline adjusting agent is sodium carbonate; the alkaline adjusting agent and the sodium carbonate in the cobalt source and the Co 2+ The molar ratio is 3 to 4.75.

[0036] Furthermore, the mass ratio of the amount of kaolinite added to the theoretically generated CoAl2O4 particles is 0.2 to 1.2, and the mass of the theoretically generated CoAl2O4 particles is calculated based on the amount of cobalt source and aluminum source added.

[0037] Furthermore, the grinding aid is anhydrous ethanol.

[0038] Furthermore, the ball mill is one of a vertical planetary ball mill, a horizontal planetary ball mill and an omnidirectional planetary ball mill.

[0039] Furthermore, the calcination temperature is 800-1100° C., and the calcination time is 2 hours.

[0040] Preferably, the calcination temperature is 1100°C.

[0041] Furthermore, step (1) specifically comprises: mixing cobalt nitrate, aluminum nitrate, kaolinite and sodium carbonate and adding the mixture into a zirconia ball mill; then adding zirconium oxide balls and anhydrous ethanol into the zirconia ball mill at a ball-to-material ratio of 10:1 to 30:1; placing the zirconia ball mill in a ball mill and grinding at 1000 rpm for 4 hours; wherein the molar ratio of cobalt nitrate to aluminum nitrate is 0.08 to 0.56; the molar ratio of sodium carbonate to cobalt nitrate is 3 to 4.75; and the mass ratio of kaolinite addition to theoretically generated CoAl2O4 particles is 0.2 to 1.2.

[0042] Furthermore, step (2) specifically includes: adding 8 mL of deionized water to the zirconia ball mill after the reaction is completed, stirring and taking out the precursor in the zirconia ball mill, repeating three times, the purpose of which is to completely collect the precursor remaining in the zirconia ball mill and on the zirconia balls (the precursor obtained after ball milling has a certain viscosity); then centrifuging the taken out precursor, washing it three times with deionized water, and placing it in a forced air drying oven at 60°C for 18 hours.

[0043] Furthermore, step (3) specifically includes: grinding and dispersing the dried precursor in an agate mortar, and then calcining it in a muffle furnace to finally obtain the kaolinite-based cobalt blue inorganic composite pigment.

[0044] Furthermore, the method for testing the chemical stability of the obtained kaolinite-based cobalt blue inorganic composite pigment is as follows: the prepared kaolinite-based cobalt blue inorganic composite pigment is dispersed in HCl solution, NaOH solution and anhydrous ethanol respectively, placed in a shock box for a certain period of time, centrifuged, washed to neutrality, and placed in a forced air drying oven for drying, and then the chromaticity value of the treated kaolinite-based cobalt blue inorganic composite pigment is tested, and the chemical stability is evaluated by calculating the chromaticity value difference before and after the treatment;

[0045] Specifically, 70 mg of the prepared kaolinite-based cobalt blue inorganic composite pigment was weighed and dispersed in 20 mL of 1M HCl solution, 1M NaOH solution and anhydrous ethanol, respectively, and placed in a shock box for 24 hours at room temperature (25°C) with a shock speed of 150 rpm. After centrifugation and washing with deionized water to neutrality, it was placed in a forced air drying oven and dried at 60°C for 12 hours. The chromaticity value of the prepared kaolinite-based cobalt blue inorganic composite pigment can be tested, and the chemical stability can be evaluated by calculating the chromaticity value difference before and after treatment.

[0046] The present invention also provides a kaolinite-based cobalt blue inorganic composite pigment, which is prepared by the above-mentioned preparation method. The kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate, wherein the CoAl2O4 particles are prepared by mixing Co in a cobalt source and an aluminum source. 2+ and Al 3+ The precursor precipitated during the wet mechanical ball milling process is calcined and crystallized, and is uniformly loaded on the surface of the kaolinite substrate. The kaolinite substrate is in the form of amorphous agglomerates formed after wet mechanical ball milling and calcination. The chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is b * The value can reach -49.92 to -42.74.

[0047] Preferably, the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is * The value can reach -49.92.

[0048] Furthermore, the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment can reach: L * :54.98~58.64、C * :42.74~50.12、a * :0.63~4.5.

[0049] The kaolinite-based cobalt blue inorganic composite pigment and the preparation method thereof provided by the present invention use kaolinite as a base material for loading spinel CoAl2O4 particles. Kaolinite is a 1:1 type layered clay mineral having the characteristics of large specific surface area, good stability, strong adsorption capacity, etc. The introduction of kaolinite can not only effectively reduce the amount of cobalt source required for the preparation of cobalt blue pigment and reduce the preparation and production cost, but also its excellent loading performance can improve the dispersibility of CoAl2O4 particles, reduce particle agglomeration, improve the product chromaticity value, and effectively reduce the mass transfer resistance of the calcination process, thereby reducing the temperature required for the high-temperature crystallization process.

[0050] The following specifically describes the kaolinite-based cobalt blue inorganic composite pigment and the preparation method thereof according to the present invention in combination with Examples 1-5, and describes the technical effects of the kaolinite-based cobalt blue inorganic composite pigment and the preparation method thereof according to the present invention in combination with Comparative Example 1:

[0051] Example 1

[0052] The preparation method of the kaolinite-based cobalt blue inorganic composite pigment of the present embodiment specifically comprises the following steps:

[0053] (1) Preparing the precursor by wet mechanical ball milling: 0.2037 g of cobalt nitrate, 1.8757 g of aluminum nitrate, 0.0495 g of kaolinite and 1.1977 g of sodium carbonate were weighed, mixed and added to a 50 mL zirconia ball mill, 66.532 g of zirconia balls (ball-to-material ratio of 20:1, sizes of 1 mm and 2 mm) and 12 mL of anhydrous ethanol were added, and the zirconia ball mill was placed in a vertical planetary ball mill at a speed of 1000 rpm for 4 h;

[0054] (2) adding 8 mL of deionized water to the zirconia ball mill after the reaction, stirring and taking out the precursor in the zirconia ball mill, repeating three times; then centrifuging the taken out precursor, washing it three times with deionized water, and drying it in a forced air drying oven at 60° C. for 18 h;

[0055] (3) Grinding and dispersing the dried precursor in an agate mortar, and calcining it in a muffle furnace at a calcination temperature of 800° C. for 2 h, to finally obtain the kaolinite-based cobalt blue inorganic composite pigment.

[0056] Example 2

[0057] The only difference between this embodiment and embodiment 1 is that in step (3), the calcination temperature is 900° C. and the calcination time is 2 h.

[0058] Example 3

[0059] The only difference between this embodiment and embodiment 1 is that in step (3), the calcination temperature is 1000° C. and the calcination time is 2 h.

[0060] Example 4

[0061] The only difference between this embodiment and embodiment 1 is that in step (3), the calcination temperature is 1100° C. and the calcination time is 2 h.

[0062] Example 5

[0063] The only difference between this embodiment and embodiment 4 is that in step (1), the amount of kaolinite added is 0.0991 g.

[0064] Comparative Example 1

[0065] This comparative example uses cobalt source and aluminum source as raw materials to prepare a cobalt blue pigment containing a single CoAl2O4 component; specifically, the following production steps are included:

[0066] (1) Weigh 0.2037 g of cobalt nitrate, 1.8757 g of aluminum nitrate, and 1.1977 g of sodium carbonate into a 50 mL zirconia ball mill, add 65.542 g of zirconia balls (ball-to-material ratio of 20:1, sizes of 1 mm and 2 mm) and 12 mL of anhydrous ethanol, and grind in a vertical planetary ball mill at a speed of 1000 rpm for 4 h;

[0067] (2) adding 8 mL of deionized water to the zirconia ball mill after the reaction, stirring and taking out the precursor in the zirconia ball mill, repeating three times; then centrifuging the taken out precursor, washing it three times with deionized water, and drying it in a forced air drying oven at 60° C. for 18 h;

[0068] (3) The dried precursor is ground and dispersed in an agate mortar, and then calcined in a muffle furnace at a calcination temperature of 1100° C. for 2 h, thereby finally obtaining a cobalt blue pigment containing a single CoAl 2 O 4 component.

[0069] The kaolinite-based cobalt blue inorganic composite pigments of Examples 1-5 were tested for performance:

[0070] 1. The chromaticity values ​​of the single CoAl2O4 cobalt blue pigment obtained in Comparative Example 1 and the kaolinite-based cobalt blue inorganic composite pigments obtained in Examples 1-5 are as follows: Figure 1 As shown in the figure, compared with the single CoAl2O4 cobalt blue pigment without kaolinite in Comparative Example 1, the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment of Examples 1-5 is significantly improved, especially the b value which can reflect the blue degree of the cobalt blue pigment. * Value (b * The smaller the value, the stronger the blue. For cobalt blue pigment, when evaluating the color of the pigment, the b *The absolute values ​​of the b* values ​​of Examples 1-5 are significantly higher than those of Comparative Example 1, and the chromaticity value of Example 4 is the best, indicating that the chromaticity value (especially b*) of the kaolinite-based cobalt blue inorganic composite pigment prepared by the method of the present invention is * value) has been significantly improved.

[0071] 2. The XRD patterns of the kaolinite-based cobalt blue inorganic composite pigments obtained in Examples 1-4 are as follows: Figure 2 As shown: it can be seen that obvious typical diffraction peaks of spinel CoAl2O4 appear at 2θ of 31.44°, 36.98°, 44.98°, 55.72°, 55.40°, and 65.64°, indicating that spinel phase CoAl2O4 particles with good crystallization are generated in the composite pigment; with the increase of calcination temperature, the degree of crystallization gradually becomes stronger, among which the spinel phase CoAl2O4 obtained by calcination at 1100°C has the best degree of crystallization; in the XRD spectrum of Example 5, the addition amount of kaolinite is increased to 0.0991g compared with that in Example 4, and the diffraction peak does not change much, indicating that the addition of kaolinite does not affect the crystallization of spinel phase CoAl2O4 particles; in addition, in the XRD spectrum of the kaolinite-based cobalt blue inorganic composite pigment obtained in Examples 1-5, the diffraction peak of the kaolinite substrate almost disappears, which is because under the action of continuous ball milling and high-temperature calcination, the crystalline phase of kaolinite is transformed into an amorphous phase.

[0072] 3. The SEM photos of the single CoAl2O4 cobalt blue pigment obtained in Comparative Example 1 and the kaolinite-based cobalt blue inorganic composite pigment obtained in Example 4 are shown in FIG. Figure 3 and Figure 4 As shown: Figure 3 As shown in FIG. 1 , when no kaolinite substrate is added, in the single cobalt blue CoAl2O4 pigment obtained in Comparative Example 1, the CoAl2O4 crystal particles show serious agglomeration phenomenon; while in Figure 4 In the embodiment 4, most of the CoAl2O4 crystal particles in the kaolinite-based cobalt blue inorganic composite pigment are evenly dispersed on the surface of the kaolinite substrate. Compared with the single CoAl2O4 cobalt blue pigment obtained in Example 1, the agglomeration of the CoAl2O4 crystal particles is significantly reduced.

[0073] 4. The reflectance spectra of the kaolinite-based cobalt blue inorganic composite pigment obtained in Examples 1-5 in the visible light range are shown in FIG. Figure 5As shown; the kaolinite-based cobalt blue inorganic composite pigment shows obvious absorption bands in the wavelength range of 530-650nm, shows obvious reflection bands in the wavelength range of 380-500nm, and has a strong reflection peak in the blue visible light range near the wavelength of 430nm; before 1100°C, with the increase of calcination temperature, the reflection of blue light by the kaolinite-based cobalt blue inorganic composite pigment gradually increases; in Example 5, the addition amount of kaolinite is increased to 0.0991g compared with Example 4. Although the reflection intensity of the prepared composite pigment in the blue light region is improved, the surface of the kaolinite cannot be completely covered, resulting in the simultaneous enhancement of its reflection in the wavelength range of 530-650nm, which leads to a slight decrease in the overall color effect, which corresponds to the chromaticity value result.

[0074] 5. The chemical stability test of the kaolinite-based cobalt blue inorganic composite pigment obtained in Example 4 was performed: 70 mg of the prepared pigment was weighed, respectively, dispersed in 20 mL of 1M HCl solution, 1M NaOH solution and anhydrous ethanol, respectively, placed in a shock box and shaken at room temperature (25°C) for 24 hours, and the shaking speed was 150 rpm, and then centrifuged and washed with deionized water to neutrality, and then placed in a forced air drying oven at 60°C for 12 hours, and then the treated composite pigment was tested for chromaticity, and the chemical stability was evaluated by calculating the chromaticity difference before and after treatment; the chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment obtained in Example 4 after treatment with different chemical reagents and the chromaticity value difference ΔE before and after treatment * As shown in Table 1, it can be seen that the chromaticity value of the prepared kaolinite-based cobalt blue inorganic composite pigment does not change much before and after treatment with various chemical reagents; among them, the chromaticity value difference ΔE after treatment with HCl solution is * (1.16) is slightly larger than that of NaOH solution (0.75) and anhydrous ethanol (0.60). The reason may be that CoAl2O4 partially dissolves in the acidic environment, which in turn affects the color value of the composite pigment. However, the color difference ΔE of all samples after treatment with various chemical reagents is * All of them are at a relatively low level (<2), indicating that the kaolinite-based cobalt blue inorganic composite pigment prepared by the present invention has good stability in acidic, alkaline and organic reagent environments.

[0075] Table 1 Chromaticity value of kaolinite-based cobalt blue inorganic composite pigment of Example 4 after being treated with different chemical reagents and the chromaticity difference ΔE between the kaolinite-based cobalt blue inorganic composite pigment and the pigment before treatment *

[0076]

[0077] In summary, the present invention adopts a more environmentally friendly wet mechanical ball milling combined with a calcination process to prepare a kaolinite-based cobalt blue inorganic composite pigment, and the product has good color performance. Compared with the traditional solid phase method and liquid phase method, the process flow of preparing composite pigments by wet mechanical ball milling is simpler and more efficient, and basically does not produce alkaline wastewater, and better meets the green chemical standards; at the same time, the introduction of kaolinite not only effectively reduces the amount of cobalt source required for the preparation of cobalt blue pigments, reduces the preparation and production costs, but also significantly improves the dispersibility of spinel CoAl2O4 particles, reduces the agglomeration of particles, and thus reduces the mass transfer resistance during the calcination process, reduces the temperature required for crystallization, and improves the chromaticity value of the product; at the same time, the addition of grinding aids helps to improve the dispersion of materials and improve grinding efficiency; in addition, the kaolinite-based cobalt blue inorganic composite pigment also exhibits good chemical stability.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a kaolinite-based cobalt blue inorganic composite pigment, characterized in that: The kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate. The preparation method of the kaolinite-based cobalt blue inorganic composite pigment specifically comprises the following steps: (1) Preparing the precursor by wet mechanical ball milling: a cobalt source, an aluminum source, kaolinite and an alkaline adjuster are mixed and added to a ball mill, and then grinding balls and a grinding aid are added to the ball mill, and the ball mill is placed in a ball mill for ball milling; (2) centrifuging, washing and drying the precursor obtained after ball milling; (3) Grinding and dispersing the dried precursor, and calcining it in a muffle furnace for a certain period of time to obtain the kaolinite-based cobalt blue inorganic composite pigment.

2. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment according to claim 1, characterized in that: The cobalt source is at least one of cobalt nitrate, cobalt chloride, cobalt sulfate, cobalt acetate and cobalt oxalate; the aluminum source is at least one of aluminum nitrate, aluminum chloride and aluminum sulfate; the cobalt source and the Co in the aluminum source 2+ With Al 3+ The molar ratio of the alkaline regulator to the cobalt source is 0.08 to 0.56; the alkaline regulator is sodium carbonate; the alkaline regulator and the sodium carbonate in the cobalt source and the Co 2+ The molar ratio is 3 to 4.75; the mass ratio of the added amount of kaolinite to the theoretically generated CoAl2O4 particles is 0.2 to 1.

2.

3. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment according to claim 1, characterized in that: The grinding aid is anhydrous ethanol.

4. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment according to claim 1, characterized in that: The ball mill adopts one of the vertical planetary ball mill, horizontal planetary ball mill and omnidirectional planetary ball mill.

5. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment according to claim 1, characterized in that: The calcination temperature is 800-1100°C and the calcination time is 2h.

6. The method for preparing the kaolinite-based cobalt blue inorganic composite pigment according to claim 1, characterized in that: Step (1) specifically comprises: mixing cobalt nitrate, aluminum nitrate, kaolinite and sodium carbonate and adding the mixture into a zirconia ball mill, then adding zirconia balls and anhydrous ethanol into the zirconia ball mill at a ball-to-material ratio of 10:1 to 30:1, placing the zirconia ball mill in a ball mill and grinding at 1000 rpm for 4 hours to obtain a precursor; Step (2) specifically comprises: adding 8 mL of deionized water to the zirconia ball mill after the reaction is completed, stirring and taking out the precursor in the zirconia ball mill, repeating three times; then centrifuging the taken out precursor, washing it three times with deionized water, and drying it in a forced air drying oven at 60° C. for 18 hours; Step (3) specifically comprises: grinding and dispersing the dried precursor in an agate mortar, and then calcining it in a muffle furnace to finally obtain the kaolinite-based cobalt blue inorganic composite pigment.

7. A kaolinite-based cobalt blue inorganic composite pigment, characterized in that: The kaolinite-based cobalt blue inorganic composite pigment is prepared by the preparation method according to any one of claims 1 to 6, wherein the kaolinite-based cobalt blue inorganic composite pigment is composed of spinel CoAl2O4 particles and a kaolinite substrate, wherein the CoAl2O4 particles are prepared by mixing Co in the cobalt source and the aluminum source. 2+ and Al 3+ The precursor precipitated during the wet mechanical ball milling process is calcined and crystallized, and is uniformly loaded on the surface of the kaolinite substrate. The kaolinite substrate is in the form of amorphous agglomerates formed after wet mechanical ball milling and calcination. The chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is b * The value can reach -49.92 to -42.

74.

8. The kaolinite-based cobalt blue inorganic composite pigment according to claim 7, characterized in that: The chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment is b * The value can reach -49.

92.

9. The kaolinite-based cobalt blue inorganic composite pigment according to claim 7, characterized in that: The chromaticity value of the kaolinite-based cobalt blue inorganic composite pigment can reach: L * :54.98~58.64、C * :42.74~50.12、a * :0.63~4.5.

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