Composite pigment as well as preparation method and application thereof

Abstract

The invention discloses a composite pigment as well as a preparation method and application thereof. The invention relates to an environment-friendly cleaning agent which is prepared from the following raw materials: methylcyclohexane, a surfactant, a cosurfactant, titanium dioxide, calcium salt and carbonate. The surfactant comprises fatty alcohol-polyoxyethylene ether and hexadecyl trimethyl ammonium chloride; relative to 100 parts by weight of methylcyclohexane, the use amount of the surfactant is 2-8 parts by weight; the dosage of the cosurfactant is 2-4 parts by weight; the dosage of the titanium dioxide is 5-10 parts by weight; the dosage of the calcium salt is 6-12 parts by weight; the use amount of the carbonate is 6-12 parts by weight. According to the composite pigment disclosed by the invention, the surface of calcium carbonate is coated with titanium dioxide, so that the composite pigment also has high covering power on the premise of ensuring that titanium dioxide has high substitution rate.

Description

Technical Field

[0001] This invention relates to the field of inorganic pigment technology, and in particular to a composite pigment, its preparation method, and its application. Background Technology

[0002] Titanium dioxide is the best white pigment, possessing advantages such as good hiding power, high gloss, high whiteness, low oil absorption, and stable chemical properties. Titanium dioxide has various crystal forms, including rutile, anatase, and tetroxide, with the rutile form exhibiting the best hiding power and being widely used in inks, coatings, papermaking, plastics, and rubber. However, its high production costs, resource consumption, and potential environmental and health risks have prompted researchers to develop alternatives. The American Titanium Pigment Company began with the production of composite pigments containing 25% TiO2. They produced a composite titanium dioxide consisting of 25% type A titanium dioxide and 75% barium sulfate using the sulfuric acid process. Before the advent of pure TiO2 in the early 20th century, it was the dominant product in the pigment market. However, the market's attention and expectation for inexpensive titanium dioxide substitutes have remained constant; their development and application research have consistently received widespread attention worldwide.

[0003] However, the research and development of composite titanium dioxide is still in its early stages, and the product performance is substandard. It can generally only replace 10% to 30% of the amount of titanium dioxide used. The main reason is that the product's hiding power and other properties are too low. Other issues include uneven coating, high production energy consumption, and environmental pollution from the waste generated.

[0004] Therefore, it is necessary to develop a composite pigment. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, a first aspect of this invention proposes a composite pigment. This composite pigment has a high titanium dioxide substitution rate and high hiding power.

[0006] A second aspect of the present invention also provides a method for preparing a composite pigment.

[0007] A third aspect of the present invention also provides an application of composite pigments.

[0008] A composite pigment according to a first aspect of the present invention comprises the following raw materials:

[0009] Methylcyclohexane, surfactants, co-surfactants, titanium dioxide, calcium salts, and carbonates;

[0010] The surfactants include fatty alcohol polyoxyethylene ether and hexadecyltrimethylammonium chloride;

[0011] The amount of the surfactant relative to 100 parts by weight of the methylcyclohexane is 2 to 8 parts by weight; the amount of the co-surfactant is 2 to 4 parts by weight; the amount of the titanium dioxide is 5 to 10 parts by weight; the amount of the calcium salt is 6 to 12 parts by weight; and the amount of the carbonate is 6 to 12 parts by weight.

[0012] According to a preferred embodiment of the present invention, the titanium dioxide is rutile titanium dioxide.

[0013] According to a preferred embodiment of the present invention, the co-surfactant includes at least one selected from n-butanol, ethanol, dodecanol, and ethyl acetate.

[0014] According to a preferred embodiment of the present invention, the carbonate includes at least one of sodium carbonate, ammonium bicarbonate, and potassium carbonate.

[0015] According to a preferred embodiment of the present invention, the calcium salt includes at least one of calcium chloride, calcium sulfate, calcium nitrate, and calcium bicarbonate.

[0016] The composite pigment according to embodiments of the present invention has at least the following beneficial effects:

[0017] This invention prepares a composite pigment using methylcyclohexane, surfactants, co-surfactants, titanium dioxide, calcium salts, and carbonates as raw materials. The composite pigment consists of titanium dioxide coated on the surface of calcium carbonate. Titanium dioxide itself has a high refractive index and strong light scattering ability, which is the main source of its hiding power. When a core-shell structure is formed, the refractive index difference between the shell material and the calcium carbonate core may further enhance the light scattering effect. Since the refractive index of the shell material differs from that of the core, light undergoes multiple reflections and scatterings at the core-shell interface, thereby improving the absorption and scattering efficiency of light and enhancing the hiding power. While ensuring a high substitution rate for titanium dioxide, this composite pigment also possesses high hiding power. This is because the combination of fatty alcohol polyoxyethylene ether and hexadecyltrimethylammonium chloride as surfactants, in addition to emulsification, can reduce the contact angle between the liquid and the solid, making it easier for the liquid to spread on the solid surface; the presence of titanium dioxide in emulsion form allows smaller particles to exist in the dispersion and provides a certain degree of isolation. The synergistic effect of surfactants further reduces interfacial tension, resulting in smaller and more uniformly distributed droplets in the microemulsion, thereby improving its stability. Methylcyclohexane, as the oil phase component, forms a stable microemulsion system with the aqueous phase under the action of surfactants, regulating the phase behavior and stability of the microemulsion.

[0018] According to a second aspect of the present invention, a method for preparing the composite pigment described in the first aspect of the present invention is provided, comprising the following steps:

[0019] S1. Titanium dioxide slurry, carbonate, surfactant, co-surfactant, methylcyclohexane and water are mixed and stirred to obtain an emulsion;

[0020] S2. Mix the calcium salt solution and the emulsion and heat them to react; then perform post-processing to obtain the final product.

[0021] According to a preferred embodiment of the present invention, in step S1, the stirring speed is 400-800 r / min.

[0022] According to a preferred embodiment of the present invention, in step S1, the stirring time is 15 to 20 minutes.

[0023] According to a preferred embodiment of the present invention, in step S2, the temperature of the heating reaction is 30-50°C.

[0024] According to a preferred embodiment of the present invention, in step S2, the calcium salt solution is mixed with the emulsion by dropwise addition.

[0025] According to a preferred embodiment of the present invention, the concentration of the titanium dioxide slurry is 5 wt.% to 15 wt.%.

[0026] According to a preferred embodiment of the present invention, the concentration of the calcium salt solution is 10 wt.% to 20 wt.%.

[0027] According to a preferred embodiment of the present invention, in step S2, the calcium salt solution is mixed with the emulsion by dropwise addition and heated to react; the result is obtained after post-treatment.

[0028] According to a preferred embodiment of the present invention, the post-processing steps include washing, filtering, and drying.

[0029] The method for preparing composite pigments according to embodiments of the present invention has at least the following beneficial effects:

[0030] 1. Good coating uniformity: In the microemulsion system, the reactants react controllably in the nanoscale microreactor, which enables titanium dioxide to be uniformly coated on the surface of calcium carbonate, reducing agglomeration and forming a regular core-shell structure.

[0031] 2. Controllable particle size: By adjusting the composition and reaction conditions of the microemulsion, the thickness of the coating layer and the particle size of calcium carbonate particles can be precisely controlled to obtain composite particles with narrow particle size distribution.

[0032] 3. Excellent functional properties: It combines the filling properties of calcium carbonate with the high opacity and UV shielding properties of titanium dioxide, which can improve the overall performance of materials in coatings, plastics and other fields.

[0033] 4. Simple and controllable process: The microemulsion method is relatively simple to operate, the reaction conditions are mild, it is easy to realize industrial production, and it is environmentally friendly.

[0034] The third aspect of this invention provides the application of the composite pigment described in the first aspect of this invention in the preparation of printing inks, coatings, plastics, paper, rubber, chemical fibers, and cosmetics.

[0035] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0036] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0037] Figure 1 This is a SEM image of the composite pigment of Embodiment 1 of the present invention;

[0038] Figure 2 This is a SEM image of the composite pigment of Embodiment 1 of the present invention;

[0039] Figure 3 This is a particle size distribution diagram of the composite pigment in Embodiment 1 of the present invention;

[0040] Figure 4 This is the FT-IR image of the composite pigment in Embodiment 1 of the present invention;

[0041] Figure 5 This is the XRD pattern of the composite pigment in Embodiment 1 of the present invention;

[0042] Figure 6 This is a comparison image of the white ink made with composite pigment replacing 33% titanium dioxide and the white ink made with pure titanium dioxide, as shown in Embodiment 1 of the present invention.

[0043] Figure 7 A comparison diagram of the white ink of Example 1 of the present invention, which uses composite pigments to replace 33% titanium dioxide, and the white ink of Comparative Example 4, which uses composite pigments to replace 33% titanium dioxide.

[0044] Figure 8 A comparison diagram of the effects of white ink with composite pigment replacing 33% titanium dioxide in Example 1 of the present invention and white ink with mixed pigment replacing 33% titanium dioxide in Comparative Example 5; Detailed Implementation

[0045] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0046] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0047] Some of the raw materials used in the embodiments of this invention are as follows:

[0048] Titanium dioxide: Shandong Dongjia Group Co., Ltd.;

[0049] Dodecylphenol polyoxyethylene ether: Tianjin Kemeio Chemical Reagent Co., Ltd.;

[0050] Hexadecyltrimethylammonium chloride: Qida Chemical Co., Ltd.;

[0051] Methylcyclohexane: Guangdong Yuantai Chemical Co., Ltd.;

[0052] Co-surfactant: n-Butanol; Henan Kangyuan Fragrance Factory Co., Ltd.

[0053] Calcium salt: Calcium chloride; Tianjin Zhonglian Chemical Reagent Co., Ltd.

[0054] Carbonate: Sodium carbonate; Tianjin Huasheng Chemical Reagent Co., Ltd.

[0055] Example 1

[0056] This example provides a composite pigment, the amounts of which are shown in Table 1, and its preparation method is as follows:

[0057] S1. Mix titanium dioxide slurry (10% mass concentration), anhydrous sodium carbonate, fatty alcohol polyoxyethylene ether, hexadecyltrimethylammonium chloride, methylcyclohexane, n-butanol and water and stir to obtain an emulsion; the magnetic stirring speed is 600 r / min; stir for 15-20 min.

[0058] S2. Add a 13.9% calcium chloride solution dropwise to the above emulsion and heat to react, obtaining a mixed solution. The dropwise addition time is 3-5 min, and the reaction temperature is 30-50℃. Then filter and wash the above mixed solution, filter it once with ethanol, and filter it once with distilled water to obtain a solid filter material. Distill it at 80℃ to recover and reuse methylcyclohexane. Dry the solid filter material at 120℃ for 1 h to obtain the final product.

[0059] Examples 2-4

[0060] Examples 2-4 provide a series of composite pigments, the amounts of which are shown in Table 1, and their preparation methods are the same as those in Example 1.

[0061] Table 1

[0062]

[0063]

[0064] Comparative Example 1

[0065] This example provides a composite pigment with the same component dosage and preparation method as Example 1, except that Comparative Example 1 lacks n-butanol.

[0066] Comparative Example 2

[0067] This example provides a composite pigment with the same component dosage and preparation method as Example 1. The difference is that in Comparative Example 2, dimethyl silicone oil is used instead of methylcyclohexane.

[0068] Comparative Example 3

[0069] This example provides a composite pigment with the same component dosage and preparation method as Example 1. The difference is that Comparative Example 3 uses Tween 80 instead of fatty alcohol polyoxyethylene ether.

[0070] Comparative Example 4

[0071] This example provides a composite pigment with the same component dosage and preparation method as Example 1. The difference is that in Comparative Example 3, distilled water is used instead of microemulsion as the reaction system for the composite pigment.

[0072] Preparation method: First, add 50g of titanium dioxide slurry and 11g of anhydrous sodium carbonate to deionized water and stir evenly; the titanium dioxide used is rutile type; the magnetic stirring speed is 600r / min, stirring for 15-20min, and the heating temperature is 30-50℃.

[0073] Then, 80g of a 13.9% calcium chloride solution was added dropwise to the above dispersion, and the mixture was heated to react and obtain a mixed solution. The calcium salt used in this invention is calcium chloride, the dropwise addition time is 3-5 minutes, and the reaction temperature is 30-50℃.

[0074] The above mixed solution is then distilled, filtered and washed, filtered once with ethanol and once with distilled water to obtain a solid filter material;

[0075] The solid filter material was dried to obtain a composite material containing titanium dioxide. The drying temperature was 120℃ and the drying time was 1 hour.

[0076] Comparative Example 5

[0077] Comparative Example 4 provides a mixed pigment of titanium dioxide and calcium carbonate, wherein the mass ratio of titanium dioxide to calcium carbonate is 4:5.

[0078] Performance testing

[0079] The composite pigment of Example 1 of this invention was subjected to SEM testing, and the results are as follows: Figure 1 and Figure 2As shown, titanium dioxide particles are coated on the surface of calcium carbonate particles. Furthermore, the particle size distribution of the composite pigment is shown in the figure below. Figure 3 As shown, D 10 =1272nm, D 50 =1739nm, D 95 =5990nm. It can be seen that its particle size distribution is relatively uniform, and it is basically concentrated in the range of about 1.5 micrometers.

[0080] Furthermore, the composite pigment prepared in Example 1 of this invention was subjected to infrared analysis, and the results are as follows: Figure 4 As shown, titanium dioxide has a thickness of 600-400 cm⁻¹. -1 Region: Rocking vibration of the titanium-oxygen bond (Ti-O). 3000-3500 cm⁻¹ -1 Region: The absorption peak is relatively weak, which is related to the small amount of water or hydroxyl groups (-OH) adsorbed on the surface of rutile titanium dioxide. 2400 cm⁻¹ -1 Overtones or combined overtones of the stretching or bending vibrations of the left and right (Ti-O) spheres.

[0081] Calcium carbonate at 3400cm -1 The OH stretching vibrations of adsorbed water or water of crystallization in the left and right samples. The characteristic absorption peak is at 1400 cm⁻¹. -1 Nearby (asymmetric stretching vibration of CO), 870cm -1 Left and right (CO3) 2- (out-of-plane deformation vibration) and 710cm -1 Left and right (CO3) 2- (such as in-plane deformation and vibration of OCO).

[0082] It exhibits the characteristic absorption peaks of titanium dioxide and calcium carbonate, at 1400 cm⁻¹. -1 The absorption peak at 667 cm⁻¹ is weaker and shifted compared to that of calcium carbonate. -1 The weaker absorption peak of the sample compared to that of titanium dioxide indicates that the two materials have combined to form a CO-Ti bond.

[0083] Furthermore, the composite pigment of Example 1 of the present invention was subjected to XRD testing, and the results are as follows: Figure 5 As shown, the XRD diffraction peaks of rutile titanium dioxide are mainly distributed between 24° and 28°. Within this range, the specific diffraction peaks corresponding to each crystal plane of rutile titanium dioxide are as follows:

[0084] (110) The diffraction peak of the crystal plane is located at 2θ=27.44°;

[0085] (101) The diffraction peak of the crystal plane is located at 2θ=36.05°;

[0086] (111) The diffraction peak of the crystal plane is located at 2θ=41.27°;

[0087] (211) The diffraction peak of the crystal plane is located at 2θ=54.32°;

[0088] (220) The diffraction peak of the crystal plane is located at 2θ=62.76°;

[0089] The composite pigment showed better XRD results, exhibiting stronger diffraction peaks for TiO2 and weaker diffraction peaks for CaCO3, indicating that titanium dioxide was located on the surface of calcium carbonate. This synthesis process is beneficial for promoting the bonding of TiO2 loaded on calcium carbonate and improving the hiding power of CaCO3 / TiO2.

[0090] The composite pigments prepared in Examples 1-4 and Comparative Examples 1-3 of the present invention were tested as follows: the results are shown in Table 2.

[0091] Whiteness: The whiteness of the sample was tested using a WSB-2 whiteness meter.

[0092] Fineness: 1. GB / T13217.3-2008: Take a small amount of ink with an ink-mixing knife and place it 50μm into the scraper. The amount of ink should be enough to fill the groove. Hold the scraper with both hands and place it vertically on the upper part of the scraper (outside the edge of the sample). Within 3 seconds, pull the scraper from the deep part of the groove to the shallow part. No residual ink should be left on the plate. Immediately observe the particle distribution in the groove. The observation result should be taken at an angle of 15° to 30° with the groove plane and read within 5 seconds.

[0093] 2. Use a laser particle size analyzer to analyze the particle size distribution of the sample.

[0094] Oil absorption: According to national standard GB / T 5211.15—2014, weigh 1-2g of the sample, place it on a glass plate, and add ink oil. During the oil addition process, use an ink-mixing knife to press and compact the sample thoroughly, ensuring that all oil particles are in contact. Start by adding 3-5 drops, and gradually add more as you approach the endpoint. When the last drop is added, the sample and oil should clump together and not break apart when lifted with the ink-mixing knife; this is the endpoint.

[0095] Opacity: The minimum amount of pigment used to just cover the black and white grids when the pigment and ink are ground into a paste and evenly applied to a black and white checkered glass plate.

[0096] Table 2

[0097]

[0098]

[0099] As shown in Table 2, the test results of Comparative Example 1 indicate that the whiteness and hiding power of the composite pigment synthesized after adding the co-surfactant n-butanol were improved to a certain extent; the test results of Comparative Example 2 indicate that the composite pigment synthesized after selecting methylcyclohexane as the oil phase of the microemulsion had the best whiteness and hiding power; the test results of Comparative Example 3 indicate that the composite pigment synthesized using fatty alcohol polyoxyethylene ether as the surfactant had the best whiteness and hiding power; the test results of Comparative Example 4 indicate that the composite pigment synthesized by the microemulsion process had lower oil absorption and improved whiteness and hiding power compared with the liquid phase precipitation method.

[0100] Furthermore, the composite pigment of Example 1, pure titanium dioxide pigment (Shandong Dongjia Group Co., Ltd.), the composite pigment of Comparative Example 3, and the mixed pigment of Comparative Example 4 were respectively applied to inks, and the preparation steps are as follows:

[0101] The preparation steps for applying pure titanium dioxide pigment to white ink (ink 1) are as follows:

[0102] 1. Add component A: distilled water (0.5g), isopropanol (4.5g), n-propyl ester (12g), ethanol (2.5g), dispersant (0.2g), vinyl chloride resin (12g), and polyurethane resin (10g), and disperse until uniform.

[0103] 2. Add component B: titanium dioxide (25g), calcium carbonate (2g), barium sulfate (5g), and gaseous silica (0.3g). After dispersing for 15 minutes, send the mixture to a grinder and grind it to a fineness of ≤15μm.

[0104] 3. Continue to add component C: polyurethane resin (18g) and chlorinated polypropylene resin (0.5g), and disperse until uniform.

[0105] 4. Finally, add component D: ethyl acetate (7.05g), disperse for 10 minutes until uniform, and then send for testing.

[0106] The composite pigment of Example 1 was applied to white ink (ink 2), and its preparation steps are as follows:

[0107] 1. Add component A: distilled water (0.5g), isopropanol (4.5g), n-propyl ester (12g), ethanol (2.5g), dispersant (0.2g), vinyl chloride resin (12g), and polyurethane resin (10g), and disperse until uniform.

[0108] 2. Add component B: composite pigment (8.33g), titanium dioxide (16.67g), calcium carbonate (2g), barium sulfate (5g), and gaseous silica (0.3g). After dispersing for 15 minutes, send the mixture to a grinder and grind it to a fineness of ≤15μm.

[0109] 3. Continue to add component C: polyurethane resin (18g) and chlorinated polypropylene resin (0.5g), and disperse until uniform.

[0110] 4. Finally, add component D: ethyl acetate (7.05g), disperse for 10 minutes until uniform, and then send for testing.

[0111] The composite pigment of Comparative Example 4 was applied to white ink (Ink 3), and its preparation steps are as follows:

[0112] 1. Add component A: distilled water (0.5g), isopropanol (4.5g), n-propyl ester (12g), ethanol (2.5g), dispersant (0.2g), vinyl chloride resin (12g), and polyurethane resin (10g), and disperse until uniform.

[0113] 2. Add component B: the composite pigment (8.33g), titanium dioxide (16.67g), calcium carbonate (2g), barium sulfate (5g), and gaseous silica (0.3g) of Comparative Example 3. After dispersing for 15 minutes, send the mixture to a grinder and grind it to a fineness of ≤15μm.

[0114] 3. Continue to add component C: polyurethane resin (18g) and chlorinated polypropylene resin (0.5g), and disperse until uniform.

[0115] 4. Finally, add component D: ethyl acetate (7.05g), disperse for 10 minutes until uniform, and then send for testing.

[0116] The mixed pigments of Comparative Example 5 were applied to white ink (Ink 4), and the preparation steps are as follows:

[0117] 1. Add component A: distilled water (0.5g), isopropanol (4.5g), n-propyl ester (12g), ethanol (2.5g), dispersant (0.2g), vinyl chloride resin (12g), and polyurethane resin (10g), and disperse until uniform.

[0118] 2. Add component B: Mixed pigment (8.33g), titanium dioxide (16.67g), calcium carbonate (2g), barium sulfate (5g), and gaseous silica (0.3g) from Comparative Example 5. Disperse for 15 minutes and then send to a grinder to grind until the fineness is ≤15μm.

[0119] 3. Continue to add component C: polyurethane resin (18g) and chlorinated polypropylene resin (0.5g), and disperse until uniform.

[0120] 4. Finally, add component D: ethyl acetate (7.05g), disperse for 10 minutes until uniform, and then send for testing.

[0121] Ink 1 and Ink 2 were applied to the OPP film by a scraper, and the result is as follows: Figure 6As shown; the effect of replacing 33% titanium dioxide in white ink with the same mass of the composite pigment from Example 1 and comparing it with white ink; when partially replacing titanium dioxide in white ink, it can achieve similar effects to pure titanium dioxide in terms of whiteness, gloss, opacity, viscosity, etc.

[0122] Ink 2 and ink 3 were applied to the OPP film by a scraper, and the result is as follows: Figure 7 As shown, in terms of the hiding power, whiteness, gloss, viscosity and other properties of white ink, the composite pigment prepared in Example 1 of this invention is better than the composite pigment synthesized by liquid-phase precipitation in Comparative Example 4.

[0123] Ink 2 and ink 4 were applied to the OPP film by a scraper, and the result was as follows: Figure 8 As shown, in terms of the hiding power, whiteness, gloss, viscosity and other properties of white ink, the composite pigment synthesized in Example 1 of this invention is better than that of Comparative Example 5, which is directly physically mixed.

[0124] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A composite pigment, characterized in that, Including the following raw materials: Methylcyclohexane, surfactants, co-surfactants, titanium dioxide, calcium salts, and carbonates; The surfactants include fatty alcohol polyoxyethylene ether and hexadecyltrimethylammonium chloride; The amount of the surfactant relative to 100 parts by weight of the methylcyclohexane is 2 to 8 parts by weight; the amount of the co-surfactant is 2 to 4 parts by weight; the amount of the titanium dioxide is 5 to 10 parts by weight; the amount of the calcium salt is 6 to 12 parts by weight; and the amount of the carbonate is 6 to 12 parts by weight.

2. The composite pigment according to claim 1, characterized in that, The titanium dioxide is rutile titanium dioxide.

3. The composite pigment according to claim 1 or 2, characterized in that, The co-surfactant includes at least one of n-butanol, ethanol, dodecanol, and ethyl acetate.

4. The composite pigment according to claim 1 or 2, characterized in that, The carbonate includes at least one of sodium carbonate, potassium carbonate, and ammonium bicarbonate.

5. A method for preparing the composite pigment as described in any one of claims 1 to 4, characterized in that, Includes the following steps: S1. Titanium dioxide slurry, carbonate, surfactant, co-surfactant, methylcyclohexane and water are mixed and stirred to obtain an emulsion; S2. Mix the calcium salt solution and the emulsion and heat them to react; then perform post-processing to obtain the final product.

6. The preparation method according to claim 5, characterized in that, In step S1, the stirring speed is 400-800 r / min.

7. The preparation method according to claim 5, characterized in that, In step S1, the stirring time is 15 to 20 minutes.

8. The preparation method according to claim 5, characterized in that, In step S2, the temperature of the heating reaction is 30–50°C.

9. The preparation method according to claim 5, characterized in that, The post-processing steps include washing, filtering, and drying.

10. The use of the composite pigment according to any one of claims 1 to 4 in the preparation of printing inks, coatings, plastics, paper, rubber, chemical fibers and cosmetics.

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