Preparation method of pigment yellow 83 for automotive coatings

Abstract

The present invention discloses a preparation method of pigment yellow 83 for automotive coatings, comprising the following steps: S1. Prepare a functionalized pigment dispersion; S2. Coat a polymer layer with a porous structure on the surface of the functionalized pigment dispersion to obtain pigment particles with a coated shell layer; S3. Perform surface modification on the pigment particles with the coated shell layer, namely, obtain pigment yellow 83 for automotive coatings. In the present invention, pigment yellow 83 is used as the core and coated with a polymer shell layer to form a core-shell structure, and the polymer shell layer has porous characteristics. This structure can not only protect the pigment core and improve its dispersion stability, but also realize performance adjustment through the pore characteristics of the shell layer, enhance the color development effect of pigment yellow 83, optimize the interfacial action and improve the durability.

Description

Technical Field

[0001] The present invention relates to the technical field of organic pigments, and particularly relates to a preparation method of Pigment Yellow 83 for automotive coatings. Background Art

[0002] With the rapid development of the automotive industry, the performance requirements for automotive coatings are continuously increasing, especially in terms of environmental friendliness, weather resistance, and color stability. Traditional organic pigments are difficult to meet the stringent requirements of modern automotive coatings for pigments due to problems such as poor dispersibility, severe photo-degradation, and poor interfacial compatibility. Especially in waterborne coating systems, the dispersion and stability of pigments directly affect the final performance of the coating. Pigment Yellow 83, as an important organic pigment, is widely used in the field of automotive coatings. Although Pigment Yellow has excellent color saturation and covering power, its high surface energy and many polar groups make it extremely easy to agglomerate in practical applications, resulting in performance deterioration. Currently, common dispersants or surfactants are used to improve the dispersibility of pigments, but the binding force between the dispersant or surfactant and the surface of the organic pigment is weak and easy to fall off; the prepared organic pigments have poor stability and are greatly affected by the environment; to further increase the dispersibility of organic pigments, the dosage of the dispersant or surfactant is increased, thereby affecting the color development performance of the organic pigment. There is also an in-situ coating method in the prior art to improve the performance of organic pigments, that is, directly initiating monomer polymerization on the surface of organic pigments to form a dense coating layer, but the coating layer is a simple dense structure, and the internal stress is difficult to release, easily causing cracking or peeling, and will also have a certain impact on the color saturation of organic pigments. Summary of the Invention

[0003] Based on the problems existing in the background art, the present invention provides a preparation method of Pigment Yellow 83 for automotive coatings. Pigment Yellow 83 is used as the core and is coated with a polymer shell layer to form a core-shell structure, and the polymer shell layer has porous characteristics. This structure can not only protect the pigment core and improve its dispersion stability, but also realize performance adjustment through the pore characteristics of the shell layer, enhance the color development effect of Pigment Yellow 83, optimize the interfacial action, and improve the durability.

[0004] The present invention is implemented through the following technical solutions:

[0005] A preparation method of Pigment Yellow 83 for automotive coatings, comprising the following steps:

[0006] S1. Disperse Pigment Yellow 83 in a mixed solution of ethyl acetate and ethanol, add cetyltrimethylammonium bromide and Tween 20, and perform ultrasonic treatment to form a uniform dispersion; add acrylamide, methyl methacrylate, and ethylene glycol dimethacrylate to the dispersion, raise the temperature for reaction, and after the reaction is completed, wash and centrifuge to obtain a functionalized pigment dispersion;

[0007] S2. Disperse the functionalized pigment dispersion in deionized water, add Span 80 and Tween 20, stir evenly to obtain the aqueous phase; add an initiator, a crosslinking agent and n-hexane to styrene, stir evenly to obtain the oil phase; drop the oil phase into the aqueous phase, homogenize using a high-speed homogenizer to generate a stable emulsion, continue to heat up, initiate the free radical polymerization reaction, add styrene for the first time, add styrene for the second time after reacting for a period of time, continue to react, cool to room temperature after the reaction is completed, wash, and centrifuge to obtain pigment particles with a coated shell layer;

[0008] S3. Disperse the pigment particles with a coated shell layer in deionized water, add trifluoropropylmethylsiloxane, heat up and stir, after the surface modification is completed, control the reaction temperature, continue to add polyethylene glycol methacrylate, after the reaction is completed, wash and centrifuge to obtain Pigment Yellow 83 for automotive coatings.

[0009] Further, in step S1, the dosage ratio of Pigment Yellow 83 to the mixed solvent is (3 - 8) g: 100 mL; the volume ratio of ethyl acetate to ethanol is (3 - 5): 1; the mass ratio of Pigment Yellow 83, cetyltrimethylammonium bromide and Tween 20 is 1: (0.03 - 0.05): (0.01 - 0.03).

[0010] Further, in step S1, the mass ratio of acrylamide, methyl methacrylate and ethylene glycol dimethacrylate is 1: (0.4 - 0.6): (0.4 - 0.6), and the total mass accounts for 10 - 15% of the dosage of Pigment 83;

[0011] The temperature for the heating reaction is 40 °C, and the reaction time is 2 - 3 h.

[0012] In step S1, the copolymerization of acrylamide and methyl methacrylate forms an amphiphilic modification layer on the surface of Pigment 83, and ethylene glycol dimethacrylate further ensures the stability of the modification layer.

[0013] Further, in step S2, in terms of parts by weight, the aqueous phase includes 5 - 8 parts of functionalized pigment, 30 - 50 parts of deionized water, 0.02 - 0.1 part of Span 80, and 0.01 - 0.05 part of Tween 20.

[0014] Further, in step S2, in terms of parts by weight, the oil phase includes 3 - 5 parts of styrene, 0.01 - 0.03 part of initiator, 0.01 - 0.03 part of crosslinking agent and 0.1 - 0.3 part of n-hexane.

[0015] Further, in step S2, the initiator is azobisisobutyronitrile, and the crosslinking agent is ethylene glycol dimethacrylate.

[0016] Further, in step S2, the dosage of the added styrene is 20 - 40% of the dosage of styrene in the oil phase.

[0017] Further, in step S2, the rotation speed of the high-speed homogenizer is 8000 - 10000 rpm, the emulsification time is 10 - 15 min, and the polymerization reaction temperature is 70 °C.

[0018] In this step, due to the amphiphilicity of the surface of the functionalized pigment, the pigment is oriented at the oil-water interface, and the formed Pickering emulsion has high stability. When heated to the polymerization reaction temperature, styrene is polymerized on the surface of the pigment with the lowest interfacial energy. Adding styrene in two portions is beneficial to the growth of the shell layer. The presence of n-hexane as a pore-forming agent reduces the viscosity of the oil phase. When the temperature rises, n-hexane volatilizes to form pores, and the presence of the cross-linking agent stabilizes the structure of the pores. Finally, the shell layer has a porous structure.

[0019] Further, in step S3, the mass ratio of the pigment particles with a coated shell layer, trifluoropropylmethylsiloxane, and poly(ethylene glycol) methacrylate is (5 - 10) : 0.2 : 0.2.

[0020] Further, in step S3, the surface modification reaction temperature of trifluoropropylmethylsiloxane is 60 ± 1 °C, and the surface modification reaction temperature of poly(ethylene glycol) methacrylate is 50 ± 0.5 °C.

[0021] Advantages of the present invention:

[0022] In the present invention, the functionalization modification endows Pigment Yellow 83 with amphiphilicity. Combining the construction of the shell layer and the surface PEGMA modification during the emulsion polymerization process effectively prevents the pigment particles from settling and aggregating in the waterborne coating system, ensuring long-term storage stability. The porous shell layer structure improves the vividness of Pigment Yellow 83 by reducing light scattering, optimizes the optical properties at the interface between Pigment Yellow 83 and the coating substrate, and the color rendering performance is more uniform and stable. The preparation process of the present invention adopts mild reaction conditions, avoiding damage to the pigment core and shell layer. At the same time, the process has strong controllability and is suitable for large-scale industrial production. Description of the Drawings

[0023] The drawings are used to provide further explanation of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0024] Figure 1 Schematic diagram of the high-speed homogenizer for mixing and homogenizing the oil phase and the water phase provided by the embodiment of the present invention Figure 1 ;

[0025] Figure 2 Schematic diagram of the high-speed homogenizer for mixing and homogenizing the oil phase and the water phase provided by the embodiment of the present invention Figure 2 ;

[0026] Figure 3 Cross-sectional view of a high-speed homogenizer for mixing and homogenizing oil phase and water phase provided by an embodiment of the present invention;

[0027] Figure 4 Partial view of a high-speed homogenizer for mixing and homogenizing oil phase and water phase provided by an embodiment of the present invention;

[0028] Figure 5 Schematic diagram of a homogenizing rotating shaft provided by an embodiment of the present invention;

[0029] Figure 6 Schematic diagram of a homogenizing rotor provided by an embodiment of the present invention;

[0030] Figure 7 Schematic diagram of a homogenizing stator provided by an embodiment of the present invention;

[0031] Figure 8 Schematic diagram of a pressing wheel provided by an embodiment of the present invention;

[0032] Figure 9 Schematic diagram of an annular material collecting hopper provided by an embodiment of the present invention;

[0033] Figure 10 Schematic diagram of a homogenizing rotating shaft and a cylindrical filter cartridge provided by an embodiment of the present invention.

[0034] Icon: Homogenizing tank 1; Tank cover 2; Homogenizing rotating shaft 3; Homogenizing rotor 4; Homogenizing stator 5; Water phase nozzle 6; Oil phase nozzle 7; Power motor 8; Swirl scraper 9; Rotor scraper 10; Worm structure 11; Worm gear 12; Axle 13; Multi-faceted sliding rod 14; Pressing wheel 15; Pressing protrusion 16; Pulling cross bar 17; Lifting ring 18; Pulling sliding column 19; Pressing spring 20; Spacing adjusting member 21; Annular material collecting hopper 22; Emulsion discharge port 23; Return pipe 24; Return nozzle 25; Cylindrical filter cartridge 26. Detailed implementation manners

[0035] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments only.

[0036] Embodiment 1

[0037] A preparation method of pigment yellow 83 for automotive coatings, comprising the following steps:

[0038] S1. Disperse 5 g of Pigment Yellow 83 in a mixed solution of 100 mL of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of cetyltrimethylammonium bromide and 0.1 g of Tween 20, and perform ultrasonic treatment to form a uniform dispersion; add 0.25 g of acrylamide, 0.025 g of methyl methacrylate, and 0.025 g of ethylene glycol dimethacrylate to the dispersion, raise the temperature to 40 °C for reaction, react for 2.5 h, wash, and centrifuge to obtain a functionalized pigment dispersion;

[0039] S2. Disperse 5 g of the functionalized pigment dispersion in 40 mL of deionized water, add 0.04 g of Span 80 and 0.02 g of Tween 20, and stir evenly to obtain an aqueous phase; add 0.01 g of azobisisobutyronitrile, 0.01 g of ethylene glycol dimethacrylate, and 0.1 g of n-hexane to 3 g of styrene, and stir evenly to obtain an oil phase; drop the oil phase into the aqueous phase, homogenize using a high-speed homogenizer, the rotation speed of the high-speed homogenizer is 8000 rpm, the emulsification time is 10 min, generate a stable emulsion, continue to raise the temperature to 70 °C, start the free radical polymerization reaction, add 1 g of styrene for the first time, add 1 g of styrene for the second time after reacting for 2 h, continue to react for 2 h, cool to room temperature after the reaction is completed, wash, and centrifuge to obtain pigment particles with a coated shell layer;

[0040] S3. Disperse 5 g of the pigment particles with a coated shell layer in 50 mL of deionized water, add 0.2 g of trifluoropropylmethylsiloxane, raise the temperature to 60 °C and stir, after the surface modification is completed, control the reaction temperature at 50 °C, continue to add 0.2 g of polyethylene glycol methacrylate, stir, after the reaction is completed, wash, and centrifuge to obtain Pigment Yellow 83 for automotive coatings.

[0041] Example 2

[0042] A preparation method of Pigment Yellow 83 for automotive coatings, comprising the following steps:

[0043] S1. Disperse 5 g of Pigment Yellow 83 in a mixed solution of 100 mL of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of cetyltrimethylammonium bromide and 0.1 g of Tween 20, and perform ultrasonic treatment to form a uniform dispersion; add 0.25 g of acrylamide, 0.025 g of methyl methacrylate, and 0.025 g of ethylene glycol dimethacrylate to the dispersion, raise the temperature to 40 °C for reaction, react for 2.5 h, wash, and centrifuge to obtain a functionalized pigment dispersion;

[0044] S2. Disperse 5 g of the functionalized pigment dispersion in 40 mL of deionized water, add 0.04 g of Span 80 and 0.02 g of Tween 20, stir evenly to obtain the aqueous phase; add 0.02 g of azobisisobutyronitrile, 0.02 g of ethylene glycol dimethacrylate and 0.2 g of n-hexane to 4 g of styrene, stir evenly to obtain the oil phase; drop the oil phase into the aqueous phase, homogenize using a high-speed homogenizer, the rotation speed of the high-speed homogenizer is 8000 rpm, the emulsification time is 10 min to generate a stable emulsion, continue to heat up to 70 °C, start the free radical polymerization reaction, add 0.8 g of styrene for the first time, after reacting for 2 h, add 0.8 g of styrene for the second time, continue to react for 2 h, after the reaction is completed, cool to room temperature, wash, and centrifuge to obtain the pigment particles coated with a shell layer;

[0045] S3. Disperse 5 g of the pigment particles coated with a shell layer in 50 mL of deionized water, add 0.2 g of trifluoropropylmethylsiloxane, heat up to 60 °C and stir, after the surface modification is completed, control the reaction temperature at 50 °C, continue to add 0.2 g of polyethylene glycol methacrylate, stir, after the reaction is completed, wash and centrifuge to obtain Pigment Yellow 83 for automotive coatings.

[0046] Comparative Example 1

[0047] A preparation method of Pigment Yellow 83 for automotive coatings, comprising the following steps:

[0048] S1. Disperse 5 g of Pigment Yellow 83 in a mixed solution of 100 mL of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of cetyltrimethylammonium bromide and 0.1 g of Tween 20, perform ultrasonic treatment to form a uniform dispersion; add 0.5 g of acrylamide and 0.025 g of ethylene glycol dimethacrylate to the dispersion, heat up to 40 °C for reaction, react for 2.5 h, wash and centrifuge to obtain the functionalized pigment dispersion;

[0049] The remaining steps are the same as those in Example 1.

[0050] Comparative Example 2

[0051] The difference between this Comparative Example 1 and Example 1 is that in step S2, 5 g of the functionalized pigment dispersion is dispersed in 40 mL of deionized water, 0.04 g of Span 80 is added, and stirred evenly to obtain the aqueous phase; the remaining steps are the same as those in Example 1.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 1 is that in step S2, 0.02 g of azobisisobutyronitrile and 0.02 g of ethylene glycol dimethacrylate are added to 4 g of styrene, and stirred evenly to obtain the oil phase; the remaining steps are the same as those in Example 1.

[0054] Comparative Example 4

[0055] The difference between this comparative example and Example 1 is that in step S2, specifically: 5 g of the functionalized pigment dispersion is dispersed in 40 mL of deionized water, 0.04 g of Span 80 and 0.02 g of Tween 20 are added, and after stirring evenly, an aqueous phase is obtained; 0.01 g of azobisisobutyronitrile, 0.01 g of ethylene glycol dimethacrylate and 0.1 g of n - hexane are added to 5 g of styrene, and after stirring evenly, an oil phase is obtained; the oil phase is added dropwise to the aqueous phase, and homogenized using a high - speed homogenizer with a rotation speed of 8000 rpm and an emulsification time of 10 min to generate a stable emulsion. Then the temperature is raised to 70 °C, and a free - radical polymerization reaction is started. After reacting for 4 h, it is cooled to room temperature after the reaction is completed, washed, and centrifuged to obtain pigment particles with a coated shell layer; the other steps are the same as those in Example 1.

[0056] Test Example

[0057] This test example shows that the Pigment Yellow 83 prepared according to the above - mentioned Examples 1 - 2 and Comparative Examples 1 - 4 is added to the automotive water - based paint for use.

[0058] Paint Preparation

[0059] 8 g of the Pigment Yellow 83 prepared in the example or comparative example is added to 40 mL of deionized water, 0.5 g of sodium polyacrylate dispersant is added, and after stirring evenly, 45 g of aqueous acrylic resin emulsion, 0.3 g of defoamer, and 0.2 g of leveling agent are added, followed by high - speed dispersion. The viscosity of the system is adjusted to 100 mPa·s, and it is filtered through a 100 - mesh filter cloth to obtain the automotive paint.

[0060] Paint Evaluation

[0061] (1) The particle size of the pigment in the paint is measured using a particle size analyzer, and the results are shown in Table 1;

[0062] (2) Take 1 mL of the paint and spin - coat it on a glass slide at a speed of 1000 rpm. The glass slide with the coated film is placed on a hot stage at 90 °C and heated for 3 min, and then placed in an oven at 230 °C and baked for another 30 min. The brightness (Y) and contrast are measured using a colorimeter and a contrast meter, and the results are shown in Table 1.

[0063] Table 1

[0064] Group D50 / nm D90 / nm Brightness (Y) Contrast ratio Example 1 246.5 326.8 92.91 10667 Example 2 251.6 331.0 93.53 10931 Comparative Example 1 306.2 412.5 90.14 5354 Comparative Example 2 288.9 401.5 91.50 5221 Comparative Example 3 224.5 315.4 89.22 6389 Comparative Example 4 311.2 427.9 90.46 5547

[0065] As can be seen from the data in Table 1, the D50 and D90 particle sizes of Pigment Yellow 83 prepared in Examples 1 and 2 are smaller than those in the comparative examples, and the brightness and contrast are larger, indicating that the Pigment Yellow 83 prepared by the present invention has better dispersibility and better color rendering performance. In Comparative Example 1, only acrylamide was used to functionalize Pigment Yellow 83 in S1, and the resulting functionalized pigment dispersion showed hydrophilicity and was difficult to stably adsorb at the oil-water interface in the Pickering emulsion, unable to effectively participate in the interfacial reaction, ultimately resulting in uneven shell polymerization. Moreover, due to the lack of hydrophobic components, the shell porosity decreased significantly, and the thickness and uniformity were also unstable. The reduction of shell porosity will reduce the ability to regulate light absorption and the contrast. In Comparative Example 2, the aqueous phase in S2 only contained Tween 20 and did not contain Span 80. The HLB value of Tween 20 is relatively high, and the HLB value of Span 80 is relatively low. Using only Tween 20, lacking a co-emulsifier with a low HLB value, the effect of reducing the interfacial tension of the emulsion is weak, resulting in insufficient emulsion stability and a decrease in the amphiphilic interfacial adsorption ability of pigment particles. Styrene cannot polymerize evenly at the pigment interface but polymerizes locally, forming an incomplete or uneven shell. In Comparative Example 3, the oil phase in S2 did not contain n-hexane. As a pore-forming agent, the lack of n-hexane causes the shell to tend to be densified, and pores are difficult to form. The densification of the shell leads to a decrease in the ability to regulate light scattering and a significant weakening of the color vividness. In Comparative Example 4, all styrene was added to the oil phase at one time in S2 instead of adding it in portions. After starting the polymerization reaction, the shell grew rapidly in the initial stage of polymerization, resulting in an increase in the local shell thickness, too fast polymerization rate, and the generation of an overly thick or irregular shell. The uneven distribution of the shell thickness leads to inconsistent color rendering effects of pigment particles and a decrease in the overall color uniformity of the coating. The purpose of adding styrene in portions is to control the thickness and uniformity of the gradually growing shell by providing monomers in portions. The further growth of the shell in the later stage of polymerization can fill the pore boundaries and stabilize the pore structure.

[0066] Example 3

[0067] Please refer to Figure 1 - 10 , in S2 of the preparation method of Pigment Yellow 83 for automotive coatings of the present invention, the oil phase is added dropwise to the aqueous phase and homogenized using a high-speed homogenizer to generate a stable emulsion; the high-speed homogenizer is one of the important factors affecting the quality of the emulsion and ultimately affects the quality of the subsequent coating;

[0068] However, in a conventional high-speed homogenizer, the oil phase and the aqueous phase are directly put into the homogenizer during homogenization, and the oil phase and the aqueous phase cannot be preliminarily mixed, resulting in low subsequent homogenization efficiency and poor emulsion stability;

[0069] In order to further improve the mixing and homogenization effect of the oil phase and the aqueous phase and improve the quality of the generated emulsion, the following high-speed homogenizer is used for homogenization processing, which is convenient for effectively dispersing oil droplets into the aqueous phase to form tiny oil droplets that are not easy to aggregate, thereby forming a stable emulsion;

[0070] The described high-speed homogenizer includes: a homogenization tank 1 and a tank cover 2 installed at the top opening of the homogenization tank 1; a homogenization rotating shaft 3 is rotatably connected in the central hole at the bottom of the homogenization tank 1, and one end of the homogenization rotating shaft 3 extending into the homogenization tank 1 is key-connected to a homogenization rotor 4. The homogenization rotor 4 is rotatably fitted above a homogenization stator 5 installed on the inner wall of the homogenization tank 1. A first inverted conical shearing surface below the homogenization rotor 4 is arranged in cooperation with a second inverted conical shearing surface above the homogenization stator 5, and a homogenization dispersion zone for shearing the oil phase and the water phase is formed between the first inverted conical shearing surface and the second inverted conical shearing surface; a water phase nozzle 6 and an oil phase nozzle 7 are installed above the side of the homogenization tank 1. The water phase nozzle 6 and the oil phase nozzle 7 are located above the homogenization rotor 4, and the ends of the water phase nozzle 6 and the oil phase nozzle 7 inserted into the homogenization tank 1 are arranged opposite to each other so that the water phase and the oil phase are jetted and collided against each other; the pulley on the homogenization rotating shaft 3 is connected to the pulley at the output end of the power motor 8 through a synchronous belt.

[0071] For the high-speed homogenizer provided by the present invention, during homogenization, the power motor 8 is started. After the power motor 8 is started, the cooperation of the pulley and the synchronous belt can drive the homogenization rotating shaft 3 to rotate around its own axis, so as to drive the homogenization rotor 4 to rotate through the homogenization rotating shaft 3. A water phase nozzle 6 and an oil phase nozzle 7 are installed above the side of the homogenization tank 1. The ends of the water phase nozzle 6 and the oil phase nozzle 7 inserted into the homogenization tank 1 are arranged opposite to each other so that the water phase and the oil phase are jetted and collided against each other. The water phase and the oil phase are jetted and collided against each other through the nozzles, and preliminary mixing can be formed before entering the homogenization dispersion zone, enhancing the contact between the two phases, realizing a more uniform phase distribution, avoiding the problem of too high or too low local concentration, being beneficial to the subsequent homogenization process, thereby improving the emulsification effect and helping to form a more uniform emulsion; in addition, through the nozzle counter-jet design, the formation of larger particles can be reduced, the aggregation of oil droplets can be avoided, thereby improving the long-term stability of the emulsion, and the energy can be utilized more effectively, reducing energy loss and improving the economy of the homogenization process; after the water phase and the oil phase are jetted and collided against each other, they fall into the homogenization dispersion zone between the homogenization rotor 4 and the homogenization stator 5. When the homogenization rotor 4 rotates relative to the homogenization stator 5, a strong shearing force is generated through the tiny gap between the homogenization rotor 4 and the homogenization stator 5, so that the substances in the water phase and the oil phase are quickly and uniformly dispersed, having multiple advantages such as enhancing the preliminary mixing effect of the water phase and the oil phase, improving the homogenization efficiency, and enhancing the emulsion stability.

[0072] A plurality of swirling scraping plates 9 are uniformly and fixedly arranged on the side of the homogenization rotor 4. The lower surfaces of the plurality of swirling scraping plates 9 are slidably fitted on the plane above the homogenization stator 5, and the side surfaces of the plurality of swirling scraping plates 9 away from the homogenization rotor 4 are slidably fitted on the inner wall surface of the homogenization tank 1; a rotor scraping plate 10 is also fixedly connected to the inner wall surface of the homogenization tank 1 through a bracket. The lower surface of the rotor scraping plate 10 is slidably fitted on the conical guiding surface above the homogenization rotor 4, and the conical guiding surface is inclined towards the plane above the homogenization stator 5.

[0073] When the homogeneous rotor 4 rotates, it can drive multiple swirling scrapers 9 to perform rotational circumferential movements. By scraping the liquid on the plane above the homogeneous stator 5 and the inner wall surface of the homogeneous tank 1 with the multiple swirling scrapers 9, it is convenient to improve the homogeneous dispersion effect of the aqueous phase and the oil phase entering the homogeneous dispersion zone between the homogeneous rotor 4 and the homogeneous stator 5, prevent liquid accumulation, and can enhance the rotational flow effect of the aqueous phase and the oil phase in the homogeneous tank 1, which helps to better mix the oil phase and the aqueous phase and improve the homogeneous efficiency; the design of the swirling scraper 9 can also better distribute the liquid, avoid the problem of too high or too low local concentration, and the uniform liquid distribution helps to form a more uniform emulsion, improving the stability and consistency of the product; the lower surface of the rotor scraper 10 is slidably fitted on the conical guiding surface above the homogeneous rotor 4, which is convenient to scrape the liquid on the conical guiding surface above the homogeneous rotor 4 onto the plane above the homogeneous stator 5. The conical guiding surface above the homogeneous rotor 4 is inclined towards the plane above the homogeneous stator 5, which can optimize the flow path of the liquid in the homogeneous tank 2. This design helps the liquid to form more appropriate hydrodynamic characteristics in the homogeneous tank 1, reduce energy loss, and improve the homogeneous efficiency; in addition, the design of the swirling scraper 9 and the rotor scraper 10 can also enhance the local shear force, which helps to more finely disperse the oil droplets, form finer particles, achieve more efficient, more uniform, and more stable emulsion preparation, and improve the production efficiency and product quality.

[0074] A worm structure 11 is provided on the shaft body of the homogeneous rotating shaft 3 below the homogeneous tank 1. A worm wheel 12 meshed with the worm structure 11 has a wheel shaft 13 rotatably arranged on the bottom support of the homogeneous tank 1. A multi-faceted slide bar 14 is slidably connected in the multi-faceted slideway of the wheel shaft 13, and a bolt screwed on the wheel shaft 13 is pressed tightly in the positioning hole of the multi-faceted slide bar 14. One end of the multi-faceted slide bar 14 is fixed with a pressing wheel 15, and pressing protrusions 16 are arranged on the wheel surface of the pressing wheel 15. The pressing wheel 15 is in rolling fit with a pulling cross bar 17 below. The pulling cross bar 17 is fixedly connected to the lower part of a lifting ring 18 through a vertical rod. The lifting ring 18 is fixedly arranged at the bottom of a plurality of pulling slide columns 19. The middle parts of the plurality of pulling slide columns 19 are hermetically slid on the bottom surface of the homogeneous tank 1. One end of the plurality of pulling slide columns 19 inserted into the homogeneous tank 1 is connected to a homogeneous stator 5 slid on the inner wall of the homogeneous tank 1. A top pressure spring 20 is sleeved on the column body of the pulling slide column 19 between the homogeneous stator 5 and the bottom surface of the homogeneous tank 1. A plurality of spacing adjusting members 21 are connected to the lifting ring 18, and the spacing adjusting members 21 are in abutting fit below the homogeneous tank 1 to fix the size of the homogeneous dispersion area between the second inverted conical shearing surface of the homogeneous stator 5 and the first inverted conical shearing surface of the homogeneous rotor 4. When the pressing protrusions 16 on the wheel surface of the pressing wheel 15 rotate to contact the pulling cross bar 17, the pulling cross bar 17 can be pressed to move downward, so as to drive the homogeneous stator 5 to move away from the homogeneous rotor 4 on the inner wall of the homogeneous tank 1 through the cooperation of the pulling cross bar 17, the vertical rod, the lifting ring 18 and the plurality of pulling slide columns 19. When the pressing protrusions 16 on the wheel surface of the pressing wheel 15 rotate to separate from the pulling cross bar 17, the homogeneous stator 5 returns to its original position under the elastic force of the plurality of top pressure springs 20.

[0075] When the homogeneous rotating shaft 3 rotates, it can drive the worm structure 11 to rotate. When the worm structure 11 rotates, it can engage the worm wheel 12 to rotate. When the worm wheel 12 rotates, it can drive the multi-faceted sliding rod 14 to rotate. When the multi-faceted sliding rod 14 rotates, it can drive the pressing wheel 15 to rotate. When the pressing wheel 15 contacts the pulling cross bar 17 below, as the pressing wheel 15 rotates, when the pressing protrusion 16 on the wheel surface of the pressing wheel 15 rotates to contact the pulling cross bar 17, it can press and drive the pulling cross bar 17 to move downward. When the pulling cross bar 17 moves downward, it can drive the lifting ring 18 to move downward through the vertical rod. The lifting ring 18 drives multiple pulling sliding columns 19 to slide downward. The multiple pulling sliding columns 19 drive the homogeneous stator 5 to move away from the homogeneous rotor 4 on the inner wall of the homogeneous tank 1, and compress multiple top pressing springs 20. At this time, the gap between the homogeneous stator 5 and the homogeneous rotor 4 increases, that is, the homogeneous dispersion area increases, which is convenient for the incompletely homogenized oil phase to fall, preventing it from affecting the subsequent uniform mixing of the water phase and the oil phase. And the intermittent increase in the gap forms a larger homogeneous dispersion area, enabling the oil phase and the water phase to have more opportunities to collide and mix with each other. In addition, appropriately increasing the gap reduces the risk of blockage of the oil phase and the water phase in the high shear force area, thereby improving the stability and reliability of the homogenization process; it also reduces the risk of aggregation of oil droplets in the high speed shear force area, contributing to the formation of a more stable emulsion and reducing local aggregation and stratification phenomena; after the pressing protrusion 16 on the wheel surface of the pressing wheel 15 rotates to separate from the pulling cross bar 17, that is, when the wheel surface of the pressing wheel 15 contacts the pulling cross bar 17 again, the homogeneous stator 5 returns to its original position under the elastic force of the multiple top pressing springs 20; it is convenient to continue the homogenization treatment of the water phase and the oil phase according to the preset requirements; the intermittent increase in the size of the homogeneous dispersion area is beneficial to the discharge of the incompletely homogenized and dispersed oil phase, facilitating the guarantee of the mixing effect of the water phase and the oil phase in the subsequent preset flow rate and flow ratio.

[0076] The spacing adjusting member 21 includes a screw member threadedly connected to the lifting ring 18. The top of the screw member is connected to a contact seat for abutting and cooperating below the homogeneous tank 1. A rubber anti-slip pad is provided at the contact between the contact seat and the homogeneous tank 1; the compression spring on the lower surface of the contact seat abuts and cooperates with the lifting ring 18; the locking rod threadedly connected to the lifting ring 18 abuts against the screw member. The setting of the spacing adjusting member 21 is used to limit the highest position of the lifting ring 18, thereby limiting the highest position of the homogeneous stator 5 and limiting the minimum gap between the homogeneous stator 5 and the homogeneous rotor 4, and also preventing the ineffective shear dispersion of the liquid caused by the contact between the homogeneous stator 5 and the homogeneous rotor 4 or too small a gap; rotating the screw member can change its contact position with the lifting ring 18, thereby driving the horizontal height of the contact seat to be adjusted to change the minimum gap between the homogeneous stator 5 and the homogeneous rotor 4 to meet different homogenization requirements; a rubber anti-slip pad is provided at the contact between the contact seat and the homogeneous tank 1, which is convenient for improving the contact effect with the homogeneous tank 1.

[0077] A ring-shaped material collecting hopper 22 is fixedly connected to the bottom of the homogeneous stator 5. The upper part of the ring-shaped material collecting hopper 22 communicates with the homogeneous dispersion area formed between the first inverted conical shearing surface and the second inverted conical shearing surface for shearing the oil phase and the water phase. The lower part of the ring-shaped material collecting hopper 22 is coaxially and sealingly sleeved on the homogeneous rotating shaft 3. A plurality of emulsion discharge ports 23 on the homogeneous rotating shaft 3 are all located inside the ring-shaped material collecting hopper 22. The plurality of emulsion discharge ports 23 on the homogeneous rotating shaft 3 communicate with the discharge channel inside the homogeneous rotating shaft 3. The bottom of the discharge channel extends out below the homogeneous rotating shaft 3.

[0078] A material collecting area for collecting the homogenized liquid is formed between the ring-shaped material collecting hopper 22 and the homogeneous rotating shaft 3. The homogenized emulsion can enter the discharge channel inside the homogeneous rotating shaft 3 through a plurality of emulsion discharge ports 23 and be output through the bottom opening of the discharge channel of the homogeneous rotating shaft 3. When the homogeneous rotating shaft 3 rotates, the positions of the plurality of emulsion discharge ports 23 are continuously changed. By rotating the emulsion discharge ports 23, the emulsion will be affected by the rotating force when being discharged, forming a swirling state, which promotes the rapid flow of the emulsion, reduces the residence time of the emulsion near the discharge port, and the swirling effect can make the emulsion form a uniform distribution near the discharge port, avoiding the phenomenon of too high or too low local concentration. The uniformly distributed emulsion can be discharged more quickly, reducing the accumulation of the emulsion near the discharge port. The swirling effect can also reduce the adhesion force of the emulsion on the inner wall of the ring-shaped material collecting hopper 22. Since the emulsion flows in a swirling state, the interaction force between the droplets is offset by the rotating force, reducing the adsorption force on the surface of the emulsion and effectively reducing the probability of the emulsion adhering to the inner wall of the material collecting hopper. The swirling effect can also produce a self-cleaning effect, that is, the emulsion continuously flushes the inner wall of the ring-shaped material collecting hopper 22 during the swirling process, taking away the possible adhered emulsion residues, enhancing the discharge speed of the emulsion while keeping the inner wall of the material collecting hopper clean, reducing the adhesion of the emulsion, and reducing the residual amount of the emulsion in the ring-shaped material collecting hopper 22.

[0079] A cylindrical filter cartridge 26 rotatably connected in the discharge channel is blocked at a plurality of emulsion discharge ports 23 on the homogeneous rotating shaft 3 to perform filtration and screening treatment on the emulsion entering the discharge channel through the plurality of emulsion discharge ports 23 on the homogeneous rotating shaft 3. One end of the cylindrical filter cartridge 26 extending out to the bottom of the discharge channel of the homogeneous rotating shaft 3 is fixed below the homogeneous tank 1 through a bracket. When the homogeneous rotating shaft 3 rotates, the cleaning brush at the emulsion discharge port 23 of the homogeneous rotating shaft 3 can brush the filter substances on the cylindrical filter cartridge 26. The top of the ring-shaped material collecting hopper 22 is connected and communicated with the top of a return pipe 24 slidably sealed on the bottom surface of the homogeneous tank 1. The bottom of the return pipe 24 is connected to a return nozzle 25 arranged in the middle of the tank cover 2 through a hose with a return pump. The return nozzle 25 is located between the water phase nozzle 6 and the oil phase nozzle 7, so that the mixed liquid that does not meet the dispersion requirements filtered out by the cylindrical filter cartridge 26 can enter the return nozzle 25 through the cooperation of the return pipe 24 and the hose with a return pump, facilitating re-mixing.

[0080] The cylindrical filter cartridge 26 is blocked at multiple emulsion discharge ports 23 on the homogeneous rotating shaft 3, and can filter and screen the emulsion entering the discharge channel through the discharge ports, effectively removing the mixed liquid that does not meet the dispersion requirements, and improving the purity and quality of the emulsion; when the homogeneous rotating shaft 3 rotates, the cleaning brush at the emulsion discharge port 23 can brush the filter on the cylindrical filter cartridge 26, keeping the filter cartridge clean and having high filtering ability, reducing the frequency of manual cleaning, improving the automation degree and filtering efficiency of the equipment; through the brushing action of the cleaning brush, the filter on the cylindrical filter cartridge 26 can be prevented from accumulating, reducing the risk of blockage of the cylindrical filter cartridge 26, keeping the filtering channel unobstructed, and improving the working efficiency and stability of the equipment; the annular material collecting hopper 22 is connected and communicated with the top of the return pipe 24 that is hermetically slid on the bottom surface of the homogeneous tank 1, and the bottom of the return pipe 24 is connected to the return nozzle 25 arranged in the middle of the tank cover 2 through a hose with a return pump, and the formed return system can send the mixed liquid that does not meet the dispersion requirements back into the homogeneous tank for re-mixing, improving the homogeneous effect of the emulsion and reducing waste; the return nozzle 25 is located between the aqueous phase nozzle 6 and the oil phase nozzle 7, so that the returned mixed liquid can be evenly remixed with the newly added aqueous phase and oil phase, achieving a more uniform mixing effect and improving the stability and consistency of the emulsion.

[0081] Finally, it should be noted that the above embodiments only represent several implementation manners of the present invention, and are not intended to limit the present invention. For those of ordinary skill in the art, any modifications, equivalent replacements, improvements, etc. made without departing from the concept of the present invention should be included within the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A preparation method of pigment yellow 83 for automotive coatings, characterized in that, It includes the following steps: S1. Disperse Pigment Yellow 83 in a mixed solution of ethyl acetate and ethanol, add cetyltrimethylammonium bromide and Tween 20, and perform ultrasonic treatment to form a uniform dispersion; add acrylamide, methyl methacrylate, and ethylene glycol dimethacrylate to the dispersion, raise the temperature for reaction, and after the reaction is completed, wash and centrifuge to obtain a functionalized pigment dispersion; S2. Disperse the functionalized pigment dispersion in deionized water, add Span 80 and Tween 20, and stir evenly to obtain an aqueous phase; add an initiator, a crosslinking agent, and n-hexane to styrene, and stir evenly to obtain an oil phase; drop the oil phase into the aqueous phase, homogenize using a high-speed homogenizer to generate a stable emulsion, continue to raise the temperature, initiate a free radical polymerization reaction, add styrene for the first time, add styrene for the second time after reacting for a period of time, continue to react, cool to room temperature after the reaction is completed, wash and centrifuge to obtain pigment particles with a coated shell layer; the rotation speed of the high-speed homogenizer is 8000 - 10000 rpm, the emulsification time is 10 - 15 min, and the polymerization reaction temperature is 70 °C; S3. Disperse the pigment particles with a coated shell layer in deionized water, add trifluoropropylmethylsiloxane, raise the temperature and stir, after the surface modification is completed, control the reaction temperature, and continue to add polyethylene glycol methacrylate, and after the reaction is completed, wash and centrifuge to obtain Pigment Yellow 83 for automotive coatings.

2. The preparation method of pigment yellow 83 for automotive coatings according to claim 1, characterized in that, In step S1, the dosage ratio of Pigment Yellow 83 to the mixed solvent is (3 - 8) g : 100 mL; the volume ratio of ethyl acetate to ethanol is (3 - 5) : 1; the mass ratio of Pigment Yellow 83, cetyltrimethylammonium bromide, and Tween 20 is 1 : (0.03 - 0.05) : (0.01 - 0.03).

3. The preparation method of Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that, In step S1, the mass ratio of acrylamide, methyl methacrylate, and ethylene glycol dimethacrylate is 1 : (0.4 - 0.6) : (0.4 - 0.6), and the total mass accounts for 10 - 15% of the dosage of Pigment 83; The temperature for the temperature-raising reaction is 40 °C, and the reaction time is 2 - 3 h.

4. The preparation method of pigment yellow 83 for automotive coatings according to claim 1, characterized in that, In step S2, in the aqueous phase by weight, it includes 5 - 8 parts of functionalized pigment, 30 - 50 parts of deionized water, 0.02 - 0.1 part of Span 80, and 0.01 - 0.05 part of Tween 20.

5. The preparation method of Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that, In step S2, in the oil phase by weight, it includes 3 - 5 parts of styrene, 0.01 - 0.03 part of initiator, 0.01 - 0.03 part of crosslinking agent, and 0.1 - 0.3 part of n-hexane.

6. The preparation method of pigment yellow 83 for automotive coatings according to claim 1, characterized in that, In step S2, the initiator is azobisisobutyronitrile, and the crosslinking agent is ethylene glycol dimethacrylate.

7. The preparation method of Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that, In step S2, the dosage of the added styrene is 20 - 40% of the dosage of styrene in the oil phase.

8. The preparation method of pigment yellow 83 for automotive coatings according to claim 1, characterized in that, In step S3, the mass ratio of the pigment particles with a coated shell layer, trifluoropropylmethylsiloxane, and polyethylene glycol methacrylate is (5 - 10) : 0.2 : 0.

2.

9. The preparation method of pigment yellow 83 for automotive coatings according to claim 1, characterized in that, In step S3, the surface modification reaction temperature of trifluoropropylmethylsiloxane is 60 ± 1 °C, and the surface modification reaction temperature of polyethylene glycol methacrylate is 50 ± 0.5 °C.

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