Preparation method of pigment yellow 83 for automobile coating

Abstract

The invention discloses a preparation method of pigment yellow 83 for an automobile coating. The preparation method comprises the following steps: S1, preparing a functional pigment dispersion; s2, coating the surface of the functionalized pigment dispersion with a polymer layer with a porous structure to obtain pigment particles coated with a shell layer; and S3, carrying out surface modification on the pigment particles coated with the shell layer to obtain the pigment yellow 83 for the automobile coating. The pigment yellow 83 serves as a core and is coated with the polymer shell layer to form a shell-core structure, the polymer shell layer has the porous characteristic, the structure can protect the pigment core and improve the dispersion stability of the pigment core, performance adjustment is achieved through the pore characteristic of the shell layer, the color development effect of the pigment yellow 83 is enhanced, the interface effect is optimized, and the durability is improved.

Description

Technical Field

[0001] The invention relates to the technical field of organic pigments, and in particular to a method for preparing pigment yellow 83 for automobile coatings. Background Art

[0002] With the rapid development of the automobile industry, the performance requirements for automobile coatings are constantly increasing, especially in terms of environmental protection, weather resistance and color stability. Traditional organic pigments are difficult to meet the stringent requirements of modern automobile coatings for pigments due to problems such as poor dispersibility, severe photodegradation and poor interfacial compatibility. Especially in water-based coating systems, the dispersion and stability of pigments directly affect the final performance of the coating. Pigment Yellow 83 is an important organic pigment and is widely used in the field of automotive coatings. Although pigment yellow has excellent color saturation and hiding power, it has high surface energy and many polar groups. It is very easy to agglomerate in practical applications, resulting in performance degradation. At present, dispersants or surfactants are often used to improve the dispersibility of pigments, but the dispersants or surfactants have weak bonding with the surface of organic pigments and are easy to fall off; the prepared organic pigments have poor stability and are greatly affected by the environment; in order to further increase the dispersibility of organic pigments, the amount of dispersants or surfactants is increased, thereby affecting the color rendering properties of organic pigments. 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 the organic pigment to form a dense coating layer, but the coating layer is a simple dense structure, the internal stress is difficult to release, and it is easy to crack or peel off, and it will also have a certain impact on the color saturation of the organic pigment. Summary of the invention

[0003] Based on the problems existing in the background technology, the present invention provides a method for preparing Pigment Yellow 83 for automotive coatings. Pigment Yellow 83 as a core is coated by a polymer shell layer to form a core-shell structure, and the polymer shell layer has a porous property. This structure can not only protect the pigment core and improve its dispersion stability, but also achieve performance adjustment through the porosity characteristics of the shell layer, thereby enhancing the color rendering effect of Pigment Yellow 83, optimizing the interface effect and improving the durability.

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

[0005] A method for preparing pigment yellow 83 for automotive coatings comprises the following steps:

[0006] S1. Dispersing Pigment Yellow 83 in a mixed solution of ethyl acetate and ethanol, adding hexadecyltrimethylammonium bromide and Tween 20, and ultrasonically treating to form a uniform dispersion; adding acrylamide, methyl methacrylate and ethylene glycol dimethacrylate to the dispersion, heating the mixture to react, and after the reaction is completed, washing and centrifuging 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 an aqueous phase; add an initiator, a crosslinking agent and n-hexane to styrene, 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 heat, start a free radical polymerization reaction, add styrene for the first time, and after a period of reaction, add styrene for the second time, continue the reaction, and after the reaction is completed, cool to room temperature, wash, and centrifuge to obtain pigment particles coated with a shell layer;

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

[0009] Furthermore, in step S1, the dosage ratio of Pigment Yellow 83 and the mixed solvent is (3-8) g:100 mL; the volume ratio of ethyl acetate and ethanol is (3-5):1; the mass ratio of Pigment Yellow 83, hexadecyltrimethylammonium 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 amount of pigment 83;

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

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

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

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

[0015] Furthermore, in step S2, the initiator is azobisisobutyronitrile and the cross-linking agent is ethylene glycol dimethacrylate.

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

[0017] Furthermore, 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, since the surface of the functionalized pigment is amphiphilic, the pigment is directionally arranged at the oil-water interface, and the formed Pickering emulsion has high stability. When the temperature is raised to the polymerization reaction temperature, styrene is polymerized limitedly on the pigment surface with the lowest interfacial energy. The addition of styrene in two times 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 evaporates to form pores. The presence of the cross-linking agent stabilizes the structure of the pores, and finally the shell layer has a porous structure.

[0019] Furthermore, in step S3, the mass ratio of the pigment particles, trifluoropropylmethylsiloxane and polyethylene glycol methacrylate in the coating shell layer is (5-10): 0.2: 0.2.

[0020] Furthermore, in step S3, the surface modification reaction temperature of trifluoropropyl methylsiloxane is 60±1°C, and the surface modification reaction temperature of polyethylene glycol methacrylate is 50±0.5°C.

[0021] Beneficial effects of the present invention:

[0022] The functional modification in the present invention makes the surface of Pigment Yellow 83 amphiphilic, and the construction of the shell layer in the emulsion polymerization process and the surface PEGMA modification effectively prevent the pigment particles from settling and agglomerating in the water-based coating system, ensuring long-term storage stability. The porous shell structure improves the color vividness of Pigment Yellow 83 by reducing light scattering, optimizes the optical properties of 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 to avoid damage to the pigment core and shell layer, and the process is highly controllable and suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying 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 of the present invention. In the accompanying drawings:

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

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

[0026] Figure 3 A cross-sectional view of a high-speed homogenizer for mixing and homogenizing an oil phase and an aqueous phase provided in an embodiment of the present invention;

[0027] Figure 4 A partial diagram of a high-speed homogenizer for mixing and homogenizing an oil phase and an aqueous phase provided in an embodiment of the present invention;

[0028] Figure 5 A schematic diagram of a homogenizing shaft provided in an embodiment of the present invention;

[0029] Figure 6 A schematic diagram of a homogenizing rotor provided in an embodiment of the present invention;

[0030] Figure 7 A schematic diagram of a homogeneous stator provided in an embodiment of the present invention;

[0031] Figure 8 A schematic diagram of a top pressure wheel provided in an embodiment of the present invention;

[0032] Fig. 9 A schematic diagram of an annular aggregate hopper provided in an embodiment of the present invention;

[0033] Fig.10 A schematic diagram of a homogenizing shaft and a cylindrical filter cartridge provided in an embodiment of the present invention.

[0034] Icons: homogenizing tank 1; tank cover 2; homogenizing 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; wheel axle 13; multi-faceted sliding rod 14; pressing wheel 15; pressing protrusion 16; pulling cross bar 17; lifting ring 18; pulling sliding column 19; lifting pressure spring 20; spacing adjustment piece 21; annular aggregation hopper 22; emulsion discharge outlet 23; reflux pipe 24; reflux nozzle 25; cylindrical filter cartridge 26. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is 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.

[0036] Example 1

[0037] A method for preparing pigment yellow 83 for automotive coatings comprises the following steps:

[0038] S1. Disperse 5 g of Pigment Yellow 83 in 100 mL of a mixed solution of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of hexadecyltrimethylammonium 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, heat 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, 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, stir evenly to obtain an oil phase; drop the oil phase into the aqueous phase, homogenize using a high-speed homogenizer at a speed of 8000 rpm and an emulsification time of 10 min to generate a stable emulsion, continue to heat to 70 ° C, start a free radical polymerization reaction, add 1 g of styrene for the first time, react for 2 h, add 1 g of styrene for the second time, continue to react for 2 h, cool to room temperature after the reaction is completed, wash, and centrifuge to obtain pigment particles coated with a shell layer;

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

[0041] Example 2

[0042] A method for preparing pigment yellow 83 for automotive coatings comprises the following steps:

[0043] S1. Disperse 5 g of Pigment Yellow 83 in 100 mL of a mixed solution of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of hexadecyltrimethylammonium 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, heat 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 an 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 an oil phase; add the oil phase dropwise to the aqueous phase, homogenize using a high-speed homogenizer at a speed of 8000 rpm and an emulsification time of 10 min to generate a stable emulsion, continue to heat to 70°C, start a free radical polymerization reaction, add 0.8 g of styrene for the first time, react for 2 h, add 0.8 g of styrene for the second time, continue to react for 2 h, cool to room temperature after the reaction is completed, wash, and centrifuge to obtain pigment particles coated with a shell layer;

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

[0046] Comparative Example 1

[0047] A method for preparing pigment yellow 83 for automotive coatings comprises the following steps:

[0048] S1. Disperse 5 g of Pigment Yellow 83 in 100 mL of a mixed solution of ethyl acetate and ethanol (volume ratio 4:1), add 0.2 g of hexadecyltrimethylammonium bromide and 0.1 g of Tween 20, and 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 to 40°C for reaction, react for 2.5 h, wash, and centrifuge to obtain a functionalized pigment dispersion;

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

[0050] Comparative Example 2

[0051] The difference between 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 an aqueous phase; the remaining steps are the same as 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 the mixture is stirred evenly to obtain an 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 step S2 is specifically as follows: 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 the mixture is stirred evenly to obtain an aqueous phase; 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 the mixture is stirred evenly to obtain an oil phase; the oil phase is added dropwise to the aqueous phase, and the mixture is homogenized using a high-speed homogenizer at a speed of 8000 rpm and an emulsification time of 10 min to generate a stable emulsion, and the temperature is continued to be raised to 70° C. to start a free radical polymerization reaction, and the reaction is carried out for 4 hours. After the reaction is completed, the mixture is cooled to room temperature, washed, and centrifuged to obtain pigment particles coated with a shell layer; the remaining steps are the same as in Example 1.

[0056] Test example

[0057] This test example illustrates the use of Pigment Yellow 83 prepared according to the above Examples 1-2 and Comparative Examples 1-4 by adding it to a water-based paint for automobiles.

[0058] Coating preparation

[0059] 8 g of Pigment Yellow 83 prepared in the embodiment or comparative example was added to 40 mL of deionized water, 0.5 g of sodium polyacrylate dispersant was added, and the mixture was stirred evenly. 45 g of aqueous acrylic resin emulsion, 0.3 g of defoamer, and 0.2 g of leveling agent were added, and the mixture was dispersed at high speed. The viscosity of the system was adjusted to 100 mPa·s, and the mixture was filtered through a 100-mesh filter cloth to obtain an automotive coating.

[0060] Coating Evaluation

[0061] (1) The particle size of the pigment in the coating was measured using a particle size analyzer. The results are shown in Table 1.

[0062] (2) Take 1 mL of the coating and spin-coat it on a glass slide at a speed of 1000 rpm. Place the coated glass slide on a hot plate at 90°C for 3 minutes and then place it in a 230°C oven for 30 minutes. Use a colorimeter and a contrast meter to test the brightness (Y) and contrast. The results are shown in Table 1.

[0063] Table 1

[0064] Group D50 / nm D90 / nm Brightness (Y) Contrast 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 particle size D50 and D90 of the pigment yellow 83 prepared in Examples 1 and 2 are smaller than those in the comparative example, 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 in S1 functionalizes the pigment yellow 83, and the obtained functionalized pigment dispersion exhibits hydrophilicity, which is difficult to stably adsorb at the oil-water interface in the Pickering emulsion and cannot effectively participate in the interfacial reaction, ultimately resulting in uneven polymerization of the shell layer, and due to the lack of hydrophobic components, the porosity of the shell layer is significantly reduced, and the thickness and uniformity are also unstable. The reduced porosity of the shell layer will reduce the ability to regulate light absorption and reduce the contrast. In Comparative Example 2, the aqueous phase in S2 contains only Tween 20, but not Span 80. Tween 20 has a higher HLB value, while Span 80 has a relatively lower HLB value. Using a single Tween 20, there is a lack of a low-HLB co-emulsifier, and the interfacial tension reduction effect of the emulsion is weak, resulting in insufficient emulsion stability, decreased amphiphilic interfacial adsorption capacity of pigment particles, and styrene cannot be uniformly polymerized at the pigment interface, but polymerizes locally to form an incomplete or uneven shell. In Comparative Example 3, the oil phase in S2 does not contain n-hexane, which is used as a pore-forming agent. In the absence of n-hexane, the shell tends 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 the color vividness is significantly weakened. In Comparative Example 4, all styrene is added to the oil in S2 at one time without adding in batches. After the polymerization reaction is started, the shell grows rapidly in the early stage of polymerization, resulting in an increase in the thickness of the local shell. The polymerization rate is too fast, resulting in an overly thick or irregular shell. The uneven distribution of the shell thickness leads to inconsistent color development of the pigment particles, and the overall uniformity of the coating color decreases. The purpose of adding styrene is to control the thickness and uniformity of the gradual growth of the shell by providing monomers in batches. The further growth of the shell in the late stage of polymerization can fill the pore boundaries and stabilize the pore structure.

[0066] Example 3

[0067] See also Figure 1-10 In S2 of the method for preparing pigment yellow 83 for automotive coatings of the present invention, the oil phase is added dropwise to the water 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, during homogenization, the oil phase and the water phase are directly put into the homogenizer by conventional high-speed homogenizers, and the oil phase and the water phase cannot be initially mixed, resulting in low subsequent homogenization efficiency and poor emulsion stability.

[0069] In order to further improve the mixing and homogenizing effect of the oil phase and the water 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 the oil droplets into the water phase to form tiny oil droplets that are not easy to aggregate, thereby forming a stable emulsion;

[0070] The high-speed homogenizer comprises: a homogenizing tank 1 and a tank cover 2 installed at the top opening of the homogenizing tank 1; a homogenizing shaft 3 is rotatably connected in the central hole at the bottom of the homogenizing tank 1, and the homogenizing shaft 3 extends into one end of the homogenizing tank 1 and is keyed to connect a homogenizing rotor 4, and the homogenizing rotor 4 is rotatably fitted above a homogenizing stator 5 installed on the inner wall of the homogenizing tank 1, and a first inverted conical shearing surface below the homogenizing rotor 4 is matched with a second inverted conical shearing surface above the homogenizing stator 5, and a homogenizing dispersion area 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 homogenizing tank 1, and the water phase nozzle 6 and the oil phase nozzle 7 are located above the homogenizing rotor 4, and the water phase nozzle 6 and the oil phase nozzle 7 are inserted into one end of the homogenizing tank 1 and are arranged opposite to each other so that the water phase and the oil phase collide with each other by impact injection; the pulley on the homogenizing shaft 3 is connected to the pulley at the output end of the power motor 8 through a synchronous belt.

[0071] The high-speed homogenizer provided by the present invention starts the power motor 8 during homogenization. After the power motor 8 is started, the cooperation of the pulley and the synchronous belt can drive the homogenizing shaft 3 to rotate around its own axis, thereby driving the homogenizing rotor 4 to rotate through the homogenizing shaft 3. A water phase nozzle 6 and an oil phase nozzle 7 are installed above the side of the homogenizing tank 1. The water phase nozzle 6 and the oil phase nozzle 7 are inserted into one end of the homogenizing tank 1 and are arranged opposite to each other so that the water phase and the oil phase are sprayed and collided against each other. The water phase and the oil phase are sprayed and collided against each other through the nozzles, and a preliminary mixing can be formed before entering the homogenizing dispersion zone, thereby enhancing the contact between the two phases, achieving a more uniform phase distribution, avoiding the problem of excessively high or low local concentrations, and facilitating the subsequent homogenization process. , thereby improving the emulsification effect and helping to form a more uniform emulsion; in addition, the nozzle hedging design can reduce the formation of larger particles and avoid oil droplet aggregation, thereby improving the long-term stability of the emulsion, and can also more effectively utilize energy, reduce energy loss, and improve the economy of the homogenization process; after the water phase and the oil phase are counter-sprayed, they fall into the homogenization dispersion area between the homogenizing rotor 4 and the homogenizing stator 5. When the homogenizing rotor 4 rotates relative to the homogenizing stator 5, a strong shear force is generated through the small gap between the homogenizing rotor 4 and the homogenizing stator 5, so that the substances in the water phase and the oil phase are quickly and evenly dispersed, which has many advantages such as enhancing the initial mixing effect of the water phase and the oil phase, improving the homogenization efficiency, and enhancing the stability of the emulsion.

[0072] A plurality of swirl scrapers 9 are evenly fixed on the side of the homogenizing rotor 4, and the lower surfaces of the plurality of swirl scrapers 9 are slidably fitted on the plane above the homogenizing stator 5, and the side surfaces of the plurality of swirl scrapers 9 away from the homogenizing rotor 4 are slidably fitted on the inner wall surface of the homogenizing tank 1; a rotor scraper 10 is also fixed to the inner wall surface of the homogenizing tank 1 through a bracket, and the lower surface of the rotor scraper 10 is slidably fitted on the conical guide surface above the homogenizing rotor 4, and the conical guide surface is inclined toward the plane above the homogenizing stator 5.

[0073] When the homogenizing rotor 4 rotates, it can drive multiple swirl scrapers 9 to rotate and circle. The multiple swirl scrapers 9 scrape the liquid on the plane above the homogenizing stator 5 and the inner wall of the homogenizing tank 1, which is convenient for improving the homogenous dispersion effect of the water phase and the oil phase entering the homogenizing dispersion area between the homogenizing rotor 4 and the homogenizing stator 5, and also prevents liquid accumulation. It can also enhance the rotational flow effect of the water phase and the oil phase in the homogenizing tank 1, which helps to better mix the oil phase and the water phase and improve the homogenization efficiency; the design of the swirl scraper 9 can also better distribute the liquid, avoid the problem of local concentration being too high or too low, and the uniform liquid distribution helps to form a more uniform emulsion and improve the stability and consistency of the product; the lower surface of the rotor scraper 10 is slidably matched on the conical guide surface above the homogenizing rotor 4, so as to scrape the liquid on the conical guide surface above the homogenizing rotor 4 to the plane above the homogenizing stator 5. The conical guide surface above the homogenizing rotor 4 is inclined toward the plane above the homogenizing stator 5, which can optimize the flow path of the liquid in the homogenizing tank 2. This design helps the liquid to form more suitable fluid dynamic characteristics in the homogenizing tank 1, reduce energy loss and improve homogenization efficiency; in addition, the design of the swirl scraper 9 and the rotor scraper 10 can also enhance the local shear force, help to disperse the oil droplets more finely, form finer particles, achieve more efficient, more uniform and more stable emulsion preparation, and improve production efficiency and product quality.

[0074] The homogenizing shaft 3 is provided with a worm structure 11 on the shaft body located below the homogenizing tank 1, and a worm wheel 12 is meshedly connected with the worm structure 11, and the wheel shaft 13 of the worm wheel 12 is rotatably arranged on the support at the bottom of the homogenizing tank 1, and a multi-faceted sliding rod 14 is slidably connected in the multi-faceted slideway of the wheel shaft 13, and the bolts threadedly connected to the wheel shaft 13 are tightly pressed in the positioning holes of the multi-faceted sliding rod 14; a top pressure wheel 15 is fixed at one end of the multi-faceted sliding rod 14, and a top pressure protrusion 16 is provided on the wheel surface of the top pressure wheel 15; the bottom of the top pressure wheel 15 is rollingly matched on the pulling cross bar 17, and the pulling cross bar 17 is fixedly connected to the bottom of the lifting ring 18 through a vertical rod, and the lifting ring 18 is fixed at the bottom of multiple pulling sliding columns 19, and the middle parts of multiple pulling sliding columns 19 are sealed and slidably arranged on the bottom surface of the homogenizing tank 1, and one end of the multiple pulling sliding columns 19 inserted into the homogenizing tank 1 is connected with the homogenizing stator 5 slidably arranged on the inner wall of the homogenizing tank 1, and the pulling The pull slide column 19 is located between the homogenizing stator 5 and the bottom surface of the homogenizing tank 1 and is sleeved with a lifting spring 20; a plurality of spacing adjustment members 21 are connected to the lifting ring 18, and the spacing adjustment members 21 are abutted and fitted under the homogenizing tank 1 to fix the size of the homogenizing dispersion area between the second inverted conical shear surface of the homogenizing stator 5 and the first inverted conical shear surface of the homogenizing rotor 4; when the pressing protrusion 16 on the wheel surface of the pressing wheel 15 rotates to contact the pulling cross bar 17, the pulling cross bar 17 can be pressed to drive the pulling cross bar 17 to move downward, thereby driving the homogenizing stator 5 to move on the inner wall of the homogenizing tank 1 in the direction away from the homogenizing rotor 4 through the cooperation of the pulling cross bar 17, the vertical bar, the lifting ring 18 and the plurality of pulling slide columns 19; when the pressing protrusion 16 on the wheel surface of the pressing wheel 15 rotates to separate from the pulling cross bar 17, the homogenizing stator 5 returns to its original position under the elastic force of the plurality of lifting springs 20.

[0075] When the homogenizing shaft 3 rotates, the worm structure 11 can be driven to rotate. When the worm structure 11 rotates, the worm gear 12 can be engaged to rotate. When the worm gear 12 rotates, the multi-faceted sliding rod 14 can be driven to rotate. When the multi-faceted sliding rod 14 rotates, the pressing wheel 15 can be driven 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, the pressing protrusion 16 can be driven to press and drive the pulling cross bar 17 to move downward. When the pulling cross bar 17 moves downward, the lifting ring 18 can be driven downward by the vertical rod, and the lifting ring 18 drives the multiple pulling slide columns 19 to slide downward. The multiple pulling slide columns 19 drive the homogenizing stator 5 to move in the direction away from the homogenizing rotor 4 on the inner wall of the homogenizing tank 1, and compress the multiple lifting springs 20. At this time, the gap between the homogenizing stator 5 and the homogenizing rotor 4 is increased, that is, the homogenizing dispersion area is increased, which is convenient for the oil phase that is not fully homogenized to fall, and prevents it from affecting the subsequent entry into the water The uniform mixing of the water phase and the oil phase, and the intermittent increase in the gap forms a larger homogeneous dispersion zone, which gives the oil phase and the water phase more opportunities to collide and mix with each other. In addition, the appropriate increase in the gap reduces the risk of blockage between 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 oil droplets agglomerating in the high-speed shear force area, which helps to form a more stable emulsion and reduce local aggregation and stratification; 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, the wheel surface of the pressing wheel 15 contacts the pulling cross bar 17 again, the homogenizing stator 5 returns to its original position under the elastic force of multiple lifting springs 20; it is convenient to continue the homogenization of the water phase and the oil phase according to the preset requirements; intermittently increase the size of the homogenous dispersion zone, which is conducive to the discharge of the oil phase that is not fully homogenously dispersed, so as to ensure the subsequent mixing effect of the water phase and the oil phase according to the preset flow rate and flow ratio.

[0076] The spacing adjustment member 21 includes a screw member threadedly connected to the lifting ring 18, the top of the screw member is connected to the abutment seat for abutting and fitting under the homogenizing tank 1, and a rubber anti-skid pad is provided at the contact point between the abutment seat and the homogenizing tank 1; the compression spring on the lower surface of the abutment seat abuts and fits on the lifting ring 18; the locking rod threadedly connected to the lifting ring 18 abuts on the screw member. The spacing adjustment member 21 is provided to limit the highest position of the lifting ring 18, thereby limiting the highest position of the homogenizing stator 5, limiting the minimum gap between the homogenizing stator 5 and the homogenizing rotor 4, and also preventing the homogenizing stator 5 and the homogenizing rotor 4 from contacting or the gap being too small, resulting in the inability to effectively shear and disperse the liquid; rotating the screw member can change its contact position with the lifting ring 18, thereby driving the horizontal height of the abutment seat to be adjusted, so as to change the minimum gap between the homogenizing stator 5 and the homogenizing rotor 4, and meet different homogenization requirements; a rubber anti-skid pad is provided at the contact point between the abutment seat and the homogenizing tank 1, so as to improve the contact effect with the homogenizing tank 1.

[0077] An annular aggregate hopper 22 is fixedly connected to the bottom of the homogenizing stator 5, and a homogenizing dispersion zone for shearing the oil phase and the water phase is formed between the upper part of the annular aggregate hopper 22 and the first inverted conical shearing surface and the second inverted conical shearing surface. A coaxial sealing sleeve is arranged on the homogenizing shaft 3 below the annular aggregate hopper 22; multiple emulsion discharge outlets 23 on the homogenizing shaft 3 are all located on the inner side of the annular aggregate hopper 22, and the multiple emulsion discharge outlets 23 on the homogenizing shaft 3 are connected to the discharge channel in the homogenizing shaft 3, and the bottom of the discharge channel is arranged below the homogenizing shaft 3.

[0078] A gathering area for collecting the homogenized liquid is formed between the annular gathering hopper 22 and the homogenizing shaft 3. The homogenized emulsion can enter the discharge channel in the homogenizing shaft 3 through multiple emulsion discharge ports 23, and be discharged through the bottom opening of the discharge channel of the homogenizing shaft 3; the positions of the multiple emulsion discharge ports 23 are constantly changed when the homogenizing shaft 3 rotates. By rotating the emulsion discharge ports 23, the emulsion is subjected to the action of a rotating force when discharged, forming a vortex state, promoting the rapid flow of the emulsion, reducing the residence time of the emulsion near the discharge port, and the vortex effect can make the emulsion form a uniform distribution near the discharge port, avoiding the phenomenon of excessively high or low local concentration, and the uniform distribution The emulsion can be discharged more quickly, reducing the accumulation of emulsion near the discharge port; the swirl effect can also reduce the adhesion of the emulsion on the inner wall of the annular hopper 22. Since the emulsion flows in a swirl state, the interaction force between the droplets is offset by the rotational force, reducing the adsorption force of the emulsion on the surface, and effectively reducing the probability of the emulsion adhering to the inner wall of the hopper; the swirl effect can also produce a self-cleaning effect, that is, the emulsion continuously flushes the inner wall of the annular hopper 22 during the swirl process, taking away the emulsion residue that may adhere, thereby enhancing the discharge speed of the emulsion while keeping the inner wall of the hopper clean, reducing the adhesion of the emulsion, and reducing the residual amount of emulsion in the annular hopper 22.

[0079] The cylindrical filter cartridge 26 rotatably connected in the discharge channel is sealed at multiple emulsion discharge ports 23 on the homogenizing shaft 3 to filter and screen the emulsion entering the discharge channel through the multiple emulsion discharge ports 23 on the homogenizing shaft 3. One end of the cylindrical filter cartridge 26 passing through the bottom of the discharge channel of the homogenizing shaft 3 is fixed to the bottom of the homogenizing tank 1 through a bracket. When the homogenizing shaft 3 rotates, the cleaning brush at the emulsion discharge port 23 of the homogenizing shaft 3 can brush the filtered material on the cylindrical filter cartridge 26; the annular aggregation hopper 22 is connected and communicated with the top of the reflux pipe 24 sealingly slidably arranged on the bottom surface of the homogenizing tank 1. The bottom of the reflux pipe 24 is connected to the reflux nozzle 25 arranged in the middle of the tank cover 2 through a hose with a reflux pump. The reflux nozzle 25 is located between the water phase nozzle 6 and the oil phase nozzle 7, so that the mixed liquid filtered out by the cylindrical filter cartridge 26 that does not meet the dispersion requirements can enter the reflux nozzle 25 through the cooperation of the reflux pipe 24 and the hose with a reflux pump, which is convenient for re-mixing.

[0080] The cylindrical filter cartridge 26 is sealed at the multiple emulsion discharge ports 23 on the homogenizing shaft 3, and can filter and screen the emulsion entering the discharge channel through the discharge ports, and can effectively remove the mixed liquid that does not meet the dispersion requirements, thereby improving the purity and quality of the emulsion; when the homogenizing shaft 3 rotates, the cleaning brush at the emulsion discharge port 23 can brush the filtered material on the cylindrical filter cartridge 26, and keep the filter cartridge clean and have high-efficiency filtering capacity, which can reduce the frequency of manual cleaning and improve the automation degree and filtering efficiency of the equipment; through the brushing action of the cleaning brush, the filtered material on the cylindrical filter cartridge 26 can be prevented from accumulating, and the risk of clogging of the cylindrical filter cartridge 26 can be reduced, and the filter cartridge 26 can be kept clean. The unobstructed filtering channel improves the working efficiency and stability of the equipment; the annular aggregation hopper 22 is connected and communicated with the top of the reflux pipe 24 which is sealed and slidably arranged on the bottom surface of the homogenizing tank 1, and the bottom of the reflux pipe 24 is connected to the reflux nozzle 25 arranged in the middle of the tank cover 2 through a hose with a reflux pump. The formed reflux system can return the mixed liquid that does not meet the dispersion requirements to the homogenizing tank for re-mixing, thereby improving the homogenization effect of the emulsion and reducing waste; the reflux nozzle 25 is located between the water phase nozzle 6 and the oil phase nozzle 7, so that the refluxed mixed liquid can be evenly re-mixed with the newly added water phase and oil phase, which can achieve a more uniform mixing effect and improve the stability and consistency of the emulsion.

[0081] Finally, it should be noted that the above-mentioned embodiments only express several implementation methods of the present invention and are not intended to limit the invention. For those skilled in the art, any modification, equivalent replacement, improvement, etc. made without departing from the concept of the present invention should be included in the protection scope of the invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for preparing Pigment Yellow 83 for automotive coatings, characterized in that: The following steps are involved: S1. Dispersing Pigment Yellow 83 in a mixed solution of ethyl acetate and ethanol, adding hexadecyltrimethylammonium bromide and Tween 20, and ultrasonically treating to form a uniform dispersion; adding acrylamide, methyl methacrylate and ethylene glycol dimethacrylate to the dispersion, heating the mixture to react, and after the reaction is completed, washing and centrifuging to obtain a functionalized pigment dispersion; S2. Disperse the functionalized pigment dispersion in deionized water, add Span 80 and Tween 20, stir evenly to obtain an aqueous phase; add an initiator, a crosslinking agent and n-hexane to styrene, 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 heat, start a free radical polymerization reaction, add styrene for the first time, and after a period of reaction, add styrene for the second time, continue the reaction, and after the reaction is completed, cool to room temperature, wash, and centrifuge to obtain pigment particles coated with a shell layer; S3. Disperse the pigment particles coated with the shell layer in deionized water, add trifluoropropyl methylsiloxane, heat and stir, and after the surface modification is completed, control the reaction temperature and continue to add polyethylene glycol methacrylate. After the reaction is completed, wash and centrifuge to obtain Pigment Yellow 83 for automotive coatings.

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

3. The method for preparing 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 amount of pigment 83; The reaction temperature is 40°C and the reaction time is 2-3h.

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

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

6. The method for preparing Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that: In step S2, the initiator is azobisisobutyronitrile, and the cross-linking agent is ethylene glycol dimethacrylate.

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

8. The method for preparing Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that: 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.

9. The method for preparing Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that: In step S3, the mass ratio of the pigment particles, trifluoropropylmethylsiloxane and polyethylene glycol methacrylate in the coating shell layer is (5-10):0.2:0.

2.

10. The method for preparing Pigment Yellow 83 for automotive coatings according to claim 1, characterized in that: In step S3, the surface modification reaction temperature of trifluoropropyl methylsiloxane is 60±1°C, and the surface modification reaction temperature of polyethylene glycol methacrylate is 50±0.5°C.

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