A diphasic conductive additive stepwise dispersed coil coating and its preparation process

Abstract

The present application relates to the technical field of conductive paint, in particular to a kind of two-phase conductive additive step-by-step dispersion coiled material paint and its preparation process.The present application overcomes the problem of poor conductive performance of polyester paint.The present application mixes pretreated carbon nanotube with polyol and polyacid, and uses the process of segmented temperature control to prepare conductive polyester, which promotes the additive to be more evenly embedded in the polyester molecular network;By introducing two kinds of conductive additives, carbon nanotube and nano zinc oxide, in steps, and using different pretreatment methods, xylene and deionized water are used to disperse the two kinds of conductive additives and add them in different stages, to improve the conductivity of the paint;By preparing a leveling agent with a fluorine-silicon block structure, a molecular chain conformational change occurs during the paint baking stage, which improves the conductive performance and appearance integrity of the paint.

Description

Technical Field

[0001] This invention relates to the field of conductive coating technology, specifically to a roll coating with stepwise dispersion of biphase conductive additives and its preparation process. Background Technology

[0002] Currently, most conductive coatings in China are used in electronic products such as mobile phones, electronic medical devices, and laptops with very ideal results. However, their application in coil coatings is relatively limited. With the continuous expansion of market demand and the broadening of application scope, certain requirements are being placed on the conductivity of coil coatings such as steel coils, aluminum coils, and sheet metal. However, the development of conductive coil coatings faces many technical bottlenecks: on the one hand, conductive additives have a relatively large proportion and are difficult to disperse evenly in the coating system, resulting in unstable coating conductivity and a tendency for sedimentation and stratification during coating storage; on the other hand, the particle characteristics of conductive additives (such as particle size and shape) can easily affect the film quality of the coating, causing surface defects such as particles, pits, and streaks, while also reducing the gloss and transparency of the paint film, severely restricting the overall performance of coil coatings.

[0003] Currently, polyurethane is widely used in the coatings industry due to its excellent mechanical properties, abrasion resistance, and weather resistance. Using polyurethane as a film-forming material to prepare conductive coil coatings can effectively improve the overall performance of the coating. However, when introducing conductivity into polyurethane coil coating systems, the problems of conductive additive dispersion and coating performance optimization have not yet been effectively solved. Therefore, developing a coil coating based on a polyurethane system with stepwise dispersion technology for two-phase conductive additives is of great significance to meeting the market demand for high-performance coil coatings.

[0004] To address this, a roll coating with stepwise dispersion of biphase conductive additives and its preparation process are proposed. Summary of the Invention

[0005] The purpose of this invention is to provide a roll coating with a stepwise dispersion of biphase conductive additives and its preparation process. The process involves mixing pretreated carbon nanotubes with polyols and polyacids, and preparing conductive polyester using a segmented temperature-controlled process to promote more uniform embedding of the additives into the polyester molecular network. By introducing carbon nanotubes and nano-zinc oxide as conductive additives stepwise, and employing different pretreatment methods, the two conductive additives are dispersed using xylene and deionized water respectively and added at different stages, thereby improving the conductivity of the coating. Furthermore, by preparing a fluorine-silicon block structure leveling agent, a molecular chain conformational transformation occurs during the coating baking stage, enhancing the coating's conductivity and appearance integrity.

[0006] To achieve the above objectives, the present invention provides the following technical solution: It should be noted that all parts in this invention are parts by weight.

[0007] This invention provides a process for preparing a coil coating with a stepwise dispersion of a biphase conductive additive. The preparation method is as follows: conductive additive one, polyol, polyacid and catalyst are added to a reaction vessel and heated and mixed using a segmented temperature control method to obtain conductive polyester; conductive additive one is dispersed in xylene to obtain a primary dispersion; conductive additive two is dispersed in deionized water to obtain a secondary dispersion; conductive polyester, primary dispersion, secondary dispersion, pigment carbon black, organosilicon defoamer and leveling agent are added to a stirred tank and mixed to obtain a coil coating. The conductive additive is obtained by treating carbon nanotubes with a silane coupling agent. Conductive additive 2 is obtained by impregnating nano zinc oxide with 1-butyl-3-methylimidazolium hexafluorophosphate; The leveling agent was prepared from hexafluorobutyl methacrylate and octaaminopropyl cage-like silsesquioxane.

[0008] Preferably, the preparation process of conductive polyester is as follows: 5 parts of conductive additive I, 50 parts of neopentyl glycol, 20 parts of 1,6-hexanediol, 65 parts of terephthalic acid, 25 parts of isophthalic acid, and 0.08 parts of tetrabutyl titanate are sequentially added to a reaction vessel and stirred at 450 rpm to ensure initial uniform mixing of the raw materials; heat transfer oil is introduced into the jacket of the reaction vessel for heating, raising the temperature of the reaction system to 80-95℃, and stirring at 400 rpm for 1-2.5 hours to allow conductive additive I to initially disperse in the system and have a certain degree of contact and fusion with the raw materials; then, the temperature is increased to 125-145℃ at 3℃ / min, the stirring speed is increased to 600 rpm, and stirring is continued for 3-5 hours to accelerate the interaction between carbon nanotubes and polyester molecular chains, promoting more uniform embedding of carbon nanotubes into the polyester molecular network; the reaction is stopped when the acid value is ≤10 mgKOH / g and the hydroxyl value reaches 50 mgKOH / g, yielding conductive polyester.

[0009] Preferably, the preparation process of conductive additive one is as follows: 20 parts of carbon nanotubes and 1 part of silane coupling agent KH550 are added to a reaction vessel, and 40 parts of anhydrous ethanol are added. Under a nitrogen protective atmosphere, the mixture is stirred at a speed of 150 rpm while the temperature is raised to 70°C. The mixture is stirred and reacted for 2-4 hours to obtain a mixture. The mixture is filtered, washed with anhydrous ethanol, and dried at 60°C for 10 hours to obtain conductive additive one.

[0010] Preferably, the preparation process of conductive additive II is as follows: 30 parts of nano zinc oxide are added to a container, and 5 parts of 1-butyl-3-methylimidazolium hexafluorophosphate are added. The mixture is ultrasonically vibrated at room temperature for 30-60 minutes to allow the ionic liquid to fully penetrate into the pores on the surface of zinc oxide. The mixture is then transferred to a rotary evaporator and rotary evaporated at 40°C under reduced pressure. Finally, it is vacuum dried at 60°C for 8 hours to obtain conductive additive II.

[0011] Preferably, the primary dispersion is a primary dispersion supported on fluorocarbon resin. The preparation process of the primary dispersion supported on fluorocarbon resin is as follows: 15 parts of conductive additive I, 2 parts of perfluoropolyether acrylate and 100 parts of xylene are added to a high-speed shear disperser and pre-dispersed at 2000-3000 rpm for 20 min; 7 parts of PTFE emulsion are added, and an ultrasonic generator is started simultaneously to maintain the synergistic effect of high-speed shear and ultrasound for 30 min to obtain the primary dispersion supported on fluorocarbon resin.

[0012] The preferred secondary dispersion preparation process is as follows: add conductive additive II to 120 parts of deionized water, add 3 parts of polymeric dispersant (BYK-163), and ultrasonically disperse for 20 minutes at an ultrasonic frequency of 30-50kHz to obtain the secondary dispersion.

[0013] Preferably, the leveling agent preparation process is as follows: 8-15 parts of hexafluorobutyl methacrylate, 0.1 parts of disulfide RAFT reagent, and 15 parts of tetrahydrofuran solution are added to a three-necked flask, and nitrogen is bubbled for 30 min to remove oxygen while mechanically stirring; then the temperature is raised to 70℃, and a tetrahydrofuran solution containing azobisisobutyronitrile is added dropwise at a rate of 1 mL / min. The reaction is maintained at this temperature for 5 h, cooled to 0℃ in an ice bath, methanol is added to precipitate the polymer, and the mixture is vacuum dried for 24 h to obtain the fluorinated prepolymer; 3.5 parts of octaamino... Propyl cage-type silsesquioxane was dispersed in 15 parts of tetrahydrofuran solution, 0.5 parts of triethylamine were added, and the mixture was sonicated for 30 min and stirred at 50-70℃ for 3 h to form an amino-activated siloxane premix. The fluorinated prepolymer was dissolved in 10 parts of tetrahydrofuran solution, the amino-activated siloxane premix was added, and the remaining 1.5 parts of dithioester RAFT reagent were injected. The mixture was reacted at 75-90℃ for 12 h, and then spray-dried after ultrafiltration to obtain a leveling agent. The amount of leveling agent used was 0.5-2 parts.

[0014] Another aspect of the present invention provides a roll coating with a stepwise dispersion of a biphase conductive additive, wherein the roll coating is prepared by any of the above-mentioned preparation processes; the roll coating is prepared by conductive polyester, conductive additive one, conductive additive two, pigment, defoamer and leveling agent.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In the preparation stage of conductive polyester, this invention involves mixing pretreated conductive additives with polyols, polyacids, and catalysts, followed by a segmented temperature-controlled heating and blending pre-dispersion process: initially, the mixture is stirred at a lower temperature to allow the conductive additives to initially disperse in the system and achieve a certain degree of contact and fusion with the raw materials; subsequently, the temperature is gradually increased to accelerate the interaction between the additives and the polyester molecular chains, promoting more uniform embedding of the additives into the polyester molecular network. Compared to traditional single-temperature heating and blending, this segmented temperature-controlled pre-dispersion method results in a more uniform and delicate distribution of the conductive additives after resin film formation, significantly improving the conductivity, gloss, and leveling properties of the coating film.

[0016] 2. This invention introduces two conductive additives, carbon nanotubes and nano-zinc oxide, in a stepwise manner, employing targeted pretreatment methods at different stages, in different media, and with different dispersion techniques to progressively improve conductivity and construct a multi-dimensional conductive network structure. After surface modification with a silane coupling agent, the carbon nanotubes form continuous long-range conductive pathways during organic phase dispersion. The nano-zinc oxide, after impregnation with an ionic liquid, has an optimized surface charge density and can remain stable in the aqueous phase through electrostatic repulsion, filling the microscopic gaps between the carbon nanotube networks. During blending, the two-phase system forms an interpenetrating network due to polarity differences. Efficient charge transport is achieved through the synergistic effect of electron conduction (carbon nanotubes) and ion migration (zinc oxide), solving the problem of resistivity fluctuations caused by uneven distribution of traditional single conductive additives, and endowing the roll coating with stable and low-impedance surface conductivity. With the assistance of fluorocarbon surfactants in xylene, carbon nanotubes form a stable micelle encapsulation structure through high-speed shearing, shielding the van der Waals forces between nanotubes and avoiding high-temperature re-agglomeration in the polyester polycondensation reaction; while nano zinc oxide is uniformly dispersed in the aqueous phase in a single-particle state with the help of the steric hindrance effect of polymeric dispersants, and its surface ionic liquid layer further buffers the interfacial tension difference with the organic system.

[0017] 3. In the fluorine-silicon block leveling agent of this invention, the fluorine segments migrate rapidly to the coating surface in the early stage of film formation due to their extremely low surface tension, reducing the overall viscosity of the system and inhibiting the formation of Bénard vortices, thus reducing orange peel defects in the paint film. The siloxane segments undergo conformational transformation in response to temperature rise during the curing stage, releasing internal stress through a cage-like structure and forming a dynamic shielding layer at high temperatures to inhibit the migration of conductive particles. Furthermore, the microphase separation characteristics of the fluorine and silicon chains allow them to form a gradient distribution in the coating, ensuring both surface hydrophobicity and antifouling properties, and enhancing adhesion at the interface through chemical bonding between amine groups and polyester. This dynamic response leveling mechanism overcomes the limitations of traditional leveling agents with their single function, enabling the coating to actively adapt to the temperature-viscosity change curve during baking and curing, ensuring a surface free of particles and dark streaks, while simultaneously improving the uniformity of the conductive network. Attached Figure Description

[0018] Figure 1The figures show the test results of conductivity and gloss of Examples 1-3 and Comparative Examples 1-2 of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Please see Figure 1 This invention provides a roll coating with a stepwise dispersion of a two-phase conductive additive and its preparation process, the technical solution of which is as follows: The material information involved in this invention is as follows: Neopentyl glycol CAS: 126-30-7; 1,6-hexanediol CAS: 629-11-8; terephthalic acid CAS: 100-21-0; isophthalic acid CAS: 121-91-5; tetrabutyl titanate CAS: 5593-70-4; carbon nanotubes CAS: 308068-56-6; silane coupling agent KH550 CAS: 919-30-2; Nano zinc oxide CAS: 1314-13-2; 1-Butyl-3-methylimidazolium hexafluorophosphate CAS: 174501-64-5; Hexafluorobutyl methacrylate CAS: 36405-47-7; Azobisisobutyronitrile CAS: 78-67-1; Carbon black was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; PTFE emulsion and perfluoropolyether acrylate were purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.; Polymer dispersant BYK-163 was purchased from Shanghai Buding Chemical Co., Ltd.; Organosilicon defoamer was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Dithioester RAFT reagent was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.; Aminopropyl cage-type silsesquioxane was prepared according to the method in patent CN101503419B.

[0021] Example 1 Five parts of conductive additive I, 50 parts of neopentyl glycol, 20 parts of 1,6-hexanediol, 65 parts of terephthalic acid, 25 parts of isophthalic acid, and 0.08 parts of tetrabutyl titanate were added sequentially to a reactor and stirred at 450 rpm to ensure initial homogeneity of the raw materials. Heat transfer oil was then introduced into the reactor jacket to raise the temperature of the reaction system to 80°C. The mixture was stirred at 400 rpm for 1 hour to allow conductive additive I to initially disperse and integrate with the raw materials. The temperature was then increased to 125°C at a rate of 3°C / min, and the stirring speed was increased to 600 rpm. Stirring continued for 3 hours to accelerate the interaction between carbon nanotubes and polyester molecular chains, promoting more uniform embedding of carbon nanotubes into the polyester molecular network. The desired effect was achieved when the acid value was ≤10 mg KOH / g and the hydroxyl value reached 50 mg KOH / g. The reaction was stopped when OH / g was reached, yielding conductive polyester. 15 parts of conductive additive one, 2 parts of perfluoropolyether acrylate, and 100 parts of xylene were added to a high-speed shear disperser and pre-dispersed at 2000 rpm for 20 min. 7 parts of PTFE emulsion were added, and an ultrasonic generator (40 kHz) was started simultaneously. The high-speed shear and ultrasonic synergistic effect was maintained for 30 min to obtain a primary dispersion of fluorocarbon resin. 25 parts of conductive additive two were added to 120 parts of deionized water, and 3 parts of polymeric dispersant were added. The mixture was ultrasonically dispersed at an ultrasonic frequency of 30 kHz for 20 min to obtain a secondary dispersion. 40 parts of conductive polyester, the primary dispersion of fluorocarbon resin, the secondary dispersion, 3 parts of pigment carbon black, 0.5 parts of silicone defoamer, and 0.5 parts of leveling agent were added to a mixing tank and mixed to obtain a coil coating.

[0022] The preparation process of conductive additive one is as follows: 20 parts of carbon nanotubes and 1 part of silane coupling agent KH550 are added to a reaction vessel, and 40 parts of anhydrous ethanol are added. Under a nitrogen protective atmosphere, the mixture is stirred at a speed of 150 rpm and heated to 70°C. The mixture is stirred and reacted for 2 hours to obtain a mixture. The mixture is filtered, washed with anhydrous ethanol, and dried at 60°C for 10 hours to obtain conductive additive one.

[0023] The preparation process of conductive additive II is as follows: 30 parts of nano zinc oxide are added to a container, and 5 parts of 1-butyl-3-methylimidazolium hexafluorophosphate are added. The mixture is ultrasonically vibrated at 40 kHz for 30 min at room temperature to allow the ionic liquid to fully penetrate into the pores on the surface of zinc oxide. The mixture is then transferred to a rotary evaporator and rotary evaporated at 40 °C under reduced pressure. Finally, it is vacuum dried at 60 °C for 8 h to obtain conductive additive II.

[0024] The leveling agent preparation process is as follows: 8 parts hexafluorobutyl methacrylate, 0.1 parts disulfide RAFT reagent, and 15 parts tetrahydrofuran solution were added to a three-necked flask. Nitrogen gas was bubbled for 30 min to remove oxygen, while mechanical stirring was performed at 300 rpm. The temperature was then raised to 70℃, and 5 parts tetrahydrofuran solution containing 0.03 parts azobisisobutyronitrile was added dropwise at a rate of 1 mL / min. The reaction was maintained at this temperature for 5 h, cooled to 0℃ in an ice bath, and methanol (volume ratio 1:3) was added to precipitate the polymer. The polymer was then vacuum dried for 24 h to obtain the fluorinated leveling agent. Prepolymer segment; 3.5 parts of octaaminopropyl cage-type silsesquioxane were dispersed in 15 parts of tetrahydrofuran solution, 0.5 parts of triethylamine were added, and the mixture was ultrasonically treated at 300W for 30 min and stirred at 50℃ for 3 h to form an amino-activated siloxane premix; the fluorinated prepolymer segment was dissolved in 10 parts of tetrahydrofuran solution, the amino-activated siloxane premix was added, and the remaining 1.5 parts of dithioester RAFT reagent were injected. The mixture was reacted at 75℃ for 12 h under nitrogen protection. After filtration through an ultrafiltration membrane, the mixture was spray-dried to obtain a leveling agent.

[0025] Example 2 The preparation method and parameters of Example 1 are the same, except that the conductive polyester is heated to 88°C for the first time and stirred for 1.7 h, and then heated to 135°C for the second time and stirred for 4 h.

[0026] Example 3 The preparation method and parameters of Example 1 are the same, except that the conductive polyester is heated to 95°C for the first time and stirred for 2.5 hours, and then heated to 145°C for the second time and stirred for 5 hours.

[0027] Comparative Example 1 The preparation method and parameters of Example 1 are the same, except that segmented temperature control was not performed when preparing conductive polyester. Instead, the temperature was directly raised to 125°C and stirred for 3 hours.

[0028] Comparative Example 2 The preparation method and parameters of Example 1 are the same, except that conductive additive 1 is not added when preparing conductive polyester. Instead, 20 parts of conductive additive 1 are prepared into a primary dispersion and added to the coating.

[0029] Experimental Example 1: Electrical Conductivity, Gloss and Appearance Testing The prepared coating was applied to the roll material and dried and cured. The film performance was tested. The conductivity was tested using the four-probe method. The gloss was tested using a 60° gloss meter according to the standard GB / T 13448-2019. The results are shown in Table 1 and... Figure 1 As shown.

[0030] From Table 1 and Figure 1As can be seen from Examples 1-3, in the stage of preparing conductive polyester, after the pretreated conductive additive is mixed with polyol, polyacid, and catalyst, a segmented temperature-controlled heating and blending pre-dispersion process is adopted: in the initial stage, the mixture is stirred at a lower temperature to allow the conductive additive to initially disperse in the system and have a certain degree of contact and fusion with the raw materials; then the temperature is gradually increased to accelerate the interaction between the additive and the polyester molecular chain, promoting the additive to be more uniformly embedded in the polyester molecular network. Compared with the traditional single-temperature heating and blending, this segmented temperature-controlled pre-dispersion method can make the conductive additive more uniformly and delicately distributed after the resin film is formed, significantly improving the conductivity, gloss, and leveling properties of the paint film. In Example 2, when preparing conductive polyester, the coating with the best performance was obtained when the temperature was first raised to 88°C and stirred for 1.7 h, and then raised to 135°C and stirred for 4 h, with a gloss of 75 GU, a conductivity of 47.55 S / m, and a smooth and even paint film appearance without transverse lines, pinholes, shrinkage cavities, or bubbles. Gradient heating can gradually promote molecular chain movement and accelerate the interaction between carbon nanotubes and polyester. In Comparative Example 1, the conductive polyester was not prepared with segmented temperature control, but was directly heated to 125℃ and stirred for 3 hours. This caused carbon nanotubes to agglomerate, failing to embed evenly into the polyester molecular network, resulting in a decrease in conductivity. Furthermore, the agglomeration of carbon nanotubes formed unevenly dispersed particles, leading to a rough paint film surface, reduced gloss, and pinholes or craters, damaging the smoothness of the paint film. In Comparative Example 2, conductive additive 1 was not added during the preparation of the conductive polyester. Instead, 20 parts of conductive additive 1 were prepared as a primary dispersion and added to the coating. Conductive additive 1 (carbon nanotubes) did not participate in the construction of the polyester molecular chain and existed only in the coating in a physically dispersed form. The interfacial bonding force was weak, and the physical dispersion was prone to agglomeration due to solvent evaporation or mechanical shearing, resulting in the breakage of conductive pathways. The physically dispersed carbon nanotube particles were large and unevenly distributed. After the paint film dried, the surface roughness increased, the gloss decreased significantly, and the paint film showed obvious particles, pinholes, or craters, resulting in a deteriorated appearance.

[0031] Examples 4-6 The preparation method and parameters of Example 2 are as follows, with specific differences shown in Table 2; in Table 2, the rotation speed is the rotation speed for preparing the primary dispersion; the ultrasonic frequency is the rotation speed for preparing the secondary dispersion; the reaction time is the stirring reaction time for preparing conductive additive one; and the oscillation time is the ultrasonic oscillation time for preparing conductive additive two.

[0032] Comparative Example 3 The preparation method and parameters are the same as in Example 2, except that the carbon nanotubes were not pretreated with a silane coupling agent.

[0033] Comparative Example 4 The preparation method and parameters are the same as in Example 2, except that the nano zinc oxide was not impregnated with an ionic liquid.

[0034] Comparative Example 5 The preparation method and parameters of Example 2 are the same, except that conductive additive one and conductive additive two are not prepared into a dispersion, but are directly added to the coating.

[0035] Comparative Example 6 The preparation method and parameters of Example 2 are the same, except that only a conductive additive is added to obtain the primary dispersion when preparing the coating.

[0036] Experiment Example 2: Conductivity Test The conductivity was tested according to the method in Experiment Example 1; the results are shown in Table 2.

[0037] As shown in Table 2, in Examples 2 and 4-6, the surface modification of carbon nanotubes with silane coupling agents enhances their hydrophobicity and compatibility with the polyester matrix, forming continuous long-range conductive pathways during organic phase dispersion. The surface charge density of nano-zinc oxide is optimized after impregnation with ionic liquids, allowing it to exist stably in the aqueous phase through electrostatic repulsion, filling the microscopic gaps between the carbon nanotube networks. Furthermore, with the assistance of fluorocarbon surfactants in xylene, carbon nanotubes form stable micelle encapsulation structures through high-speed shearing, shielding the van der Waals forces between nanotubes and preventing high-temperature re-agglomeration during polyester polycondensation. Nano-zinc oxide, in the aqueous phase, is uniformly dispersed as single particles thanks to the steric hindrance effect of polymeric dispersants. Its surface ionic liquid layer further buffers the interfacial tension difference with the organic system. This process design achieves functionalized directional arrangement of additives through spatial site control, enhancing the compatibility and matching of conductive additives with resin and coating systems. In Example 5, the coating exhibited the best conductivity, with a conductivity of 47.86 S / m, when the rotation speed was 2600 rpm, the ultrasonic frequency was 45 kHz, the reaction time was 3.2 h, and the oscillation time was 50 min. In Comparative Example 3, the carbon nanotubes were not pretreated with a silane coupling agent, and their interaction with the polyester molecular chains was mainly physical adsorption, resulting in weak binding force and low surface energy. This led to easy aggregation in the polyester system, reducing the effective conductive pathway and hindering electron conduction. In Comparative Example 4, the nano-zinc oxide was not impregnated with an ionic liquid, resulting in uneven surface charge distribution and easy aggregation. Aggregated nano-zinc oxide reduced contact with conductive components such as carbon nanotubes, lowering the synergistic conductivity effect; furthermore, its poor compatibility with polyester and other components led to defects in the coating, hindering electron conduction. In Comparative Example 5, conductive additives one and two were not prepared as dispersions but directly added to the coating. The conductive additives easily aggregated in the coating, making it difficult to distribute evenly throughout the system, resulting in a discontinuous conductive network and a significant decrease in conductivity. Carbon nanotubes and zinc oxide nanoparticles form a biphase conductive network. Carbon nanotubes provide the main conductive pathways, while zinc oxide nanoparticles fill the gaps and enhance electron conduction. In Comparative Example 6, the primary dispersion prepared by adding only conductive additives during coating preparation lacks the synergistic effect of zinc oxide nanoparticles and cannot form a biphase conductive network, resulting in a decrease in conductivity.

[0038] Examples 7-9 The preparation method and parameter conditions are the same as those in Example 5, and the specific differences are shown in Table 3.

[0039] Comparative Example 7 The preparation method and parameters were the same as in Example 5, except that no leveling agent was added.

[0040] Comparative Example 8 The preparation method and parameters of Example 5 are the same, except that BYK-333 is used as the leveling agent.

[0041] Experiment Example 3: Adhesion and Appearance Test Adhesion was tested according to the standard GB / T9286-2022; the results are shown in Table 3.

[0042] As shown in Table 3, in Examples 5 and 7-9, no cells were detached in the cross-cut test of the paint film, and the paint film had a smooth and even appearance without orange peel defects. By preparing a fluorine-silicon block structure leveling agent, the fluorine segments migrate rapidly to the coating surface in the early stage of film formation due to their extremely low surface tension, reducing the overall viscosity of the system and inhibiting the formation of Bénard vortices, thus reducing orange peel defects in the paint film. The siloxane segments undergo conformational transformation in response to temperature rise during the curing stage, releasing internal stress through a cage structure, and forming a dynamic shielding layer at high temperatures to inhibit the migration of conductive particles. Furthermore, the microphase separation characteristics of the fluorine and silicon chains allow them to form a gradient distribution in the coating, ensuring both surface hydrophobicity and antifouling properties, and enhancing adhesion at the interface through chemical bonding between amine groups and polyester. This dynamic response leveling mechanism breaks through the single-function limitations of traditional leveling agents, enabling the coating to actively adapt to the temperature-viscosity change curve during baking and curing, ensuring that the coating surface is free of particles and dark lines. In Comparative Example 7, without the addition of a leveling agent, the paint film exhibited insufficient interfacial bonding and decreased adhesion due to uneven surface tension during drying. Furthermore, the paint's insufficient fluidity prevented the effective elimination of defects such as brush marks, roller marks, pinholes, and orange peel during application. The resulting paint film had a rough surface, poor smoothness, and even pinholes or cracks. In Comparative Example 8, using BYK-333 as a leveling agent effectively reduced brush marks and orange peel. However, due to its lack of fluorine content, its ability to reduce surface tension was weak, making it difficult to suppress pinholes (especially those caused by residual grease on the substrate surface). Additionally, the smoothness and gloss of the resulting paint film were slightly lower than those achieved with fluorosilicone leveling agents.

[0043] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A preparation process for a roll coating with a stepwise dispersion of a two-phase conductive additive, characterized in that: The preparation method is as follows: conductive additive one, polyol, polyacid and catalyst are added to a reaction vessel and heated and blended using a segmented temperature control method to obtain conductive polyester; conductive additive one is dispersed in xylene to obtain a primary dispersion; conductive additive two is dispersed in deionized water to obtain a secondary dispersion; the conductive polyester, the primary dispersion, the secondary dispersion, pigment, defoamer and leveling agent are added to a stirred tank and mixed to obtain the coil coating; The preparation process of the conductive polyester is as follows: the conductive additive, the polyol, the polyacid and tetrabutyl titanate are added to the reaction vessel and stirred and mixed; heat transfer oil is introduced into the jacket of the reaction vessel for heating, and the temperature of the reaction system is stirred and mixed; then the temperature is raised again, the stirring speed is increased and stirring is continued to obtain the conductive polyester. The primary dispersion is a primary dispersion of fluorocarbon resin supported on a substrate. The preparation process of the primary dispersion of the fluorocarbon resin supported on a substrate is as follows: the conductive additive I, perfluoropolyether acrylate and xylene are added to a high-speed shear disperser for pre-dispersion; PTFE emulsion is added, and an ultrasonic generator is started simultaneously to react and obtain the primary dispersion of the fluorocarbon resin supported on a substrate. The leveling agent is prepared as follows: Hexafluorobutyl methacrylate, disulfide RAFT reagent, and tetrahydrofuran solution are added to a three-necked flask, nitrogen is introduced to remove oxygen, and mechanical stirring is performed simultaneously; after heating, the tetrahydrofuran solution containing azobisisobutyronitrile is added dropwise, the reaction is carried out at a constant temperature, and then cooled in an ice bath. Methanol is added to precipitate the polymer, and the polymer is dried under vacuum to obtain a fluorinated prepolymer; octaaminopropyl cage-type silsesquioxane is dispersed in the tetrahydrofuran solution, triethylamine is added, and the mixture is ultrasonically treated to form an amino-activated siloxane premix; The fluorinated prepolymer is dissolved in the tetrahydrofuran solution, the amino-activated siloxane premix is ​​added, and the remaining dithioester RAFT reagent is injected to react and obtain the leveling agent. The conductive additive is obtained by treating carbon nanotubes with a silane coupling agent. The conductive additive 2 is obtained by impregnating nano zinc oxide with 1-butyl-3-methylimidazolium hexafluorophosphate; The leveling agent is prepared from hexafluorobutyl methacrylate and octaaminopropyl cage-type silsesquioxane.

2. The preparation process of a roll coating with stepwise dispersion of a dual-phase conductive additive according to claim 1, characterized in that: The preparation process of the first conductive additive is as follows: the carbon nanotubes and the silane coupling agent are added to a reaction vessel, anhydrous ethanol is added, and the mixture is stirred under a nitrogen protective atmosphere. After heating, the mixture is stirred to obtain the first conductive additive.

3. The preparation process of a roll coating with a stepwise dispersion of a dual-phase conductive additive according to claim 1, characterized in that: The preparation process of the conductive additive II is as follows: the nano zinc oxide is added to a container, 1-butyl-3-methylimidazolium hexafluorophosphate is added, and the conductive additive II is obtained after ultrasonic oscillation.

4. The preparation process of a roll coating with a stepwise dispersion of a dual-phase conductive additive according to claim 1, characterized in that: The secondary dispersion is prepared as follows: the conductive additive II is added to the deionized water, a polymeric dispersant is added, and the mixture is ultrasonically dispersed to obtain the secondary dispersion.

5. A roll coating with a stepwise dispersion of a two-phase conductive additive, characterized in that: The biphase conductive additive stepwise dispersion coil coating is prepared by the preparation process described in any one of claims 1-4; the biphase conductive additive stepwise dispersion coil coating is prepared by conductive polyester, conductive additive one, conductive additive two, pigment, defoamer and leveling agent.

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