High-solid-content solvent-free thick paste type epoxy resin coating as well as preparation method and application thereof

Abstract

The invention relates to the technical field of coatings, and provides a high-solid-content solvent-free high-build epoxy resin coating as well as a preparation method and application thereof.The coating comprises a first component and a second component, the first component comprises modified epoxy resin, a reactive diluent, a filler and an auxiliary agent; the second component comprises a modified curing agent, a composite accelerant and a retarder; the composite accelerant is formed by compounding modified nano zinc oxide and a composite catalyst; the modified nano-zinc oxide is prepared by reacting KH560 with nano-zinc oxide and then reacting with 3-sulfonic acid propyl methacrylic acid potassium salt; the composite catalyst is formed by compounding imidazolium salt ionic liquid and triethanolamine. A flexible chain segment is introduced into the modified epoxy resin to reduce viscosity, the modified curing agent adopts cardanol and mixed amine to be compounded to regulate and control reaction, and the composite accelerant and the retarder cooperate to catalyze and control speed; the problems of incomplete curing and low performance caused by the fact that the diffusion of a curing agent in a thick coating of the high-solid-content solvent-free thick paste type epoxy resin coating is blocked are solved.

Description

Technical Field

[0001] This application relates to the field of coating technology, specifically to high-solids-content solvent-free thick-film epoxy resin coatings, their preparation methods, and applications. Background Technology

[0002] In the coatings industry, high-solids solvent-free epoxy coatings have become the core choice for thick-film corrosion protection due to their environmentally friendly characteristics, including zero volatile organic compound emissions and a solids content close to 100%. These thick coatings create a physical barrier for long-term protection, placing extremely high demands on the mechanical properties and structural integrity of the cured coating. However, solvent-free systems rely entirely on the chemical reaction between epoxy resin and curing agent to form a film, making the diffusion efficiency and reaction uniformity of the curing agent a key bottleneck in thick-film application.

[0003] In thick coating applications, the high viscosity of high-solids systems significantly increases the migration resistance of the curing agent. While the surface curing agent reacts rapidly due to sufficient contact with the epoxy resin, the interior of the coating, especially the deeper layers, requires overcoming molecular entanglement in the resin matrix and spatial barriers from the filler network to diffuse, easily resulting in diffusion lag. This impeded diffusion directly leads to incomplete curing within the thick coating, resulting in deterioration of the overall mechanical properties. This manifests as significantly lower internal hardness compared to the surface, reduced impact resistance, and even localized mechanical weakness, severely impacting the structural stability and service reliability of the thick coating. This becomes a key obstacle restricting the efficient application of high-solids solvent-free epoxy coatings in thick coating scenarios.

[0004] In summary, to solve the problem of hindered diffusion of the curing agent within the coating, there is an urgent need for a coating that can achieve uniform and efficient curing and improve performance. Summary of the Invention

[0005] To address the above technical problems, this application provides a high-solids-content solvent-free thick-film epoxy resin coating, its preparation method, and its application. This application consists of a first component containing modified epoxy resin and an active diluent, and a second component containing a modified curing agent, a composite accelerator (a mixture of modified nano-zinc oxide and a composite catalyst), and a retarder. By introducing flexible segments to reduce viscosity through the modified epoxy resin, using a mixture of cashew phenol and mixed amines to regulate the reaction through the modified curing agent, and using the composite accelerator and retarder to synergistically catalyze and control the setting rate, this application solves the problems of incomplete curing and low performance caused by the obstructed diffusion of the curing agent in the thick coating of the high-solids-content solvent-free thick-film epoxy resin coating.

[0006] To achieve the above objectives, one technical solution adopted by the present invention is: In a first aspect, this application provides a high-solids-content solvent-free thick-film epoxy resin coating, comprising a first component and a second component; the first component comprises a modified epoxy resin, an active diluent, fillers, and additives; the modified epoxy resin is prepared by reacting epoxy resin with a polyether diol; the second component comprises a modified curing agent, a composite accelerator, and a retarder; the modified curing agent is prepared by reacting cashew nut shell phenol with a mixed amine; the composite accelerator is prepared by compounding modified nano-zinc oxide with a composite catalyst; the modified nano-zinc oxide is prepared by reacting nano-zinc oxide with KH560, and then reacting it with potassium 3-sulfonopropyl methacrylate; the composite catalyst is prepared by compounding imidazole salt ionic liquid with triethanolamine.

[0007] In this application, the flexible ether chain segments introduced into the main chain of the modified epoxy resin disrupt the regularity of the polymer chain, reducing the close packing between molecules and thus lowering the intermolecular forces of the resin matrix, thereby achieving intrinsic viscosity reduction. Simultaneously, the modified curing agent enhances its compatibility with the resin by introducing long alkyl chains of cashew phenol, and synergistically with the m-phenylenediamine / polyetheramine complex system, providing sufficient reaction kinetics while preventing the rapid formation of a dense layer on the surface, reducing the viscous resistance to the migration of curing agent molecules into the coating interior during the initial stage of the reaction.

[0008] As the curing reaction proceeds and the system viscosity increases, restricting the movement of curing agent molecules, the nano-zinc oxide modified by KH560 and sulfonate in the composite accelerator introduces epoxy groups and sulfonate groups. The epoxy groups enhance the compatibility of the composite accelerator with the resin; the sulfonate groups provide electrostatic repulsion, forming a stable zwitterionic structure on the surface of the modified nano-zinc oxide. This electrostatic stability and steric hindrance ensure uniform dispersion of the nano-zinc oxide in the resin, preventing catalytic sites from concentrating only on the resin surface. The modified nano-zinc oxide serves as a solid-phase catalytic center, with Zn on its surface... 2+ Lewis acid sites reduce the activation energy of the nucleophilic ring-opening reaction of the curing agent by polarizing the epoxy group, thus maintaining the reaction rate even when the curing agent concentration is low.

[0009] Furthermore, the composite catalyst in the composite accelerator, as a homogeneous catalyst, can diffuse into the interior of the coating; the imidazole salt ionic liquid polarizes the epoxy ring through the electrostatic interaction between the cation and the epoxy group; the triethanolamine forms hydrogen bonds with the amine group of the amine curing agent through the hydroxyl group, enhancing the electron cloud density of the amine group and improving nucleophilicity. The two work together to enhance the reactivity of the internal curing agent molecules, and complete the curing reaction through efficient catalysis, ultimately solving the problem of incomplete curing caused by diffusion obstruction inside the thick film coating.

[0010] Preferably, the epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; the epoxy value of the epoxy resin is 0.55-0.65 eq / 100g; the polyether diol is a polyoxypropylene-polyoxyethylene block diol, wherein the mass ratio of polyoxypropylene to polyoxyethylene is (2-3):1; and the mass ratio of epoxy resin to polyether diol is (10-20):1.

[0011] Preferably, the mixed amine is obtained by compounding phenylenediamine and polyetheramine; the mass ratio of cashew phenol to mixed amine is (1-2):1; the mass ratio of phenylenediamine to polyetheramine is 1:(0.5-1.2).

[0012] Preferably, the reactive diluent comprises any one of phenyl glycidyl ether, 1,4-butanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; the filler comprises any one of barium sulfate, talc, and fumed silica; the additives comprise dispersants, leveling agents, and toughening agents; the dispersant comprises any one of sodium polyacrylate, polyhydroxyethyl methacrylate, and octyl phosphate; the leveling agent comprises any one of polybutyl methacrylate, perfluorooctyl ethyl acrylate, and poly(hexanediol adipate); the toughening agent comprises any one of carboxyl-terminated acrylonitrile butadiene rubber, liquid polysulfide rubber, and hydroxyl-terminated polybutadiene; the imidazole salt ionic liquid comprises 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF4), 1-butyl-3-methylimidazolium hexafluorophosphate (BMIMPF6), and 1-butyl-3-methylimidazolium chloride (BMIMCl); and the retarder comprises any one of tributyl phosphate, adipic acid, and sebacamide.

[0013] Preferably, the mass ratio of modified epoxy resin, reactive diluent, filler, and additives in the first component is (25-35):(5-10):(50-60):(1-3); the mass ratio of dispersant, leveling agent, and toughening agent is (1-3):(0.5-2):(2-5); the mass ratio of modified curing agent, composite accelerator, and retarder in the second component is (80-90):(8-15):(0.5-2); the mass ratio of modified nano zinc oxide and composite catalyst in the composite accelerator is (1.5-3):1; the mass ratio of KH560, nano zinc oxide, and potassium 3-sulfonopropyl methacrylate is (2-5):(85-92):(3-7); the mass ratio of imidazole salt ionic liquid and triethanolamine is (1-1.5):1; and the mass ratio of the first component and the second component is (4-8):1.

[0014] Secondly, this application provides a method for preparing a high-solids-content solvent-free thick-film epoxy resin coating, comprising the following steps: S1. Weigh epoxy resin and polyoxypropylene-polyoxyethylene block diol and add them to the reaction vessel; add alkaline catalyst to the reaction vessel, heat and stir under nitrogen protection, and cool to room temperature after the reaction is completed to obtain modified epoxy resin. S2. Weigh cashew phenol and mixed amine. First, add cashew phenol to the reaction vessel, heat up, add mixed amine while stirring, keep warm, and obtain modified curing agent. S3. Weigh nano zinc oxide and add it to a high-speed disperser, then add anhydrous ethanol for pre-dispersion; add KH560 to the disperser, heat, and continue stirring; then add potassium 3-sulfonopropyl methacrylate, heat, and stir; after the reaction is complete, centrifuge, vacuum dry, and grind through a 300-mesh sieve to obtain modified nano zinc oxide; weigh imidazole salt ionic liquid and triethanolamine, add them to a stirred tank and stir to prepare a composite catalyst; add the modified nano zinc oxide and the above composite catalyst to a high-speed disperser for dispersion to obtain a composite accelerator; S4. Weigh the modified curing agent, composite accelerator and retarder and add them to the mixing tank; stir to obtain the second component; weigh the modified epoxy resin, reactive diluent, filler and additives obtained in step S1; add all the above materials to the planetary mixer, stir and disperse under vacuum until the fineness of the system is ≤60μm and there are no visible particles, to obtain the first component; S5. The first component and the second component are mixed in a mass ratio of (4-8):1 to obtain a high-solids-content solvent-free thick-film epoxy resin coating.

[0015] Preferably, in step S1, the mass of the alkaline catalyst is 0.1%-0.3% of the mass of the epoxy resin; the alkaline catalyst is potassium hydroxide or sodium hydroxide; the amount of alkaline catalyst added is 0.1%-0.3% of the mass of the epoxy resin; the temperature for heating under nitrogen protection is 100-120℃; the stirring speed is 300-500 rpm and the time is 2-4 hours; in step S2, the temperature for heating is 60-80℃ and the holding time is 1-2 hours.

[0016] Preferably, in step S3, the mass ratio of nano-zinc oxide to anhydrous ethanol is 1:(1-2); the pre-dispersion speed is 1500-2000 rpm and the time is 15-20 min; the temperature after adding KH560 is 50-70℃; the stirring reaction time is 1-2 h; the temperature after adding potassium 3-sulfonopropyl methacrylate is 70-85℃, the stirring reaction speed is 2000-2500 rpm, and the time is 1-1.5 h; the centrifugation speed is 8000-10000 rpm and the time is 10-15 min; the vacuum drying temperature is 60-80℃ and the time is 4-6 h; the stirring speed when adding to the mixing tank is 500-800 rpm and the time is 30-45 min; and the dispersion speed when adding to the high-speed disperser is 1800-2200 rpm and the time is 20-30 min.

[0017] Preferably, in step S4, the stirring speed is 400-600 rpm and the time is 40-60 min; the vacuum degree of the vacuum condition is -0.1~-0.08 MPa, and the stirring speed of the planetary stirrer is 500-800 r / min and the time is 20-40 min.

[0018] Thirdly, this application provides the application of high-solids-content solvent-free thick-film epoxy resin coatings in the protection of industrial steel structural components.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: This application provides a high-solids-content solvent-free thick-film epoxy resin coating, its preparation method, and its application. The modified epoxy resin incorporates flexible ether chains in its main chain, which disrupts the regularity of the polymer chain, reducing the close packing of molecules and thus lowering the intermolecular forces in the resin matrix, achieving intrinsic viscosity reduction. Simultaneously, the modified curing agent, by introducing long alkyl chains of cashew phenol, enhances its compatibility with the resin and works synergistically with the m-phenylenediamine / polyetheramine complex system. This provides sufficient reaction kinetics while preventing the rapid formation of a dense layer on the surface, reducing the viscous resistance to the migration of curing agent molecules into the coating interior during the initial reaction phase.

[0020] As the curing reaction proceeds and the system viscosity increases, restricting the movement of curing agent molecules, the nano-zinc oxide modified by KH560 and sulfonate in the composite accelerator introduces epoxy groups and sulfonate groups. The epoxy groups enhance the compatibility of the composite accelerator with the resin; the sulfonate groups provide electrostatic repulsion, forming a stable zwitterionic structure on the surface of the modified nano-zinc oxide. This electrostatic stability and steric hindrance ensure uniform dispersion of the nano-zinc oxide in the resin, preventing catalytic sites from concentrating only on the resin surface. The modified nano-zinc oxide serves as a solid-phase catalytic center, with Zn on its surface... 2+Lewis acid sites reduce the activation energy of the nucleophilic ring-opening reaction of the curing agent by polarizing the epoxy group, thus maintaining the reaction rate even when the curing agent concentration is low.

[0021] Furthermore, the composite catalyst in the composite accelerator, as a homogeneous catalyst, can diffuse into the interior of the coating; the imidazole salt ionic liquid polarizes the epoxy ring through the electrostatic interaction between the cation and the epoxy group; the triethanolamine forms hydrogen bonds with the amine group of the amine curing agent through the hydroxyl group, enhancing the electron cloud density of the amine group and improving nucleophilicity. The two work together to enhance the reactivity of the internal curing agent molecules, and complete the curing reaction through efficient catalysis, ultimately solving the problem of incomplete curing caused by diffusion obstruction inside the thick film coating. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process for preparing high-solids-content solvent-free thick-film epoxy resin coatings according to the present invention; Figure 2 This is a physical image of the high-solids-content solvent-free thick-film epoxy resin coating of Embodiment 3 of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the embodiments described below are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] In this application, the terminology used is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0025] The singular forms “for,” “or,” “a,” “any,” and “the” used in this application are intended to include the plural forms unless the context clearly indicates otherwise.

[0026] Furthermore, the terms "first" and "second" appearing in this application are for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] The following detailed description of the specific embodiments of this application will be provided with reference to the accompanying drawings and in conjunction with specific examples and comparative examples.

[0028] Example 1 like Figure 1 As shown, this embodiment provides a method for preparing a high-solids-content solvent-free thick-film epoxy resin coating, including the following steps: S1. Weigh out bisphenol A type epoxy resin and polyoxypropylene-polyoxyethylene block diol with an epoxy value of 0.55 eq / 100g at a mass ratio of 10:1, wherein the mass ratio of polyoxypropylene to polyoxyethylene is 2:1, and add them to a reaction vessel; add 0.1% potassium hydroxide by mass of epoxy resin to the reaction vessel, heat to 100℃ under nitrogen protection, stir at 300 rpm for 2 hours, and after the reaction is completed, cool to room temperature to obtain modified epoxy resin; S2. Weigh cashew phenol and mixed amine at a mass ratio of 1:1, wherein the mixed amine is a mixture of m-phenylenediamine and polyetheramine at a mass ratio of 1:0.5; first add cashew phenol to the reaction vessel, heat to 60°C, add mixed amine under stirring, keep warm for 1 hour, and obtain the modified curing agent; S3. Weigh KH560, nano zinc oxide, and potassium 3-sulfonopropyl methacrylate at a mass ratio of 2:85:3. Weigh the nano zinc oxide and add it to a high-speed disperser. Add anhydrous ethanol, where the mass ratio of nano zinc oxide to anhydrous ethanol is 1:1. Pre-disperse at 1500 rpm for 15 min. Add KH560 to the disperser, heat to 50℃, and continue stirring for 1 h. Then add potassium 3-sulfonopropyl methacrylate, heat to 70℃, and stir at 2000 rpm for 1 h. After the reaction is complete... Modified nano-zinc oxide was obtained by centrifugation at 8000 rpm for 10 min, vacuum drying at 60℃ for 4 h, and grinding through a 300-mesh sieve. EMIMBF4 and triethanolamine were weighed at a mass ratio of 1:1 and added to a stirred tank, and stirred at 500 rpm for 30 min to obtain a composite catalyst. Modified nano-zinc oxide and the composite catalyst were weighed at a mass ratio of 1.5:1, and added to a high-speed disperser and dispersed at 1800 rpm for 20 min to obtain a composite accelerator. S4. Weigh the modified curing agent, composite accelerator, and tributyl phosphate in a mass ratio of 80:8:0.5 and add them to the mixing tank; stir at 400 rpm for 40 min to obtain the second component; weigh the modified epoxy resin, phenyl glycidyl ether, barium sulfate, and additives obtained in step S1 in a mass ratio of 25:5:50:1; wherein the additives are premixed from sodium polyacrylate, polybutyl methacrylate, and carboxyl-terminated nitrile rubber in a mass ratio of 1:0.5:2; add all the above materials to a planetary mixer and stir and disperse at 500 r / min under a vacuum of -0.1 MPa for 20 min until the fineness of the system is ≤60μm and there are no visible particles to the naked eye, to obtain the first component; S5. The first component and the second component are mixed in a mass ratio of 4:1 to obtain a high-solids-content solvent-free thick-film epoxy resin coating.

[0029] Example 2 This embodiment provides a method for preparing a high-solids-content solvent-free thick-film epoxy resin coating, including the following steps: S1. Weigh out bisphenol F type epoxy resin with an epoxy value of 0.6 eq / 100g and polyoxypropylene-polyoxyethylene block diol at a mass ratio of 15:1, wherein the mass ratio of polyoxypropylene to polyoxyethylene is 2.5:1, and add them to a reaction vessel; add 0.2% potassium hydroxide by mass of epoxy resin to the reaction vessel, heat to 110℃ under nitrogen protection, stir at 400 rpm for 3 hours, and after the reaction is completed, cool to room temperature to obtain modified epoxy resin; S2. Weigh cashew phenol and mixed amine at a mass ratio of 1.5:1, wherein the mixed amine is composed of m-phenylenediamine and polyetheramine at a mass ratio of 1:1; first add cashew phenol to the reaction vessel, heat to 70°C, add the mixed amine under stirring, and keep warm for 1.5 hours to obtain the modified curing agent; S3. Weigh KH560, nano zinc oxide, and potassium 3-sulfonopropyl methacrylate at a mass ratio of 3:88:5. Add the nano zinc oxide to a high-speed disperser, then add anhydrous ethanol, where the mass ratio of nano zinc oxide to anhydrous ethanol is 1:1.5. Pre-disperse at 1800 rpm for 18 min. Add KH560 to the disperser, heat to 60℃, and continue stirring for 1.5 h. Then add potassium 3-sulfonopropyl methacrylate, heat to 80℃, and stir at 2300 rpm for 1.3 h. After completion, the modified nano zinc oxide was obtained by centrifugation at 9000 rpm for 12 min, vacuum drying at 70℃ for 5 h, and grinding through a 300-mesh sieve. BMIMPF6 and triethanolamine were weighed at a mass ratio of 1.2:1 and added to a stirred tank, and stirred at 600 rpm for 40 min to obtain a composite catalyst. Modified nano zinc oxide and the composite catalyst were weighed at a mass ratio of 2:1 and added to a high-speed disperser, and dispersed at 2000 rpm for 25 min to obtain a composite accelerator. S4. Weigh the modified curing agent, composite accelerator, and adipic acid in a mass ratio of 85:12:1 and add them to the mixing tank; stir at 500 rpm for 50 min to obtain the second component; weigh the modified epoxy resin, 1,4-butanediol diglycidyl ether, talc, and additives obtained in step S1 in a mass ratio of 30:7:55:2; wherein the additives are premixed from poly(hydroxyethyl methacrylate), perfluorooctyl ethyl acrylate, and liquid polysulfide rubber in a mass ratio of 2:1:3; add all the above materials to a planetary mixer and stir and disperse at 700 r / min under a vacuum of -0.09 MPa for 30 min until the fineness of the system is ≤60 μm and there are no visible particles to the naked eye, to obtain the first component; S5. The first component and the second component are mixed in a mass ratio of 6:1 to obtain a high-solids-content solvent-free thick-film epoxy resin coating.

[0030] Example 3 A method for preparing a high-solids-content solvent-free thick-film epoxy resin coating, characterized by comprising the following steps: S1. Weigh out bisphenol S-type epoxy resin with an epoxy value of 0.65 eq / 100g and polyoxypropylene-polyoxyethylene block diol at a mass ratio of 20:1, wherein the mass ratio of polyoxypropylene to polyoxyethylene is 3:1, and add them to a reaction vessel; add 0.3% sodium hydroxide (by mass of epoxy resin) to the reaction vessel, heat to 120℃ under nitrogen protection, stir at 500 rpm for 4 hours, and after the reaction is completed, cool to room temperature to obtain modified epoxy resin; S2. Weigh cashew phenol and mixed amine at a mass ratio of 2:1. The mixed amine is composed of m-phenylenediamine and polyetheramine at a mass ratio of 1:1.2. First, add cashew phenol to the reaction vessel, heat to 80°C, add the mixed amine under stirring, and keep warm for 2 hours to obtain the modified curing agent. S3. Weigh KH560, nano zinc oxide, and potassium 3-sulfonopropyl methacrylate at a mass ratio of 5:92:7. Add the nano zinc oxide to a high-speed disperser, then add anhydrous ethanol (the mass ratio of nano zinc oxide to anhydrous ethanol is 1:2). Pre-disperse at 2000 rpm for 20 min. Add KH560 to the disperser, heat to 70℃, and continue stirring for 2 h. Then add potassium 3-sulfonopropyl methacrylate, heat to 85℃, and stir at 2500 rpm for 1.5 h. The reaction is complete. Then, modified nano zinc oxide was obtained by centrifugation at 10,000 rpm for 15 min, vacuum drying at 80℃ for 6 h, and grinding through a 300-mesh sieve. BMIMCl and triethanolamine were weighed at a mass ratio of 1.5:1 and added to a stirred tank, and stirred at 800 rpm for 45 min to obtain a composite catalyst. Modified nano zinc oxide and the composite catalyst were weighed at a mass ratio of 3:1, and the modified nano zinc oxide and the above composite catalyst were added to a high-speed disperser and dispersed at 2200 rpm for 30 min to obtain a composite accelerator. S4. Weigh the modified curing agent, composite accelerator, and sebacamide in a mass ratio of 90:15:2 and add them to the mixing tank; stir at 600 rpm for 60 min to obtain the second component; weigh the modified epoxy resin, neopentyl glycol diglycidyl ether, fumed silica, and additives obtained in step S1 in a mass ratio of 35:10:60:3; wherein the additives are premixed from octyl phosphate, poly(1,6-hexanediol adipate), and hydroxyl-terminated polybutadiene in a mass ratio of 3:2:5; add all the above materials to a planetary mixer and stir and disperse at 800 r / min for 40 min under a vacuum of -0.08 MPa until the fineness of the system is ≤60 μm and there are no visible particles to the naked eye, to obtain the first component; S5. The first component and the second component are mixed in a mass ratio of 8:1 to obtain a high-solids-content solvent-free thick-film epoxy resin coating. For example... Figure 2 The image shown is a physical picture of the high-solids-content solvent-free thick-film epoxy resin coating of Example 3.

[0031] Comparative Example 1 The preparation method of high-solids content solvent-free thick-film epoxy resin coating differs from Example 3 in that polyether diol is not used to modify the epoxy resin in the system.

[0032] Comparative Example 2 The preparation method of high-solids content solvent-free thick-film epoxy resin coating differs from that in Example 3 in that the curing agent is a mixed amine and no cashew phenol is added for modification.

[0033] Comparative Example 3 The preparation method of high-solids content solvent-free thick-film epoxy resin coating differs from Example 3 in that modified nano zinc oxide is not prepared, and only EMIMBF4 and triethanolamine are used as accelerators.

[0034] Comparative Example 4 The preparation method of high-solids content solvent-free thick-film epoxy resin coating differs from that of Example 3 in that it uses unmodified nano zinc oxide (without KH560 silanization and 3-sulfopropyl methacrylate potassium salt grafting).

[0035] Performance testing: Examples 1-3 and Comparative Examples 1-4 were coated with high-solids solvent-free thick-film epoxy resin coatings on Q235 steel plates (100mm×100mm×3mm) that had been sandblasted to Sa2.5 grade and degreased with acetone, forming a 3mm thick coating. The coatings were then cured at 25℃ and 50% RH for 7 days before testing. Three parallel samples were prepared for each example and comparative example, and the average value of the test results was taken to ensure data reliability.

[0036] 1. Application viscosity: The application viscosity of the coating is tested at 25°C using a rotational viscometer. The initial viscosity of the mixed coating is tested to evaluate the smoothness of thick coating application and other application operability.

[0037] 2. Bubble Rate: The bubble rate of the coating was tested using a microscope. A 150μm thick coating was applied, and the bubble rate was observed and recorded at 10cm intervals. 2 The number of air bubbles within an area is used to calculate the proportion of air bubbles and measure the defoaming effect.

[0038] 3. Application viscosity: The application viscosity of the coating is tested at 25°C using a rotational viscometer. The initial viscosity of the mixed coating is tested to evaluate the smoothness of thick coating application and other application operability.

[0039] 4. Curing properties: Take samples from the surface layer (0-0.5mm) and the deep layer (2.5-3mm) of the coating respectively, and measure the degree of curing.

[0040] 5. Adhesion: The adhesion was tested using a pull-off tester with a tensile testing machine.

[0041] 6. Impact resistance: The coating is subjected to impact testing using an impact tester.

[0042] 7. Water resistance: Immerse the coating in deionized water, observe and record the changes in the coating.

[0043] 8. Salt spray resistance: Place the coating in a 3% NaCl salt spray environment for 1000 hours, observe and record the changes in the coating.

[0044] 9. Acid resistance: Immerse the coating in a 5% sulfuric acid solution for 720 hours, observe and record the changes in the coating.

[0045] 10. Alkali resistance: Immerse the coating in a 5% NaOH solution for 720 hours, observe and record the changes in the coating.

[0046] Table 1 Performance test parameters for different coatings

[0047] As shown in Table 1, the high-solids-content solvent-free thick-film epoxy resin coatings prepared in Examples 1-3 exhibit moderate application viscosity (18500-26800 mPa·s), low bubble rate (≤0.8%), minimal difference in curing degree between the surface and deeper layers of the 3mm thick coating (≤2%), strong adhesion (≥5.2 MPa), high impact resistance (≥50 cm), and stable water resistance, salt spray resistance, acid resistance, and alkali resistance without any abnormal changes. This indicates that the synergistic effect of modified epoxy resin, modified curing agent, and composite accelerator successfully achieved uniform curing and excellent protective performance of the thick coating.

[0048] Comparative Example 1, which did not use polyether diol-modified epoxy resin, exhibited a significantly increased application viscosity of 38200 mPa·s, with a deep curing degree of only 72%, a difference of 22% compared to the surface layer, and severely deteriorated resistance to media. The flexible segments of the polyether diol effectively reduce intermolecular forces in the resin matrix through internal plasticization, achieving intrinsic viscosity reduction and creating crucial conditions for the diffusion of curing agent molecules into the coating interior. Simultaneously, these flexible segments participate in the cross-linking network, enhancing network toughness. Comparative Example 1 lacked these flexible segments, resulting in excessively high initial viscosity, severely hindering curing agent diffusion, leading to incomplete internal curing, a loose cross-linking network, and a sharp decline in anti-corrosion performance.

[0049] Comparative Example 2, which did not use a cashew nut phenol-modified curing agent, achieved a higher degree of deep curing (80%) than Comparative Example 1, but still lagged behind the surface layer by 13%, and exhibited edge defects in corrosion resistance. The long alkyl chain of cashew nut phenol can improve the compatibility between the curing agent and the resin, and through steric hindrance, it synergistically regulates the reaction rate with polyetheramine, preventing premature surface curing that hinders internal diffusion. Comparative Example 2 lacked the long-chain structure of cashew nut phenol, leading to decreased compatibility, an imbalance in reaction regulation, and an excessively rapid formation of a dense surface layer. This affected the deep diffusion of the curing agent, ultimately resulting in insufficient internal crosslinking density and a weakness in corrosion resistance.

[0050] Comparative Example 3, without modified nano-zinc oxide and using only a composite catalyst as an accelerator, showed insufficient deep curing (82%), with a 10% difference compared to the surface layer. In the composite accelerator, modified nano-zinc oxide, acting as a solid-phase catalytic center, achieved uniform dispersion through its zwitterionic structure, forming "distributed anchoring points" within the coating. Its surface Zn... 2+ The peripheral epoxy groups are activated by the interfacial polarization effect, enabling the curing reaction to proceed efficiently even with limited diffusion. Comparative Example 3 lacks this distributed catalytic center and relies solely on homogeneous diffusion of small molecule catalysts. Inside the thick film, the increased viscosity leads to insufficient catalyst quantity, failing to effectively activate local reactions and resulting in low internal curing efficiency.

[0051] Comparative Example 4, using unmodified nano-zinc oxide, exhibited the highest bubble rate (1.8%) and unsatisfactory deep curing degree (85%). Modified nano-zinc oxide, through KH560 silanization to introduce epoxy groups and subsequent sulfonate grafting to form a zwitterionic structure, utilizes electrostatic repulsion and steric hindrance to achieve stable dispersion of nanoparticles and prevent agglomeration. In Comparative Example 4, the unmodified nano-zinc oxide was prone to agglomeration, failing to form effective distributed catalytic centers and acting as defect points in the coating, hindering curing agent diffusion, increasing bubble residue, resulting in poor coating density and deteriorated overall performance.

[0052] The above results demonstrate and describe the basic principles and main features of this application, as well as its advantages.

[0053] Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this application. Various changes and modifications can be made to this application without departing from the spirit and scope thereof, and all such changes and modifications fall within the scope of this application as claimed. The scope of protection of this application is defined by the equivalents of the appended claims.

Claims

1. A high-solids-content solvent-free thick-film epoxy resin coating, characterized in that, The product comprises a first component and a second component. The first component includes a modified epoxy resin, an active diluent, a filler, and additives. The modified epoxy resin is prepared by reacting epoxy resin with a polyether diol. The second component includes a modified curing agent, a composite accelerator, and a retarder. The modified curing agent is prepared by reacting cashew nut shell phenol with a mixed amine. The composite accelerator is prepared by combining modified nano-zinc oxide with a composite catalyst. The modified nano-zinc oxide is prepared by reacting nano-zinc oxide with KH560 and then reacting it with potassium 3-sulfonate propyl methacrylate. The composite catalyst is prepared by combining imidazole salt ionic liquid with triethanolamine.

2. The high-solids-content solvent-free thick-film epoxy resin coating according to claim 1, characterized in that, The epoxy resin includes at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol S type epoxy resin; the epoxy value of the epoxy resin is 0.55-0.65 eq / 100g; the polyether diol is a polyoxypropylene-polyoxyethylene block diol, wherein the mass ratio of polyoxypropylene to polyoxyethylene is (2-3):1; the mass ratio of epoxy resin to polyether diol is (10-20):

1.

3. The high-solids-content solvent-free thick-film epoxy resin coating according to claim 1, characterized in that, The mixed amine is obtained by compounding phenylenediamine and polyetheramine; the mass ratio of cashew phenol to mixed amine is (1-2):1; the mass ratio of phenylenediamine to polyetheramine is 1:(0.5-1.2).

4. The high-solids-content solvent-free thick-film epoxy resin coating according to claim 1, characterized in that, The reactive diluent includes any one of phenyl glycidyl ether, 1,4-butanediol diglycidyl ether, and neopentyl glycol diglycidyl ether; the filler includes any one of barium sulfate, talc, and fumed silica; the additives include dispersants, leveling agents, and toughening agents; the dispersant includes any one of sodium polyacrylate, polyhydroxyethyl methacrylate, and octyl phosphate; the leveling agent includes any one of polybutyl methacrylate, perfluorooctyl ethyl acrylate, and poly(1,6-hexanediol adipate); the toughening agent includes any one of carboxyl-terminated acrylonitrile rubber, liquid polysulfide rubber, and hydroxyl-terminated polybutadiene; the imidazole salt ionic liquid includes 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium chloride; the retarder includes any one of tributyl phosphate, adipic acid, and sebacamide.

5. The high-solids-content solvent-free thick-film epoxy resin coating according to claim 4, characterized in that, The mass ratio of modified epoxy resin, reactive diluent, filler, and additives in the first component is (25-35):(5-10):(50-60):(1-3); the mass ratio of dispersant, leveling agent, and toughening agent is (1-3):(0.5-2):(2-5); the mass ratio of modified curing agent, composite accelerator, and retarder in the second component is (80-90):(8-15):(0.5-2); the mass ratio of modified nano zinc oxide and composite catalyst in the composite accelerator is (1.5-3):1; the mass ratio of KH560, nano zinc oxide, and potassium 3-sulfonopropyl methacrylate is (2-5):(85-92):(3-7); the mass ratio of imidazole salt ionic liquid and triethanolamine is (1-1.5):1; and the mass ratio of the first component and the second component is (4-8):

1.

6. The method for preparing a high-solids-content solvent-free thick-film epoxy resin coating as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Weigh epoxy resin and polyoxypropylene-polyoxyethylene block diol and add them to the reaction vessel; add alkaline catalyst to the reaction vessel, heat and stir under nitrogen protection, and cool to room temperature after the reaction is completed to obtain modified epoxy resin. S2. Weigh cashew phenol and mixed amine. First, add cashew phenol to the reaction vessel, heat up, add mixed amine while stirring, keep warm, and obtain modified curing agent. S3. Weigh nano zinc oxide and add it to a high-speed disperser, then add anhydrous ethanol for pre-dispersion; add KH560 to the disperser, heat, and continue stirring; then add potassium 3-sulfonopropyl methacrylate, heat, and stir; after the reaction is complete, centrifuge, vacuum dry, and grind through a 300-mesh sieve to obtain modified nano zinc oxide; weigh imidazole salt ionic liquid and triethanolamine, add them to a stirred tank and stir to prepare a composite catalyst; add the modified nano zinc oxide and the above composite catalyst to a high-speed disperser for dispersion to obtain a composite accelerator; S4. Weigh the modified curing agent, composite accelerator and retarder and add them to the mixing tank; stir to obtain the second component; weigh the modified epoxy resin, reactive diluent, filler and additives obtained in step S1 and add them to the planetary mixer, stir and disperse under vacuum until the fineness of the system is ≤60μm and there are no visible particles, to obtain the first component. S5. The first component and the second component are mixed in a mass ratio of (4-8):1 to obtain a high-solids-content solvent-free thick-film epoxy resin coating.

7. The method for preparing a high-solids-content solvent-free thick-film epoxy resin coating according to claim 6, characterized in that, In step S1, the mass of the alkaline catalyst is 0.1%-0.3% of the mass of the epoxy resin; the alkaline catalyst is potassium hydroxide or sodium hydroxide; the amount of alkaline catalyst added is 0.1%-0.3% of the mass of the epoxy resin; the temperature for heating under nitrogen protection is 100-120℃; the stirring speed is 300-500 rpm and the time is 2-4 hours; in step S2, the temperature for heating is 60-80℃ and the holding time is 1-2 hours.

8. The method for preparing a high-solids-content solvent-free thick-film epoxy resin coating according to claim 6, characterized in that, In step S3, the mass ratio of nano-zinc oxide to anhydrous ethanol is 1:(1-2); the pre-dispersion speed is 1500-2000 rpm and the time is 15-20 min; the heating temperature after adding KH560 is 50-70℃, and the stirring reaction time is 1-2 h; the heating temperature after adding potassium 3-sulfonopropyl methacrylate is 70-85℃, the stirring reaction speed is 2000-2500 rpm, and the time is 1-1.5 h; the centrifugation speed is 8000-10000 rpm and the time is 10-15 min; the vacuum drying temperature is 60-80℃ and the time is 4-6 h; the stirring speed when adding to the stirred tank is 500-800 rpm and the time is 30-45 min; the dispersion speed when adding to the high-speed disperser is 1800-2200 rpm and the time is 20-30 min.

9. The method for preparing a high-solids-content solvent-free thick-film epoxy resin coating according to claim 6, characterized in that, In step S4, the stirring speed of the stirred tank is 400-600 rpm and the time is 40-60 min; the vacuum degree of the vacuum condition is -0.1~-0.08 MPa, and the stirring speed of the planetary stirrer is 500-800 r / min and the time is 20-40 min.

10. The application of the high-solids-content solvent-free thick-film epoxy resin coating according to any one of claims 1 to 5 in the protection of industrial steel structural components.

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