High solid solventless high build epoxy resin coating, method of manufacture and use

Abstract

The application relates to the technical field of paint, and provides high-solid-solvent-free thick paste type epoxy resin paint, a preparation method and application, the paint comprises a first component and a second component; the first component comprises modified epoxy resin, active diluent, filler and auxiliary agent; the second component comprises modified curing agent, composite accelerator and retarder; the composite accelerator 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-sulfopropyl methacrylate potassium salt; the composite catalyst is formed by compounding imidazole salt ionic liquid and triethanolamine. In the application, the flexible chain segment is introduced into the modified epoxy resin to reduce viscosity, the cashew phenol and mixed amine are compounded to regulate the reaction of the modified curing agent, and the composite accelerator and the retarder are synergistically catalyzed to control the speed, so that the problems of incomplete curing and low performance caused by the diffusion blockage of the curing agent in the thick coating layer of the high-solid-solvent-free thick paste type epoxy resin paint are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of coatings, in particular to a high-solid-solvent-free thick paste type epoxy resin coating, a preparation method and application. BACKGROUND

[0002] In the field of coatings, high-solid-solvent-free epoxy coatings have become the core choice for thick coating corrosion prevention scenarios due to their environmental protection characteristics of no volatile organic compound emission and solid content close to 100%, and long-term protection is achieved by building a physical barrier through a thick coating layer, and the mechanical properties and structural integrity of the cured coating layer are extremely high. However, the solvent-free system completely depends on the chemical reaction of epoxy resin and curing agent to complete film formation, and the diffusion efficiency and reaction uniformity of the curing agent become the key bottleneck of thick coating construction.

[0003] In thick coating layer construction, the high viscosity characteristics of the high-solid system significantly increase the migration resistance of the curing agent: the surface curing agent can quickly react due to sufficient contact with the epoxy resin, while the curing agent in the interior of the coating layer, especially in the deep layer, needs to overcome the molecular entanglement of the resin matrix and the spatial barrier of the filler network for diffusion, and diffusion lag phenomenon is prone to occur. Diffusion blockage directly leads to incomplete curing reaction in the interior of the thick coating layer, thereby degrading the overall mechanical properties of the coating layer, which is manifested as a significant decrease in internal hardness compared to the surface, a decrease in impact resistance, and even the presence of local mechanical performance short boards, which seriously affects the structural stability and service reliability of the thick coating layer, and becomes a key obstacle to the efficient application of high-solid-solvent-free epoxy coatings in thick coating scenarios.

[0004] In summary, in order to solve the above-mentioned problem of curing agent diffusion blockage in the coating, a coating is needed to achieve uniform and efficient curing and performance improvement. SUMMARY

[0005] To solve the above technical problems, the application provides a high-solid-solvent-free thick paste type epoxy resin coating, a preparation method and application. The application is composed of a first component containing modified epoxy resin, active diluent, etc. and a second component containing modified curing agent, composite accelerator (modified nano zinc oxide and composite catalyst) and retarder. The modified epoxy resin is introduced to reduce the viscosity by introducing flexible segments, the modified curing agent is compounded with cashew phenol and mixed amine to regulate the reaction, and the composite accelerator and retarder are used to control the speed of catalysis, thereby solving the problem of incomplete curing and low performance caused by curing agent diffusion blockage in the interior of the high-solid-solvent-free thick paste type epoxy resin coating.

[0006] In order to achieve the above purposes, one technical scheme adopted by the application is:

[0007] In a first aspect, the application provides a high solid content solvent-free thick paste type epoxy resin coating, comprising a first component and a second component; the first component comprises a modified epoxy resin, a reactive diluent, a filler and an auxiliary agent; the modified epoxy resin is prepared by reacting an 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 cardanol with a mixed amine; the composite accelerator is compounded by a 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-sulfopropyl methacrylate potassium salt; the composite catalyst is compounded by imidazole salt ionic liquid and triethanolamine.

[0008] In the application, the flexible ether bond segment introduced in the main chain of the modified epoxy resin reduces the close packing between molecules by destroying the regularity of the polymer chain, thereby reducing the intermolecular force of the resin matrix and realizing intrinsic viscosity reduction. At the same time, the modified curing agent improves the compatibility with the resin by introducing the long alkyl chain of cardanol, and cooperates with the mixed system of m-xylylenediamine / polyether amine to provide sufficient reaction power while avoiding the formation of a dense layer on the surface and reducing the viscous resistance of the curing agent molecules to migrate to the inside of the coating during the initial stage of the reaction.

[0009] When the curing reaction proceeds and the viscosity of the system rises, the movement of the curing agent molecules is limited. In the composite accelerator, the nano zinc oxide modified by KH560 and sulfonate introduces epoxy groups and sulfonate groups, wherein the epoxy groups enhance the compatibility of the composite accelerator with the resin; the sulfonate groups can provide electrostatic repulsion and form a stable zwitterionic structure on the surface of the modified nano zinc oxide, which uniformly disperses the nano zinc oxide in the resin by means of electrostatic stabilization and steric hindrance, avoiding the concentration of catalytic sites on the surface of the resin. As a solid phase catalytic center, the Zn 2+ The Lewis acid sites on the surface of the modified nano zinc oxide polarize the epoxy groups, reduce the activation energy of the nucleophilic ring-opening reaction of the curing agent, and maintain the reaction rate under the condition of low curing agent concentration.

[0010] In addition, the composite catalyst in the composite accelerator can diffuse into the interior of the coating as a homogeneous catalyst; the imidazole salt ionic liquid polarizes the epoxy ring through the electrostatic interaction between the cation and the epoxy group; the triethanolamine forms a hydrogen bond with the amine group of the amine curing agent through the hydroxyl group, enhancing the electron cloud density of the amine group and improving the nucleophilicity, and the two synergistically improve the reaction activity of the internal curing agent molecules, complete the curing reaction through efficient catalysis, and finally solve the problem of incomplete curing caused by diffusion obstruction in the interior of the thick film coating.

[0011] Preferably, the epoxy resin comprises at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin; the epoxy value of the epoxy resin is 0.55-0.65 eq / 100g; the polyether diol is polyoxypropylene-polyoxyethylene block diol, wherein the mass ratio of the polyoxypropylene and polyoxyethylene is (2-3):1; the mass ratio of the epoxy resin and polyether diol is (10-20):1.

[0012] Preferably, the mixed amine is obtained by compounding methylene dianiline and polyether amine; the mass ratio of the cardanol and mixed amine is (1-2):1; the mass ratio of the methylene dianiline and polyether amine is 1:(0.5-1.2).

[0013] Preferably, the active 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 auxiliary agent comprises dispersant, leveling agent and toughening agent; the dispersant comprises any one of sodium polyacrylate, polyhydroxyethyl methacrylate and octyl phosphate ester, the leveling agent comprises any one of polybutyl methacrylate, perfluoro octyl ethyl acrylate and polyhexamethylene adipate, the toughening agent comprises any one of carboxyl-terminated butyl nitrile rubber, liquid polysulfide rubber and hydroxyl-terminated polybutadiene; the imidazole salt ionic liquid comprises 1-ethyl-3-methyl imidazole tetrafluoroborate (EMIMBF4), 1-butyl-3-methyl imidazole hexafluorophosphate (BMIMPF6) and 1-butyl-3-methyl imidazole chloride (BMIMCl); the retarder comprises any one of tributyl phosphate, adipic acid and sebacamide.

[0014] Preferably, the mass ratio of the modified epoxy resin, active diluent, filler and auxiliary agent in the first component is (25-35):(5-10):(50-60):(1-3); the mass ratio of the dispersant, leveling agent and toughening agent is (1-3):(0.5-2):(2-5); the mass ratio of the modified curing agent, composite accelerator and retarder in the second component is (80-90):(8-15):(0.5-2); the mass ratio of the modified nano zinc oxide and composite catalyst in the composite accelerator is (1.5-3):1; the mass ratio of the KH560, nano zinc oxide and 3-sulfopropyl methacrylate potassium salt is (2-5):(85-92):(3-7); the mass ratio of the imidazole salt ionic liquid and triethanolamine is (1-1.5):1; the mass ratio of the first component and the second component is (4-8):1.

[0015] In the second aspect, the application provides a preparation method of high solid content solvent-free thick paste type epoxy resin paint, comprising the following steps:

[0016] S1, weigh epoxy resin and polyoxypropylene-polyoxyethylene block dihydric alcohol into a reaction kettle; add a basic catalyst to the reaction kettle, stir after warming under nitrogen protection, and cool to room temperature after reaction is completed to obtain a modified epoxy resin;

[0017] S2, weigh cardanol and mixed amine, first add cardanol into a reaction kettle, warm, and add mixed amine under stirring to obtain a modified curing agent;

[0018] S3, weigh nano zinc oxide into a high-speed disperser, pre-disperse by adding anhydrous ethanol; add KH560 to the disperser, warm, and continue to stir; then add 3-sulfopropyl methacrylate potassium salt, warm, and stir; centrifuge after reaction is completed, vacuum dry, and grind through a 300-mesh sieve to obtain modified nano zinc oxide; weigh imidazole salt ionic liquid and triethanolamine, add into a stirring kettle to stir to prepare a composite catalyst; add the modified nano zinc oxide and the composite catalyst into a high-speed disperser to disperse to obtain a composite accelerator;

[0019] S4, weigh the modified curing agent, the composite accelerator, and the retarder into a stirring kettle; stir to obtain a second component; weigh the modified epoxy resin prepared in step S1, the active diluent, the filler, and the additive; add all the materials into a planetary stirrer, disperse under vacuum conditions until the fineness of the system is ≤60 μm and no visible particles are present to obtain a first component;

[0020] S5, the first component and the second component are mixed in a mass ratio of (4-8):1 to obtain a high-solidity solvent-free thick paste type epoxy resin coating.

[0021] Preferably, the mass of the basic catalyst in step S1 is 0.1%-0.3% of the mass of the epoxy resin; the basic catalyst is potassium hydroxide or sodium hydroxide; the addition amount of the basic catalyst is 0.1%-0.3% of the mass of the epoxy resin; the temperature of warming under nitrogen protection is 100-120℃; the stirring speed is 300-500 rpm, and the time is 2-4 h; the temperature of warming in step S2 is 60-80℃, and the holding time is 1-2 h.

[0022] Preferably, the mass ratio of the nano zinc oxide to the anhydrous ethanol in step S3 is 1: (1-2); the pre-dispersing rotation speed is 1500-2000 rpm, and the time is 15-20 min; the temperature of the heating after adding KH560 is 50-70 DEG C; the stirring reaction time is 1-2 h; the heating temperature of adding 3-sulfopropyl methacrylate potassium salt is 70-85 DEG C, the stirring rotation speed is 2000-2500 rpm, and the time is 1-1.5 h; the centrifugal rotation speed is 8000-10000 rpm, and the time is 10-15 min; the vacuum drying temperature is 60-80 DEG C, and the time is 4-6 h; the stirring rotation speed of adding the stirring kettle is 500-800 rpm, and the time is 30-45 min; and the dispersion speed of adding the high-speed dispersion machine is 1800-2200 rpm, and the time is 20-30 min.

[0023] Preferably, the stirring speed in step S4 is 400-600 rpm, and the time is 40-60 min; the vacuum degree of the vacuum condition is -0.1 ~ -0.08 MPa, the stirring rotation speed of the planetary stirring is 500-800 r / min, and the time is 20-40 min.

[0024] In a third aspect, the application provides the application of the high solid content solvent-free thick paste type epoxy resin coating in the protection of industrial steel structures.

[0025] Compared with the prior art, the application has the beneficial effects that:

[0026] The application provides a high solid content solvent-free thick paste type epoxy resin coating, a preparation method and an application. The flexible ether bond segment introduced in the main chain of the modified epoxy resin reduces the close packing between molecules by destroying the regularity of the polymer chain, thereby reducing the intermolecular force of the resin matrix and realizing intrinsic viscosity reduction. At the same time, the modified curing agent improves the compatibility with the resin by introducing the long alkyl chain of cardanol, and cooperates with the compounding system of m-xylylenediamine / polyether amine, thereby providing sufficient reaction power while avoiding the formation of a dense layer on the surface and reducing the viscous resistance of the curing agent molecules to migrate to the inside of the coating in the early stage of the reaction.

[0027] When the curing reaction proceeds and the viscosity of the system rises, the movement of the curing agent molecules is limited. Among the composite accelerators, the nano zinc oxide modified by KH560 and sulfonate enhances the compatibility of the composite accelerator with the resin through the introduction of epoxy groups, and provides electrostatic repulsion through the introduction of sulfonate, thereby forming a stable zwitterionic structure on the surface of the modified nano zinc oxide. The nano zinc oxide is uniformly dispersed in the resin by virtue of electrostatic stabilization and steric hindrance, thereby avoiding the concentration of the catalytic sites on the surface of the resin. As a solid phase catalytic center, the Zn 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.

[0028] 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

[0029] 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;

[0030] 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

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] Example 1

[0037] 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:

[0038] S1, by mass ratio 10:1, take the epoxy value 0.55 eq / 100g of bisphenol A type epoxy resin and polyoxypropylene-polyoxyethylene block diol, wherein the mass ratio of polyoxypropylene and polyoxyethylene is 2:1, into the reaction kettle; add 0.1% of the mass of the epoxy resin potassium hydroxide to the reaction kettle, heat to 100℃ under nitrogen protection, stir at 300rpm for 2 hours, cool to room temperature after the reaction is completed, and obtain the modified epoxy resin;

[0039] S2, by mass ratio 1:1, take cardanol and mixed amine, wherein the mixed amine is compounded by m-xylylenediamine and polyether amine with a mass ratio of 1:0.5; first add cardanol into the reaction kettle, heat to 60℃, add mixed amine under stirring, and keep warm for 1 hour to obtain the modified curing agent;

[0040] S3, by mass ratio 2:85:3, take KH560, nano zinc oxide and 3-sulfopropyl methacrylate potassium salt, take nano zinc oxide into a high-speed disperser, add anhydrous ethanol, wherein the mass ratio of nano zinc oxide to anhydrous ethanol is 1:1, pre-disperse at 1500rpm for 15min; add KH560 into the disperser, heat to 50℃, continue to stir for 1h; then add 3-sulfopropyl methacrylate potassium salt, heat to 70℃, stir at 2000rpm for 1h; after the reaction is completed, centrifuge at 8000rpm for 10min, vacuum dry at 60℃ for 4h, and grind through a 300 mesh sieve to obtain the modified nano zinc oxide; by mass ratio 1:1, take EMIMBF4 and triethanolamine into a stirred kettle, stir at 500rpm for 30min to prepare a composite catalyst; by mass ratio 1.5:1, take the modified nano zinc oxide and the composite catalyst, add the modified nano zinc oxide and the composite catalyst into a high-speed disperser, disperse at 1800rpm for 20min to obtain a composite accelerator;

[0041] S4, by mass ratio 80:8:0.5, take the modified curing agent, the composite accelerator and tributyl phosphate into a stirred kettle; stir at 400rpm for 40min to obtain the second component; by mass ratio 25:5:50:1, take the modified epoxy resin prepared in step S1, phenyl glycidyl ether, barium sulfate and auxiliary agent; wherein the auxiliary agent is premixed by sodium polyacrylate, polybutyl methacrylate and carboxyl-terminated butyl nitrile rubber with a mass ratio of 1:0.5:2; add all the above materials into a planetary mixer, stir and disperse at 500r / min under a vacuum degree of-0.1MPa for 20min, until the fineness of the system is ≤60μm and no visible particles are present, to obtain the first component;

[0042] S5, the first component and the second component are mixed in a mass ratio of 4:1 to obtain a high solid content solvent-free thick paste type epoxy resin coating.

[0043] Example 2

[0044] The embodiment provides a preparation method of high solid content solvent-free thick paste type epoxy resin paint, comprising the following steps:

[0045] S1, according to the mass ratio of 15:1, the epoxy value 0.6 eq / 100g for bisphenol F type epoxy resin and polyoxypropylene-polyoxyethylene block diol, wherein the mass ratio of polyoxypropylene and polyoxyethylene is 2.5:1, is added to the reaction kettle; 0.2% of the mass of the epoxy resin is added to the reaction kettle, and the temperature is raised to 110℃ under nitrogen protection, and stirred at 400rpm for 3 hours, and then cooled to room temperature after reaction, to obtain a modified epoxy resin;

[0046] S2, according to the mass ratio of 1.5:1, cashew phenol and mixed amine are weighed, wherein the mixed amine is compounded by m-xylylenediamine and polyether amine according to the mass ratio of 1:1; first, the cashew phenol is added to the reaction kettle, the temperature is raised to 70℃, and the mixed amine is added under stirring, and the temperature is kept for 1.5 hours to obtain a modified curing agent;

[0047] S3, according to the mass ratio of 3:88:5, KH560, nano zinc oxide and 3-sulfopropyl methacrylate potassium salt are weighed, and the nano zinc oxide is added to a high-speed dispersing machine, and anhydrous ethanol is added, wherein the mass ratio of nano zinc oxide to anhydrous ethanol is 1:1.5, and the pre-dispersion is carried out at 1800rpm for 18min; KH560 is added to the dispersing machine, and the temperature is raised to 60℃, and the stirring is continued for 1.5h; then 3-sulfopropyl methacrylate potassium salt is added, the temperature is raised to 80℃, and the stirring is carried out at 2300rpm for 1.3h; after the reaction is completed, the centrifugation is carried out at 9000rpm for 12min, the vacuum drying is carried out at 70℃ for 5h, and the grinding is carried out through a 300 mesh sieve, to obtain modified nano zinc oxide; according to the mass ratio of 1.2:1, BMIMPF6 and triethanolamine are weighed and added to a stirring kettle, and the stirring is carried out at 600rpm for 40min to prepare a composite catalyst; according to the mass ratio of 2:1, the modified nano zinc oxide and the composite catalyst are weighed, and the modified nano zinc oxide and the composite catalyst are added to a high-speed dispersing machine, and the dispersion is carried out at 2000rpm for 25min to obtain a composite promoter;

[0048] S4, the modified curing agent, composite accelerator and adipic acid are weighed according to the mass ratio of 85:12:1 and added into the stirring kettle; stirring at 500 rpm for 50 min, to obtain the second component; the modified epoxy resin prepared in step S1, 1, 4-butanediol diglycidyl ether, talc and auxiliary agent are weighed according to the mass ratio of 30:7:55:2; wherein the auxiliary agent is pre-mixed by poly (hydroxyethyl methacrylate), perfluoro octyl ethyl acrylate and liquid polysulfur rubber according to the mass ratio of 2:1:3; all the above materials are added into the planetary mixer, and stirred and dispersed at 700 r / min under the vacuum degree of-0.09 MPa for 30 min, until the fineness of the system is ≤60 μm and no visible particles are observed, to obtain the first component;

[0049] S5, the first component and the second component are mixed according to the mass ratio of 6:1, to obtain the high solid content solvent-free thick paste type epoxy resin coating.

[0050] Example 3

[0051] The preparation method of the high solid content solvent-free thick paste type epoxy resin coating, characterized in that, comprising the following steps:

[0052] S1, the epoxy resin of 0.65 eq / 100g of bisphenol S type and polyoxypropylene-polyoxyethylene block diol are weighed according to the mass ratio of 20:1, wherein the mass ratio of polyoxypropylene and polyoxyethylene is 3:1, and added into the reaction kettle; 0.3% of sodium hydroxide of the mass of the epoxy resin is added into the reaction kettle, heated to 120℃ under nitrogen protection, and stirred at 500 rpm for 4 hours, then cooled to room temperature after reaction to obtain the modified epoxy resin;

[0053] S2, cashew phenol and mixed amine are weighed according to the mass ratio of 2:1, and the mixed amine is compounded by m-xylylenediamine and polyether amine according to the mass ratio of 1:1.2; first, the cashew phenol is added into the reaction kettle, heated to 80℃, and the mixed amine is added under stirring, and the modified curing agent is obtained after 2 hours of incubation;

[0054] S3, take KH560, nano zinc oxide and 3-sulfopropyl potassium methacrylate by mass ratio 5:92:7, take nano zinc oxide into high-speed dispersion machine, add anhydrous ethanol, the mass ratio of nano zinc oxide and anhydrous ethanol is 1:2, pre-disperse at 2000 rpm for 20 min; add KH560 into the dispersion machine, heat to 70℃, continue to stir for 2h; add 3-sulfopropyl potassium methacrylate, heat to 85℃, stir at 2500 rpm for 1.5h; after the reaction is completed, centrifuge at 10000 rpm for 15 min, vacuum dry at 80℃ for 6h, and grind through a 300 mesh sieve to obtain modified nano zinc oxide; take BMIMCl and triethanolamine by mass ratio 1.5:1, add into the stirred tank, stir at 800 rpm for 45 min to prepare a composite catalyst; take modified nano zinc oxide and composite catalyst by mass ratio 3:1, add modified nano zinc oxide and the above composite catalyst into a high-speed dispersion machine, disperse at 2200 rpm for 30 min to obtain a composite accelerator;

[0055] S4, take modified curing agent, composite accelerator and sebacamide by mass ratio 90:15:2 and add into the stirred tank; stir at 600 rpm for 60 min to obtain the second component; take modified epoxy resin prepared in step S1, neopentyl glycol diglycidyl ether, fumed silica and auxiliary agent by mass ratio 35:10:60:3; wherein the auxiliary agent is a premix of octyl phosphate, polyhexa-methylene adipate and hydroxyl-terminated polybutadiene by mass ratio 3:2:5; add all the above materials into a planetary stirrer, stir and disperse at 800 r / min under a vacuum degree of-0.08 MPa for 40 min until the system fineness is ≤60 μm and no visible particles are present to obtain the first component;

[0056] S5, mix the first component and the second component by mass ratio 8:1 to obtain a high solid content solvent-free thick paste type epoxy resin coating. As shown in Figure 2 the physical map of the high solid content solvent-free thick paste type epoxy resin coating of Example 3.

[0057] Comparative Example 1

[0058] The preparation method of the high solid content solvent-free thick paste type epoxy resin coating is different from that of Example 3 in that the polyether diol modified epoxy resin is not used in the system.

[0059] Comparative Example 2

[0060] The preparation method of the high solid content solvent-free thick paste type epoxy resin coating is different from that of Example 3 in that the curing agent is a mixed amine and no cashew phenol modification is added.

[0061] Comparative Example 3

[0062] The preparation method of the high solid content solvent-free thick paste type epoxy resin coating is different from that of Example 3 in that the modified nano zinc oxide is not prepared, and only EMIMBF4 and triethanolamine are used as accelerators.

[0063] Comparative Example 4

[0064] The preparation method of the high solid content solvent-free thick paste type epoxy resin coating is different from that of Example 3 in that the unmodified nano zinc oxide (without silanization by KH560 and 3-sulfopropyl methacrylate potassium salt grafting) is used.

[0065] Performance test:

[0066] The high solid content solvent-free thick paste type epoxy resin coatings of Examples 1-3 and Comparative Examples 1-4 are brushed on Q235 steel plates (100mm x 100mm x 3mm) that are sandblasted to Sa2.5 level and degreased with acetone, and are coated to a thickness of 3mm, and are tested after being cured at 25°C, 50% RH for 7d; three parallel samples are prepared for each example and comparative example, and the test results are averaged to ensure data reliability.

[0067] 1. Construction viscosity: The construction viscosity of the coating is tested at 25°C using a rotary viscometer, the initial viscosity of the mixed coating is tested, and the smoothness of thick paste coating and other construction operability are evaluated.

[0068] 2. Bubble rate: The bubble rate of the coating is tested using a microscope, the coating is coated to a thickness of 150μm, the number of bubbles in an area of 10cm 2 is observed and recorded, and the bubble proportion is calculated to measure the defoaming effect.

[0069] 3. Construction viscosity: The construction viscosity of the coating is tested at 25°C using a rotary viscometer, the initial viscosity of the mixed coating is tested, and the smoothness of thick paste coating and other construction operability are evaluated.

[0070] 4. Curing property: Samples are taken from the surface layer (0-0.5mm) and deep layer (2.5-3mm) of the coating, respectively, and the curing degree is measured.

[0071] 5. Adhesion: The adhesion of the coating is tested using a pull-off method and a tensile testing machine.

[0072] 6. Impact resistance: The impact resistance of the coating is tested using an impact tester.

[0073] 7. Water resistance: The coating is immersed in deionized water, and the changes in the coating are observed and recorded.

[0074] 8. Salt spray resistance: The coating is placed in a 3% NaCl salt spray environment for 1000h, and the changes in the coating are observed and recorded.

[0075] 9. Acid resistance: immerse the coating in 5% sulfuric acid solution for 720h, observe and record the changes of the coating.

[0076] 10. Alkali resistance: immerse the coating in 5% NaOH solution for 720h, observe and record the changes of the coating.

[0077] Table 1. Performance test parameters of different coatings

[0078]

[0079] As can be seen from Table 1, the high solid content solvent-free thick paste type epoxy resin coating prepared in Examples 1-3 has moderate construction viscosity (18500-26800 mPa·s), low bubble rate (≤0.8%), small difference (≤2%) between the curing degree of the surface layer and the deep layer of the 3mm thick coating, strong adhesion (≥5.2 MPa), high impact resistance (≥50 cm), and stable water resistance, salt spray resistance, acid resistance and alkali resistance without abnormal changes. This shows that through the synergistic effect of modified epoxy resin, modified curing agent and composite accelerator, uniform curing and excellent protective performance of thick coating are successfully achieved.

[0080] Comparative Example 1 does not use polyether diol modified epoxy resin, and its construction viscosity is significantly increased to 38200 mPa·s, the deep layer curing degree is only 72%, and the difference with the surface layer is 22%, and the medium resistance performance is seriously deteriorated. The flexible segment of polyether diol can effectively reduce the intermolecular force of the resin matrix through internal plasticization, realize intrinsic viscosity reduction, and create key conditions for the diffusion of curing agent molecules into the coating interior; at the same time, its flexible segment participates in the crosslinking network, and the network toughness is improved. The absence of the flexible segment in Comparative Example 1 results in too high initial viscosity of the system, which seriously hinders the diffusion of the curing agent, causes incomplete curing in the interior, and makes the crosslinking network loose, resulting in a sharp decline in corrosion resistance.

[0081] Comparative Example 2 does not use cardanol modified curing agent, and although its deep layer curing degree (80%) is better than that of Comparative Example 1, there is still a 13% difference with the surface layer, and the corrosion resistance has edge defects. The long alkyl chain of cardanol can improve the compatibility of the curing agent and the resin, and through the space steric effect, it can coordinate with polyether amine to regulate the reaction rate, and avoid the premature curing of the surface layer hindering the internal diffusion. The absence of the long chain structure of cardanol in Comparative Example 2 results in a decrease in compatibility and an imbalance in reaction regulation, and the dense layer of the surface layer is formed too quickly, which affects the deep diffusion of the curing agent, and finally leads to insufficient internal crosslinking density, resulting in a short board in corrosion resistance.

[0082] Comparative Example 3 did not use modified nano-zinc oxide, only used composite catalyst as accelerator, and its deep curing degree (82%) was insufficient, with a 10% gap with the surface layer. In the composite accelerator, modified nano-zinc oxide served as a solid-phase catalytic center, and uniform dispersion was achieved by means of a zwitterionic structure, forming a "distributed anchor point" inside the coating. The surface Zn 2+ Through the interface polarization effect, the surrounding epoxy groups were activated, and the curing reaction could still be carried out efficiently after diffusion limitation. Comparative Example 3 lacked this distributed catalytic center and relied only on the homogeneous diffusion of small molecule catalysts. In the thick film, the viscosity increased, resulting in insufficient catalyst, which could not effectively activate the local reaction, leading to low internal curing efficiency.

[0083] Comparative Example 4 used unmodified nano-zinc oxide, which had the highest bubble rate (1.8%) and unsatisfactory deep curing degree (85%). Modified nano-zinc oxide introduced epoxy groups through silanization with KH560, and then formed a zwitterionic structure through sulfonate grafting. Electrostatic repulsion and steric hindrance were used to achieve stable dispersion of nanoparticles, avoiding agglomeration. In Comparative Example 4, unmodified nano-zinc oxide was prone to agglomeration, which not only failed to form an effective distributed catalytic center, but also introduced defects into the coating, hindering the diffusion of the curing agent, increasing bubble residues, and leading to poor coating density and deteriorated comprehensive performance.

[0084] The above results show and describe the basic principles and main features of the present application and the advantages of the present application.

[0085] Those skilled in the art should understand that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection claimed by the present 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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