High-adhesion acrylic coating and preparation method thereof

Abstract

The invention relates to a high-adhesion acrylic coating and a preparation method thereof, and belongs to the technical field of coatings. The core lies in that a novel epoxy modified monomer is designed and synthesized, the monomer is successfully applied to copolymerization modification of an acrylic emulsion by introducing a crown ether structure into an epoxy group in situ, and after the prepared modified acrylic emulsion and an auxiliary agent are prepared into a coating, the initial adhesive force of the coating is remarkably improved through the epoxy group; and through the in-situ toughening effect of the crown ether structure, stress can be effectively absorbed during external force impact, and brittle falling of the coating is prevented. Tests show that the coating keeps high hardness and good flexibility, meanwhile, the adhesive force retention rate after impact and scraping of the coating is far better than that of a traditional epoxy modified coating, synergistic improvement of the adhesive force and the toughness is achieved, and the coating has remarkable application value.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a high-adhesion acrylic coating and its preparation method. Background Technology

[0002] Acrylic coatings are a type of coating that uses acrylic resin as the main film-forming substance. They possess excellent weather resistance, color retention, chemical resistance, and mechanical properties, and are widely used in the automotive, construction, furniture, electronic equipment, and plastic products industries. The advantages of acrylic coatings lie in their fast drying speed, high hardness, vibrant colors, and environmental friendliness, meeting diverse industrial needs. However, while acrylic coatings perform well on polar substrates such as metals, their adhesion to non-polar or low surface energy substrates is insufficient. This is mainly because the interaction between the polar groups of acrylic resin and the low surface energy interface is weak, failing to form strong chemical bonds, leading to easy peeling or detachment of the coating and limiting its application range.

[0003] To improve the adhesion of acrylic coatings to low-surface-area substrates such as glass and plastics, existing technologies typically employ epoxy resin modification. Epoxy modification enhances the bond strength between the coating and the substrate by introducing epoxy groups. However, epoxy modification also introduces significant drawbacks: the high crosslinking density and rigid molecular chain structure of epoxy resins increase the brittleness of the coating. When subjected to external forces such as scratches, impacts, or deformation, the internal stress of the coating cannot be effectively released, easily leading to microcracks or overall brittle fracture, resulting in detachment and failure. This brittleness allows the coating to be damaged during daily use by minor impacts or temperature changes, losing its protective and decorative functions.

[0004] To address the brittleness issue caused by epoxy modification, existing technologies often improve toughness by compounding toughening materials. However, these toughening agents, as physical dopants, may be unevenly distributed in the coating, migrating or segregating, which can interfere with the interfacial chemical bonding formed by epoxy modification, leading to weakened adhesion. For example, poor compatibility between the toughening agent and epoxy resin can form a weak boundary layer at the interface, reducing the bonding strength between the coating and the substrate, which contradicts the original intention of epoxy modification to enhance adhesion. Therefore, existing technologies have been caught in a dilemma of balancing coating toughness and adhesion: either improve adhesion through epoxy modification at the expense of toughness, or improve toughness through toughening agents at the expense of adhesion. This contradiction limits the application of acrylic coatings in high-performance fields. Summary of the Invention

[0005] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a high-adhesion acrylic coating and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] A high-adhesion acrylic coating, using modified acrylic emulsion as the film-forming material and compounded with other additives to form an emulsion-type coating, specifically includes the following three aspects:

[0008] 1. Synthesis of epoxy-modified monomers

[0009] Step A1: Mix allyl glycidyl ether, chloroalkanol and toluene, heat to 80-90℃ under nitrogen protection, add tetrabutylammonium bromide and stir for 3-4 hours. After the reaction is completed, remove toluene by rotary evaporation under reduced pressure. Wash the substrate with water and separate the aqueous phase. After drying, obtain intermediate 1.

[0010] Step A2: Mix intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, heat to 60-70℃ and reflux for 8-10 h under nitrogen protection, cool and filter after the reaction is complete, and then remove tetrahydrofuran by rotary evaporation to obtain intermediate 2.

[0011] Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine and dioxane, heat to 40-50℃ and stir for 6-7 hours. Then add sodium hydroxide solution and continue heating to 90-100℃ for 1.5-2.2 hours. After the reaction is complete, dry with anhydrous magnesium sulfate and filter. Then remove dioxane by rotary evaporation under reduced pressure to obtain the epoxy-modified monomer.

[0012] In the above reaction process, the selection and formulation of raw materials are as follows:

[0013] In step A1, the ratio of allyl glycidyl ether, chloroalkanol, tetrabutylammonium bromide and toluene is 0.1 mol: 0.1 mol: 0.25-0.33 g: 120-160 mL, and the chloroalkanol reacts with allyl glycidyl ether in a ring-opening reaction.

[0014] Preferably, the chloroalkanol is one of 8-chloro-1-octanol and 10-chloro-1-decanol, which has good reactivity. At the same time, the steric hindrance effect of the subsequent introduction of crown ether ring structure at this alkyl chain length can effectively maintain a certain adhesion enhancement effect after modification.

[0015] In step A2, the ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1 mol: 0.1 mol: 8-10 mL: 350-420 mL, and intermediate 1 undergoes a substitution reaction with aza-12-crown ether-4.

[0016] In step A3, the ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 2.2-3.5 mL: 6.5-8.2 g: 270-330 mL. Epichlorohydrin undergoes ring-opening with intermediate 2, followed by ring-closure under strong alkaline conditions, thus introducing epoxy modification.

[0017] The synthesis process route for the above epoxy-modified monomers is as follows:

[0018]

[0019] 2. Synthesis of modified acrylic emulsion

[0020] The epoxy-modified monomer was premixed with an isopropanol aqueous solution, and then the acrylic monomer was added and mixed well. The temperature was raised to 40°C, and ammonium persulfate solution was slowly added to start the reaction. The temperature was maintained at 70±2°C for 4.5-5 hours. After the reaction was completed, sodium thiosulfate solution was added to quench the reaction. Isopropanol was removed by rotary evaporation at a constant temperature. The solid content was adjusted to 48±2% and the pH value to 7-8 with deionized water and ammonia to obtain the modified acrylic emulsion.

[0021] Preferably, the acrylic monomer is a mixture of acrylic acid, hydroxyethyl acrylate and polyethylene glycol methacrylate in a weight ratio of 1:0.4-0.55:0.13-0.18.

[0022] Preferably, the amount of epoxy-modified monomer used is 9.5-13.2 wt% of acrylic monomer. At this copolymerization amount, the adhesion performance of the coating is stable.

[0023] 3. Preparation of acrylic coatings

[0024] The components by weight percentage are: defoamer 0.12-0.15wt%, leveling agent 0.24-0.31wt%, wetting agent 0.18-0.25wt%, and preservative 0.05-0.07wt%, with the balance being modified acrylic emulsion.

[0025] The coating is prepared by adding each component raw material in sequence, mixing them evenly, and then degassing under reduced pressure to obtain an acrylic coating.

[0026] The beneficial effects of this invention are:

[0027] The core advantage of this invention lies in its ability to reconstruct the interfacial bonding mechanism and stress dissipation pathway between the coating and the substrate at the molecular scale by introducing a finely structured epoxy-modified monomer, thereby overcoming the bottleneck of achieving both adhesion and toughness in traditional technologies. This modified monomer is not simply a physical mixture of epoxy groups and crown ethers; rather, it uses chemical synthesis to integrate flexible crown ether rings as side chains into the rigid epoxy framework in situ. This structure exhibits a dynamic and intelligent response mechanism when the coating is subjected to external impact or scratches: on the one hand, the strong covalent bonds formed between the epoxy groups and the substrate surface provide a solid and reliable initial adhesion, firmly anchoring the coating to the substrate; on the other hand, when stress is transmitted from the outside to the interface, the rigid epoxy network tends to concentrate the stress, and at this moment, the crown ether rings on its side chains act as "molecular-level shock absorbers." The large, rotatable ring structure of crown ether rings can effectively absorb and disperse incoming mechanical energy through the rotation of ether bonds and instantaneous changes in molecular conformation. This transforms concentrated stress, which would otherwise lead to crack initiation and propagation, into the extension and creep of molecular chain segments. This process forms a microscopic plastic deformation buffer at the interface between the coating and the substrate. It not only prevents the formation of microcracks but, more importantly, protects the crucial chemical bonds between the epoxy groups and the substrate, preventing their destruction under dynamic loads. Therefore, even if the coating surface is dented due to severe impact or scratched by hard objects, the underlying adhesion interface remains intact, exhibiting excellent post-impact and post-scratching adhesion. Compared to existing compound toughening technologies, this "in-situ toughening" mechanism ensures that the toughening units exist uniformly and stably within the polymer crosslinking network, eliminating the risk of migration or segregation. Therefore, it does not weaken adhesion and significantly improves its long-term protective performance and reliability under harsh environments. Detailed Implementation

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: A high-adhesion acrylic coating was prepared, and the specific implementation method is as follows:

[0030] (1) Preparation of modified acrylic emulsion

[0031] Step A1: Allyl glycidyl ether, 8-chloro-1-octanol and toluene were mixed and heated to 80°C under nitrogen protection. Tetrabutylammonium bromide was added and the mixture was stirred for 3.3 h. The ratio of allyl glycidyl ether, 8-chloro-1-octanol, tetrabutylammonium bromide and toluene was 0.1 mol: 0.1 mol: 0.25 g: 120 mL. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure. The substrate was washed with water and the aqueous phase was separated. After drying, intermediate 1 was obtained.

[0032] Step A2: Take intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, mix them well, heat to 60℃ and reflux for 8.5h under nitrogen protection. The ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1mol:0.1mol:8mL:350mL. After the reaction is completed, cool and filter, and then remove tetrahydrofuran by rotary evaporation to obtain intermediate 2.

[0033] Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, and dioxane, heat to 40℃ and stir for 6.2 h. Dissolve sodium hydroxide in water to form a saturated solution at room temperature, add the sodium hydroxide solution, and continue heating to 90℃ for 1.7 h. The ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 2.2 mL: 6.5 g: 270 mL. After the reaction is complete, dry with anhydrous magnesium sulfate and filter. Then remove dioxane by rotary evaporation under reduced pressure to obtain the epoxy-modified monomer.

[0034] Emulsions prepared by copolymerization of epoxy-modified monomers:

[0035] Premix the epoxy-modified monomer with an isopropanol aqueous solution, then add the acrylic monomer and mix well. Heat to 40℃, slowly add ammonium persulfate solution to start the reaction, and maintain the temperature at 70±2℃ for 4.5h. The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, and polyethylene glycol methacrylate (average molecular weight 300) in a weight ratio of 1:0.4:0.18. The amount of epoxy-modified monomer is 11.5wt% of the acrylic monomer, the volume fraction of the isopropanol aqueous solution is 50%, and the amount is 2.3 times that of the acrylic monomer. The ammonium persulfate solution is a saturated aqueous solution at room temperature, and the amount of ammonium persulfate is 0.8wt% of the acrylic monomer and epoxy-modified monomer. After the reaction is completed, sodium thiosulfate solution is added to quench the reaction. The isopropanol is removed by rotary evaporation at a constant temperature. The solid content is adjusted to 48±2% and the pH value is adjusted to 7-8 with deionized water and ammonia to obtain the modified acrylic emulsion.

[0036] (2) Preparation of acrylic coating

[0037] Raw materials are calculated as follows by weight percentage: defoamer 0.12wt%, TEGO Airex 902W; leveling agent 0.26wt%, BYK-333; wetting agent 0.2wt%, TEGO Wet 270; preservative 0.05wt%, Proxel GXL; balance modified acrylic emulsion.

[0038] Each component raw material was added sequentially, stirred and dispersed at 600 rpm for 15 min, and then degassed under reduced pressure to 1 kPa for 10 min to obtain an acrylic coating.

[0039] Example 2: A high-adhesion acrylic coating was prepared, and the specific implementation method is as follows:

[0040] (1) Preparation of modified acrylic emulsion

[0041] Step A1: Allyl glycidyl ether, 8-chloro-1-octanol and toluene were mixed and heated to 85°C under nitrogen protection. Tetrabutylammonium bromide was added and the mixture was stirred for 3 hours. The ratio of allyl glycidyl ether, 8-chloro-1-octanol, tetrabutylammonium bromide and toluene was 0.1 mol: 0.1 mol: 0.28 g: 130 mL. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure. The substrate was washed with water and the aqueous phase was separated. After drying, intermediate 1 was obtained.

[0042] Step A2: Take intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, mix them well, heat to 65℃ and reflux for 8 hours under nitrogen protection. The ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1mol:0.1mol:9mL:370mL. After the reaction is completed, cool and filter, and then remove tetrahydrofuran by rotary evaporation to obtain intermediate 2.

[0043] Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, and dioxane, heat to 42℃ and stir for 6 hours. Dissolve sodium hydroxide in water to form a saturated solution at room temperature, add the sodium hydroxide solution, and continue heating to 95℃ for 1.5 hours. The ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 2.5 mL: 7 g: 290 mL. After the reaction is complete, dry with anhydrous magnesium sulfate and filter. Then remove dioxane by rotary evaporation under reduced pressure to obtain the epoxy-modified monomer.

[0044] Emulsions prepared by copolymerization of epoxy-modified monomers:

[0045] Premix the epoxy-modified monomer with an isopropanol aqueous solution, then add the acrylic monomer and mix well. Heat to 40℃, slowly add ammonium persulfate solution to start the reaction, and maintain the temperature at 70±2℃ for 5 hours. The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, and polyethylene glycol methacrylate (average molecular weight 300) in a weight ratio of 1:0.45:0.17. The amount of epoxy-modified monomer is 9.5 wt% of the acrylic monomer, the volume fraction of the isopropanol aqueous solution is 50%, and the amount is 2.3 times that of the acrylic monomer. The ammonium persulfate solution is a saturated aqueous solution at room temperature, and the amount of ammonium persulfate is 0.8 wt% of the acrylic monomer and epoxy-modified monomer. After the reaction is completed, sodium thiosulfate solution is added to quench the reaction. The isopropanol is removed by rotary evaporation at a constant temperature. The solid content is adjusted to 48±2% and the pH value is adjusted to 7-8 with deionized water and ammonia to obtain the modified acrylic emulsion.

[0046] (2) Preparation of acrylic coating

[0047] Raw materials are calculated as follows by weight percentage: defoamer 0.13wt%, TEGO Airex 902W; leveling agent 0.24wt%, BYK-333; wetting agent 0.18wt%, TEGO Wet 270; preservative 0.07wt%, Proxel GXL; balance modified acrylic emulsion.

[0048] Each component raw material was added sequentially, stirred and dispersed at 600 rpm for 15 min, and then degassed under reduced pressure to 1 kPa for 10 min to obtain an acrylic coating.

[0049] Example 3: A high-adhesion acrylic coating was prepared, and the specific implementation method is as follows:

[0050] (1) Preparation of modified acrylic emulsion

[0051] Step A1: Allyl glycidyl ether, 10-chloro-1-decyl alcohol and toluene were mixed and heated to 90°C under nitrogen protection. Tetrabutylammonium bromide was added and the mixture was stirred for 3.7 h. The ratio of allyl glycidyl ether, 10-chloro-1-decyl alcohol, tetrabutylammonium bromide and toluene was 0.1 mol: 0.1 mol: 0.33 g: 160 mL. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure. The substrate was washed with water and the aqueous phase was separated. After drying, intermediate 1 was obtained.

[0052] Step A2: Take intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, mix them well, heat to 70℃ and reflux for 9.5 h under nitrogen protection. The ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1 mol: 0.1 mol: 10 mL: 420 mL. After the reaction is completed, cool and filter, and then remove tetrahydrofuran by rotary evaporation to obtain intermediate 2.

[0053] Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, and dioxane, heat to 50°C and stir for 6.5 h. Dissolve sodium hydroxide in water to form a saturated solution at room temperature, add the sodium hydroxide solution, and continue heating to 100°C for 2 h. The ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 3.5 mL: 8.2 g: 330 mL. After the reaction is complete, dry with anhydrous magnesium sulfate and filter. Then remove dioxane by rotary evaporation under reduced pressure to obtain the epoxy-modified monomer.

[0054] Emulsions prepared by copolymerization of epoxy-modified monomers:

[0055] Premix the epoxy-modified monomer with an isopropanol aqueous solution, then add the acrylic monomer and mix well. Heat to 40℃, slowly add ammonium persulfate solution to start the reaction, and maintain the temperature at 70±2℃ for 5 hours. The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, and polyethylene glycol methacrylate (average molecular weight 300) in a weight ratio of 1:0.5:0.13. The amount of epoxy-modified monomer is 13.2 wt% of the acrylic monomer, the volume fraction of the isopropanol aqueous solution is 50%, and the amount is 2.6 times that of the acrylic monomer. The ammonium persulfate solution is a saturated aqueous solution at room temperature, and the amount of ammonium persulfate is 0.9 wt% of the acrylic monomer and epoxy-modified monomer. After the reaction is completed, sodium thiosulfate solution is added to quench the reaction. The isopropanol is removed by rotary evaporation at a constant temperature. The solid content is adjusted to 48±2% and the pH value is adjusted to 7-8 with deionized water and ammonia to obtain the modified acrylic emulsion.

[0056] (2) Preparation of acrylic coating

[0057] Raw materials are calculated by weight percentage as follows: defoamer 0.15wt%, TEGO Airex 902W; leveling agent 0.31wt%, BYK-333; wetting agent 0.25wt%, TEGO Wet 270; preservative 0.06wt%, Proxel GXL; balance modified acrylic emulsion.

[0058] Each component raw material was added sequentially, stirred and dispersed at 600 rpm for 15 min, and then degassed under reduced pressure to 1 kPa for 10 min to obtain an acrylic coating.

[0059] Example 4: A high-adhesion acrylic coating was prepared, and the specific implementation method is as follows:

[0060] (1) Preparation of modified acrylic emulsion

[0061] Step A1: Allyl glycidyl ether, 10-chloro-1-decyl alcohol and toluene were mixed and heated to 88°C under nitrogen protection. Tetrabutylammonium bromide was added and the mixture was stirred for 4 hours. The ratio of allyl glycidyl ether, 10-chloro-1-decyl alcohol, tetrabutylammonium bromide and toluene was 0.1 mol: 0.1 mol: 0.3 g: 160 mL. After the reaction was completed, toluene was removed by rotary evaporation under reduced pressure. The substrate was washed with water and the aqueous phase was separated. After drying, intermediate 1 was obtained.

[0062] Step A2: Take intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, mix them well, heat to 70℃ and reflux for 10h under nitrogen protection. The ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1mol:0.1mol:9mL:420mL. After the reaction is completed, cool and filter, and then remove tetrahydrofuran by rotary evaporation to obtain intermediate 2.

[0063] Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, and dioxane, heat to 50°C and stir for 7 hours. Dissolve sodium hydroxide in water to form a saturated solution at room temperature, add the sodium hydroxide solution, and continue heating to 95°C for 2.2 hours. The ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide, and dioxane is 0.1 mol: 0.1 mol: 3 mL: 7.8 g: 320 mL. After the reaction is complete, dry with anhydrous magnesium sulfate and filter. Then remove dioxane by rotary evaporation under reduced pressure to obtain the epoxy-modified monomer.

[0064] Emulsions prepared by copolymerization of epoxy-modified monomers:

[0065] Premix the epoxy-modified monomer with an isopropanol aqueous solution, then add the acrylic monomer and mix well. Heat to 40℃, slowly add ammonium persulfate solution to start the reaction, and maintain the temperature at 70±2℃ for 5 hours. The acrylic monomer is composed of acrylic acid, hydroxyethyl acrylate, and polyethylene glycol methacrylate (average molecular weight 300) in a weight ratio of 1:0.5:0.15. The amount of acrylic monomer is the standard, the amount of epoxy-modified monomer is 12wt% of the acrylic monomer, the volume fraction of the isopropanol aqueous solution is 50%, and the amount is 2.5 times that of the acrylic monomer. The ammonium persulfate solution is a saturated aqueous solution at room temperature, and the amount of ammonium persulfate is 0.9wt% of the acrylic monomer and epoxy-modified monomer. After the reaction is completed, sodium thiosulfate solution is added to quench the reaction, and isopropanol is removed by rotary evaporation at a constant temperature. The solid content is adjusted to 48±2% and the pH value is adjusted to 7-8 with deionized water and ammonia to obtain the modified acrylic emulsion.

[0066] (2) Preparation of acrylic coating

[0067] Raw materials are calculated as follows by weight percentage: defoamer 0.14wt%, TEGO Airex 902W; leveling agent 0.28wt%, BYK-333; wetting agent 0.22wt%, TEGO Wet 270; preservative 0.06wt%, Proxel GXL; balance modified acrylic emulsion.

[0068] Each component raw material was added sequentially, stirred and dispersed at 600 rpm for 15 min, and then degassed under reduced pressure to 1 kPa for 10 min to obtain an acrylic coating.

[0069] Comparative Example 1 is a control example of Example 3, in which the epoxy-modified monomer in the implementation process was replaced by an equal amount of allyl glycidyl ether, and the rest of the implementation process was exactly the same.

[0070] Comparative Example 2, also referring to Example 3, replaced the acrylic emulsion with commercially available WR-888W type epoxy modified acrylic emulsion, and the rest of the implementation process was exactly the same.

[0071] Comparative Example 3, based on Comparative Example 2, additionally added 5.5 wt% of FORTEGRA™ 304 toughening agent to the epoxy-modified acrylic emulsion, with the rest of the implementation process being exactly the same.

[0072] Take a 100×100×3mm molded PE board, wipe it clean and dry the surface, coat it with the acrylic coating prepared above, control the dry film thickness to be 50±5μm, and cure it at room temperature for 7 days to make a sample.

[0073] Referring to the ASTM D3359-2023 standard, use a multi-blade cutter to cut a 1×1mm grid on the coating surface, apply 3M 600 tape tightly to the grid, and quickly peel it off to evaluate the adhesion level.

[0074] Referring to the ASTM D522-2021 standard, the specimen was bent around a tapered shaft of different diameters to check whether the coating cracked or peeled. The smallest shaft diameter through which no cracks passed was recorded to characterize the macroscopic strength and toughness of the coating.

[0075] Following the above sample preparation method, Q235 steel plate was used as the coating substrate, acrylic coating was cured on the surface, and the uncoated surface was impregnated with paraffin wax and sealed. According to ASTM D2794-2019 standard, a 1.5J impact was applied to the coating, and then 1mL of sodium chloride solution was dropped at the impact site. After standing for 24h, the corrosion current was detected to characterize the protective performance of the coating under impact.

[0076] The specific test results are shown in Table 1:

[0077] Table 1

[0078]

[0079] As shown in Table 1, the acrylic coatings of the examples all achieved an adhesion rating of 4B, demonstrating excellent adhesion performance. The coatings exhibited excellent toughness and high integrity under impact. The corrosion current indicates that the coatings remained almost intact during the test, without significant damage or accelerated corrosion. In contrast, the coatings of Comparative Examples 1 and 2 showed a sharp increase in corrosion current after impact, indicating significant coating damage and corrosion.

[0080] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0081] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A high-adhesion acrylic coating, characterized in that, The components are: defoamer 0.12-0.15wt%, leveling agent 0.24-0.31wt%, wetting agent 0.18-0.25wt%, and preservative 0.05-0.07wt%, with the balance being modified acrylic emulsion; The modified acrylic emulsion is copolymerized from acrylic monomer and 9.5-13.2 wt% of epoxy modifying monomer, wherein the epoxy modifying monomer is prepared by: Step A1: Premix allyl glycidyl ether, chloroalkanol and toluene, heat to 80-90℃ under nitrogen protection, add tetrabutylammonium bromide and stir for 3-4 hours to prepare intermediate 1; Step A2: Mix intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran, and reflux at 60-70°C for 8-10 hours under nitrogen protection to prepare intermediate 2; Step A3: Mix intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine and dioxane, heat to 40-50℃ and stir for 6-7 hours. Then add sodium hydroxide solution and continue to heat to 90-100℃ for 1.5-2.2 hours to prepare epoxy-modified monomer.

2. The high-adhesion acrylic coating according to claim 1, characterized in that, The ratio of allyl glycidyl ether, chloroalkanol, tetrabutylammonium bromide and toluene is 0.1 mol: 0.1 mol: 0.25-0.33 g: 120-160 mL.

3. The high-adhesion acrylic coating according to claim 2, characterized in that, Chloroalkanol is one of 8-chloro-1-octanol and 10-chloro-1-decanol.

4. The high-adhesion acrylic coating according to claim 3, characterized in that, The ratio of intermediate 1, aza-12-crown ether-4, triethylamine and tetrahydrofuran is 0.1 mol: 0.1 mol: 8-10 mL: 350-420 mL.

5. The high-adhesion acrylic coating according to claim 4, characterized in that, The ratio of intermediate 2, epichlorohydrin, N,N-dimethylbenzylamine, sodium hydroxide and dioxane is 0.1 mol: 0.1 mol: 2.2-3.5 mL: 6.5-8.2 g: 270-330 mL.

6. The high-adhesion acrylic coating according to claim 1, characterized in that, The acrylic monomer is a mixture of acrylic acid, hydroxyethyl acrylate and polyethylene glycol methacrylate in a weight ratio of 1:0.4-0.55:0.13-0.

18.

7. The high-adhesion acrylic coating according to claim 6, characterized in that, The modified acrylic emulsion has a solid content of 48±2% and a pH value of 7-8.

8. A method for preparing a high-adhesion acrylic coating according to any one of claims 1-7, characterized in that, Specifically, the raw materials are added sequentially and mixed evenly, and then degassed under reduced pressure to obtain an acrylic coating.

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