Waterborne epoxy paint suitable for containers and preparation method of waterborne epoxy paint

Abstract

The invention relates to the technical field of epoxy resin paint, and discloses waterborne epoxy paint suitable for containers and a preparation method of the waterborne epoxy paint. A component A of the waterborne epoxy paint comprises, by weight, 100 parts of waterborne epoxy resin and 0.5-0.8 part of a flash rust inhibitor; the component B comprises 6-8 parts by weight of a polyamide curing agent, 5-12 parts by weight of an organosilicon sulfonate polyurethane toughening agent and 0.2-1 part by weight of graphene oxide; the organic silicon polyurethane flexibilizer can play a role of a dispersing agent, the dispersity of graphene in the waterborne epoxy paint is improved, the main chain of the organic silicon polyurethane flexibilizer contains imino groups, the organic silicon polyurethane flexibilizer can be subjected to a curing reaction with epoxy resin, a flexible organic polysiloxane molecular chain is bonded into an epoxy resin molecular chain, and the flexibility of the waterborne epoxy paint is improved. A good toughening effect is achieved, so that the flexibility, the impact resistance and the corrosion resistance of a paint film are improved.

Description

Technical Field

[0001] The invention relates to the technical field of epoxy resin paints, in particular to a water-based epoxy paint suitable for containers and a preparation method thereof. Background Art

[0002] Epoxy resin paints have excellent insulation properties and high mechanical strength, and are widely used in containers, ships, cars, instruments and equipment, sports equipment, etc. Improving the toughness and anti-corrosion properties of epoxy resins is a research hotspot. Polyurethane has good toughness, elasticity and mechanical properties, and is widely used in epoxy resin paints. Polysiloxane has high toughness, strong water resistance and good anti-corrosion properties, and can play a certain toughening role on epoxy resins. Patent CN116284655B discloses a preparation method of graphene-organic silicon synergistically enhanced polyurethane grafted modified epoxy resin, in which graphene is modified with isocyanate, and a small molecular weight polyhydroxy silane is used as a bridging agent to connect it to a linear polyurethane polymer to obtain a graphene-organic silicon synergistically enhanced polyurethane prepolymer, which is grafted and copolymerized with epoxy resin to improve the toughness, heat resistance and other properties of epoxy resin. However, the patent requires the graphene to be modified with isocyanate, the preparation method is relatively complicated, and the anti-corrosion properties of epoxy resin are not improved. Summary of the invention

[0003] (I) Technical problem to be solved: The present invention provides a water-based epoxy paint suitable for containers with good anti-corrosion performance and high toughness.

[0004] (II) Technical solution: A water-based epoxy paint suitable for containers, consisting of component A and component B, wherein component A includes 100 parts by weight of water-based epoxy resin, 0.5-0.8 parts by weight of anti-flash rust agent, 0.4-0.7 parts by weight of defoaming agent, and 0.3-0.6 parts by weight of leveling agent; component B is 6-8 parts by weight of polyamide curing agent, 5-12 parts by weight of organosilicon sulfonate polyurethane toughening agent, and 0.2-1 parts by weight of graphene oxide.

[0005] The preparation method of the organosilicon sulfonate polyurethane toughening agent is as follows:

[0006] (1) Add glycidoxypropyl-terminated polydimethylsiloxane and 2-aminoethanesulfonic acid in a molar ratio of 1:(2-2.2) to tetrahydrofuran, stir and react at 40-50°C for 8-12h, concentrate under reduced pressure, and dry to obtain hydroxyiminosulfonic acid polysiloxane. The reaction formula is:

[0007]

[0008] (2) Add hydroxysulfonic acid polysiloxane and di-tert-butyl dicarbonate in a molar ratio of 1:(2.2-2.4) to the solvent in an ice water bath, stir and react at 20-25°C for 6-8h, concentrate under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain hydroxy-Boc aminosulfonic acid polysiloxane. The reaction formula is:

[0009]

[0010] (3) Add dried polyethylene glycol, hydroxy-Boc aminosulfonic acid polysiloxane and dibutyltin dilaurate to butanone solvent, heat to 70-80°C in a nitrogen atmosphere, add diisocyanate monomer, react for 3-5h, then add 1,4-butanediol, react for 1-1.5h, concentrate under reduced pressure, add the product to dichloromethane, stir and add trifluoroacetic acid, stir at 20-30°C for 4-6h, concentrate under reduced pressure, wash with sodium bicarbonate solution and sodium hydroxide solution in turn, and dry to obtain an organosilicon sulfonate polyurethane toughening agent.

[0011] Preferably, the solvent in (2) is dichloromethane, tetrahydrofuran or acetonitrile.

[0012] Preferably, the molar ratio of polyethylene glycol, hydroxy-Boc aminosulfonic acid polysiloxane and diisocyanate monomer in (3) is (0.6-0.8):(0.2-0.4):(2.4-2.6):(1.2-1.3). The diisocyanate monomer is hexamethylene diisocyanate, toluene diisocyanate or isophorone diisocyanate.

[0013] Preferably, the volume ratio of dichloromethane to trifluoroacetic acid in (3) is 1:(0.4-0.6).

[0014] Preferably, the preparation method of the water-based epoxy paint suitable for containers is: add an anti-flash rust agent, a defoaming agent, and a leveling agent to a water-based epoxy resin, stir and mix to obtain component A; add graphene oxide to water, add an organosilicon sulfonate polyurethane toughening agent after ultrasonic dispersion, stir for 1-2 hours, and then add a polyamide curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0015] The technical effect of the invention is that the terminal epoxy group of the glycidoxypropyl-terminated polydimethylsiloxane is reacted with 2-aminoethanesulfonic acid, and then the imino group is Boc protected by di-tert-butyl dicarbonate to obtain hydroxy-Boc aminosulfonic acid polysiloxane, which contains hydroxyl groups at both ends, and then the polysiloxane is polymerized with polyethylene glycol and diisocyanate monomers, and the Boc protecting group is removed by trifluoroacetic acid / dichloromethane and neutralized with sodium hydroxide to obtain an organic silicon sulfonate polyurethane toughening agent containing imino groups and sulfonate groups.

[0016] The present invention adds graphene oxide and organosilicon sulfonate polyurethane toughening agent to waterborne epoxy resin. The polyurethane toughening agent contains hydrophilic sulfonate groups, which improves the hydrophilicity and water solubility of polyurethane, has good dispersibility in waterborne epoxy resin emulsion, and does not cause sedimentation. In addition, the sulfonate groups of the polyurethane toughening agent interact with the surface of graphene oxide through hydrogen bonds and the like, and can play the role of a dispersant, improve the dispersibility of graphene in waterborne epoxy paint, reduce the phenomenon of agglomeration and sedimentation of graphene oxide, and make the waterborne epoxy paint have good storage stability.

[0017] The organosilicon polyurethane toughening agent of the present invention can play the role of a dispersant, improve the dispersibility of graphene in water-based epoxy paint, reduce the agglomeration of graphene oxide, and is conducive to improving the mechanical properties of water-based epoxy paint. In addition, the main chain of the organosilicon polyurethane toughening agent contains an imino group, which can play the role of a curing agent, undergo a curing reaction with the epoxy resin, and bond the flexible organopolysiloxane molecular chain to the epoxy resin molecular chain, which plays a good toughening role, thereby improving the flexibility and impact resistance of the paint film. In addition, the polyurethane toughening agent and the epoxy resin form a stable polysiloxane chemical cross-linking network, which can inhibit corrosive media such as acids, bases, and salts from entering the paint film matrix, and the uniformly dispersed graphene plays a role in blocking the corrosive medium, thereby improving the anti-corrosion performance of the paint film. DETAILED DESCRIPTION

[0018] For ease of understanding of the present invention, preferred embodiments of the present invention are provided below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0019] The waterborne epoxy resin of the present invention has a solid content of 50%; Shandong Chengtai Chemical Co., Ltd.; graphene oxide, model HL-GO, Shanghai Hanlang New Material Technology Co., Ltd. Defoamer, DF 5800C, Nanjing Chuhai New Material Technology Co., Ltd. Leveling agent WL-104E, Nanjing Chuhai New Material Technology Co., Ltd. Anti-flash rust agent, Defros-T750, Shenzhen Longdi Chemical Co., Ltd. Glycidoxypropyl terminated polydimethylsiloxane, Wuhan Lanabai Pharmaceutical Chemical Co., Ltd. Dihydroxy terminated polydimethylsiloxane, Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.

[0020] Embodiment 1:

[0021] (1) Add 20 mmol of glycidoxypropyl-terminated polydimethylsiloxane and 40 mmol of 2-aminoethanesulfonic acid to 200 mL of tetrahydrofuran, stir and react at 45° C. for 12 h, concentrate under reduced pressure, and dry to obtain hydroxyiminosulfonic acid polysiloxane.

[0022] (2) Add 30 mmol of hydroxysulfonic acid polysiloxane and 70 mmol of di-tert-butyl dicarbonate to 300 mL of acetonitrile solvent in an ice-water bath, stir and react at 20° C. for 8 h, concentrate under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain hydroxy-Boc aminosulfonic acid polysiloxane.

[0023] (3) Add 80 mmol of dried polyethylene glycol 1000, 20 mmol of hydroxy-Boc aminosulfonic acid polysiloxane, and 0.12 g of dibutyltin dilaurate to 300 mL of butanone solvent, heat to 75°C in a nitrogen atmosphere, add 240 mmol of toluene diisocyanate, react for 5 h, then add 120 mmol of 1,4-butanediol, react for 1 h, and concentrate under reduced pressure. Add the product to 2 L of dichloromethane, stir, then add 1 L of trifluoroacetic acid, stir at 25°C for 6 h, and concentrate under reduced pressure. Wash with sodium bicarbonate solution and sodium hydroxide solution in turn, and dry to obtain an organosilicon sulfonate polyurethane toughening agent.

[0024] (4) Add 8 g of anti-rust agent, 5 g of defoamer, and 6 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 2 g of graphene oxide to 100 mL of water, add 50 g of organosilicon sulfonate polyurethane toughening agent after ultrasonic dispersion, stir for 1 hour, and then add 80 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0025] Embodiment 2:

[0026] (1) Add 20 mmol of glycidoxypropyl-terminated polydimethylsiloxane and 44 mmol of 2-aminoethanesulfonic acid to 250 mL of tetrahydrofuran, stir and react at 40° C. for 12 h, concentrate under reduced pressure, and dry to obtain hydroxyiminosulfonic acid polysiloxane.

[0027] (2) Add 30 mmol of hydroxysulfonic acid polysiloxane and 72 mmol of di-tert-butyl dicarbonate to 400 mL of dichloromethane solvent in an ice-water bath, stir and react at 25° C. for 6 h, concentrate under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain hydroxy-Boc aminosulfonic acid polysiloxane.

[0028] (3) Add 70 mmol of dried polyethylene glycol 1000, 30 mmol of hydroxy-Boc aminosulfonic acid polysiloxane, and 0.1 g of dibutyltin dilaurate to 400 mL of butanone solvent, heat to 80°C in a nitrogen atmosphere, add 260 mmol of isophorone diisocyanate, react for 3 h, then add 130 mmol of 1,4-butanediol, react for 1.5 h, and concentrate under reduced pressure. Add the product to 2 L of dichloromethane, stir, then add 0.8 L of trifluoroacetic acid, stir at 30°C for 4 h, and concentrate under reduced pressure. Wash with sodium bicarbonate solution and sodium hydroxide solution in turn, and dry to obtain an organosilicon sulfonate polyurethane toughening agent.

[0029] (4) Add 6 g of anti-rust agent, 7 g of defoaming agent and 3 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 5 g of graphene oxide to 150 mL of water, add 70 g of organosilicon sulfonate polyurethane toughening agent after ultrasonic dispersion, stir for 2 h, and then add 74 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0030] Embodiment 3:

[0031] (1) Add 20 mmol of glycidoxypropyl-terminated polydimethylsiloxane and 40 mmol of 2-aminoethanesulfonic acid to 200 mL of tetrahydrofuran, stir and react at 50° C. for 8 h, concentrate under reduced pressure, and dry to obtain hydroxyiminosulfonic acid polysiloxane.

[0032] (2) Add 30 mmol of hydroxysulfonic acid polysiloxane and 66 mmol of di-tert-butyl dicarbonate to 300 mL of tetrahydrofuran solvent in an ice-water bath, stir and react at 20° C. for 8 h, concentrate under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain hydroxy-Boc aminosulfonic acid polysiloxane.

[0033] (3) Add 60 mmol of dried polyethylene glycol 1000, 40 mmol of hydroxy-Boc aminosulfonic acid polysiloxane, and 0.15 g of dibutyltin dilaurate to 400 mL of butanone solvent, heat to 70°C in a nitrogen atmosphere, add 260 mmol of hexamethylene diisocyanate, react for 5 h, then add 130 mmol of 1,4-butanediol, react for 1 h, and concentrate under reduced pressure. Add the product to 2 L of dichloromethane, stir, then add 1.2 L of trifluoroacetic acid, stir at 20°C for 6 h, and concentrate under reduced pressure. Wash with sodium bicarbonate solution and sodium hydroxide solution in turn, and dry to obtain an organosilicon sulfonate polyurethane toughening agent.

[0034] (4) Add 5 g of anti-flash rust agent, 7 g of defoamer, and 4 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 7 g of graphene oxide to 200 mL of water, add 100 g of organosilicon sulfonate polyurethane toughening agent after ultrasonic dispersion, stir for 2 h, and then add 67 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0035] Embodiment 4:

[0036] (1) Add 5 g of anti-flash rust agent, 4 g of defoamer, and 6 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 10 g of graphene oxide to 200 mL of water, add 120 g of organosilicon sulfonate polyurethane toughening agent (prepared in the same manner as in Example 1) after ultrasonic dispersion, stir for 2 h, and then add 60 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0037] Comparative Example 1:

[0038] (1) Add 8 g of anti-flash rust agent, 5 g of defoamer, and 6 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 2 g of graphene oxide to 100 mL of water, add 80 g of polyamide 650 curing agent after ultrasonic dispersion, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0039] Comparative Example 2:

[0040] (1) Add 80 mmol of dried polyethylene glycol 1000, 20 mmol of dihydroxy-terminated polydimethylsiloxane, and 0.12 g of dibutyltin dilaurate to 300 mL of butanone solvent, heat to 75°C in a nitrogen atmosphere, add 240 mmol of toluene diisocyanate, react for 5 h, then add 120 mmol of 1,4-butanediol, react for 1 h, concentrate under reduced pressure, and dry to obtain silicone polyurethane.

[0041] (2) Add 8 g of anti-rust agent, 5 g of defoamer, and 6 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 2 g of graphene oxide to 100 mL of water, add 50 g of silicone polyurethane after ultrasonic dispersion, stir for 1 hour, and then add 80 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0042] Comparative Example 3:

[0043] (1) Add 80 mmol of dried polyethylene glycol 1000, 20 mmol of hydroxy-Boc aminosulfonic acid polysiloxane, and 0.12 g of dibutyltin dilaurate to 300 mL of butanone solvent, heat to 75°C in a nitrogen atmosphere, add 240 mmol of toluene diisocyanate, react for 5 h, then add 120 mmol of 1,4-butanediol, react for 1 h, concentrate under reduced pressure, wash with sodium hydroxide solution, and dry to obtain organosilicon sulfonate polyurethane.

[0044] (2) Add 8 g of anti-flash rust agent, 5 g of defoaming agent, and 6 g of leveling agent to 1000 g of water-based epoxy resin, stir and mix to obtain component A; add 2 g of graphene oxide to 100 mL of water, add 50 g of organosilicon sulfonate polyurethane after ultrasonic dispersion, stir for 1 hour, and then add 80 g of polyamide 650 curing agent, stir and disperse to obtain component B; add component B to component A, stir and mix to obtain a water-based epoxy paint suitable for containers.

[0045] The storage stability of waterborne epoxy paint was tested according to the method of GB / T 6753.3-1986. The storage temperature was 25°C and the storage time was 7-21 days. No polyamide 650 curing agent was added to the waterborne epoxy paint during the test.

[0046] The water-based epoxy paint was sprayed on the surface of the substrate and cured at 120°C for 4 hours to form a paint film coating.

[0047] Impact resistance was tested according to GB / T 1732-2020. Salt spray resistance was tested according to GB / T 1771-2007. Cross-cut test and adhesion grade test were performed according to GB / T 9286-2021. Flexibility was tested according to GB T / 1731-2020.

[0048] Table 1: Test results

[0049]

[0050] As shown in Table 1, graphene oxide and organosilicon sulfonate polyurethane toughening agent are added to the waterborne epoxy paint of Examples 1-4. The polyurethane toughening agent contains a hydrophilic sulfonate group, which improves the hydrophilicity and water solubility of the polyurethane, has good dispersibility in the waterborne epoxy resin emulsion, and does not cause sedimentation. In addition, the sulfonate group of the polyurethane toughening agent interacts with the surface of graphene oxide through hydrogen bonds, etc., and can play the role of a dispersant, improve the dispersibility of graphene in the waterborne epoxy paint, and reduce the phenomenon of agglomeration and sedimentation of graphene oxide, so that the waterborne epoxy paint has good storage stability.

[0051] In Comparative Example 1, no organosilicon sulfonate polyurethane toughening agent was added. During long-term storage, graphene oxide was prone to agglomeration and sedimentation, and the storage stability of the water-based epoxy paint was poor.

[0052] Comparative Example 2 uses dihydroxy-terminated polydimethylsiloxane as a raw material, and the obtained silicone polyurethane does not contain hydrophilic sulfonate groups. The hydrophilicity and water solubility of the polyurethane are poor, and the dispersibility in the water-based epoxy resin emulsion is poor, and sedimentation is easy to occur. Moreover, the polyurethane does not contain sulfonate groups, and cannot interact with the surface of graphene oxide such as hydrogen bonds, and cannot play the role of a dispersant. The dispersibility of graphene in water-based epoxy paint cannot be improved, and the phenomenon of graphene oxide agglomeration and sedimentation cannot be reduced, resulting in poor storage stability of the water-based epoxy paint.

[0053] The organosilicon sulfonate polyurethane of Comparative Example 3 contains hydrophilic sulfonate groups, has good dispersibility in the water-based epoxy resin emulsion, and can act as a dispersant to improve the dispersibility of graphene in the water-based epoxy paint, reduce the agglomeration and sedimentation of graphene oxide, and make the water-based epoxy paint have good storage stability.

[0054] Table 2: Test results

[0055]

[0056] As shown in Table 2, the waterborne epoxy paint in Examples 1-4 has good adhesion grade, high flexibility and impact resistance, and salt spray resistance reaches 384-504h, showing excellent toughness, mechanical properties and corrosion resistance. This is because the organosilicon polyurethane toughening agent can play the role of a dispersant, improve the dispersibility of graphene in waterborne epoxy paint, reduce the agglomeration of graphene oxide, and is conducive to improving the mechanical properties of waterborne epoxy paint, and the main chain of the organosilicon polyurethane toughening agent contains imino groups, which can play the role of a curing agent, and a curing reaction occurs with epoxy resin, and a flexible organopolysiloxane molecular chain is bonded to the epoxy resin molecular chain, which plays a good toughening effect, thereby improving the flexibility and impact resistance of the paint film. And the polyurethane toughening agent and epoxy resin are formed into a stable polysiloxane chemical cross-linking network, which can inhibit the corrosive media such as acids, alkalis and salts from entering the paint film matrix, and the uniformly dispersed graphene plays the role of blocking the corrosive media, thereby improving the corrosion resistance of the paint film.

[0057] Comparative Example 1 did not add the organosilicon polyurethane toughening agent, which did not play the role of toughening and dispersing graphene, and the toughness, mechanical properties and corrosion resistance of the paint film were poor.

[0058] The organosilicon polyurethane of Comparative Example 2 does not contain sulfonate groups and imino groups, and thus cannot disperse graphene, nor can it undergo a curing reaction with epoxy resin. The organosilicon polyurethane has poor compatibility with epoxy resin and poor toughening effect, resulting in poor toughness, mechanical properties, and corrosion resistance of the paint film.

[0059] The organosilicon sulfonate polyurethane of Comparative Example 3 does not contain imino groups and cannot undergo a curing reaction with epoxy resin. The organosilicon polyurethane has poor compatibility with epoxy resin and poor toughening effect, resulting in poor toughness, mechanical properties and corrosion resistance of the paint film.

[0060] This specific embodiment is merely an explanation of the present invention and is not a limitation of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by the patent law.

Claims

1. A water-based epoxy paint suitable for containers, characterized in that: The waterborne epoxy paint comprises a component A and a component B, wherein the component A comprises 100 parts by weight of a waterborne epoxy resin, 0.5-0.8 parts by weight of an anti-flash rust agent, 0.4-0.7 parts by weight of a defoamer, and 0.3-0.6 parts by weight of a leveling agent; the component B comprises 6-8 parts by weight of a polyamide curing agent, 5-12 parts by weight of an organosilicon sulfonate polyurethane toughening agent, and 0.2-1 parts by weight of graphene oxide; The preparation method of the organosilicon sulfonate polyurethane toughening agent is: (1) adding glycidoxypropyl-terminated polydimethylsiloxane and 2-aminoethanesulfonic acid to tetrahydrofuran, stirring for reaction, concentrating under reduced pressure, and drying to obtain hydroxyiminosulfonic acid polysiloxane; (2) adding hydroxysulfonic acid polysiloxane and di-tert-butyl dicarbonate to the solvent in an ice water bath, stirring for reaction, concentrating under reduced pressure, washing with sodium bicarbonate solution, and drying to obtain hydroxy-Boc aminosulfonic acid polysiloxane; (3) Add dried polyethylene glycol, hydroxy-Boc aminosulfonic acid polysiloxane and dibutyltin dilaurate to butanone solvent, heat to 70-80°C in a nitrogen atmosphere, add diisocyanate monomer, react for 3-5h, then add 1,4-butanediol, react for 1-1.5h, concentrate under reduced pressure, add the product to dichloromethane, stir and add trifluoroacetic acid, stir at 20-30°C for 4-6h, concentrate under reduced pressure, wash with sodium bicarbonate solution and sodium hydroxide solution in turn, and dry to obtain an organosilicon sulfonate polyurethane toughening agent.

2. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The molar ratio of the glycidoxypropyl-terminated polydimethylsiloxane to 2-aminoethanesulfonic acid in (1) is 1:(2-2.2).

3. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The reaction in (1) is carried out at 40-50°C for 8-12 hours.

4. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The solvent in (2) is dichloromethane, tetrahydrofuran or acetonitrile.

5. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The molar ratio of hydroxysulfonic acid polysiloxane to di-tert-butyl dicarbonate in (2) is 1:(2.2-2.4).

6. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The reaction in (2) is carried out at 20-25°C for 6-8 hours.

7. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The molar ratio of polyethylene glycol, hydroxy-Boc aminosulfonic acid polysiloxane and diisocyanate monomer in (3) is (0.6-0.8):(0.2-0.4):(2.4-2.6):(1.2-1.3).

8. The water-based epoxy paint suitable for containers according to claim 7, characterized in that: The diisocyanate monomer is hexamethylene diisocyanate, toluene diisocyanate or isophorone diisocyanate.

9. The water-based epoxy paint suitable for containers according to claim 1, characterized in that: The volume ratio of dichloromethane to trifluoroacetic acid in (3) is 1:(0.4-0.6).

10. A method for preparing a water-based epoxy paint suitable for containers according to any one of claims 1 to 9, characterized in that: The preparation method comprises the following steps: adding an anti-flash rust agent, a defoaming agent and a leveling agent to a water-based epoxy resin, stirring and mixing, and obtaining a component A; adding graphene oxide to water, adding an organosilicon sulfonate polyurethane toughening agent after ultrasonic dispersion, stirring for 1-2 hours, and then adding a polyamide curing agent, stirring and dispersing, and obtaining a component B; adding the component B to the component A, stirring and mixing, and obtaining a water-based epoxy paint suitable for containers.

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