Preparation method and application of hyperbranched multi-arm star epoxy resin emulsifier

Abstract

The application discloses a preparation method of a hyperbranched multi-arm star epoxy resin emulsifier and application thereof, and relates to the field of water-based epoxy emulsion. The preparation method of the hyperbranched multi-arm star epoxy resin emulsifier comprises the following steps: synthesizing a hyperbranched polyether hydrophobic core containing rich epoxy end groups by using a polyhydroxy compound and a polyfunctional epoxy compound, and then grafting polyethylene glycol monomethyl ether onto the hydrophobic core through a hydroxyl ring-opening epoxy reaction. Compared with traditional linear emulsifiers, the rich active end groups of the hyperbranched emulsifier can not only introduce a large number of hydrophilic segments to obtain better emulsifying capacity, but also can retain sufficient reaction sites to participate in the curing of the system, thereby reducing the negative influence of free emulsifiers on the coating.

Description

Technical Field

[0001] This invention belongs to the field of waterborne epoxy emulsions, and in particular relates to a method for preparing a hyperbranched multi-arm star-shaped epoxy resin emulsifier and its application. Background Technology

[0002] Epoxy coatings are increasingly widely used in corrosion protection due to their excellent adhesion to metal substrates and chemical resistance. However, with increasingly stringent environmental protection requirements, low VOC emissions have become a crucial indicator for coating products. Traditional solvent-based epoxy coatings, due to their high VOC emissions, can no longer meet this requirement. Waterborne epoxy coatings, which use water instead of organic solvents as the dispersion medium, offer a simple and safe process with low construction costs, making them a popular direction for the green development of epoxy coatings.

[0003] Epoxy resins are inherently hydrophobic, so emulsifiers are needed to improve their dispersibility in water and reduce epoxy particle size. Traditional macromolecular emulsifiers, with larger molecular weights of their hydrophilic segments, can more effectively cover epoxy particles, resulting in better emulsification and less migration. However, excessively long hydrophilic chains can also lead to deeper entanglement between particles, increasing the viscosity of the emulsion system. This is detrimental to the preparation of high-performance waterborne epoxy emulsions, and the greater steric hindrance can also affect the subsequent curing of the coating.

[0004] Hyperbranched polymers offer a novel solution to the problems associated with traditional linear emulsifiers. In waterborne epoxy systems, hyperbranched emulsifiers, with their highly branched topology and abundant active end groups, can effectively overcome some of the limitations of traditional macromolecular emulsifiers. On one hand, the branched structure reduces chain entanglement, shrinks latex particle volume, and prevents aggregation and sedimentation. On the other hand, the abundant active end groups can be designed to create reactive hyperbranched emulsifiers. While introducing a large number of hydrophilic segments to enhance their emulsifying ability, these emulsifiers retain sufficient reactive sites to participate in the curing of the system, limiting emulsifier migration and thus comprehensively improving the overall performance of waterborne epoxy coatings.

[0005] Currently, there are few domestic reports on research regarding waterborne epoxy hyperbranched emulsifiers. Patent CN105131305A reports a waterborne epoxy hyperbranched emulsifier obtained by grafting an epoxide containing both hydrophilic and hydrophobic segments onto hyperbranched polyethyleneimine (PEI) as the core. The hydrophilicity and hydrophobicity of the emulsifier can be freely adjusted, having little impact on the viscosity of the emulsion system. Furthermore, its abundant terminal epoxy groups can improve compatibility with the matrix resin and participate in curing crosslinking, enhancing the overall performance of the coating film. However, the synthesis cycle of the emulsifier in this invention is relatively long, and solvents are involved in the synthesis process. Yuan from Anhui University of Technology... Meihua et al. synthesized a branched emulsifier by ring-opening reaction of trimethylolpropane triglycidyl ether, PEG4000 and epoxy resin E-51 under Lewis acid catalysis, and prepared a stable waterborne epoxy emulsion by phase inversion method. The synthesis steps of this emulsifier are simple and efficient. However, its chemical structure is unclear and the degree of branching is low. In addition, this emulsifier does not contain epoxy groups and cannot participate in the curing of the coating film. It is easy to migrate, thus affecting the overall performance of the coating film. [Yuan Meihua, Gu Xupeng, Chang Xinglong et al., Preparation and performance study of waterborne epoxy emulsion, Colloids and Polymers, 2013, 31(2):57~59]. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a hyperbranched multi-arm star-shaped epoxy resin emulsifier that has a simple synthesis process, low cost, no solvent involvement, and contains active groups.

[0007] The first objective of this invention is to provide a method for preparing a hyperbranched multi-arm star-shaped epoxy resin emulsifier, comprising adding a polyhydroxy compound, a polyfunctional epoxy compound, and a catalyst into a reactor, maintaining a nitrogen atmosphere, reacting at a temperature of 100–140°C for 6–16 h to obtain a hyperbranched polyether epoxy resin; then adding polyethylene glycol monomethyl ether, maintaining a nitrogen atmosphere, reacting at a temperature of 120–160°C for 4–12 h to obtain the hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0008] The polyhydroxy compound is one or more of hydroquinone, resorcinol, bisphenol A, bisphenol F, trimethylolethane, trimethylolpropane, and pentaerythritol;

[0009] The polyfunctional epoxy compound is one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, and pentaerythritol glycidyl ether.

[0010] The sum of the functionalities of the polyhydroxy compound and the polyfunctional epoxy compound is greater than or equal to 5.

[0011] In one embodiment, the catalyst is one or more of tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydroxide, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide, triphenylphosphine, and boron trifluoride ether.

[0012] In one embodiment, the catalyst is added at a rate of 0.5 to 1.5 wt% of the total mass of the polyhydroxy compound and the polyfunctional epoxy compound.

[0013] In one embodiment, the molar ratio of the polyhydroxy compound and the polyfunctional epoxy compound is 1:2 to 1:3.

[0014] In one embodiment, the polyethylene glycol monomethyl ether has a molecular weight of one or more of 1000, 2000, 4000, and 6000.

[0015] In one embodiment, the polyethylene glycol monomethyl ether has a molecular weight of one or more of 2000, 4000, and 6000.

[0016] A molecular weight that is too small will affect storage stability, while a molecular weight that is too high will affect particle size.

[0017] In one embodiment, the molar ratio of epoxy groups in the hyperbranched polyether epoxy resin to hydroxyl groups in the polyethylene glycol monomethyl ether is 1:0.1 to 1:0.7.

[0018] In one embodiment, the molar ratio of epoxy groups in the hyperbranched polyether epoxy resin to hydroxyl groups in the polyethylene glycol monomethyl ether is 1:0.3 to 1:0.5.

[0019] When polyethylene glycol monomethyl ether participates in the reaction, the ratio of epoxy to hydroxyl groups should not be too small. If the molar ratio is too small, the water solubility will be poor and the stability will decrease. When the molar ratio is 1:0.5, the emulsion particle size is larger, and the number of reactive groups will also decrease, which will affect the curing of the coating.

[0020] A second objective of this invention is to provide a hyperbranched multi-arm star-shaped epoxy resin emulsifier prepared by the above-described preparation method.

[0021] The third objective of this invention is to provide a method for preparing an aqueous epoxy emulsion. The method involves weighing 5-10 parts of the hyperbranched multi-arm star-shaped epoxy resin emulsifier as described in claim 7, 90-110 parts of bisphenol A type epoxy resin, and 0-10 parts of organic solvent. The mixture is heated to 60°C and stirred. Under high-speed shearing at 2000 rpm, deionized water is added dropwise. Once the emulsion undergoes an inversion, changing from water-in-oil to oil-in-water, the addition of water is stopped, and the high-speed shearing is maintained for 2 hours. After shearing is complete, the speed is reduced to 900 rpm, and water is added for dispersion for another 0.5 hours. The solid content of the emulsion is adjusted to 60 wt%, thus obtaining a stable aqueous epoxy emulsion.

[0022] In one embodiment, 5-10 parts of hyperbranched emulsifier, 90-110 parts of bisphenol A epoxy resin, and 0-10 parts of organic solvent are weighed into a dispersion tank, and the mixture is heated to 60°C and stirred. After all components are mixed evenly, the stirring speed is increased, and deionized water is slowly added dropwise under high-speed shearing at 2000 rpm. Once the emulsion undergoes an inversion, changing from water-in-oil to oil-in-water, the addition of water is stopped, and the current high-speed shearing is maintained for 2 hours. After shearing is complete, the stirring speed is reduced to 900 rpm, and water is added and dispersed for another 0.5 hours. The solid content of the emulsion is adjusted to 60 wt% to obtain a stable aqueous epoxy emulsion.

[0023] In one embodiment, the organic solvent used in the preparation of the waterborne epoxy emulsion is one or more of ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, propylene glycol monobutyl ether, and propylene glycol dimethyl ether.

[0024] A fourth objective of this invention is to provide the application of the above-mentioned hyperbranched multi-arm star-shaped epoxy resin emulsifier in waterborne epoxy coatings.

[0025] In one embodiment, the waterborne epoxy coating comprises, by mass parts, component A and component B; component A is a waterborne epoxy curing agent; component B is the waterborne epoxy emulsion of claim 8; and component A and component B are mixed at a molar ratio of epoxy equivalent to active hydrogen of 1:1 to 1.2:1 to obtain the coating.

[0026] In one embodiment, other additives are added during the preparation of the two-component waterborne epoxy coating; the other additives are one or more of defoamers, leveling agents, and thickeners.

[0027] Beneficial effects

[0028] This invention provides a one-pot method for preparing hyperbranched multi-arm star-shaped epoxy resin emulsifiers. First, a hyperbranched polyether hydrophobic core is prepared using the A2+B3 method, ensuring a high degree of branching in the emulsifier. Then, polyethylene glycol monomethyl ether is used to cap the hydrophobic core, introducing a large number of hydrophilic segments into the emulsifier structure. The synthesis process of the hyperbranched multi-arm star-shaped epoxy resin emulsifier is simple, solvent-free, and requires no purification, exhibiting high commercial potential. Furthermore, its branched structure is easily controllable.

[0029] The hyperbranched emulsifier prepared in this invention possesses a highly branched topological structure, which effectively reduces chain entanglement and lowers the viscosity of the emulsion system. The emulsifier can move and align better, completely encapsulating latex particles, resulting in smaller particle size and higher emulsion stability in the prepared waterborne epoxy emulsion. The abundant end groups of the hyperbranched polymer can introduce a large number of hydrophilic segments, enhancing the emulsifying ability of the emulsifier and thus reducing the amount of emulsifier added, minimizing the adverse effects of emulsifier residue on coating performance. Furthermore, some of the retained epoxy end groups can participate in the cross-linking and curing of the system, thereby restricting the movement of the emulsifier and improving the overall performance of the coating. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments, including but not limited to the following embodiments.

[0031] Examples 1-7 describe the preparation of hyperbranched polyether hydrophobic cores. Examples 8-16 describe the preparation of hyperbranched multi-arm star-shaped epoxy resin emulsifiers. Examples 17-28 describe the application of hyperbranched multi-arm star-shaped epoxy resin emulsifiers in the preparation of waterborne epoxy emulsions. Examples 29-32 describe the application of hyperbranched multi-arm star-shaped epoxy resin emulsifiers in waterborne epoxy floor coatings.

[0032] The synthetic raw materials involved in this invention can all be obtained through commercial means.

[0033] Example 1: Synthesis method of hyperbranched polyether hydrophobic core

[0034] 6.85g of bisphenol A, 27.21g of trimethylolpropane triglycidyl ether and 0.34g of tetrabutylammonium bromide were weighed into a reactor, heated to 120℃, and reacted under a nitrogen atmosphere for 12h. After the reaction was completed, the physicochemical properties of the hyperbranched polyether epoxy resin are shown in Table 1.

[0035] Example 2:

[0036] In this example, the reaction temperature was changed from 120°C to 100°C, and the reaction time was changed from 12 h to 16 h, while other conditions remained the same as in Example 1. The physicochemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0037] Example 3:

[0038] In this example, the reaction temperature was changed from 120°C to 140°C and the reaction time was changed from 12 hours to 6 hours, while other conditions remained the same as in Example 1. The physicochemical properties of the resulting hyperbranched polyether epoxy resin are shown in Table 1.

[0039] Example 4:

[0040] 6.85g of bisphenol A, 22.68g of trimethylolpropane triglycidyl ether and 0.15g of tetrabutylammonium bromide were weighed and placed in a reactor. Other conditions were as shown in Example 1. The physicochemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0041] Example 5:

[0042] 6.85g of bisphenol A, 18.14g of trimethylolpropane triglycidyl ether and 0.37g of tetrabutylammonium bromide were weighed and placed in a reactor. Other conditions were as shown in Example 1. The physicochemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0043] Example 6:

[0044] 4.02 g of trimethylolpropane, 35.29 g of bisphenol A diglycidyl ether and 0.39 g of tetrabutylammonium bromide were weighed and placed in a reactor. Other conditions were as shown in Example 1. The physicochemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0045] Example 7:

[0046] 4.02 g of trimethylolpropane, 15.66 g of ethylene glycol diglycidyl ether and 0.20 g of tetrabutylammonium bromide were weighed and placed in a reactor. Other conditions were as shown in Example 1. The physicochemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0047] Table 1: Physicochemical properties of the hydrophobic core of hyperbranched polyether

[0048]

[0049]

[0050] Table 1 shows the physicochemical data of the hydrophobic cores of the hyperbranched polyethers prepared in Examples 1-7. The number-average molecular weights of the hyperbranched polyethers range from 2000 to 5700, exhibiting moderate molecular weights and narrow molecular weight distributions. Furthermore, the degree of branching is between 0.4 and 0.8, demonstrating the structural characteristics of hyperbranched polymers. Additionally, the epoxy values ​​of the hyperbranched polyethers are all between 0.2 and 0.3 mol / 100g, and the abundant epoxy groups provide sufficient reaction sites for subsequent modification and curing processes.

[0051] Example 8: Synthesis method of hyperbranched multi-arm star-shaped epoxy resin emulsifier

[0052] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 334.8g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. The temperature was raised to 140°C and the reaction was carried out under a nitrogen atmosphere for 8 hours to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0053] Comparative Example 9:

[0054] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 87.3g of polyethylene glycol monomethyl ether 1000 were weighed and placed in a reactor. The reaction temperature was changed from 140℃ to 160℃ and the reaction time was shortened from 8h to 4h. Other conditions were as shown in Example 8 to obtain the emulsifier.

[0055] Example 10:

[0056] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 167.4g of polyethylene glycol monomethyl ether 2000 were weighed and placed in a reactor. The reaction temperature was changed from 140℃ to 150℃ and the reaction time was shortened from 8h to 6h. Other conditions were as shown in Example 8, and a hyperbranched multi-arm star-shaped epoxy resin emulsifier was obtained.

[0057] Example 11:

[0058] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 502.2g of polyethylene glycol monomethyl ether 6000 were weighed and placed in a reactor. The reaction temperature was changed from 140℃ to 120℃ and the reaction time was increased from 8h to 12h. Other conditions were as shown in Example 8, and a hyperbranched multi-arm star-shaped epoxy resin emulsifier was obtained.

[0059] Example 12:

[0060] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.1. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 111.6g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. Other conditions were as shown in Example 8 to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0061] Example 13:

[0062] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.5. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 558g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. Other conditions were as shown in Example 8 to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0063] Example 14:

[0064] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.7. 100g of the hyperbranched hydrophobic core synthesized in Example 1 and 781.2g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. Other conditions were as shown in Example 8 to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0065] Example 15:

[0066] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 6 and 273.6g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. Other conditions were as shown in Example 8 to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0067] Example 16:

[0068] The molar ratio of epoxy groups to hydroxyl groups was controlled at 1:0.3. 100g of the hyperbranched hydrophobic core synthesized in Example 7 and 357.6g of polyethylene glycol monomethyl ether 4000 were weighed and placed in a reactor. Other conditions were as shown in Example 8 to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier.

[0069] Comparative Example 17: A method for preparing an aqueous epoxy emulsion

[0070] Weigh 2g of nitrocellulose emulsifier, 20g of bisphenol A epoxy resin, and 1g of ethylene glycol monobutyl ether into a dispersion tank, and heat to 60℃ while stirring. After all components are mixed evenly, increase the stirring speed and slowly add deionized water dropwise at a high-speed shearing speed of 2000rpm. Once the emulsion undergoes an inversion, changing from water-in-oil to oil-in-water, stop adding water and maintain the current high-speed shearing speed for 2 hours. After shearing is complete, reduce the speed to 900rpm and continue adding water for dispersion for 0.5 hours. Adjust the solid content of the emulsion to 60wt% to obtain the aqueous epoxy emulsion.

[0071] Example 18:

[0072] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 8. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0073] Example 19:

[0074] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 8. At the same time, the amount of emulsifier added was reduced to 1g. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0075] Example 20:

[0076] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 8. At the same time, the amount of emulsifier added was reduced to 1.5g. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0077] Comparative Example 21:

[0078] Based on Comparative Example 17, the nisu emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 9, and the rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0079] Comparative Example 22:

[0080] Based on Comparative Example 17, the nisu emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 10. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0081] Example 23:

[0082] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 11. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0083] Example 24:

[0084] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 12. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0085] Example 25:

[0086] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 13. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0087] Example 26:

[0088] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 14. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0089] Example 27:

[0090] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 15. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0091] Example 28:

[0092] Based on Comparative Example 17, the emulsifier was replaced with the hyperbranched multi-arm star-shaped epoxy resin emulsifier synthesized in Example 16. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the resulting emulsion are shown in Table 2.

[0093] Table 2: Relevant Properties of Waterborne Epoxy Emulsions

[0094]

[0095] Table 2 shows the relevant performance data of the aqueous epoxy emulsions prepared in Examples 17-28. Using the commercial emulsifier Nexium as a comparative example 17, it can be seen from Examples 18-20 that as the amount of hyperbranched multi-arm star-shaped epoxy resin emulsifier added increases, the emulsion particle size decreases, the stability improves, and it exhibits a better emulsification effect than Nexium emulsifier.

[0096] As can be seen from Comparative Examples 21-22 and Example 23, the relative molecular mass of polyethylene glycol monomethyl ether also has a significant impact on the emulsion particle size. Polyethylene glycol monomethyl ether with a relative molecular mass of 1000 and 2000 has poor emulsion particle size and stability, while polyethylene glycol monomethyl ether with a relative molecular mass of 6000 has superior emulsion particle size and stability.

[0097] As can be seen from Examples 24-26, the hydrophilic-lipophilic ratio in the emulsifier structure has a significant impact on the particle size and stability of the emulsion. When the molar ratio of epoxy groups to hydroxyl groups is 1:0.3 or 1:0.5, the emulsion particle size is below 1000 nm, exhibiting excellent emulsion stability and storage stability.

[0098] Examples 27 and 28 demonstrate the emulsifying ability of the emulsifier after hydrophobic core transformation, with emulsion particle size reaching approximately 500 nm and excellent stability.

[0099] Comparative Example 29: A method for preparing a waterborne epoxy coating

[0100] Component A was prepared by uniformly mixing 10g of waterborne epoxy curing agent Honghui 7016, 0.1g of defoamer, 1g of leveling agent, and 0.5g of thickener. Component B was prepared by weighing 50g of the waterborne epoxy emulsion prepared in Comparative Example 17. The two were then mixed to obtain a coatable waterborne epoxy coating. The coating was applied to a cleaned steel plate using a scraper and allowed to stand at room temperature until the coating was surface dry. Then, it was placed in an oven at 60℃ for 8 hours to obtain the sample for testing. The coating test method was carried out according to the national standard in Table 3. The relevant properties of the obtained coating are shown in Tables 4 and 5.

[0101] Table 3: Coating Film Performance Test Standards

[0102] Coating performance instrument National Standard thickness Film thickness gauge GB / T13452.2-2008 Adhesion Hundred-grid knife GB / T9286-2021 Pencil hardness Pencil Hardness Tester GB / T6739-2022 flexibility T-bending tester GB / T30791-2014 Impact resistance Paint film impactor GB / T1732-2020 Chemical resistance / GB / T9274-1988

[0103] Example 30:

[0104] Based on Comparative Example 29, component B was replaced with the waterborne epoxy emulsion prepared in Example 18. At the same time, the amount of waterborne epoxy curing agent Honghui 7016 added was increased to 11g. The rest of the preparation process was the same as that of Comparative Example 29. The relevant properties of the obtained coating are shown in Tables 4 and 5.

[0105] Example 31:

[0106] Based on Comparative Example 29, component B was replaced with the waterborne epoxy emulsion prepared in Example 27. At the same time, the amount of waterborne epoxy curing agent Honghui 7016 added was increased to 12g. The rest of the preparation process was the same as that of Comparative Example 29. The relevant properties of the obtained coating are shown in Tables 4 and 5.

[0107] Example 32:

[0108] Based on Comparative Example 29, the B component was replaced with the aqueous epoxy emulsion prepared in Example 28. The rest of the preparation process was the same as that of Comparative Example 29. The relevant properties of the resulting coating are shown in Tables 4 and 5.

[0109] The basic properties and media resistance of the coatings are shown in Tables 4 and 5. The flexibility and impact strength of the coatings in Examples 30-32 were significantly improved compared to Comparative Example 29, while the adhesion and pencil hardness of the coatings did not decrease. The alkali resistance, acid resistance, water resistance, and salt water resistance of the coatings in Examples 30-32 were also significantly improved compared to Comparative Example 29.

[0110] Table 4: Basic Properties of the Coating

[0111]

[0112]

[0113] Table 5: Chemical resistance of coatings (unit: hours)

[0114]

[0115] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A method for preparing a hyperbranched multi-arm star-shaped epoxy resin emulsifier, characterized in that, A polyhydroxy compound, a polyfunctional epoxy compound, and a catalyst are added to a reactor, and a nitrogen atmosphere is maintained. The reaction temperature is 100–140°C, and the reaction time is 6–16 h to obtain a hyperbranched polyether epoxy resin. Polyethylene glycol monomethyl ether is added, and a nitrogen atmosphere is maintained. The reaction temperature is 120–160°C, and the reaction time is 4–12 h to obtain a hyperbranched multi-arm star-shaped epoxy resin emulsifier. The polyhydroxy compound is one or more of hydroquinone, resorcinol, bisphenol A, bisphenol F, trimethylolethane, trimethylolpropane, and pentaerythritol; The polyfunctional epoxy compound is one or more of bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, glycerol triglycidyl ether, and pentaerythritol glycidyl ether. The sum of the functionalities of the polyhydroxy compound and the polyfunctional epoxy compound is greater than or equal to 5; The molar ratio of the polyhydroxy compound and the polyfunctional epoxy compound is 1:2 to 1:3; the molecular weight of the polyethylene glycol monomethyl ether is 4000 or 6000; the molar ratio of the epoxy groups in the hyperbranched polyether epoxy resin to the hydroxyl groups in the polyethylene glycol monomethyl ether is 1:0.3 to 1:0.

7.

2. The preparation method according to claim 1, characterized in that, The catalyst is one or more of tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium hydroxide, ethyltriphenylphosphine chloride, ethyltriphenylphosphine bromide, triphenylphosphine, and boron trifluoride ether.

3. The preparation method according to claim 1, characterized in that, The catalyst addition amount is 0.5 to 1.5 wt% of the total mass of the polyhydroxy compound and the polyfunctional epoxy compound.

4. The preparation method according to claim 1, characterized in that, The molar ratio of epoxy groups in hyperbranched polyether epoxy resin to hydroxyl groups in polyethylene glycol monomethyl ether is 1:0.3 to 1:0.

5.

5. The hyperbranched multi-arm star-shaped epoxy resin emulsifier prepared by the preparation method according to any one of claims 1 to 4.

6. A method for preparing an aqueous epoxy emulsion, characterized in that, Weigh 5-10 parts of the hyperbranched multi-arm star-shaped epoxy resin emulsifier as described in claim 5, 90-110 parts of bisphenol A type epoxy resin, and 0-10 parts of organic solvent, heat to 60°C and stir; under high-speed shearing at 2000 rpm, add deionized water dropwise, and after the emulsion undergoes an inversion, changing from water-in-oil to oil-in-water, stop adding water and maintain high-speed shearing for 2 hours; after shearing is completed, reduce the speed to 900 rpm, continue adding water to disperse for 0.5 hours, and adjust the solid content of the emulsion to 60 wt% to obtain a stable waterborne epoxy emulsion.

7. The application of the waterborne epoxy emulsion according to claim 6 in waterborne epoxy coatings.

8. The application according to claim 7, characterized in that, The waterborne epoxy coating comprises, by mass parts, component A and component B; component A is a waterborne epoxy curing agent; component B is the waterborne epoxy emulsion of claim 6; and component A and component B are mixed at a molar ratio of epoxy equivalent to active hydrogen of 1:1 to 1.2:1 to obtain the coating.

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