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

Abstract

The invention discloses a preparation method and application of a hyperbranched multi-arm star-shaped epoxy resin emulsifier, and relates to the field of waterborne epoxy emulsions. The preparation method of the hyperbranched multi-arm star-shaped epoxy resin emulsifier comprises the following steps: synthesizing a hyperbranched polyether hydrophobic core containing rich epoxy end groups from a polyhydroxy compound and a polyfunctional epoxy compound, and grafting methoxypolyethylene glycol to the hydrophobic core through hydroxyl epoxy-opening reaction. Compared with a traditional linear emulsifier, the hyperbranched emulsifier has the advantages that abundant active end groups can introduce a large number of hydrophilic chain segments to obtain better emulsifying capacity, sufficient reaction sites can be reserved to participate in curing of a system, and negative effects on a coating due to dissociation of the emulsifier are reduced.

Description

Technical Field

[0001] The invention belongs to the field of waterborne epoxy emulsions, and in particular relates to a preparation method and application of a hyperbranched multi-arm star-shaped epoxy resin emulsifier. Background Art

[0002] Epoxy coatings are increasingly widely used in the field of corrosion protection due to their excellent metal substrate adhesion and chemical resistance. However, with the increasing requirements for environmental protection, low VOC emissions have become an important indicator for coating products. Traditional solvent-based epoxy coatings can no longer meet this requirement due to their high VOC emissions. Water-based epoxy coatings use water instead of organic solvents as a dispersion medium. The process is simple and safe, and the construction cost is low. It is one of the hot directions for the green development of epoxy coatings.

[0003] Epoxy resin itself is hydrophobic, so emulsifiers need to be added to improve its dispersibility in water and reduce the epoxy particle size. For traditional macromolecular emulsifiers, the larger the molecular weight of the hydrophilic chain segment, the more fully the emulsifier can cover the epoxy particles, which has a better emulsification effect and is not easy to migrate. However, too long hydrophilic chains will also deepen the entanglement between particles, resulting in an increase in the viscosity of the emulsified system, which is not conducive to the preparation of water-based epoxy emulsions with excellent performance. In addition, its large steric hindrance will also affect the subsequent curing of the coating.

[0004] Hyperbranched polymers provide a new solution to the problems of traditional linear emulsifiers. In waterborne epoxy systems, hyperbranched emulsifiers can effectively compensate for some of the problems of traditional macromolecular emulsifiers with their highly branched topological structure and abundant active end groups. On the one hand, the branched structure can reduce chain entanglement, reduce the volume of latex particles, and prevent aggregation and sedimentation; on the other hand, the abundant active end groups can be designed to be reactive hyperbranched emulsifiers, which can introduce a large number of hydrophilic segments to enhance their emulsification ability while retaining sufficient reaction sites to participate in the curing of the system, limiting the migration of the emulsifier, thereby comprehensively improving the comprehensive performance of waterborne epoxy coatings.

[0005] At present, there are few research reports on water-based epoxy hyperbranched emulsifiers in China. Patent CN105131305A reports a method of using hyperbranched polyethyleneimine (PEI) as the core and grafting epoxides containing hydrophilic and hydrophobic segments to finally obtain a water-based epoxy hyperbranched emulsifier. The hydrophilicity and hydrophobicity of the emulsifier can be freely adjusted, and the viscosity of the emulsified system has little effect. In addition, the rich epoxy groups at the end can improve the compatibility with the matrix resin, and can also participate in curing and cross-linking to improve the comprehensive performance of the coating. 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 the catalysis of Lewis acid, and prepared a stable water-based epoxy emulsion by phase inversion. The synthesis steps of the emulsifier are simple and efficient, but its chemical structure is unclear and the degree of branching is low. In addition, the emulsifier does not contain epoxy groups and cannot participate in the curing of the coating. It is easy to migrate, thus affecting the comprehensive performance of the coating [Yuan Meihua, Gu Xupeng, Chang Xinglong et al., Preparation and performance study of water-based epoxy emulsion, Colloids and Polymers, 2013, 31(2): 57-59]. Summary of the invention

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

[0007] The first object of the present 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 to 140° C., and reacting for 6 to 16 hours to obtain a hyperbranched polyether epoxy resin; adding polyethylene glycol monomethyl ether, maintaining a nitrogen atmosphere, reacting at a temperature of 120 to 160° C., and reacting for 4 to 12 hours to obtain a 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 etherate.

[0012] In one embodiment, the amount of catalyst added is 0.5-1.5 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 to the polyfunctional epoxy compound is 1:2 to 1:3.

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

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

[0016] If the relative molecular weight of polyethylene glycol monomethyl ether is too small, it will affect the storage stability, and if it is too high, it will affect the particle size.

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

[0018] In one embodiment, 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 1:0.5.

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

[0020] The second object of the present invention is to provide a hyperbranched multi-arm star-shaped epoxy resin emulsifier prepared by the above-mentioned preparation method.

[0021] The third object of the present invention is to provide a method for preparing an aqueous epoxy emulsion, comprising weighing 5 to 10 parts of the hyperbranched multi-arm star-shaped epoxy resin emulsifier according to claim 7, 90 to 110 parts of bisphenol A epoxy resin, and 0 to 10 parts of an organic solvent, heating the mixture to 60° C. and stirring the mixture; adding deionized water dropwise at a high speed of 2000 rpm, and stopping adding water after the emulsion undergoes a phase inversion from oil-in-water to water-in-oil, and maintaining the high speed shearing for 2 hours; reducing the speed to 900 rpm after the shearing is completed, and continuing to add water for dispersion for 0.5 hours, and adjusting the solid content of the emulsion to 60wt%, a stable aqueous epoxy emulsion can be obtained.

[0022] In one embodiment, 5 to 10 parts of hyperbranched emulsifier, 90 to 110 parts of bisphenol A epoxy resin, and 0 to 10 parts of organic solvent are weighed into a dispersion tank, and the temperature is raised to 60°C and stirred. After all components are evenly mixed, the stirring rate is increased, and deionized water is slowly added dropwise under high-speed shearing at 2000 rpm. After the emulsion undergoes a phase inversion from oil-in-water to water-in-oil, water is stopped from being added, and the current speed is maintained for high-speed shearing for 2 hours. After the shearing is completed, the speed is reduced to 900 rpm, and water is continued to be added for dispersion for 0.5 hours, and the solid content of the emulsion is adjusted to 60wt%, and a stable water-based epoxy emulsion can be obtained.

[0023] In one embodiment, the organic solvent used in the preparation process of the aqueous 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] The fourth object of the present invention is to provide the use of the above-mentioned hyperbranched multi-arm star-shaped epoxy resin emulsifier in water-based epoxy coatings.

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

[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 a defoaming agent, a leveling agent, and a thickener.

[0027] Beneficial Effects

[0028] The invention prepares a hyperbranched multi-arm star-shaped epoxy resin emulsifier by a one-pot method, firstly prepares a hyperbranched polyether hydrophobic core by an A2+B3 method, thereby ensuring that the emulsifier has a high degree of branching, and then uses polyethylene glycol monomethyl ether to partially end-cap the hydrophobic core, thereby 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, does not contain solvents and does not require purification, has high commercial potential, and its branched structure is easy to regulate.

[0029] The hyperbranched emulsifier prepared by the present invention has a highly branched topological structure, which can effectively reduce chain entanglement and reduce the viscosity of the emulsified system. The emulsifier can be better arranged in motion and completely cover the latex particles, so that the particle size of the prepared water-based epoxy emulsion is smaller and the emulsion stability is higher. The rich end groups of the hyperbranched polymer can introduce a large number of hydrophilic segments, improve the emulsification ability of the emulsifier, thereby reducing the amount of emulsifier added and reducing the adverse effects of the residual emulsifier on the coating performance. In addition, the partially retained epoxy end groups can participate in the cross-linking and curing of the system, thereby limiting the movement of the emulsifier and improving the comprehensive performance of the coating. DETAILED DESCRIPTION

[0030] The present invention is further described below in conjunction with the embodiments, and the present invention includes but is not limited to the following embodiments.

[0031] Among them, Examples 1 to 7 are the preparation of hyperbranched polyether hydrophobic cores. Examples 8 to 16 are the preparation of hyperbranched multi-arm star-shaped epoxy resin emulsifiers. Examples 17 to 28 are the application of hyperbranched multi-arm star-shaped epoxy resin emulsifiers in the preparation process of water-based epoxy emulsions. Examples 29 to 32 are the application of hyperbranched multi-arm star-shaped epoxy resin emulsifiers in water-based epoxy floor coatings.

[0032] The synthetic raw materials involved in the present invention can all be obtained from commercial channels.

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

[0034] 6.85 g of bisphenol A, 27.21 g of trimethylolpropane triglycidyl ether and 0.34 g of tetrabutylammonium bromide were weighed into a reactor, the temperature was raised to 120° C., and the reaction was carried out in a nitrogen atmosphere for 12 h. After the reaction was completed, the physical and chemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0035] Embodiment 2:

[0036] Example Based on Example 1, the reaction temperature was changed from 120° C. to 100° C., and the reaction time was changed from 12 h to 16 h. Other conditions were the same as those in Example 1. The physical and chemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0037] Embodiment 3:

[0038] Example Based on Example 1, the reaction temperature was changed from 120° C. to 140° C., and the reaction time was changed from 12 h to 6 h. Other conditions were the same as those in Example 1. The physical and chemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0039] Embodiment 4:

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

[0041] Embodiment 5:

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

[0043] Embodiment 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 physical and chemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

[0045] Embodiment 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 physical and chemical properties of the obtained hyperbranched polyether epoxy resin are shown in Table 1.

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

[0048]

[0049]

[0050] Table 1 shows the physicochemical data of the hyperbranched polyether hydrophobic core prepared in Examples 1 to 7. The number average molecular weight of the hyperbranched polyether is between 2000 and 5700, with a moderate molecular weight, a narrow molecular weight distribution, and a degree of branching between 0.4 and 0.8, which has the structural characteristics of a hyperbranched polymer. In addition, the epoxy value of the hyperbranched polyether is between 0.2 and 0.3 mol / 100 g, and the abundant epoxy groups can provide sufficient reaction sites for subsequent modification and curing processes.

[0051] Example 8: Synthesis of Hyperbranched Multi-arm Star-shaped Epoxy Resin Emulsifier

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

[0053] Comparative Example 9:

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

[0055] Embodiment 10:

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

[0057] Embodiment 11:

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

[0059] Embodiment 12:

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

[0061] Embodiment 13:

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

[0063] Embodiment 14:

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

[0065] Embodiment 15:

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

[0067] Embodiment 16:

[0068] The molar ratio of epoxy group to hydroxyl group was controlled to be 1:0.3, 100 g of the hyperbranched hydrophobic core synthesized in Example 7 was weighed, and 357.6 g of polyethylene glycol monomethyl ether 4000 was 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: Preparation method of a water-based epoxy emulsion

[0070] Weigh 2g of Naisu emulsifier, 20g of bisphenol A epoxy resin, and 1g of ethylene glycol monobutyl ether into a dispersion tank, heat to 60°C and stir. After all components are evenly mixed, increase the stirring rate, slowly add deionized water under high-speed shearing at 2000rpm, and stop adding water after the emulsion undergoes a phase reversal from oil-in-water to water-in-oil. Maintain the current speed and high-speed shearing for 2h. After the shearing is completed, reduce the speed to 900rpm, continue to add water and disperse for 0.5h, and adjust the solid content of the emulsion to 60wt%, thus obtaining a water-based epoxy emulsion.

[0071] Embodiment 18:

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

[0073] Embodiment 19:

[0074] On the basis of Comparative Example 17, the naisol 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 g. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the obtained emulsion are shown in Table 2.

[0075] Embodiment 20:

[0076] On the basis of Comparative Example 17, the Naisu 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 1.5 g. The rest of the preparation process was the same as that of Comparative Example 17. The relevant properties of the obtained emulsion are shown in Table 2.

[0077] Comparative Example 21:

[0078] On the basis of Comparative Example 17, the Naisol 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 Comparative Example 17. The relevant properties of the obtained emulsion are shown in Table 2.

[0079] Comparative Example 22:

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

[0081] Embodiment 23:

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

[0083] Embodiment 24:

[0084] On the basis of Comparative Example 17, the Naisol 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 obtained emulsion are shown in Table 2.

[0085] Embodiment 25:

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

[0087] Embodiment 26:

[0088] On the basis of Comparative Example 17, the Naisol 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 obtained emulsion are shown in Table 2.

[0089] Embodiment 27:

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

[0091] Embodiment 28:

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

[0093] Table 2: Relevant properties of waterborne epoxy emulsion

[0094]

[0095] Table 2 shows the relevant performance data of the water-based epoxy emulsions prepared in Examples 17 to 28, with the commercial emulsifier Naisol as comparative example 17. It can be seen from Examples 18 to 20 that with the increase in the amount of hyperbranched multi-arm star-shaped epoxy resin emulsifier added, the emulsion particle size decreases, the stability is improved, and it exhibits a better emulsification effect than the Naisol emulsifier.

[0096] It can be seen from Comparative Examples 21-22 and Example 23 that the relative molecular mass of polyethylene glycol monomethyl ether also has a great influence on the emulsion particle size. The emulsion particle size and stability of polyethylene glycol monomethyl ether with relative molecular mass of 1000 and 2000 are poor, and the polyethylene glycol monomethyl ether with relative molecular mass of 6000 has better emulsion particle size and stability.

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

[0098] Examples 27 and 28 demonstrate the emulsifying ability of the emulsifier after the hydrophobic core is transformed. The emulsion particle size reaches about 500 nm and the stability is excellent.

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

[0100] 10g of waterborne epoxy curing agent Honghui 7016, 0.1g of defoamer, 1g of leveling agent, and 0.5g of thickener were mixed evenly as component A, and 50g of the waterborne epoxy emulsion prepared in comparative example 17 was weighed as component B. The two were blended to obtain a waterborne epoxy coating that can be applied. The coating was applied on a cleaned steel plate using a scraper, and allowed to stand at room temperature. After the coating was dry, it was placed in an oven at 60°C for curing for 8 hours to obtain a test sample. 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: Paint film performance test standards

[0102] Paint film properties instrument National Standard thickness Film Thickness Tester GB / T13452.2-2008 Adhesion 100-grid knife GB / T9286-2021 Pencil hardness Pencil Hardness Tester GB / T6739-2022 Flexibility T-type bending testing machine GB / T30791-2014 Impact resistance Paint film impactor GB / T1732-2020 Chemical resistance / GB / T9274-1988

[0103] Embodiment 30:

[0104] Example Based on Comparative Example 29, component B was replaced with the water-based epoxy emulsion prepared in Example 18. At the same time, the amount of water-based epoxy curing agent Honghui 7016 added was increased to 11 g. 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] Embodiment 31:

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

[0107] Embodiment 32:

[0108] Example Based on Comparative Example 29, component B 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 obtained coating are shown in Tables 4 and 5.

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

[0110] Table 4: Basic properties of coatings

[0111]

[0112]

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

[0114]

[0115] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing a hyperbranched multi-arm star-shaped epoxy resin emulsifier, characterized in that: Add polyhydroxy compounds, polyfunctional epoxy compounds and catalysts into a reactor, maintain a nitrogen atmosphere, the reaction temperature is 100-140° C., the reaction time is 6-16 hours, and a hyperbranched polyether epoxy resin is obtained; polyethylene glycol monomethyl ether is added, maintain a nitrogen atmosphere, the reaction temperature is 120-160° C., the reaction time is 4-12 hours, and a hyperbranched multi-arm star-shaped epoxy resin emulsifier is obtained; 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.

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 etherate.

3. The preparation method according to claim 1, characterized in that: The amount of catalyst added is 0.5-1.5wt% 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 the polyhydroxy compound to the polyfunctional epoxy compound is 1:2 to 1:

3.

5. The preparation method according to claim 1, characterized in that: The molecular weight of the polyethylene glycol monomethyl ether is one or more of 1000, 2000, 4000, and 6000; preferably, the molecular weight of the polyethylene glycol monomethyl ether is 2000, 4000, or 6000.

6. The preparation method according to claim 1, characterized in that: The molar ratio of the epoxy groups in the hyperbranched polyether epoxy resin to the hydroxyl groups in the polyethylene glycol monomethyl ether is 1:0.1 to 1:0.7, preferably 1:0.3 to 1:0.

5.

7. The hyperbranched multi-arm star-shaped epoxy resin emulsifier prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing an aqueous epoxy emulsion, characterized in that: Weigh 5 to 10 parts of the hyperbranched multi-arm star-shaped epoxy resin emulsifier according to claim 7, 90 to 110 parts of bisphenol A epoxy resin, and 0 to 10 parts of an organic solvent, heat to 60°C and stir; under a high-speed shear of 2000 rpm, add deionized water dropwise, and after the emulsion undergoes a phase inversion from oil-in-water to water-in-oil, stop adding water and maintain the high-speed shear for 2 hours; after the shearing is completed, reduce the speed to 900 rpm, continue to add water to disperse for 0.5 hours, and adjust the solid content of the emulsion to 60wt%, so as to obtain a stable water-based epoxy emulsion.

9. Use of the hyperbranched multi-arm star-shaped epoxy resin emulsifier according to claim 7 in waterborne epoxy coatings.

10. The use according to claim 9, characterized in that: The waterborne epoxy coating comprises component A and component B in parts by mass; the component A is a waterborne epoxy curing agent; the component B is the waterborne epoxy emulsion according to claim 8; and the component A and the component B are mixed at a molar ratio of epoxy equivalent:active hydrogen of 1:1 to 1.2:1 to obtain the coating.

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