One-component polyurethane-modified epoxy resin emulsion, its manufacturing process and application

Abstract

A manufacturing process for a one-component polyurethane-modified epoxy resin emulsion, characterized in that it comprises the following steps: mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent, and polymerization inhibitor to obtain a mixed solution, wherein the epoxy resin has an epoxy equivalent of ≥ 300 g / equivalent; mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate, and organometallic catalyst, and carrying out an addition polymerization reaction to obtain a polyurethane prepolymer; mixing the mixed solution and the polyurethane prepolymer, carrying out an addition reaction, emulsification with the addition of water, and subsequent removal of the ketone solvent to obtain a water-based polyurethane epoxy emulsion.Mixing the water-based polyurethane epoxy emulsion with alkyldiamine, carrying out a Michael addition-ring-opening addition reaction to obtain a one-component polyurethane-modified epoxy resin emulsion, wherein the dialkyl maleate comprises one or more of diethyl maleate, dibutyl maleate and diisooctyl maleate.

Description

The present application claims priority from a Chinese patent application filed on November 1, 2023, with the Chinese Patent Office under application number CN202311434997.7 entitled “One-component polyurethane-modified epoxy resin emulsion, its manufacturing process and application”. The entire content of that application is incorporated herein by reference. TECHNICAL AREA The present application belongs to the technical field of water-based epoxy resins and relates in particular to a manufacturing process based on a one-component polyurethane-modified epoxy resin emulsion. STATE OF THE ART Water-based epoxy resins are a widely used group of polymer materials. Depending on whether the epoxy resins are dissolved or dispersed in water, they can be divided into water-soluble epoxy resins and epoxy resin emulsions. Epoxy resin emulsions are of particular interest due to their low viscosity and ease of handling. However, most commercially available epoxy resin emulsions currently on the market use low molecular weight liquid epoxy resins that remain liquid after the solvent evaporates. Therefore, these epoxy resin emulsions can rarely be used alone but must be combined with a hardener to form a solid, three-dimensional network structure that can be used. Consequently, there is a pressing need to develop an epoxy resin emulsion that can cure directly into a film without the addition of a hardener. CN104448212A discloses a process for producing an epoxy resin-modified polyurethane-acrylate oligomer, comprising: subjecting diethanolamine and phthalic anhydride to a reaction to obtain a carboxy-containing diol-polyurethane chain extender; subjecting the carboxy-containing diol-polyurethane chain extender, bisphenol-A epoxy resin, and acrylic acid to a mixing reaction to obtain an epoxy-modified polyol chain extender; and adding the epoxy-modified polyol chain extender to a polyurethane-acrylate reaction system to obtain an epoxy resin-modified polyurethane-acrylate oligomer. CONTENT OF THE PRESENT INVENTION In view of this, the object of the present application is to provide a manufacturing process for a one-component polyurethane-modified epoxy resin emulsion, wherein the one-component polyurethane-modified epoxy resin emulsion produced according to the present application can be used as a single component and can cure independently without epoxy hardener to form a coating film. The object of the present invention is achieved by the following embodiments: The present application provides a manufacturing process for a one-component polyurethane-modified epoxy resin emulsion with the features of claim 1, comprising the following steps: Mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent, and polymerization inhibitor to obtain a mixed solution; wherein the epoxy resin has an epoxy equivalent of ≥ 300 g / equivalent; Mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate, and organometallic catalyst and carrying out an addition polymerization reaction to obtain a polyurethane prepolymer;Mixing the mixed solution and the polyurethane prepolymer and carrying out an addition reaction, carrying out emulsification with the addition of water and subsequent removal of the ketone solvent to obtain a water-based polyurethane epoxy emulsion; mixing the water-based polyurethane epoxy emulsion with alkyldiamine, carrying out a Michael addition-ring-opening addition reaction to obtain a one-component polyurethane-modified epoxy resin emulsion, wherein the dialkyl maleate comprises one or more of diethyl maleate, dibutyl maleate, and diisooctyl maleate. Preferably, the monohydroxy acrylate comprises one or more of hydroxyethyl acrylate, hydroxypropyl acrylate, and hydroxybutyl acrylate; the ketone solvent comprises one or more of acetone, butanone, and cyclohexanone.The polymerization inhibitor comprises one or more of hydroquinone, tert-butylcatechol, and p-hydroxyanisole. Preferably, the molar ratio of the monohydroxyacrylate to the dialkyl maleate is 0.5–1:0.5–1; the mass of the polymerization inhibitor is 0.1–1.5% of the mass of the monohydroxyacrylate; the mass of the epoxy resin is 80–100% of the total mass of the monohydroxyacrylate, dialkyl maleate, ketone solvent, and aprotic polar solvent. Preferably, the polyethylene glycol has a molecular weight of 300–2000 Da; the polyetherdiol and the polyesterdiol each have a molecular weight of 1000–2000 Da independently. The polyetherdiol comprises polypropylene glycol and / or polytetrahydrofurandiol; the diisocyanate comprises one or more of toluene diisocyanate, isofrone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and trimethylhexane diisocyanate;The organometallic catalyst comprises an organic tin catalyst and / or an organic bismuth catalyst; the ratio of the sum of the amounts of hydroxyl groups in the polyether diol and / or polyester diol and polyethylene glycol to the amount of isocyanate groups in the diisocyanate is 0.2–0.8:1; the mass of the organometallic catalyst constitutes 0.001–0.1% of the mass of the diisocyanate; the molar ratio of the isocyanate groups in the diisocyanate to the hydroxyl groups in the monohydroxy acrylate is 1:0.3–0.5. The addition polymerization reaction is preferably carried out at a temperature of 60–90 °C for a period of 2–6 hours. The water-based polyurethane epoxy emulsion preferably has a solids content of 30–50% by weight.The addition reaction is carried out at a temperature of 60-90 °C for a time of 2-6 hours. Preferably, the emulsification is carried out at a temperature of 40-50 °C for a time of 1-5 hours. Preferably, the alkyldiamine comprises one or more of ethylenediamine, 1,4-butanediamine, and 1,6-hexanediamine; the ratio of the sum of the amounts of monohydroxyacrylate and dialkyl maleate to the amount of alkyldiamine is 1:1; the Michael addition-ring-opening addition reaction is carried out at a temperature of ≤ 50 °C for a time of 2-5 hours. In the present application, epoxy resin, monohydroxy acrylate, and dialkyl maleate are mixed to obtain a mixed solution; polyethylene glycol, polyetherdiol, and / or polyesterdiol diisocyanate are subjected to addition polymerization to obtain a polyurethane prepolymer; the addition reaction of the monohydroxy acrylate and diisocyanate, as well as the addition reaction of the isocyanate groups of the diisocyanate and the secondary hydroxyl groups of the epoxy resin, yields an acrylic acid-terminated water-based polyurethane-epoxy resin emulsion, in which the water-based polyurethane is introduced into the epoxy resin by covalent bonds, increasing the toughness of the epoxy resin and simultaneously enabling its self-emulsification, resulting in an acrylic acid-terminated water-based polyurethane-epoxy resin emulsion with a core-shell structure consisting of a hydrophilic polyurethane shell and an epoxy resin core.The acrylic acid end groups and the dialkyl maleate in the water-based polyurethane epoxy emulsion are then each subjected to a Michael addition reaction with alkyldiamine to convert the alkyldiamine to secondary alkylamine, forming a secondary amine-modified water-based polyurethane epoxy emulsion. Subsequently, within the particles of the water-based polyurethane epoxy emulsion, the secondary amine groups and the epoxy resin undergo a ring-opening addition reaction (chain extension reaction) to increase the molecular weight of the epoxy resin and produce a one-component polyurethane-modified epoxy resin emulsion that can be cured alone, without the addition of an epoxy hardener, to form a coating film. Because the chain extension reaction takes place within the emulsion core, the one-component polyurethane-modified epoxy resin emulsion also exhibits high stability. BRIEF DESCRIPTION OF THE DRAWINGS The present application provides a manufacturing process for a one-component polyurethane-modified epoxy resin emulsion, comprising the following steps: mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent and polymerization inhibitor to obtain a mixed solution; wherein the epoxy resin has an epoxy equivalent of ≥ 300 g / equivalent; Mixing polyethylene glycol, polyetherdiol and / or polyesterdiol, diisocyanate and organometallic catalyst and carrying out an addition polymerization reaction to obtain a polyurethane prepolymer; Mixing the mixed solution and the polyurethane prepolymer and carrying out an addition reaction, carrying out emulsification with the addition of water and subsequent removal of the ketone solvent to obtain a water-based polyurethane epoxy emulsion; Mixing the water-based polyurethane epoxy emulsion with alkyldiamine, carrying out a Michael addition-ring-opening addition reaction to obtain a one-component polyurethane-modified epoxy resin emulsion, wherein the dialkyl maleate comprises one or more of diethyl maleate, dibutyl maleate, and diisooctyl maleate. In the present application, unless otherwise stated, the materials and equipment used are commercially available products in this field. In the present application, epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent and polymerization inhibitor are mixed to obtain a mixed solution; wherein the epoxy resin has an epoxy equivalent of ≥ 300 g / equivalent. In the present application, the monohydroxyacrylate preferably comprises one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate, more preferably hydroxyethyl acrylate. In the present application, the dialkyl maleate according to the invention comprises one or more of diethyl maleate, dibutyl maleate, and diisooctyl maleate. In the present application, the stoichiometric ratio of the monohydroxyacrylate to the dialkyl maleate is preferably 0.5-1:0.5-1, more preferably 0.6-0.9:0.6-0.9, and most preferably 0.7-0.8:0.7-0.8. In the present application, the polymerization inhibitor preferably comprises one or more of hydroquinone, tert-butylcatechol, and p-hydroxyanisole, more preferably p-hydroxyanisole. In the present application, the mass of the polymerization inhibitor preferably constitutes 0.1–1.5% of the mass of the monohydroxyacrylate, more preferably 0.5–1%, and more preferably 0.6–0.8%. In the present application, the ketone solvent comprises one or more of acetone, butanone and cyclohexanone, more preferably acetone. In the present application, the aprotic polar solvent is preferably one or more of propylene glycol methyl ether, ethylene glycol monobutyl ether, propylene glycol methyl ether acetate and ethylene glycol methyl ether acetate, more preferably propylene glycol methyl ether acetate and / or ethylene glycol methyl ether acetate. In the present application, the epoxy resin preferably comprises one or more of E31, E20, E12, E09, E06 and E03, more preferably E06 and / or E03. In the present application, the mass of the epoxy resin preferably constitutes 80-100% of the total mass of the monohydroxyacrylate, dialkyl maleate, ketone solvent and aprotic polar solvent, more preferably 85-95%, and most preferably 88-90%. In the present application, the process preferably comprises, after mixing, further heating a mixed slurry obtained by mixing under reflux until the epoxy resin is completely dissolved, in order to obtain a mixed solution. In the present application, the reflux heating is preferably carried out at a temperature of 30-90 °C, more preferably 40-80 °C, and most preferably 50-60 °C. In the present application, the epoxy resin is dissolved by reflux heating in the monohydroxyacrylate and dialkyl maleate to obtain a mixed solution. In the present application, polyethylene glycol, polyetherdiol and / or polyesterdiol, diisocyanate and organometallic catalyst are mixed and subjected to an addition polymerization to obtain a polyurethane prepolymer. In the present application, the polyethylene glycol preferably has a molecular weight of 300-2000 Da, more preferably 500-1500 Da, most preferably 550-1000 Da. In the present application, the polyetherdiol and the polyesterdiol preferably have a molecular weight of 1000-2000 Da independently of each other. In the present application, the polyetherdiol preferably comprises polypropylene glycol and / or polytetrahydrofurandiol; the polyesterdiol is preferably a polyesterdiol based on adipic acid and alkyldiol. In the present application, the diisocyanate comprises one or more of toluene diisocyanate, isofrone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and trimethylhexane diisocyanate, more preferably toluene diisocyanate and / or isofrone diisocyanate. In the present application, the ratio of the sum of the amounts of hydroxyl groups in the polyether diol and / or polyester diol and polyethylene glycol to the amount of isocyanate groups in the diisocyanate is 0.2–0.8:1, more preferably 0.3–0.7:1, and most preferably 0.4–0.5:1. In the present application, the ratio of the isocyanate groups in the diisocyanate to the hydroxyl groups in the monohydroxyacrylate is 1:0.3–0.5, more preferably 1:0.4. In the present application, polyethylene glycols with different molecular weights, polyetherdiol and / or polyesterdiol with different structures and molecular weights, and diisocyanates with different structures are used to produce polyurethane prepolymers with different structures and polarities. The resulting one-component polyurethane-modified epoxy resin emulsion can be adapted in its polarity by using different polyurethane component structures to suit different uses (e.g., according to the principle of "like dissolves like"). If the polarity of the polyurethane component is high, the epoxy resin emulsion dissolves more readily in water, which is a polar liquid, during use, and its water resistance is lower.Therefore, the water resistance of the low-polarity polyurethane component is better, and the one-component polyurethane-modified epoxy resin emulsion has a wide adaptability. In the present application, the organometallic catalyst preferably comprises an organic tin catalyst and / or an organic bismuth catalyst. In the present application, the mass of the organometallic catalyst preferably constitutes 0.001–0.1% of the mass of the diisocyanate, more preferably 0.01–0.5%, and most preferably 0.04–0.1%. In the present application, the addition polymerization reaction is preferably carried out at a temperature of 60-90 °C, more preferably 65-85 °C, most preferably 75-80 °C; the addition polymerization reaction is preferably carried out for a time of 2-6 hours, more preferably 3-5 hours, most preferably 4 hours. After obtaining the mixed solution and the polyurethane prepolymer, in the present application the mixed solution is mixed with the polyurethane prepolymer and subjected to an addition reaction, then emulsification is carried out with the addition of water and the ketone solvent is removed to obtain a water-based polyurethane epoxy emulsion. In the present application, the addition reaction is preferably carried out at a temperature of 60-90 °C, more preferably 65-85 °C, most preferably 75-80 °C; the addition reaction is preferably carried out for a time of 2-6 hours, more preferably 3-5 hours, most preferably 4 hours. In the present application, during the addition reaction, the diisocyanate and the monohydroxy acrylate are subjected to an addition reaction, and the isocyanate groups of the diisocyanate and the secondary hydroxyl groups of the epoxy resin are subjected to an addition reaction. The present application does not contain any particular restriction on the amount of water, as long as the solids content of the water-based polyurethane epoxy emulsion can reach 30-50 wt.%; the solids content of the water-based polyurethane epoxy emulsion is further preferably 35-45 wt.%, most preferably 40-43 wt.%. In the present application, the emulsification is preferably carried out at a temperature of 40-50 °C, more preferably 42-48 °C, most preferably 43-45 °C; the emulsification is preferably carried out for a time of 1-5 hours, more preferably 2-4 hours, most preferably 3 hours. In the present application, the removal of the ketone solvent is preferably carried out by distillation under reduced pressure. The present application does not specifically restrict the conditions of distillation under reduced pressure, as long as the ketone solvent can be completely removed without destroying other components. In the present application, the water-based polyurethane is introduced into the epoxy resin by covalent bonds with an epoxy equivalent of ≥ 300 g / equivalent, which on the one hand increases the toughness of the epoxy resin and on the other hand enables its self-emulsification, resulting in an acrylic acid-terminated water-based polyurethane-epoxy resin emulsion with a core-shell structure consisting of a hydrophilic polyurethane shell and an epoxy resin core. After obtaining the water-based polyurethane epoxy emulsion, in the present application the water-based polyurethane epoxy emulsion is mixed with the alkyldiamine and subjected to a Michael addition-ring-opening addition reaction to obtain a one-component polyurethane-modified epoxy resin emulsion. In the present application, the alkyldiamine preferably comprises one or more of ethylenediamine, 1,4-butanediamine, and 1,6-hexanediamine, more preferably ethylenediamine and / or 1,4-butanediamine; the ratio of the sum of the amounts of monohydroxyacrylate and dialkyl maleate to the amount of alkyldiamine is preferably 1:1. In the present application, the alkyldiamine is preferably used in the form of an aqueous solution of alkyldiamine, wherein the concentration of the aqueous solution of alkyldiamine is preferably 50% by weight; the alkyldiamine is preferably added dropwise, and the dropwise addition is preferably carried out for a period of 1-6 hours, more preferably 2-5 hours, and most preferably 3-4 hours; the dropwise addition is preferably carried out at room temperature and with stirring. In the present application, the Michael addition-ring-opening-addition reaction is preferably carried out at a temperature of ≤50 °C, more preferably 25-40 °C, and most preferably 30-35 °C; the Michael addition-ring-opening-addition reaction is preferably carried out for a time of 2-5 hours, more preferably 3-4 hours. In the present application, the Michael addition-ring-opening-addition reaction comprises a Michael addition reaction and a ring-opening-addition reaction; wherein the Michael addition reaction comprises a Michael addition reaction of the dialkyl maleate and the alkyldiamine and a Michael addition reaction of the acrylic acid end groups and the alkyldiamine; the ring-opening-addition reaction is a ring-opening-addition reaction of the secondary amine groups and the epoxy groups in the water-based polyurethane epoxy emulsion. In the present application, the Michael addition-ring-opening-addition reaction preferably comprises a first Michael addition-ring-opening-addition reaction and a second Michael addition-ring-opening-addition reaction, which are carried out successively.In the present application, the first Michael addition-ring-opening-addition reaction is preferably carried out at room temperature; the first Michael addition-ring-opening-addition reaction is preferably carried out for a time of 1-2 hours, more preferably 1.2-1.8 hours and most preferably 1.4-1.6 hours; the second Michael addition-ring-opening-addition reaction is preferably carried out at a temperature of 40-50 °C, more preferably 42-48 °C and most preferably 43-45 °C; the second Michael addition-ring-opening-addition reaction is preferably carried out for a time of 1-3 hours, more preferably 1.5-2.5 hours, most preferably 1.8-2 hours. To further illustrate the present application, the manufacturing processes of a one-component polyurethane-modified epoxy resin emulsion provided according to the present application are described in detail in connection with the exemplary embodiments, but the exemplary embodiments cannot be understood as limitations of the scope of protection of the present application. In all embodiments and comparative examples of the present application, the epoxy resins E06, E03 and E20 were purchased from Jiangsu Sanmu Chemical Co., Ltd.; the polyethylene glycol PEG1000 with a molecular weight of 1000 Da was purchased from Shanghai Dongda Chemical Co., Ltd.; the polypropylene glycol DL2000 with a molecular weight of 2000 Da was purchased from Shandong Bluestar Dongda Co., Ltd.; the organic bismuth catalyst MC-710 was purchased from Beijing Baiyuan Chemical Co., Ltd. Example 1 6660 g of solid epoxy resin E06, 464 g of hydroxyethyl acrylate, 912 g of dibutyl maleate, 3300 g of acetone, 2000 g of propylene glycol methyl ether acetate and 0.50 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 2000 g of polyethylene glycol (PEG1000), 2000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 1112 g of isofrone diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 17,840 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion (the water-based polyurethane-epoxy emulsion comprised a mixture of epoxy resin, dialkyl maleate, and acrylic acid-terminated polyurethane). At room temperature and with stirring, 480 g of a 50 wt% aqueous solution of ethylenediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours, then the temperature was increased to 50 °C and the reaction was carried out for another 2 hours, and then the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Example 2 6660 g of solid epoxy resin E06, 464 g of hydroxyethyl acrylate, 1360 g of diisooctyl maleate, 2860 g of acetone, 2000 g of ethylene glycol methyl ether acetate and 0.50 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 2000 g of polyethylene glycol (PEG1000), 2000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 871 g of toluene diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 18,210 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 704 g of a 50% solution of 1,4-butanediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours. Then, at an elevated temperature of 50 °C, the reaction was carried out for another 2 hours. Finally, the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Example 3 6660 g of solid epoxy resin E03, 696 g of hydroxyethyl acrylate, 1360 g of diisooctyl maleate, 2860 g of acetone, 2000 g of ethylene glycol methyl ether acetate and 0.60 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 1500 g of polyethylene glycol (PEG1000), 1000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 1112 g of isofrone diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 17,710 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 880 g of a 50 wt% solution of 1,4-butanediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours. Then, at an elevated temperature of 50 °C, the reaction was carried out for another 2 hours. Finally, the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Example 4 6660 g of solid epoxy resin E03, 696 g of hydroxyethyl acrylate, 1360 g of diisooctyl maleate, 2860 g of acetone, 1000 g of propylene glycol methyl ether acetate, 1000 g of ethylene glycol methyl ether acetate and 0.60 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 1500 g of polyethylene glycol (PEG1000), 1000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 1112 g of isofrone diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 16,570 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 480 g of a 50 wt% ethylenediamine solution was added dropwise to the above emulsion over 4 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours. Then, at an elevated temperature of 50 °C, the reaction was carried out for another 2 hours. Finally, the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Example 5 6660 g of solid epoxy resin E20, 464 g of hydroxyethyl acrylate, 1376 g of diethyl maleate, 3300 g of acetone, 2000 g of propylene glycol methyl ether acetate and 0.50 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 2000 g polyethylene glycol (PEG1000), 2000 g dried polypropylene glycol (DL2000), 0.20 g organic bismuth catalyst (MC-710), 667 g isofrone diisocyanate, and 349 g toluene diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 16,570 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 880 g of a 50 wt% solution of 1,4-butanediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours. Then, at an elevated temperature of 50 °C, the reaction was carried out for another 2 hours. Finally, the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Comparative example 1 6660 g of solid epoxy resin E06, 912 g of dibutyl maleate, 3300 g of acetone, 2000 g of propylene glycol methyl ether acetate and 0.50 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 2000 g of polyethylene glycol (PEG1000), 2000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 1112 g of isofrone diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 19,145 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 480 g of a 50 wt% aqueous solution of ethylenediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours, then the temperature was increased to 50 °C and the reaction was carried out for another 2 hours, and then the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Comparative example 2 6660 g of solid epoxy resin E06, 464 g of hydroxyethyl acrylate, 3300 g of acetone, 2000 g of propylene glycol methyl ether acetate and 0.50 g of p-hydroxyanisole were placed in a reactor and heated under reflux at 70 °C until the solid epoxy resin was completely dissolved to obtain a mixed solution. 2000 g of polyethylene glycol (PEG1000), 2000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), and 1112 g of isofrone diisocyanate were placed in a reactor, stirred uniformly, and heated to 75 °C. After 4 hours of reaction, a polyurethane prepolymer was obtained. The mixed solution was added to the reactor containing the polyurethane prepolymer. The mixture was reacted under reflux at 70 °C for 3 hours and then cooled to 40 °C. 18,470 g of water were added to the reactor and the contents were stirred at 40 °C for 3 hours. The acetone was removed by distillation under reduced pressure, and the mixture was cooled to room temperature to obtain a water-based polyurethane-epoxy emulsion. At room temperature and with stirring, 480 g of a 50 wt% aqueous solution of ethylenediamine was added dropwise to the above emulsion over 2 hours. After the dropwise addition was complete, the reaction was carried out for 2 hours, then the temperature was increased to 50 °C and the reaction was carried out for another 2 hours, and then the temperature was lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion. Test example 1 Table 1 shows the basic parameters of the one-component polyurethane-modified epoxy resin emulsions prepared in embodiments 1-5 and comparative examples 1-2, where appearance, solids content, pH, viscosity, particle size, thermal storage stability, freeze-thaw stability, centrifugal stability, and dilution stability were tested with reference to GB / T 11175-2021. The particle size of the emulsion was measured using a Zetasizer Nano ZS particle size analyzer when the emulsion was diluted with water to 1 wt%. Viscosity was measured directly at 25 °C using a Brookfield Viscometer DV1. The epoxy content of the emulsion was determined using the hydrochloric acid-acetone method according to the national standard GB-T1677-2008. Volatile organic compounds were tested with reference to GB / T 23986-2009.Storage stability: The emulsion was left to stand at 15-30 °C and observed for the formation of precipitates; centrifugal stability: 30 ml of emulsion were placed in a centrifuge and the centrifugal stability of the emulsion was tested at 3000 rpm for 30 minutes; thermal storage stability: 100 ml of emulsion was heated at 50 °C for 12 hours, cooled to room temperature, and stored for 12 hours. The process was repeated to observe for the formation of precipitates; freeze-thaw stability: 50 ml of emulsion was placed in a refrigerator at -5 ± 2 °C and removed after 18 hours, then left to stand at 23 ± 2 °C for 6 hours. The process was repeated to observe for the formation of precipitates; dilution stability: 10 ml of emulsion was diluted to a solids content of 2-3 wt.The mixture was diluted by -% and left to stand at room temperature for 48 hours to observe whether precipitates formed (an emulsion that emits blue light indicates that the particle size of the emulsion after dilution is small and the stability is good). Table 1: Basic parameters of the one-component polyurethane-modified epoxy resin emulsions prepared in embodiments 1-5 and comparative examples 1-2. Appearance: White emulsion, white emulsion, white emulsion, white emulsion, white emulsion, white emulsion Solids content (wt%) 40% 40% 40% 40% 40% 40% pH 7,37,37,67,67,68,08,0 Viscosity (mPa·s at 25 °C) 220 220 260 320 320 320 180 Particle size (nm) 320 300 320 320 320 660 520 Storage stability (day) > 180 > 180 > 180 > 180 > 180 < 60 < 120 Thermal storage stability (times) 6666613 Freeze-thaw stability (times) 5555513 Centrifugal stability (times) 5555511 Dilution stability Blue light emulsion Blue light emulsion Blue light emulsion Blue light emulsion Blue light emulsion Unstable Relatively stable Volatile organic compounds (wt%) 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% 0.1% As can be seen from Table 1, the one-component polyurethane-modified epoxy resin emulsions produced according to the present application had a small particle size and good stability. However, the one-component polyurethane-modified epoxy resin emulsions produced in Comparative Examples 1-2 had a large particle size and low stability. Example 6 The one-component polyurethane-modified epoxy resin emulsions produced in embodiments 1-5 and comparative examples 1-2 were each sprayed onto the surface of steel plates, dried at room temperature for 30 minutes, dried at 90 °C for 5 minutes, and then dried at 180 °C for 5 minutes. The properties of the coating films were then tested (the coating film thickness was 55-60 µm).The test results are shown in Table 2, with the tests being carried out according to the following test methods or standards: pencil hardness of the lacquer film according to GB / T 6739-2006; flexibility of the lacquer film according to GB / T 1731-2020; cross-cut adhesion test according to GB / T 9286-2021; wet film adhesion: test panels were immersed in distilled water at 25 °C for 144 hours, dried, and then tested with a cross-cut adhesion test; salt spray resistance according to GB / T 1771-2007. Table 2: Test results of the properties of the lacquer films. Example 1: Flat and transparent; 2H < 1 mm; Level 0; Level 1800 hours Example 2: Flat and transparent; 2H < 1 mm; Stage 0; Stage 1800 hours Example 3: Flat and transparent, 2H < 1 mm, Level 0, Level 1800 hours Flat design and 2H < 1 mm, Stage 0, Stage 1900 hours example 4 transparent Example 5: Flat and transparent, 2H < 1 mm, Stage 0, Stage 1900 hours Comparison example 1: Grainy appearance, 1H < 1 mm, Level 3, Level 7100 hours Comparison example 2: Grainy appearance 1H< 1 mm Stage 2 Stage 6100 hours Table 2 shows that the one-component polyurethane-modified epoxy resin emulsions produced according to the present application can be dried and cured directly without a hardener, resulting in a coating film with suitable hardness, good flexibility, good adhesion, and excellent salt spray resistance. However, the coating films produced in Comparative Examples 1-2 had a granular appearance and low hardness, adhesion, and salt spray resistance. Although the present embodiments have described the present application in detail, they represent only a part of the embodiments of the present application, not all of them, and other embodiments can be acquired without inventiveness in accordance with the embodiments in the present application, all of which are covered by the protection of the present application.

Claims

A manufacturing process for a one-component polyurethane-modified epoxy resin emulsion, characterized in that it comprises the following steps: mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent, and polymerization inhibitor to obtain a mixed solution, wherein the epoxy resin has an epoxy equivalent of ≥ 300 g / equivalent; mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate, and organometallic catalyst, and carrying out an addition polymerization reaction to obtain a polyurethane prepolymer; mixing the mixed solution and the polyurethane prepolymer, carrying out an addition reaction, emulsification with the addition of water, and subsequent removal of the ketone solvent to obtain a water-based polyurethane epoxy emulsion;Mixing the water-based polyurethane epoxy emulsion with alkyldiamine, carrying out a Michael addition-ring-opening addition reaction to obtain a one-component polyurethane-modified epoxy resin emulsion, wherein the dialkyl maleate comprises one or more of diethyl maleate, dibutyl maleate and diisooctyl maleate. Manufacturing process according to claim 1, wherein the monohydroxyacrylate comprises one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate; the ketone solvent comprises one or more of acetone, butanone and cyclohexanone; the polymerization inhibitor comprises one or more of hydroquinone, tert-butylcatechin and p-hydroxyanisole. Manufacturing process according to claim 1 or 2, wherein the molar ratio of the monohydroxyacrylate to the dialkyl maleate is 0.5-1:0.5-1; the mass of the polymerization inhibitor is 0.1-1.5% of the mass of the monohydroxyacrylate; the mass of the epoxy resin is 80-100% of the total mass of the monohydroxyacrylate, dialkyl maleate, ketone solvent and aprotic polar solvent. Manufacturing process according to claim 1, wherein the aprotic polar solvent is one or more of propylene glycol methyl ether, ethylene glycol monobutyl ether, propylene glycol methyl ether acetate and ethylene glycol methyl ether acetate. A manufacturing process according to claim 1, wherein the polyethylene glycol has a molecular weight of 300-2000 Da; the polyether diol and the polyester diol independently have a molecular weight of 1000-2000 Da; the polyether diol comprises polypropylene glycol and / or polytetrahydrofuran diol; the diisocyanate comprises one or more of toluene diisocyanate, isofrone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and trimethylhexane diisocyanate; the organometallic catalyst comprises an organic tin catalyst and / or an organic bismuth catalyst; the ratio of the sum of the amounts of hydroxyl groups in the polyether diol and / or polyester diol and polyethylene glycol to the amount of isocyanate groups in the diisocyanate is 0.2-0.8:1; the mass of the organometallic catalyst is 0.001-0.1% of the mass of the diisocyanate;The stoichiometric ratio of the isocyanate groups in the diisocyanate to the hydroxyl groups in the monohydroxyacrylate is 1:0.3-0.

5. Manufacturing process according to claim 1 or 5, characterized in that the polyesterdiol is a polyesterdiol produced from adipic acid and alkyldiol. Manufacturing process according to claim 1 or 5, characterized in that the addition polymerization reaction is carried out at a temperature of 60-90 °C for a period of 2-6 hours. Manufacturing process according to claim 1, characterized in that the water-based polyurethane epoxy emulsion has a solids content of 30-50 wt.%; the addition reaction is carried out at a temperature of 60-90 °C for a time of 2-6 hours. Manufacturing process according to claim 1 or 8, characterized in that the emulsification is carried out at a temperature of 40-50 °C for a period of 1-5 hours. Manufacturing process according to claim 1, characterized in that the alkyldiamine comprises one or more of ethylenediamine, 1,4-butanediamine and 1,6-hexanediamine; the ratio of the sum of the amounts of monohydroxyacrylate and dialkyl maleate to the amount of alkyldiamine is 1:1; the Michael addition-ring-opening addition reaction is carried out at a temperature of ≤ 50 °C for a time of 2-5 hours. Manufacturing process according to claim 1 or 10, wherein the Michael addition-ring-opening-addition reaction comprises a first Michael addition-ring-opening-addition reaction and a second Michael addition-ring-opening-addition reaction, which are carried out successively; wherein the first Michael addition-ring-opening-addition reaction is carried out at a temperature of room temperature for a time of 1-2 hours; the second Michael addition-ring-opening-addition reaction is carried out at a temperature of 40-50 °C for a time of 1-3 hours.