Single-component polyurethane-modified epoxy resin emulsion, and preparation method therefor and use thereof

Abstract

The present application belongs to the technical field of waterborne epoxy resins. Provided are a single-component polyurethane-modified epoxy resin emulsion, and a preparation method therefor and the use thereof. In the present application, by introducing waterborne polyurethane into an epoxy resin by means of a covalent bond, the toughness of the epoxy resin is improved, the self-emulsification of the epoxy resin is also achieved, and an acrylic-acid-terminated waterborne polyurethane epoxy emulsion of a core-shell structure comprising a hydrophilic polyurethane shell and an epoxy resin core is formed. Acrylic acid end groups and dialkyl maleate in the waterborne polyurethane epoxy emulsion separately undergo the Michael addition reaction with an alkyl diamine to convert the alkyl diamine into an alkyl secondary amine, thereby forming a secondary-amino-modified waterborne polyurethane epoxy emulsion; then, secondary amino groups and the epoxy resin are subjected to a ring-opening addition reaction in waterborne polyurethane epoxy emulsion particles, thereby increasing the molecular weight of the epoxy resin; and the prepared single-component polyurethane-modified epoxy resin emulsion can be independently cured to form a paint film without the need to add an epoxy curing agent.

Description

One-component polyurethane modified epoxy resin emulsion and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 1, 2023, with application number CN202311434997.7 and invention name “A one-component polyurethane modified epoxy resin emulsion, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of waterborne epoxy resins, and specifically relates to a one-component polyurethane-modified epoxy resin emulsion, a preparation method thereof, and an application thereof. Background Art

[0003] Waterborne epoxy resins are a widely used class of polymer materials. Depending on how they dissolve or disperse in water, they can be divided into water-soluble epoxy resins and epoxy resin emulsions. Epoxy resin emulsions have attracted widespread attention due to their low viscosity and ease of use. However, most commercially available epoxy resin emulsions utilize low-molecular-weight liquid epoxy resins, which become liquid after solvent evaporation. Consequently, epoxy resin emulsions are rarely used on their own and are only useful when combined with a curing agent to form a solid, three-dimensional network structure. Therefore, there is an urgent need to develop an epoxy resin emulsion that can directly cure to form a film without the addition of a curing agent.

[0004] Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a one-component polyurethane-modified epoxy resin emulsion and its preparation method and application. The one-component polyurethane-modified epoxy resin emulsion prepared in this application can be used as a single component and can be cured alone to form a paint film without the need for an epoxy curing agent.

[0006] In order to achieve the above objectives, this application adopts the following technical solutions:

[0007] The present application provides a method for preparing a one-component polyurethane-modified epoxy resin emulsion, comprising the following steps:

[0008] Mixing an epoxy resin, a monohydroxy acrylate, a dialkyl maleate, a ketone solvent, an aprotic polar solvent, and a polymerization inhibitor to obtain a mixed solution, wherein the epoxy equivalent of the epoxy resin is greater than or equal to 300 g / eq;

[0009] Mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate and an organic metal catalyst to carry out addition polymerization to obtain a polyurethane prepolymer;

[0010] The mixed solution is mixed with a polyurethane prepolymer to carry out an addition reaction, water is added for emulsification, and the ketone solvent is removed to obtain a waterborne polyurethane epoxy emulsion;

[0011] The waterborne polyurethane epoxy emulsion is mixed with alkyl diamine, and subjected to Michael addition-ring opening addition reaction to obtain a single-component polyurethane modified epoxy resin emulsion.

[0012] Preferably, the monohydroxy acrylate includes one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate;

[0013] The dialkyl maleate includes one or more of diethyl maleate, dibutyl maleate and diisooctyl maleate;

[0014] The ketone solvent includes one or more of acetone, butanone and cyclohexanone;

[0015] The polymerization inhibitor includes one or more of hydroquinone, tert-butylcatechol and p-hydroxyanisole.

[0016] Preferably, the molar ratio of the monohydroxy acrylate to the dialkyl maleate is 0.5-1:0.5-1;

[0017] The mass of the polymerization inhibitor is 0.1 to 1.5% of the mass of the monohydroxy acrylate;

[0018] The mass of the epoxy resin is 80-100% of the total mass of the monohydroxy acrylate, dialkyl maleate, ketone solvent and aprotic polar solvent.

[0019] Preferably, the molecular weight of the polyethylene glycol is 300 to 2000 Da;

[0020] The molecular weights of the polyether diol and the polyester diol are independently 1000 to 2000 Da; the polyether diol comprises polypropylene glycol and / or polytetramethylene glycol;

[0021] The diisocyanate includes one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and trimethylhexane diisocyanate;

[0022] The organometallic catalyst includes an organotin catalyst and / or an organobismuth catalyst;

[0023] The ratio of the sum of the amount 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 to 0.8:1;

[0024] The mass of the organometallic catalyst is 0.001 to 0.1% of the mass of the diisocyanate;

[0025] The molar ratio of the isocyanate group in the diisocyanate to the hydroxyl group in the monohydroxy acrylate is 1:0.3-0.5.

[0026] Preferably, the temperature of the addition polymerization reaction is 60-90° C., and the time is 2-6 hours.

[0027] Preferably, the solid content of the aqueous polyurethane epoxy emulsion is 30 to 50 wt%;

[0028] The temperature of the addition reaction is 60-90° C., and the time is 2-6 hours.

[0029] Preferably, the emulsification temperature is 40-50° C., and the emulsification time is 1-5 hours.

[0030] Preferably, the alkyl diamine includes one or more of ethylenediamine, 1,4-butanediamine and 1,6-hexanediamine;

[0031] The ratio of the sum of the amounts of the monohydroxy acrylate and the dialkyl maleate to the amount of the alkyl diamine is 1:1;

[0032] The temperature of the Michael addition-ring-opening addition reaction is ≤50° C., and the reaction time is 2 to 5 hours.

[0033] The present application provides a one-component polyurethane-modified epoxy resin emulsion prepared by the preparation method described in the above technical solution.

[0034] The present application provides the use of the one-component polyurethane-modified epoxy resin emulsion described in the above technical solution in coatings and / or anti-corrosion materials.

[0035] The present application comprises mixing epoxy resin, monohydroxy acrylate and dialkyl maleate to obtain a mixed solution; subjecting polyethylene glycol, polyether diol and / or polyester diol and diisocyanate to addition polymerization to obtain a polyurethane prepolymer; generating an acrylic acid-terminated waterborne polyurethane epoxy emulsion through addition reaction of monohydroxy acrylate and diisocyanate, and addition reaction of isocyanate groups of diisocyanate and secondary hydroxyl groups of epoxy resin; introducing the waterborne polyurethane into the epoxy resin via covalent bonds, thereby increasing the toughness of the epoxy resin and achieving self-emulsification of the epoxy resin, thereby forming an acrylic acid-terminated waterborne polyurethane epoxy emulsion having a core-shell structure with a hydrophilic polyurethane as an outer shell and an epoxy resin as a core. The acrylic acid end groups and dialkyl maleate in the aqueous polyurethane epoxy emulsion then undergo Michael addition reactions with alkyl diamines, converting the alkyl diamines into secondary alkyl amines to form a secondary amine-modified aqueous polyurethane epoxy emulsion. Subsequently, within the aqueous polyurethane epoxy emulsion particles, the secondary amino groups undergo a ring-opening addition (chain extension) reaction with the epoxy resin, increasing the molecular weight of the epoxy resin and producing a single-component polyurethane-modified epoxy resin emulsion. This single-component polyurethane-modified epoxy resin emulsion can be cured to form a paint film without the addition of an epoxy curing agent. Furthermore, because the chain extension reaction occurs within the emulsion core, the single-component polyurethane-modified epoxy resin emulsion is highly stable. DETAILED DESCRIPTION

[0036] The present application provides a method for preparing a one-component polyurethane-modified epoxy resin emulsion, comprising the following steps:

[0037] Mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent and polymerization inhibitor to obtain a mixed solution; the epoxy equivalent of the epoxy resin is ≥300 g / eq;

[0038] Mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate and an organic metal catalyst to carry out addition polymerization to obtain a polyurethane prepolymer;

[0039] The mixed solution is mixed with a polyurethane prepolymer to carry out an addition reaction, water is added for emulsification, and the ketone solvent is removed to obtain a waterborne polyurethane epoxy emulsion;

[0040] The waterborne polyurethane epoxy emulsion is mixed with alkyl diamine, and subjected to Michael addition-ring opening addition reaction to obtain a single-component polyurethane modified epoxy resin emulsion.

[0041] In this application, unless otherwise specified, the materials and equipment used are commercially available products in this field.

[0042] The present application mixes epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent and polymerization inhibitor to obtain a mixed solution; the epoxy equivalent of the epoxy resin is ≥300 g / eq.

[0043] In the present application, the monohydroxy acrylate preferably includes one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate, more preferably hydroxyethyl acrylate.

[0044] In the present application, the dialkyl maleate preferably includes one or more of diethyl maleate, dibutyl maleate, and diisooctyl maleate. In the present application, the molar ratio of the monohydroxy acrylate 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.

[0045] In the present application, the polymerization inhibitor preferably includes one or more of hydroquinone, tert-butyl catechol and p-hydroxyanisole, more preferably p-hydroxyanisole. In the present application, the mass of the polymerization inhibitor is preferably 0.1-1.5% of the mass of the monohydroxy acrylate, more preferably 0.5-1%, and more preferably 0.6-0.8%.

[0046] In the present application, the ketone solvent includes one or more of acetone, butanone and cyclohexanone, more preferably acetone.

[0047] 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.

[0048] 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 is preferably 80-100% of the total mass of the monohydroxy acrylate, dialkyl maleate, ketone solvent, and aprotic polar solvent, more preferably 85-95%, and most preferably 88-90%.

[0049] In the present application, after the mixing, the mixed slurry is preferably heated and refluxed until the epoxy resin is completely dissolved, thereby obtaining a mixed solution. In the present application, the temperature of the heating and reflux is preferably 30 to 90°C, more preferably 40 to 80°C, and most preferably 50 to 60°C. In the present application, the epoxy resin is dissolved in the monohydroxy acrylate and dialkyl maleate by heating and reflux to obtain a mixed solution.

[0050] In the present application, polyethylene glycol, polyether diol and / or polyester diol, diisocyanate and an organic metal catalyst are mixed and subjected to addition polymerization reaction to obtain a polyurethane prepolymer.

[0051] In the present application, the molecular weight of the polyethylene glycol is preferably 300-2000 Da, more preferably 500-1500 Da, and most preferably 550-1000 Da.

[0052] In the present application, the molecular weight of the polyether diol and polyester diol is preferably independently 1000-2000 Da. In the present application, the polyether diol preferably includes polypropylene glycol and / or polytetramethylene glycol; and the polyester diol is preferably a polyester diol based on adipic acid and an alkyl diol.

[0053] In the present application, the diisocyanate preferably includes one or more of toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, and trimethylhexane diisocyanate, and is more preferably toluene diisocyanate and / or isophorone diisocyanate. In the present application, the ratio of the sum of the amount of hydroxyl groups in the polyether diol and / or polyester diol and polyethylene glycol to the amount of isocyanate groups in the diisocyanate is preferably 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 amount of isocyanate groups in the diisocyanate to the amount of hydroxyl groups in the monohydroxy acrylate is preferably 1:0.3-0.5, more preferably 1:0.4.

[0054] The present application prepares polyurethane prepolymers with different structures and polarities by using polyethylene glycols of different molecular weights, polyether diols and / or polyester diols of different structures and molecular weights, and diisocyanates of different structures. The prepared one-component polyurethane-modified epoxy resin emulsion can adjust the polarity through polyurethane components of different structures to adapt to different uses (for example, according to the principle of like dissolves like, water is a polar liquid. If the polyurethane component has strong polarity, the epoxy resin emulsion is more soluble in water during use and has poor water resistance. Therefore, the low-polarity polyurethane component has better water resistance). The one-component polyurethane-modified epoxy resin emulsion has a wider adaptability.

[0055] In the present application, the organometallic catalyst preferably includes an organotin catalyst and / or an organobismuth catalyst. In the present application, the mass of the organometallic catalyst is preferably 0.001 to 0.1% of the mass of the diisocyanate, more preferably 0.01 to 0.5%, and most preferably 0.04 to 0.1%.

[0056] In the present application, the temperature of the addition polymerization reaction is preferably 60-90°C, more preferably 65-85°C, and most preferably 75-80°C; the time of the addition polymerization is preferably 2-6h, more preferably 3-5h, and most preferably 4h.

[0057] After obtaining the mixed solution and the polyurethane prepolymer, the present application mixes the mixed solution with the polyurethane prepolymer, performs an addition reaction, adds water for emulsification, and then removes the ketone solvent to obtain a waterborne polyurethane epoxy emulsion.

[0058] In the present application, the temperature of the addition reaction is preferably 60-90°C, more preferably 65-85°C, and most preferably 75-80°C; the time of the addition reaction is preferably 2-6 hours, more preferably 3-5 hours, and most preferably 4 hours. In the present application, during the addition reaction, the diisocyanate and the monohydroxy acrylate undergo an addition reaction, and the isocyanate group of the diisocyanate and the secondary hydroxyl group of the epoxy resin undergo an addition reaction.

[0059] The present application has no particular limitation on the amount of water, as long as the solid content of the aqueous polyurethane epoxy emulsion reaches 30-50 wt %. The solid content of the aqueous polyurethane epoxy emulsion is more preferably 35-45 wt %, and most preferably 40-43 wt %.

[0060] In the present application, the emulsification temperature is preferably 40-50°C, more preferably 42-48°C, and most preferably 43-45°C; the emulsification time is preferably 1-5h, more preferably 2-4h, and most preferably 3h.

[0061] In the present application, the method for removing the ketone solvent is preferably vacuum distillation. The present application does not specifically limit the conditions of the vacuum distillation, as long as the ketone solvent can be completely removed without damaging other components.

[0062] In this application, water-based polyurethane is introduced into an epoxy resin with an epoxy equivalent of ≥300g / eq through a covalent bond, which, on the one hand, increases the toughness of the epoxy resin and, on the other hand, realizes the self-emulsification of the epoxy resin, forming a core-shell structure with a hydrophilic polyurethane as the shell and an epoxy resin as the core, and an acrylic acid-terminated water-based polyurethane epoxy emulsion.

[0063] After obtaining the waterborne polyurethane epoxy emulsion, the present application mixes the waterborne polyurethane epoxy emulsion with an alkyl diamine and performs a Michael addition-ring-opening addition reaction to obtain a single-component polyurethane-modified epoxy resin emulsion.

[0064] In the present application, the alkyldiamine preferably includes 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 the monohydroxyacrylate and dialkyl maleate to the amount of the alkyldiamine is preferably 1:1. In the present application, the alkyldiamine is preferably used in the form of an aqueous solution of alkyldiamine, the concentration of which is preferably 50 wt%. The alkyldiamine is preferably added dropwise, with the addition time preferably being 1 to 6 hours, more preferably 2 to 5 hours, and most preferably 3 to 4 hours. The dropwise addition is preferably carried out at room temperature with stirring.

[0065] In the present application, the temperature of the Michael addition-ring-opening addition reaction is preferably ≤50°C, more preferably 25-40°C, and most preferably 30-35°C; the time of the Michael addition-ring-opening addition reaction is preferably 2-5 hours, more preferably 3-4 hours. In the present application, the Michael addition-ring-opening addition reaction includes a Michael addition reaction and a ring-opening addition reaction; the Michael addition reaction includes a Michael addition reaction of a dialkyl maleate and an alkyl diamine, and a Michael addition reaction of an acrylic acid terminal group and an alkyl diamine; the ring-opening reaction is a ring-opening addition reaction of a secondary amine group and an epoxy group in the waterborne polyurethane epoxy emulsion.

[0066] In the present application, the Michael addition-ring-opening addition reaction preferably includes a first Michael addition-ring-opening addition reaction and a second Michael addition-ring-opening addition reaction carried out in sequence. In the present application, the temperature of the first Michael addition-ring-opening addition reaction is preferably room temperature; the time of the first Michael addition-ring-opening addition reaction is preferably 1 to 2 hours, more preferably 1.2 to 1.8 hours, and most preferably 1.4 to 1.6 hours; the temperature of the second Michael addition-ring-opening addition reaction is preferably 40 to 50°C, more preferably 42 to 48°C, and most preferably 43 to 45°C; the time of the second Michael addition-ring-opening addition reaction is preferably 1 to 3 hours, more preferably 1.5 to 2.5 hours, and most preferably 1.8 to 2 hours.

[0067] The present application provides a one-component polyurethane-modified epoxy resin emulsion prepared by the preparation method described in the above technical solution.

[0068] The present application provides the use of the one-component polyurethane-modified epoxy resin emulsion described in the above technical solution in coatings and / or anti-corrosion materials.

[0069] In order to further illustrate the present application, the one-component polyurethane-modified epoxy resin emulsion provided by the present application, its preparation method and application are described in detail below in combination with examples, but they should not be understood as limiting the scope of protection of the present application.

[0070] In all the examples and comparative examples of the present application, epoxy resins E06, E03 and E20 were purchased from Jiangsu Sanmu Chemical Co., Ltd.; polyethylene glycol PEG1000, molecular weight 1000Da, was purchased from Shanghai Dongda Chemical Co., Ltd.; polypropylene glycol DL2000, molecular weight 2000Da, was purchased from Shandong Bluestar Dongda Co., Ltd.; and organic bismuth catalyst MC-710 was purchased from Beijing Baiyuan Chemical Co., Ltd.

[0071] Example 1

[0072] 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 added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0073] 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 isophorone diisocyanate were added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0074] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 17840 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by distillation under reduced pressure, and the temperature was cooled to room temperature to obtain an aqueous polyurethane epoxy emulsion (the aqueous polyurethane epoxy emulsion includes a mixture of epoxy resin, dialkyl maleate, and acrylate-terminated polyurethane).

[0075] Under room temperature and stirring conditions, 480 g of 50 wt% aqueous ethylenediamine solution was added dropwise to the above emulsion within 2 h. After the addition was complete, the mixture was reacted for 2 h, then heated to 50° C. and reacted for 2 h. The mixture was cooled to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0076] Example 2

[0077] 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 added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0078] 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 added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0079] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 18210 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0080] Under room temperature and stirring conditions, 704 g of 50% 1,4-butanediamine aqueous solution was added dropwise to the above emulsion within 2 hours. After the addition was completed, the reaction was carried out for 2 hours, and then the temperature was raised to 50° C. to react for 2 hours. The temperature was then lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0081] Example 3

[0082] 6660 g of solid epoxy resin E03, 696 g of hydroxyethyl acrylate, 1360 g of diisooctyl maleate, 2860 g of acetone, 2000 g of propylene glycol methyl ether acetate and 0.60 g of p-hydroxyanisole were added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0083] 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 isophorone diisocyanate were added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0084] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 17710 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0085] Under room temperature and stirring conditions, 880 g of 50 wt% 1,4-butanediamine aqueous solution was added dropwise to the above emulsion within 2 h. After the addition was completed, the reaction was carried out for 2 h. The temperature was then raised to 50° C. and the reaction was carried out for 2 h. The temperature was then lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0086] Example 4

[0087] 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 added to a reactor and heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0088] 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 isophorone diisocyanate were added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0089] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 16570 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0090] Under room temperature and stirring conditions, 480 g of 50 wt% aqueous ethylenediamine solution was added dropwise to the above emulsion within 4 h. After the addition was complete, the mixture was reacted for 2 h, then heated to 50° C. and reacted for 2 h. The mixture was cooled to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0091] Example 5

[0092] 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 added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0093] 2000 g of polyethylene glycol (PEG1000), 2000 g of dried polypropylene glycol (DL2000), 0.20 g of organic bismuth catalyst (MC-710), 667 g of isophorone diisocyanate and 349 g of toluene diisocyanate were added to the reactor, stirred evenly, heated to 75 ° C, and reacted for 4 hours to obtain a polyurethane prepolymer.

[0094] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 16570 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0095] Under room temperature and stirring conditions, 880 g of 50 wt% 1,4-butanediamine aqueous solution was added dropwise to the above emulsion within 2 h. After the addition was completed, the reaction was carried out for 2 h. The temperature was then raised to 50° C. and the reaction was carried out for 2 h. The temperature was then lowered to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0096] Comparative Example 1

[0097] 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 added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0098] 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 isophorone diisocyanate were added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0099] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 19145 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0100] Under room temperature and stirring conditions, 480 g of 50 wt% aqueous ethylenediamine solution was added dropwise to the above emulsion within 2 h. After the addition was complete, the mixture was reacted for 2 h, then heated to 50° C. and reacted for 2 h. The mixture was cooled to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0101] Comparative Example 2

[0102] 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 added to a reaction kettle, and the mixture was heated under reflux at 70° C. until the solid epoxy resin was completely dissolved to obtain a mixed solution.

[0103] 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 isophorone diisocyanate were added to a reactor, stirred evenly, heated to 75° C., and reacted for 4 h to obtain a polyurethane prepolymer.

[0104] The mixed solution was added to a reactor containing a polyurethane prepolymer, refluxed at 70°C for 3 hours, and then cooled to 40°C. 18470 g of water was added to the reactor, stirred at 40°C for 3 hours, acetone was removed by vacuum distillation, and the temperature was cooled to room temperature to obtain a waterborne polyurethane epoxy emulsion.

[0105] Under room temperature and stirring conditions, 480 g of 50 wt% aqueous ethylenediamine solution was added dropwise to the above emulsion within 2 h. After the addition was complete, the mixture was reacted for 2 h, then heated to 50° C. and reacted for 2 h. The mixture was cooled to room temperature to obtain a one-component polyurethane-modified epoxy resin emulsion.

[0106] Test Example 1

[0107] Table 1 lists the basic parameters of the one-component polyurethane-modified epoxy resin emulsions prepared in Examples 1-5 and Comparative Examples 1-2. Appearance, solids content, pH, viscosity, particle size, thermal storage stability, freeze-thaw stability, centrifugal stability, and dilution stability were tested in accordance with GB / T 11175-2021. The emulsion particle size was measured using a Zetasizer Nano ZS, with the emulsion diluted with water to 1 wt%. The viscosity was measured using a Brookfield DV1 viscometer at 25°C. The epoxy value of the emulsion was determined according to the hydrochloric acid-acetone method in accordance with GB-T 1677-2008. Volatile organic compounds were tested in accordance with GB / T 23986-2009. Storage stability: let it stand at 15-30℃ and observe whether there is precipitation; centrifugal stability: take 30mL of emulsion and place it in a centrifuge, and test the centrifugal stability of the emulsion at 3000r / min for 30min; hot storage stability: heat 100mL of emulsion at 50℃ for 12h, cool to room temperature and store for 12h, repeat the operation to observe whether there is precipitation; freeze-thaw stability: take 50mL of emulsion and place it in a -5±2℃ low temperature box, take it out after 18h, and place it at 23±2℃ for 6h, repeat the operation to observe whether there is precipitation; dilution stability: take 10mL of emulsion and dilute it to a solid content of 2-3wt%, let it stand at room temperature for 48h, and observe whether there is precipitation (blue light emulsion: the emulsion has its own blue light, which indicates that the particle size is smaller after dilution and the stability is good).

[0108] Table 1 Basic parameters of the one-component polyurethane modified epoxy resin emulsions prepared in Examples 1 to 5 and Comparative Examples 1 to 2

[0109] As shown in Table 1, the one-component polyurethane-modified epoxy resin emulsion prepared in this application has a smaller particle size and better stability, while the one-component polyurethane-modified epoxy resin emulsions prepared in Comparative Examples 1 and 2 have a larger particle size and poorer stability.

[0110] Example 6

[0111] The one-component polyurethane-modified epoxy resin emulsions prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were sprayed onto the surface of a steel plate, dried at room temperature for 30 minutes, dried at 90°C for 5 minutes, and dried at 180°C for 5 minutes, and then the paint film performance was tested (the paint film thickness was 55 to 60 μm). The test results are shown in Table 2, where the tests were conducted in accordance with the following test methods or standards: paint film pencil hardness, GB / T 6739-2006; paint film flexibility, GB / T 1731-2020; adhesion by cross-hatch method, GB / T 9286-2021; wet film adhesion: the test panel was immersed in distilled water at 25°C for 144 hours, and then the adhesion was tested by cross-hatch method after drying; salt spray resistance, GB / T 1771-2007.

[0112] Table 2 Paint film performance test results

[0113] As shown in Table 2, the one-component polyurethane-modified epoxy resin emulsion prepared in this application can be directly dried and cured without a curing agent, producing a paint film with suitable hardness, good flexibility, good adhesion, and excellent salt spray resistance. In contrast, the paint films prepared in Comparative Examples 1 and 2 had a grainy appearance and exhibited low hardness, adhesion, and salt spray resistance.

[0114] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A method for preparing a one-component polyurethane-modified epoxy resin emulsion, characterized in that: The following steps are involved: Mixing epoxy resin, monohydroxy acrylate, dialkyl maleate, ketone solvent, aprotic polar solvent and polymerization inhibitor to obtain a mixed solution; the epoxy equivalent of the epoxy resin is ≥300 g / eq; Mixing polyethylene glycol, polyether diol and / or polyester diol, diisocyanate and an organic metal catalyst to carry out addition polymerization to obtain a polyurethane prepolymer; The mixed solution is mixed with a polyurethane prepolymer to carry out an addition reaction, water is added for emulsification, and the ketone solvent is removed to obtain a waterborne polyurethane epoxy emulsion; The waterborne polyurethane epoxy emulsion is mixed with alkyl diamine to carry out Michael addition-ring opening addition reaction to obtain a single-component polyurethane modified epoxy resin emulsion.

2. The preparation method according to claim 1, characterized in that: The monohydroxy acrylate includes one or more of hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxybutyl acrylate; The dialkyl maleate includes one or more of diethyl maleate, dibutyl maleate and diisooctyl maleate; The ketone solvent includes one or more of acetone, butanone and cyclohexanone; The polymerization inhibitor includes one or more of hydroquinone, tert-butylcatechol and p-hydroxyanisole.

3. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the monohydroxy acrylate to the dialkyl maleate is 0.5-1:0.5-1; The mass of the polymerization inhibitor is 0.1 to 1.5% of the mass of the monohydroxy acrylate; The mass of the epoxy resin is 80-100% of the total mass of the monohydroxy acrylate, dialkyl maleate, ketone solvent and aprotic polar solvent.

4. The preparation method according to claim 1, characterized in that: 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.

5. The preparation method according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 300 to 2000 Da; The molecular weights of the polyether diol and the polyester diol are independently 1000-2000 Da; the polyether diol includes polypropylene glycol and / or polytetramethylene glycol; The diisocyanates include toluene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate One or more of diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate and trimethylhexane diisocyanate; The organometallic catalyst includes an organotin catalyst and / or an organobismuth catalyst; The ratio of the sum of the amount 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 to 0.8:1; The mass of the organic metal catalyst is 0.001 to 0.1% of the mass of the diisocyanate; The molar ratio of the isocyanate group in the diisocyanate to the hydroxyl group in the monohydroxy acrylate is 1:0.3-0.

5.

6. The preparation method according to claim 1 or 5, characterized in that: The polyester diol is a polyester diol prepared from adipic acid and alkyl diol.

7. The preparation method according to claim 1 or 5, characterized in that: The temperature of the addition polymerization reaction is 60-90° C., and the time is 2-6 hours.

8. The preparation method according to claim 1, characterized in that: The solid content of the aqueous polyurethane epoxy emulsion is 30 to 50 wt %; The temperature of the addition reaction is 60-90° C. and the time is 2-6 hours.

9. The preparation method according to claim 1 or 8, characterized in that: The emulsification temperature is 40-50° C. and the emulsification time is 1-5 hours.

10. The preparation method according to claim 1, characterized in that: The alkyl diamine includes one or more of ethylenediamine, 1,4-butanediamine and 1,6-hexanediamine; The ratio of the sum of the amounts of the monohydroxy acrylate and the dialkyl maleate to the amount of the alkyl diamine is 1:1; The temperature of the Michael addition-ring-opening addition reaction is ≤50°C and the time is 2 to 5 hours.

11. The preparation method according to claim 1 or 10, characterized in that: 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 performed in sequence; the temperature of the first Michael addition-ring-opening addition reaction is room temperature, and the time is 1 to 2 hours; The temperature of the second Michael addition-ring-opening addition reaction is 40-50° C., and the time is 1-3 hours.

12. A one-component polyurethane-modified epoxy resin emulsion prepared by the preparation method according to any one of claims 1 to 11.

13. Use of the one-component polyurethane-modified epoxy resin emulsion according to claim 12 in coatings.

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