Monoether amine modified nonionic waterborne epoxy emulsion as well as preparation and application thereof

Abstract

The invention discloses a monoether amine modified nonionic waterborne epoxy emulsion as well as preparation and application thereof, and belongs to the field of waterborne industrial anticorrosive coatings. The monoether amine modified nonionic waterborne epoxy emulsion is prepared from the following raw materials: E-20 epoxy resin, dipropylene glycol monomethyl ether, ethylene glycol monobutyl ether, monoether amine, propylene glycol monomethyl ether, a nonionic epoxy emulsifier and deionized water. The nonionic waterborne epoxy emulsion disclosed by the invention is prepared by modifying monoether amine and emulsifying by adopting a nonionic emulsifier, and the prepared nonionic waterborne epoxy emulsion is uniform in appearance, free of mechanical impurities, less than or equal to 0.50 mu m in particle size and 7-8 in pH value.

Description

Technical Field

[0001] The invention belongs to the field of water-based industrial anticorrosive coatings, and specifically relates to a monoetheramine-modified nonionic water-based epoxy emulsion and a preparation method and application thereof. Background Art

[0002] With the increasing awareness of environmental protection, the trend of "oil out and water in" in the coatings industry has become a general trend. Waterborne epoxy anti-corrosion coatings are one of the most widely used anti-corrosion primers due to their low VOC content, high adhesion and good corrosion resistance. However, their key raw materials, waterborne epoxy emulsions and curing agents, are mainly monopolized by foreign companies such as Hanson and Huntsman in the United States, especially in the field of waterborne epoxy industrial paints with high salt spray resistance requirements.

[0003] Traditional waterborne epoxy coatings are mainly a mixture of waterborne epoxy resin emulsion and filler particle dispersion, and then made into two-component epoxy anticorrosive coatings by adding various performance additives, pigments, fillers, etc., in order to achieve the required construction performance, film quality and stable storage period. The research on waterborne epoxy coatings mainly adopts methods such as epoxy water-based, epoxy structure modification, expansion monomer modification, and filling with inorganic fillers to improve the performance of epoxy resin, improve its adhesion to metal, and chemical resistance and oil resistance. However, due to the poor outdoor weather resistance of epoxy resin, the paint film is easy to powder, lose gloss, and has poor fullness, so traditional waterborne epoxy coatings are often used as primers, and their large-scale application is limited.

[0004] The physical properties of epoxy resin itself determine that it is insoluble in water. If epoxy resin is made water-based without changing the molecular structure of the epoxy resin itself, the only way is to use emulsification technology to make epoxy resin into a dispersion or emulsion. How to select an emulsifier or prepare an epoxy-specific emulsifier becomes a technical difficulty. From a thermodynamic point of view, epoxy dispersions or emulsions are in a non-thermodynamic equilibrium state and are in a metastable state. Water-based epoxies are prone to demulsification, water separation, and agglomeration. Improving the stability of water-based epoxies and extending the storage period become technical difficulties. If the molecular structure of epoxy resin is changed, hydrophilic functional groups are introduced, and epoxy resin is made water-based, epoxy resin can be made into a self-emulsifying water-based epoxy dispersion, but the change in molecular structure often also means a huge change in performance. The introduction of such hydrophilic groups will lead to a significant decrease in the water resistance and corrosion resistance of epoxy resins. How to control the amount of hydrophilic functional groups introduced and the related process parameters and formulas of grafting modification are also the main technical difficulties faced.

[0005] The existing water-based epoxy resin preparation methods are mainly divided into two types: external emulsification method and self-emulsification method, each with its own advantages and disadvantages. The external emulsification method is to use the method of adding an external surfactant to forcibly emulsify the epoxy resin under high shear to obtain a water-based epoxy resin emulsion. The product prepared by this method has a large particle size and poor storage stability and water resistance. The self-emulsification method uses the reactivity of the active groups of the epoxy resin to introduce hydrophilic groups or segments into the epoxy resin molecules, thereby increasing the hydrophilic-lipophilic balance value and enabling it to be freely dispersed in water. In the self-emulsification method, it can be divided into: salt formation method and non-ionic modification method; among them, the water-based epoxy resin emulsion prepared by the salt formation method has the disadvantages of being sensitive to pH value, poor water resistance, and poor anti-corrosion effect; the non-ionic modification method is to introduce hydrophilic polyoxyethylene segments into the epoxy resin molecular skeleton by appropriate methods to obtain a modified epoxy resin containing hydrophilic segments, and then make it self-dispersed in water. The non-ionic modification method does not require an external emulsifier, and the prepared water-based epoxy resin emulsion has good stability, small particle size, and excellent comprehensive performance of the coating film, so it is suitable for practical application. After searching, most of the epoxy resin water-based patents currently applied in China are mainly based on anionic water-based epoxy emulsions and cationic water-based epoxy emulsions, and there are few related patent technologies for preparing non-ionic water-based epoxy emulsions by chemical reaction method modified by monoether amine. Summary of the invention

[0006] The purpose of the present invention is to provide a monoetheramine-modified nonionic waterborne epoxy emulsion and its preparation and application in view of the shortcomings of the prior art pointed out in the background technology. The nonionic waterborne epoxy emulsion of the present invention selects monoetheramine-modified epoxy resin and is prepared by emulsification using a nonionic epoxy emulsifier.

[0007] In order to achieve the above object, the present invention adopts the following technical solution: The invention provides a monoetheramine-modified nonionic waterborne epoxy emulsion, which is composed of the following raw materials in parts by weight: 43-47 parts of E-20 epoxy resin, 2-4 parts of dipropylene glycol methyl ether, 6-8 parts of ethylene glycol monobutyl ether, 1.5-3 parts of monoetheramine, 2-6 parts of propylene glycol methyl ether, 10-12.5 parts of nonionic epoxy emulsifier and 25-30 parts of deionized water.

[0008] Furthermore, the nonionic epoxy emulsifier is composed of the following raw materials in parts by weight: 40-44 parts of polyethylene glycol 8000, 2-4 parts of E-44 epoxy resin, 3-6 parts of E-20 epoxy resin, 2-5 parts of propylene glycol methyl ether, 0.2-0.5 parts of catalyst, 6-8.3 parts of dipropylene glycol methyl ether, and 37.5-41.5 parts of deionized water.

[0009] Furthermore, the catalyst is boron trifluoride etherate.

[0010] Furthermore, the preparation method of the nonionic epoxy emulsifier comprises the following specific steps: (1) Place polyethylene glycol 8000 and E-44 epoxy resin into a clean reactor, heat to 55-65°C, stir until the materials are completely melted, and heat to 100-110°C while evacuating the reactor, and keep warm for 60 minutes; (2) After vacuuming, cool to 60-65°C and add a mixed solution of propylene glycol methyl ether containing boron trifluoride ethyl ether dropwise within 15-30 minutes; (3) Slowly and evenly raise the temperature to 90-95°C, keep warm for 1 hour, and take samples to test the water dispersibility; if the water dispersion is unqualified, continue to add the second portion of the mixed solution of propylene glycol methyl ether containing boron trifluoride ether and keep warm for 1 hour, and so on, until the water dispersion is qualified; (4) After the water dispersion is qualified, add E-20 epoxy resin; after the E-20 epoxy resin is melted, add propylene glycol methyl ether solution containing boron trifluoride etherate at 90-95°C, raise the temperature to 95-105°C and keep it warm for 1 hour, take a sample to measure the water dispersibility, and add the mixed solution of propylene glycol methyl ether containing boron trifluoride etherate after the water dispersibility is qualified, and keep it warm at 100-110°C for 2.5 hours; (5) After the insulation is completed, cool the mixture to below 100°C, add dipropylene glycol methyl ether and deionized water to dilute the mixture, and then keep the mixture at 80-90°C for 15 minutes.

[0011] The present invention also provides a method for preparing the above-mentioned monoetheramine-modified nonionic waterborne epoxy emulsion, the specific steps of which are as follows: (1) Add E-20 epoxy resin, dipropylene glycol methyl ether and ethylene glycol monobutyl ether in a clean reactor in order, raise the temperature to 50-60°C, stir and maintain at 60-70°C until all the materials are melted; (2) At 60-70°C, add monoetheramine and propylene glycol methyl ether, and heat uniformly to 90-100°C and keep warm for 1 hour; (3) Cool down to 85°C, add non-ionic epoxy emulsifier in four batches, add each batch once every 30 minutes, control the temperature at 80-90°C, and after adding non-ionic epoxy emulsifier, raise the temperature to 88-92°C and keep warm for 30 minutes; (4) Cool down to 85°C and evenly add deionized water. The final temperature is maintained at 80-83°C during the addition. Add the water evenly within 2.5-3.0 hours. After adding the deionized water, keep it at 80°C for 2 hours, cool down to 60°C, filter, and package.

[0012] The present invention also provides the use of the non-ionic water-based epoxy emulsion in the preparation of water-based epoxy anticorrosive coatings.

[0013] A water-based epoxy anticorrosive coating, composed of the following raw materials in parts by weight: Component A: 18-22.6 parts of deionized water, 0.8-1.2 parts of dispersant, 0.2-0.4 parts of silicone defoamer, 0.2-0.4 parts of leveling agent, 0.1-0.5 parts of water-based bentonite, 8-12 parts of rutile titanium dioxide, 0.1-0.3 parts of phthalocyanine blue, 0.2-0.4 parts of carbon black, 8-12 parts of 1250 mesh precipitated barium sulfate, 2-5 parts of sericite powder, 7-11 parts of zinc phosphate, 40-50 parts of monoetheramine modified water-based epoxy emulsion; Component B: 8-12 parts of water-based epoxy curing agent.

[0014] Compared with the prior art, the beneficial technical effects of the present invention are: (1) The nonionic waterborne epoxy emulsion of the present invention is modified with monoetheramine and prepared by emulsification with a nonionic emulsifier. The prepared nonionic waterborne epoxy emulsion has a uniform appearance, is free of mechanical impurities, has a particle size of ≤0.50 μm, and a pH value of 7-8.

[0015] (2) The nonionic waterborne epoxy emulsion of the present invention has a simple synthesis process, low overall cost, and is suitable for industrial large-scale production.

[0016] (3) The performance of the waterborne epoxy anticorrosive coating prepared by using the non-ionic waterborne epoxy emulsion of the present invention meets the coating technical index requirements of the industry and the fields of petrochemical and coal metallurgy. DETAILED DESCRIPTION

[0017] The technical solution of the present invention will be described clearly and completely in conjunction with the embodiments below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Example 1 A monoetheramine-modified nonionic waterborne epoxy emulsion is composed of the following raw materials, measured by weight: 43 g of E-20 epoxy resin, 2 g of dipropylene glycol methyl ether, 6 g of ethylene glycol monobutyl ether, 3 g of monoetheramine, 6 g of propylene glycol methyl ether, 10 g of nonionic epoxy emulsifier and 30 g of deionized water.

[0019] The nonionic epoxy emulsifier is composed of the following raw materials in parts by weight: 40g of polyethylene glycol 8000, 4g of E-44 epoxy resin, 6g of E-20 epoxy resin, 2g of propylene glycol methyl ether, 0.5g of catalyst, 6g of dipropylene glycol methyl ether, and 41.5g of deionized water, wherein the catalyst is boron trifluoride ether.

[0020] Put polyethylene glycol 8000 and E-44 epoxy resin into a clean reactor, heat it to 55℃, stir until the materials are completely melted, and then heat it to 100℃ while vacuuming, and keep it warm for 60min; after vacuuming, cool it to 60℃, and add a mixed solution of propylene glycol methyl ether containing boron trifluoride ether within 30min; slowly heat it to 90℃, keep it warm for 1h, and take samples to test the water dispersibility; if the water dispersion is unqualified, continue to add the second portion of the mixed solution of propylene glycol methyl ether containing boron trifluoride ether and keep it warm for 1h, and so on, until the water dispersion is qualified; after the water dispersion is qualified, add E-20 epoxy resin; after the E-20 epoxy resin is melted, Add propylene glycol methyl ether solution containing boron trifluoride ethyl ether dropwise at 90°C, raise the temperature to 95°C and keep warm for 1 hour, take samples to measure water dispersibility, add propylene glycol methyl ether mixed solution containing boron trifluoride ethyl ether after the water dispersibility is qualified, and keep warm at 100°C for 2.5 hours; after the insulation is completed, cool to below 100°C, add dipropylene glycol methyl ether and deionized water to dilute, and keep warm at 80°C for 15 minutes to obtain non-ionic epoxy emulsifier.

[0021] In a clean reactor, E-20 epoxy resin, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether are sequentially added, ventilated and heated to 60°C, stirred and maintained at 70°C until all the materials are melted; at 60°C, monoetheramine and propylene glycol methyl ether are added, and the temperature is uniformly raised to 90°C and kept warm for 1h; the temperature is lowered to 85°C, and non-ionic epoxy emulsifier is added in four batches, each batch is added once every 30min, and the temperature is controlled at 90°C. After the non-ionic epoxy emulsifier is added, the temperature is raised to 92°C and kept warm for 30min; the temperature is lowered to 85°C, and deionized water is uniformly added dropwise, and the final temperature is maintained at 80°C during the addition. The uniform addition is completed within 3h, and the temperature is maintained at 80°C for 2h after the deionized water is added, and the temperature is lowered to 60°C, filtered, and packaged. After testing, the non-ionic water-based epoxy emulsion prepared in this embodiment has a uniform appearance, no mechanical impurities, an average particle size of 400nm, and a pH value of 7.2.

[0022] Example 2 A monoetheramine-modified nonionic waterborne epoxy emulsion is composed of the following raw materials, measured by weight: 45 g of E-20 epoxy resin, 3 g of dipropylene glycol methyl ether, 7 g of ethylene glycol monobutyl ether, 2.5 g of monoetheramine, 4 g of propylene glycol methyl ether, 11 g of nonionic epoxy emulsifier and 27.50 g of deionized water.

[0023] The nonionic epoxy emulsifier is composed of the following raw materials by weight: 42.5 g of polyethylene glycol 8000, 3 g of E-44 epoxy resin, 4 g of E-20 epoxy resin, 3.5 g of propylene glycol methyl ether, 0.3 g of catalyst, 6.5 g of dipropylene glycol methyl ether, and 40.2 g of deionized water, wherein the catalyst is boron trifluoride ether.

[0024] Put polyethylene glycol 8000 and E-44 epoxy resin into a clean reactor, heat it to 60℃, stir until the materials are completely melted, and then heat it to 105℃ while vacuuming, and keep it warm for 60min; after vacuuming, cool it to 63℃, and add a mixed solution of propylene glycol methyl ether containing boron trifluoride ether within 23min; slowly heat it to 92℃, keep it warm for 1h, and take samples to test the water dispersibility; if the water dispersion is unqualified, continue to add the second portion of the mixed solution of propylene glycol methyl ether containing boron trifluoride ether and keep it warm for 1h, and so on, until the water dispersion is qualified; after the water dispersion is qualified, add E-20 epoxy resin; after the E-20 epoxy resin is melted, Add propylene glycol methyl ether solution containing boron trifluoride ethyl ether dropwise at 93°C, raise the temperature to 100°C and keep warm for 1 hour, take samples to measure water dispersibility, add propylene glycol methyl ether mixed solution containing boron trifluoride ethyl ether after the water dispersibility is qualified, and keep warm at 105°C for 2.5 hours; after the insulation is completed, cool to below 100°C, add dipropylene glycol methyl ether and deionized water to dilute, and keep warm at 85°C for 15 minutes to obtain non-ionic epoxy emulsifier.

[0025] In a clean reactor, E-20 epoxy resin, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether are sequentially added, ventilated and heated to 55°C, stirred and maintained at 65°C until all the materials are melted; at 65°C, monoetheramine and propylene glycol methyl ether are added, and the temperature is uniformly raised to 95°C for 1h; the temperature is lowered to 85°C, and non-ionic epoxy emulsifier is added in four batches, each batch is added once every 30min, and the temperature is controlled at 85°C. After the non-ionic epoxy emulsifier is added, the temperature is raised to 90°C for 30min; the temperature is lowered to 85°C, and deionized water is uniformly added dropwise. The final temperature during the addition is maintained at 81.5°C, and the uniform addition is completed within 2.7h. After the deionized water is added, it is maintained at 80°C for 2h, cooled to 60°C, filtered, and packaged. After testing, the non-ionic waterborne epoxy emulsion prepared in this embodiment has a uniform appearance, no mechanical impurities, an average particle size of 320nm, and a pH value of 7.5.

[0026] Example 3 A monoetheramine-modified nonionic waterborne epoxy emulsion is composed of the following raw materials, measured by weight: 47 g of E-20 epoxy resin, 4 g of dipropylene glycol methyl ether, 8 g of ethylene glycol monobutyl ether, 1.5 g of monoetheramine, 2 g of propylene glycol methyl ether, 12.5 g of nonionic epoxy emulsifier and 25 g of deionized water.

[0027] The nonionic epoxy emulsifier is composed of the following raw materials by weight: 44g polyethylene glycol 8000, 2g E-44 epoxy resin, 3g E-20 epoxy resin, 5g propylene glycol methyl ether, 0.2g catalyst, 8.3g dipropylene glycol methyl ether, and 37.5g deionized water, wherein the catalyst is boron trifluoride ether.

[0028] Put polyethylene glycol 8000 and E-44 epoxy resin into a clean reactor, heat it to 65℃, stir until the materials are completely melted, and then heat it to 110℃ while vacuuming, keep it warm for 60min, and the final vacuum degree is not less than 0.065MPa; after vacuuming, cool it to 65℃, and add a mixed solution of propylene glycol methyl ether containing boron trifluoride ether within 15min; slowly heat it to 95℃, keep it warm for 1h, and take samples to test the water dispersibility; if the water dispersion is unqualified, continue to add the second portion of the mixed solution of propylene glycol methyl ether containing boron trifluoride ether and keep it warm for 1h, and so on, until the water dispersion is qualified; after the water dispersion is qualified, add E-20 epoxy resin; after the E-20 epoxy resin is melted, Add propylene glycol methyl ether solution containing boron trifluoride ethyl ether dropwise at 95°C, raise the temperature to 105°C and keep warm for 1 hour, take samples to measure water dispersibility, add propylene glycol methyl ether mixed solution containing boron trifluoride ethyl ether after the water dispersibility is qualified, and keep warm at 110°C for 2.5 hours; after the insulation is completed, cool to below 100°C, add dipropylene glycol methyl ether and deionized water to dilute, and keep warm at 90°C for 15 minutes to obtain non-ionic epoxy emulsifier.

[0029] In a clean reactor, E-20 epoxy resin, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether are sequentially added, ventilated and heated to 50°C, stirred and maintained at 60°C until all the materials are melted; at 70°C, monoetheramine and propylene glycol methyl ether are added, and the temperature is uniformly raised to 100°C and kept warm for 1h; the temperature is lowered to 85°C, and non-ionic epoxy emulsifier is added in four batches, each batch is added once every 30min, and the temperature is controlled at 80°C. After the non-ionic epoxy emulsifier is added, the temperature is raised to 88°C and kept warm for 30min; the temperature is lowered to 85°C, and deionized water is uniformly added dropwise, and the final temperature is maintained at 83°C during the addition. The uniform addition is completed within 2.5h, and the temperature is maintained at 80°C for 2h after the deionized water is added, and the temperature is lowered to 60°C, filtered, and packaged. After testing, the non-ionic water-based epoxy emulsion prepared in this embodiment has a uniform appearance, no mechanical impurities, an average particle size of 380nm, and a pH value of 7.8.

[0030] Example 4 20.2 g of deionized water, 0.8 g of dispersant, 0.2 g of silicone defoamer, 0.2 g of leveling agent, 0.1 g of water-based bentonite, 10 g of rutile titanium dioxide, 0.3 g of phthalocyanine blue, 0.2 g of carbon black, 12 g of 1250 mesh precipitated barium sulfate, 5 g of sericite powder and 11 g of zinc phosphate were sequentially put into a stirring kettle, and stirred at a speed of 1500-2000 r / min for 2 h to obtain a water slurry; 40 g of monoether amine-modified water-based epoxy emulsion was added to the prepared water slurry, mixed evenly to obtain component A, and component A was mixed with 12 g of water-based epoxy curing agent to prepare a water-based epoxy anti-corrosion coating.

[0031] Example 5 22.6 g of deionized water, 1 g of dispersant, 0.3 g of silicone defoamer, 0.3 g of leveling agent, 0.3 g of water-based bentonite, 8 g of rutile titanium dioxide, 0.2 g of phthalocyanine blue, 0.3 g of carbon black, 10 g of 1250 mesh precipitated barium sulfate, 3 g of sericite powder and 9 g of zinc phosphate were sequentially put into a stirring kettle, and stirred at a speed of 1500-2000 r / min for 2 h to obtain a water slurry; 45 g of monoether amine-modified water-based epoxy emulsion was added to the prepared water slurry, mixed evenly to obtain component A, and component A was mixed with 10 g of water-based epoxy curing agent to prepare a water-based epoxy anti-corrosion coating.

[0032] Example 6 18 g of deionized water, 1.2 g of dispersant, 0.4 g of silicone defoamer, 0.4 g of leveling agent, 0.5 g of water-based bentonite, 12 g of rutile titanium dioxide, 0.1 g of phthalocyanine blue, 0.4 g of carbon black, 8 g of 1250 mesh precipitated barium sulfate, 2 g of sericite powder and 7 g of zinc phosphate were sequentially put into a stirring kettle, and stirred at a speed of 1500-2000 r / min for 2 h to obtain a water slurry; 50 g of monoether amine-modified water-based epoxy emulsion was added to the prepared water slurry, mixed evenly to obtain component A, and component A was mixed with 8 g of water-based epoxy curing agent to prepare a water-based epoxy anti-corrosion coating.

[0033] Comparative Example Different from Example 4, in this comparative example, a commercially available epoxy emulsion is used to replace the monoetheramine-modified waterborne epoxy emulsion in Example 4 in equal amounts to prepare component A of the industrial anticorrosive coating, and a waterborne epoxy curing agent is used to prepare an industrial anticorrosive coating. The coatings of Examples 4-6 and the comparative example were tested for performance, and the results are shown in the following table.

[0034] Water resistance Salt spray resistance Touch Dry Get down to business Example 1 432 hours 672 hours 40 minutes 16 hours Example 2 480 hours 624 hours 30 minutes 16 hours Example 3 480 hours 720 hours 30 minutes 16 hours Comparative Example 1 240 hours 300 hours 60 minutes 24 hours In comparison, the waterborne epoxy anticorrosive coating of the present invention has significantly improved water resistance and salt spray resistance, and shortened surface drying and actual drying time due to the use of monoetheramine modified waterborne epoxy emulsion. It can be seen that the performance index of the waterborne epoxy anticorrosive coating prepared by the present invention using monoetheramine modified waterborne epoxy emulsion exceeds the industry standard requirements of traditional solvent-based epoxy resin coatings and waterborne epoxy resin anticorrosive coatings, and solves the problem of unstable performance of conventional waterborne epoxy emulsions.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the technical solution and conceptual invention of the present invention should be included in the protection scope of the present invention.

Claims

1. A monoetheramine-modified nonionic aqueous epoxy emulsion, characterized in that: The invention is composed of the following raw materials in parts by weight: 43-47 parts of E-20 epoxy resin, 2-4 parts of dipropylene glycol methyl ether, 6-8 parts of ethylene glycol monobutyl ether, 1.5-3 parts of monoether amine, 2-6 parts of propylene glycol methyl ether, 10-12.5 parts of nonionic epoxy emulsifier and 25-30 parts of deionized water; The nonionic epoxy emulsifier is composed of the following raw materials in parts by weight: 40-44 parts of polyethylene glycol 8000, 2-4 parts of E-44 epoxy resin, 3-6 parts of E-20 epoxy resin, 2-5 parts of propylene glycol methyl ether, 0.2-0.5 parts of catalyst, 6-8.3 parts of dipropylene glycol methyl ether, and 37.5-41.5 parts of deionized water; The catalyst is boron trifluoride etherate.

2. The monoetheramine-modified nonionic aqueous epoxy emulsion according to claim 1, characterized in that: The preparation method of the nonionic epoxy emulsifier comprises the following specific steps: (1) Put polyethylene glycol 8000 and E-44 epoxy resin into a clean reactor, heat it to 55-65°C, stir until the materials are completely melted, and then heat it to 100-110°C while evacuating the vacuum, and keep it warm for 60 minutes; (2) After the vacuuming is completed, the temperature is lowered to 60-65° C., and a mixed solution of propylene glycol methyl ether containing boron trifluoride ethyl ether is added dropwise within 15-30 minutes; (3) Slowly and evenly raise the temperature to 90-95°C, keep warm for 1 hour, and take samples to test the water dispersibility; if the water dispersion is unqualified, continue to dropwise add the second portion of the mixed solution of propylene glycol methyl ether containing boron trifluoride ether and keep warm for 1 hour, and so on, until the water dispersion is qualified; (4) After the water dispersion is qualified, add E-20 epoxy resin; after the E-20 epoxy resin is melted, add propylene glycol methyl ether solution containing boron trifluoride etherate at 90-95°C, raise the temperature to 95-105°C and keep it warm for 1 hour, take a sample to measure the water dispersibility, and add the mixed solution of propylene glycol methyl ether containing boron trifluoride etherate after the water dispersibility is qualified, and keep it warm at 100-110°C for 2.5 hours; (5) After the heat preservation is completed, the temperature is lowered to below 100°C, dipropylene glycol methyl ether and deionized water are added to dilute, and the mixture is kept at 80-90°C for 15 minutes.

3. A method for preparing the monoetheramine-modified nonionic aqueous epoxy emulsion according to claim 1 or 2, characterized in that: The specific steps are as follows: (1) Add E-20 epoxy resin, dipropylene glycol methyl ether, and ethylene glycol monobutyl ether in order into a clean reactor, raise the temperature to 50-60° C., stir and maintain at 60-70° C. until all the materials are melted; (2) At 60-70°C, add monoetheramine and propylene glycol methyl ether, and uniformly raise the temperature to 90-100°C and keep warm for 1 hour; (3) Cooling to 85°C, adding nonionic epoxy emulsifier in four batches, adding each batch once every 30 minutes, controlling the temperature at 80-90°C, and raising the temperature to 88-92°C and keeping the temperature for 30 minutes after adding the nonionic epoxy emulsifier; (4) Cool down to 85°C, evenly add deionized water, and keep the final temperature at 80-83°C during the addition. Add the deionized water evenly within 2.5-3.0 hours. After adding the deionized water, keep the temperature at 80°C for 2 hours, cool down to 60°C, filter, and package.

4. Use of the monoetheramine-modified nonionic waterborne epoxy emulsion as claimed in claim 1 or 2 in the preparation of waterborne epoxy anticorrosive coatings.

5. A water-based epoxy anticorrosive coating, characterized in that: The invention comprises the monoetheramine-modified nonionic aqueous epoxy emulsion according to any one of claims 1 to 2 or the monoetheramine-modified nonionic aqueous epoxy emulsion prepared by the preparation method according to claim 3.

6. A waterborne epoxy anticorrosive coating according to claim 5, characterized in that: By weight, it is composed of the following raw materials: Component A: 18-22.6 parts of deionized water, 0.8-1.2 parts of dispersant, 0.2-0.4 parts of organosilicon defoamer, 0.2-0.4 parts of leveling agent, 0.1-0.5 parts of water-based bentonite, 8-12 parts of rutile titanium dioxide, 0.1-0.3 parts of phthalocyanine blue, 0.2-0.4 parts of carbon black, 8-12 parts of 1250 mesh precipitated barium sulfate, 2-5 parts of sericite powder, 7-11 parts of zinc phosphate, 40-50 parts of monoetheramine modified water-based epoxy emulsion; Component B: 8-12 parts of water-based epoxy curing agent.