Self-emulsifying polyether amine curing agent, preparation method and application thereof

Abstract

The application discloses a self-emulsifying polyether amine curing agent and a preparation method and application thereof, and belongs to the field of high polymer materials. According to the application, components A-F are composed of polypropylene glycol or polytetrahydrofuran glycol with a molecular weight range of 800-2000, component B is selected from at least one of isophorone diamine, dicyclohexyl methane diamine or xylylenediamine, component C is at least one of epoxy derivatives containing long-chain alkyl and aromatic ring structures, component D is polyethylene glycol monomethyl ether amine with a polymerization degree range of 2-5 or an amine compound containing a sulfonic acid group, component E is a tertiary amine compound, and component F is at least one of a hindered phenol antioxidant and a phosphite antioxidant. The curing agent is reliably enhanced in reaction activity at normal temperature, the nucleophilic activity of terminal amino groups is significantly improved while excellent water dispersibility is maintained, and thus the curing rate at normal temperature is greatly accelerated.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a self-emulsifying polyetheramine curing agent, its preparation method, and its application. Background Technology

[0002] Polyetheramine curing agents are core epoxy curing materials with low viscosity, high flexibility, excellent compatibility, and controllable reactivity. They are widely used in water-based anti-corrosion coatings, wind power composite materials, building protective coatings, conductive adhesives, and many other fields. With the continuous upgrading of global environmental protection policies, low VOC, solvent-free, and water-based curing agents have become the mainstream development trend in the curing agent industry. Water-based modified polyetheramine curing agents have gradually replaced traditional solvent-based curing agents and have become a key focus of industry research and development and industrialization.

[0003] In existing waterborne polyetheramine curing agent modification technologies, to address issues such as poor water dispersibility, easy system stratification, and insufficient emulsification stability, the industry commonly employs modification methods that introduce long-chain hydrophilic groups. This increases the hydrophilic content of the molecular structure to ensure the stability of the waterborne system. However, this modification method has inherent technical drawbacks. The long-chain flexible hydrophilic groups create a significant spatial encapsulation and physical shielding effect on the nucleophilic active centers of the amino groups at the ends of the polyetheramine molecules, greatly hindering the nucleophilic addition reaction between the amino active groups and the epoxy groups of the epoxy resin. This directly leads to a significant decrease in the room temperature curing rate of the curing agent. Conventional highly hydrophilic modified polyetheramine curing agents exhibit a 30% to 50% decrease in room temperature curing efficiency compared to unmodified products, and commonly suffer from slow surface drying, long drying cycles, low-temperature curing failure, and insufficient crosslinking density. Furthermore, the large-scale introduction of hydrophilic groups also increases the water absorption rate of the cured coating and reduces its water resistance and damp heat resistance, creating a technical contradiction where water dispersibility, curing activity, and coating durability cannot be simultaneously achieved. Existing conventional modification technologies struggle to achieve a synergistic balance among these three aspects.

[0004] On the other hand, waterborne polyetheramine curing agents are often compounded with highly reactive metal powders such as zinc powder and aluminum powder to prepare functional coating materials, which are widely used in heavy-duty anti-corrosion, conductivity, and electromagnetic shielding applications. However, existing technologies lack effective interface isolation mechanisms adapted to highly reactive metal powders, leading to two core problems: poor storage stability and safety risks. Highly reactive metal powders have large specific surface areas and high surface energies, making them highly susceptible to hydrolysis reactions with water molecules in aqueous systems, continuously releasing hydrogen gas. This also causes oxidation, deactivation, agglomeration, and sedimentation of the metal powder. Furthermore, the ether bonds and active amino groups in the polyetheramine structure further catalyze the hydrolysis reaction, exacerbating system degradation and significantly shortening the storage life of the compounded system, far below the storage period required for industrial production. Simultaneously, the continuous accumulation of hydrogen gas in a closed system can easily lead to issues such as container bulging and excessive pressure, posing significant safety hazards such as cap overflow and explosion. The conventional isolation methods currently used in the industry, such as silane coupling agent passivation and organic polymer coating, have drawbacks such as easy hydrolysis failure of the coating layer, weak interfacial bonding, and sacrificing the anti-corrosion and conductivity properties of the coating. They cannot simultaneously ensure storage stability, usage safety, and film-forming performance.

[0005] In addition, the existing polyetheramine curing agent technology system has many shortcomings: insufficient curing activity at low temperatures, easy moisture absorption and whitening, and inability to adapt to low-temperature construction scenarios; viscosity control and the requirements for high solid content and high activity are mutually restrictive, making it difficult to balance low viscosity workability and low VOC environmental protection requirements; poor UV aging resistance of polyether segments, easy yellowing and chalking of cured coatings, and insufficient adaptability to heavy anti-corrosion and weather-resistant application scenarios.

[0006] While existing publicly available patents have proposed some improvements to address the aforementioned technical pain points, they still fail to fundamentally solve the core problems facing the industry. For example, patent application number CN202411623137.2, entitled "A Modified Polyetheramine Waterborne Epoxy Curing Agent and Its Preparation Method and Application," mixes polyetheramine, bisphenol A type epoxy resin, and polyether alcohol diglycidyl ether for addition processing. Chain extension reaction yields an addition product; the addition product is mixed with a monoepoxide compound and subjected to an end-capping reaction to obtain an end-capping product; the end-capping product is mixed with water and dispersed to obtain a modified polyetheramine waterborne epoxy curing agent. This patent focuses on improving the water dispersibility of the curing agent, but does not specifically address the problem of the hydrophilic long chain shielding the activity of amino groups. It suffers from slow curing rate and reliance on high-temperature curing, thus losing the core advantage of room-temperature application in waterborne systems. Patent CN116986960A, titled "A Method for Regulating the Interface Layer of Highly Active Metal Powder through Fluoropolymer Coating," uses a fluoropolymer coating to coat metal powder. While this can temporarily isolate moisture, the coating has poor compatibility with the polyetheramine curing agent, easily detaching during film formation, leading to isolation failure; furthermore, the fluorinated raw materials are costly and environmentally unfriendly.

[0007] The existing patent CN112341604A, entitled "An Emulsion-type Epoxy Curing Agent and Its Preparation Method", uses silane-potassium silicate composite passivation. Although it extends the storage life to 36 hours, the passivation layer will hinder the cathodic protection of the metal powder and reduce the anti-corrosion performance of the coating. It requires subsequent heat treatment to restore its activity, which increases the complexity of construction.

[0008] Existing patent CN201811092198.5, entitled "A Polyetheramine-type Waterborne Epoxy Curing Agent for Epoxy Resin and its Preparation Method," describes a method that involves adding 400 parts by weight of polyetheramine D-400 to 100 parts by weight of maleic anhydride and reacting at 80-85°C for 2 hours. Then, another 300 parts by weight of polyetheramine D-400 are added to the reaction vessel, and the reaction is maintained at 95-100°C for 2 hours. The mixture is then heated to 200°C at a rate of 5°C / min and reacted for 3 hours, with the generated water distilled off during the reaction. Cooling yields the polyetheramine-type waterborne epoxy resin curing agent. While this patent employs a multi-step composite modification method (addition-end-capping-emulsification, polyamide-polyetheramine copolymerization) to balance the defects of a single property, it suffers from numerous side reactions, complex processes, high energy consumption, and poor overall performance balance, failing to meet the application requirements of high-end fields.

[0009] In summary, current waterborne polyetheramine curing agents generally suffer from an imbalance between hydrophilic modification and curing activity, and lack an effective interface isolation mechanism in highly active metal compound systems. There is no mature technical solution that can simultaneously achieve excellent water dispersibility, high room temperature curing activity, and safety in use. Therefore, it is necessary to develop a high-performance polyetheramine curing agent with controllable structure, no activity shielding, and dynamic interface isolation function to meet the urgent needs of the current technology in this field. Summary of the Invention

[0010] The purpose of this invention is to overcome at least one deficiency of the prior art and provide a self-emulsifying polyetheramine curing agent and its preparation method. This curing agent can significantly improve the curing reaction activity at room temperature and effectively improve the storage stability of systems containing highly active metal fillers.

[0011] The technical solution adopted in this invention is: In a first aspect, the present invention provides a self-emulsifying polyetheramine curing agent, which, by weight, is composed of the following raw materials: Component A: 40-60 portions; Component B: 15-25 parts; Component C: 10-20 parts; Component D, 5-15 parts; Component E: 0.1-0.5 parts; Component F: 0.1-0.3 parts; Component A is polypropylene glycol or polytetrahydrofuran glycol with a molecular weight range of 800-2000. Component B is selected from at least one of isophorone diamine, dicyclohexylmethane diamine, or phenylenediamine; The C component is at least one of the epoxy derivatives containing long-chain alkyl groups and aromatic ring structures; The D component is a short-chain polyethylene glycol monomethyl ether amine or an amine compound containing sulfonic acid groups, with a degree of polymerization ranging from 2 to 5. The E component is a tertiary amine compound; The F component is at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0012] In some instances, component A is polypropylene glycol with a molecular weight range of 1000-1500, or polytetrahydrofuran glycol with a molecular weight range of 800-1200.

[0013] In some instances, component B is isophorone diamine, or a mixture of dicyclohexylmethane diamine and phenylenediamine in a 1:1 mass ratio.

[0014] In some instances, component C is selected from one or more of phenyl glycidyl ether, dodecyl glycidyl ether, bisphenol A diglycidyl ether, or nonylphenol glycidyl ether.

[0015] In some instances, component D is polyethylene glycol monomethyl ether amine with a degree of polymerization between 3 and 4, or an amine compound containing sulfonic acid groups with a degree of polymerization between 3 and 4.

[0016] In some instances, component E is selected from triethylamine, N,N-dimethylethanolamine, or benzyldimethylamine.

[0017] In some instances, the F component is selected from a mixture of hindered phenolic antioxidants and phosphite antioxidants in a 1:1 mass ratio.

[0018] Secondly, the present invention provides a method for preparing a self-emulsifying polyetheramine curing agent, comprising the following steps: Dehydration treatment: Dehydrate component A; Mixing and maturation: Add components B, E and C to component A and mix and mature to obtain a matured intermediate raw material; End-capping reaction: Component D is added to the matured intermediate raw material to carry out an end-capping reaction, and the end-capped raw material is obtained; Homogenization is performed by adding component F to the end-capped raw material, followed by cooling to obtain a curing agent.

[0019] In some instances, the mixing and maturation step involves cooling the reaction system of component A to 60-90°C, adding components B and E, stirring and mixing thoroughly, then slowly adding component C dropwise, controlling the dropwise addition time within the range of 2-4 hours, and then maintaining the temperature and maturing for 3-5 hours after the dropwise addition is complete.

[0020] In some instances, the self-emulsifying polyetheramine curing agent is used in the preparation of waterborne epoxy resin curing systems and waterborne anti-corrosion coatings containing metal fillers.

[0021] The beneficial effects of this invention are: (1) The polyether polyol backbone of this application is polypropylene glycol or polytetrahydrofuran glycol with a molecular weight in the range of 800-2000; the diamine chain extender is selected from one or more of isophorone diamine, dicyclohexylmethane diamine or phenylenediamine; the hydrophobic modified monomer is an epoxy derivative containing a long-chain alkyl or aromatic ring structure, which forms a rigid micro-region in the molecular structure of the final curing agent; the hydrophilic end-capping agent is a short-chain polyethylene glycol monomethyl ether amine or an amine compound containing a sulfonic acid group, and its degree of polymerization is strictly controlled between 2 and 5 to avoid steric hindrance caused by excessively long hydrophilic segments. By combining hydrophobic rigid segments with hydrophilic segments of limited length in a specific ratio, a unique "core-shell" microphase separation molecular structure was constructed. This structure effectively overcomes the shielding effect of hydrophilic groups on the amino active center, while limiting the length of the hydrophilic segments to eliminate steric hindrance. This reliably enhances the reactivity of the curing agent at room temperature. While maintaining excellent water dispersibility, the nucleophilic activity of its terminal amino groups is significantly improved, thereby greatly accelerating the curing rate at room temperature.

[0022] (2) The formation of the hydrophobic core in this application not only protects the active center, but also provides a natural interface isolation barrier for the highly active metal filler, which greatly reduces the probability of side reactions between zinc powder and water, and effectively overcomes the problem of poor storage stability of zinc-rich primer.

[0023] (3) There is a significant synergistic effect among the components. The introduction of hydrophobic monomers not only did not reduce the water content, but also promoted a finer emulsion particle size distribution through microphase separation, thereby improving the density and salt spray resistance of the coating.

[0024] (4) The curing agent prepared in this application can achieve stable emulsification without the addition of organic solvents. The resulting coating has a denser microstructure and its salt spray corrosion resistance and impact resistance are significantly better than those of traditional water-based curing agent systems. Detailed Implementation

[0025] The following disclosure provides many different implementations or examples for different ways of implementing the present invention.

[0026] Unless otherwise specified, all raw materials or reagents used in this invention are commercially available products well known in the art.

[0027] This invention provides a self-emulsifying polyetheramine curing agent, which, by weight, is composed of the following raw materials: Component A: 40-60 portions; Component B: 15-25 parts; Component C: 10-20 parts; Component D, 5-15 parts; Component E: 0.1-0.5 parts; Component F: 0.1-0.3 parts; Component A is polypropylene glycol or polytetrahydrofuran glycol with a molecular weight range of 800-2000. Component B is selected from at least one of isophorone diamine, dicyclohexylmethane diamine, or phenylenediamine; The C component is at least one of the epoxy derivatives containing long-chain alkyl groups and aromatic ring structures; The D component is a short-chain polyethylene glycol monomethyl ether amine or an amine compound containing sulfonic acid groups, with a degree of polymerization ranging from 2 to 5. The E component is a tertiary amine compound; The F component is at least one of hindered phenolic antioxidants and phosphite antioxidants.

[0028] In this invention, component A is preferably polypropylene glycol with a molecular weight in the range of 1000-1500, or polytetrahydrofuran glycol with a molecular weight in the range of 800-1200.

[0029] In this invention, component B is isophorone diamine, or a mixture of dicyclohexylmethane diamine and phenylenediamine in a mass ratio of 1:1.

[0030] In this invention, component C is selected from one or more of phenyl glycidyl ether, dodecyl glycidyl ether, bisphenol A diglycidyl ether, or nonylphenol glycidyl ether. When component C is a mixture of two or more epoxy derivatives containing long-chain alkyl or aromatic ring structures, the mass ratio between the components is 1:1 to 2:1.

[0031] In this invention, component D is preferably polyethylene glycol monomethyl ether amine with a degree of polymerization between 3 and 4, or an amine compound containing sulfonic acid groups with a degree of polymerization between 3 and 4.

[0032] In this invention, component E is selected from one of triethylamine, N,N-dimethylethanolamine or benzyldimethylamine.

[0033] In this invention, component F is selected from a mixture of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1:1, or from antioxidant 1010.

[0034] In this invention, the average particle size of the micelles formed by the spontaneous emulsification of the self-emulsifying polyetheramine curing agent in water is 50-150 nm.

[0035] In this invention, the amino content of the self-emulsifying polyetheramine curing agent reaches more than 95% of the theoretically calculated value.

[0036] This invention also provides a method for preparing a self-emulsifying polyetheramine curing agent, comprising the following steps: The first step is dehydration treatment. Component A is added to the reactor, nitrogen gas is introduced for protection, and the temperature is raised to 80-120℃ for vacuum dehydration treatment. The dehydration time is 1-2 hours. The second step is to mix and mature the reaction system. Cool the reaction system to 60-90℃, add components B and E, stir and mix evenly, then slowly add component C dropwise, controlling the dropwise addition time to be within 2-4 hours. After the dropwise addition is completed, keep it warm and mature for 3-5 hours. The third step is the end-capping reaction. The reaction system of the second step is heated to 90-130℃, and component D is added to carry out the end-capping reaction. The reaction time is controlled at 4-8 hours. The fourth step is homogenization. Component F is added to the reaction system from the third step, and the mixture is stirred at 70-100℃ for 0.5-1.5 hours to homogenize it. Then, it is cooled to room temperature and discharged to obtain the curing agent.

[0037] In this invention, in the first step, the vacuum degree of the vacuum dehydration process is preferably -0.09 to -0.095 MPa.

[0038] In this invention, during the second step, the reaction temperature is preferably maintained in the range of 60-90°C during the dropwise addition of component C.

[0039] In the third step of this invention, the reaction process is monitored by sampling and measuring the amine value, and the reaction is stopped when the amino content in the system reaches more than 95% of the theoretically calculated value.

[0040] In this invention, in the fourth step, the cooling process after homogenization is natural cooling to room temperature.

[0041] This invention provides the application of the self-emulsifying polyetheramine curing agent described in the above-mentioned technical solution in the preparation of waterborne epoxy coatings and waterborne anti-corrosion coatings containing metal fillers. The waterborne anti-corrosion coating containing metal fillers is a zinc-rich primer.

[0042] The present invention does not impose any special limitations on the method of application described herein; it may be applied in accordance with methods known in the art.

[0043] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0044] Example 1 A self-emulsifying polyetheramine curing agent, by weight: 50 parts polypropylene glycol, 20 parts isophorone diamine, 15 parts phenyl glycidyl ether, 10 parts polyethylene glycol monomethyl etheramine, 0.3 parts triethylamine, and 0.2 parts hindered phenolic antioxidant.

[0045] Polypropylene glycol (molecular weight 1000, manufacturer: Dow Chemical). Isophorone diamine (manufacturer: Evonik, product model: VESTAMIN IPD). Phenyl glycidyl ether (manufacturer: Hexion, product model: HELOXYModifier 7). Polyethylene glycol monomethyl etheramine (degree of polymerization 3, manufacturer: Huntsman, product model: JEFFAMINE M-600). Triethylamine (manufacturer: Sigma-Aldrich, purity ≥99%).

[0046] Preparation process flow: S101: Add 50 parts of polypropylene glycol to a four-necked reactor equipped with a stirrer, thermometer, condenser and nitrogen protection port, start stirring, purge the air in the reactor with nitrogen, heat to 120°C, and dehydrate under vacuum of -0.09MPa for 1 hour until no water is distilled out. S102: Cool the reactor temperature to 60℃, add 20 parts of isophorone diamine and 0.3 parts of triethylamine, stir and mix evenly, then slowly add 15 parts of phenyl glycidyl ether, controlling the dropping rate and the dropping time is 2 hours. After the dropping is completed, keep it warm and mature for 3 hours, maintaining the temperature at 60℃ during this period, so that the hydrophobic segments can be fully integrated into the main chain to form a microphase separation precursor. S103: Heat the reactor to 90℃, add 10 parts of polyethylene glycol monomethyl ether amine for end-capping reaction, strictly control the reaction temperature and time, the reaction time is 8 hours, and take samples every 1 hour to measure the amine value until the amino content in the system reaches more than 95% of the theoretically calculated value. S104: Add 0.2 parts of antioxidant to the reaction system, continue stirring at 70°C for 0.5 hours for homogenization, then stop heating and allow to cool naturally to room temperature to obtain the self-emulsifying polyetheramine curing agent product.

[0047] Example 2 Compared with Example 1, this embodiment adjusts the type and molecular weight range of the polyether polyol skeleton, the composition and range of each component, and the reaction conditions of the preparation process.

[0048] A self-emulsifying polyetheramine curing agent, comprising, by weight, 40 parts polytetrahydrofuran glycol, 15 parts dicyclohexylmethanediamine, 10 parts dodecyl glycidyl ether, 5 parts polyethylene glycol monomethyl etheramine, 0.1 parts N,N-dimethylethanolamine, and 0.1 parts phosphite antioxidant. Polytetrahydrofuran glycol (molecular weight 800, manufacturer: BASF, product model: PolyTHF1000).

[0049] Dicyclohexylmethanediamine (manufacturer: Covestro, product model: Laromin C260). Dodecyl glycidyl ether (hydrophobic modified monomer, manufacturer: Cardolite, product model: NX-2002).

[0050] Polyethylene glycol monomethyl etheramine (degree of polymerization 2, manufacturer: Huntsman, product model: JEFFAMINE M-200). N,N-Dimethylethanolamine (catalyst, manufacturer: Air Products, product model: DEEA). Phosphite antioxidant (manufacturer: Addivant, product model: Weston 618).

[0051] Preparation process flow: S201: Add 40 parts of polytetrahydrofuran diol to a four-necked reactor equipped with a stirrer, thermometer, condenser and nitrogen protection port, start stirring, purge the air in the reactor with nitrogen, heat to 80°C, and dehydrate under vacuum of -0.095MPa for 2 hours until no water is distilled out. S202: Cool the reactor temperature to 90℃, add 15 parts of dicyclohexylmethanediamine and 0.1 parts of N,N-dimethylethanolamine, stir and mix evenly, then slowly add 10 parts of dodecyl glycidyl ether, controlling the dropping rate, and the dropping time is 4 hours. After the dropping is completed, keep it warm and mature for 5 hours, during which the temperature is maintained at 90℃, so that the hydrophobic segments can be fully incorporated into the main chain to form a microphase separation precursor. S203: Heat the reactor to 130℃, add 5 parts of polyethylene glycol monomethyl ether amine for end-capping reaction, strictly control the reaction temperature and time, the reaction time is 8 hours, and take samples every 1 hour to measure the amine value until the amino content in the system reaches more than 95% of the theoretically calculated value. S204: Add 0.1 parts of phosphite antioxidant to the reaction system, continue stirring at 100℃ for 1.5 hours for homogenization, then stop heating and allow to cool naturally to room temperature to obtain the self-emulsifying polyetheramine curing agent product.

[0052] Example 3 Aromatic epoxy derivatives are used to replace aliphatic ones, and the composition, range, and reaction conditions of each component are different.

[0053] A self-emulsifying polyetheramine curing agent, by weight: 60 parts polypropylene glycol, 25 parts phenylenediamine, 20 parts bisphenol A diglycidyl ether, 10 parts amine compound containing sulfonic acid groups, 0.5 parts triethylamine, and 0.3 parts antioxidant 1010. Polypropylene glycol (molecular weight 1500, manufacturer: Dow Chemical).

[0054] Benzene dimethylamine (manufacturer: Mitsubishi Gas Chemical, product model: MXDA). Bisphenol A diglycidyl ether (hydrophobic modified monomer, manufacturer: Olin, product model: EPI-REZ 510). Amine compounds containing sulfonic acid groups (degree of polymerization equivalent to 4, manufacturer: Toho Chemical, product model: Aqualon HS).

[0055] Preparation process flow: S301: Add 60 parts of polypropylene glycol to the reactor, heat to 90-120℃ under nitrogen protection, and dehydrate under vacuum for 1-1.5 hours; S302: Cool to 70-90℃, add 25 parts of phenylenediamine and 0.5 parts of triethylamine, mix well, and then add 20 parts of bisphenol A diglycidyl ether dropwise over 3-4 hours. After the addition is complete, keep warm and mature for 4-5 hours. S303: Heat to 100-130℃, add 10 parts of an amine compound containing sulfonic acid groups, and react for 6-8 hours; S304: Add 0.3 parts of antioxidant 1010, homogenize and stir at 80-100℃ for 1-1.5 hours, then cool and discharge.

[0056] Example 4 This embodiment uses a higher amount of hydrophilic end-capping agent and a higher degree of polymerization.

[0057] A self-emulsifying polyetheramine curing agent, by weight: 58 parts polypropylene glycol (molecular weight 1000), 18 parts isophorone diamine, 12 parts phenyl glycidyl ether, 11 parts polyethylene glycol monomethyl etheramine, 0.3 parts triethylamine, and 0.2 parts antioxidant 1010. The polyethylene glycol monomethyl etheramine (degree of polymerization 5, manufacturer: Huntsman, product model: JEFFAMINE M-600, using a higher molecular weight batch).

[0058] Preparation process flow: S401: Add 58 parts of polypropylene glycol to the reactor, heat to 80-110℃, and dehydrate under vacuum for 1.5-2 hours; S402: Cool to 60-85℃, add 18 parts isophorone diamine and 0.3 parts triethylamine, and add 12 parts phenyl glycidyl ether dropwise over 2-3 hours. After the addition is complete, keep warm and mature for 3-4 hours. S403: Heat to 90-120℃, add 11 parts of polyethylene glycol monomethyl etheramine, and react for 5-7 hours; S404: Add 0.2 parts of antioxidant 1010, homogenize and stir at 70-90℃ for 0.5-1 hour, then cool and discharge.

[0059] Example 5 This embodiment changes the type of catalyst and the combination of antioxidants to optimize reaction efficiency and long-term storage stability.

[0060] A self-emulsifying polyetheramine curing agent, by weight: 50 parts polytetrahydrofuran glycol, 21 parts a compound of dicyclohexylmethanediamine and phenylenediamine, 17 parts nonylphenol glycidyl ether, 10 parts polyethylene glycol monomethyl etheramine, 0.5 parts benzyl dimethylamine, and 0.3 parts an antioxidant compound of hindered phenol and phosphite. Polytetrahydrofuran glycol (molecular weight 1200). Dicyclohexylmethanediamine and phenylenediamine (1:1 mass ratio compound). Nonylphenol glycidyl ether (hydrophobic modified monomer, manufacturer: Cardolite, product model: NC-514). Polyethylene glycol monomethyl etheramine (degree of polymerization 4). Benzyl dimethylamine (catalyst, manufacturer: Air Products, product model: BDMA). A antioxidant compound of hindered phenol and phosphite (1:1 mass ratio).

[0061] Preparation process flow: S501: Add 50 parts of polytetrahydrofuran diol to the reactor, heat to 85-115℃, and dehydrate under vacuum for 1-2 hours; S502: Cool to 65-90℃, add 21 parts of mixed diamine and 0.5 parts of benzyl dimethylamine, and add 17 parts of nonylphenol glycidyl ether dropwise over 2.5-4 hours. After the addition is complete, keep warm and mature for 3.5-5 hours. S503: Heat to 95-130℃, add 10 parts of polyethylene glycol monomethyl etheramine, and react for 4.5-7.5 hours; S504: Add 0.3 parts of compound antioxidant, homogenize and stir at 75-100℃ for 1-1.5 hours, then cool and discharge.

[0062] Example 6 This embodiment uses a lower proportion of the hydrophobic monomer phenyl glycidyl ether.

[0063] A self-emulsifying polyetheramine curing agent, by weight: 56 parts polypropylene glycol (molecular weight 1000), 23 parts isophorone diamine, 10 parts phenyl glycidyl ether, 10 parts amine compound containing sulfonic acid groups (degree of polymerization equivalent to 2), 0.3 parts triethylamine, and 0.2 parts antioxidant 1010. The preparation method is the same as in Example 1.

[0064] Example 7 This embodiment uses a high molecular weight polyether backbone.

[0065] A self-emulsifying polyetheramine curing agent, by weight: 55 parts polypropylene glycol (molecular weight 1800-2000), 19 parts dicyclohexylmethanediamine, 14 parts dodecyl glycidyl ether, 11 parts amine compound containing sulfonic acid groups (degree of polymerization equivalent to 3), 0.3 parts triethylamine, and 0.3 parts antioxidant 1010. The preparation method is the same as in Example 1.

[0066] Example 8 This embodiment adjusts the reaction temperature window, especially the temperature during the end-capping reaction stage.

[0067] A self-emulsifying polyetheramine curing agent, by weight: 53 parts of polytetrahydrofuran diol (molecular weight 1000), 20 parts of isophorone diamine, 15 parts of phenyl glycidyl ether, 10 parts of an amine compound containing sulfonic acid groups (equivalent degree of polymerization 5), 0.4 parts of triethylamine, and 0.2 parts of antioxidant 1010.

[0068] Preparation process flow: S801: Add 53 parts of polytetrahydrofuran diol to the reactor, heat to 80-120℃, and dehydrate under vacuum for 1-2 hours; S802: Cool to 60-90℃, add 20 parts isophorone diamine and 0.4 parts triethylamine, and add 15 parts phenyl glycidyl ether dropwise over 2-4 hours. After the addition is complete, keep warm and mature for 3-5 hours. S803: Heat to 110-130℃ (higher than in Example 1), add 10 parts of polyethylene glycol monomethyl etheramine, and react for 4-6 hours (shorten the time). S804: Add 0.2 parts of antioxidant 1010, homogenize and stir at 70-100℃ for 0.5-1.5 hours, then cool and discharge.

[0069] Example 9 This embodiment uses a composite hydrophobic monomer, combining aromatic and long-chain alkyl groups.

[0070] A self-emulsifying polyetheramine curing agent, by weight: 51 parts polypropylene glycol (molecular weight 1200), 21 parts isophorone diamine, 8 parts phenyl glycidyl ether, 8 parts dodecyl glycidyl ether, 10 parts polyethylene glycol monomethyl etheramine (degree of polymerization 3), 0.3 parts triethylamine, and 0.3 parts antioxidant 1010.

[0071] Preparation process flow: S901: Add 51 parts of polypropylene glycol to the reactor, heat to 80-120℃, and dehydrate under vacuum for 1-2 hours; S902: Cool to 60-90℃, add 21 parts isophorone diamine and 0.3 parts triethylamine, and add a mixture of 8 parts phenyl glycidyl ether and 8 parts dodecyl glycidyl ether dropwise over 2-4 hours. After the addition is complete, keep warm and mature for 3-5 hours. S903: Heat to 90-130℃, add 10 parts of polyethylene glycol monomethyl etheramine, and react for 4-8 hours; S904: Add 0.3 parts of antioxidant 1010, homogenize and stir at 70-100℃ for 0.5-1.5 hours, then cool and discharge.

[0072] Example 10 This embodiment uses a composite hydrophobic monomer, combining aromatic and long-chain alkyl groups.

[0073] A self-emulsifying polyetheramine curing agent, by weight: 51 parts polypropylene glycol (molecular weight 1200), 21 parts isophorone diamine, 8 parts phenyl glycidyl ether, 4 parts dodecyl glycidyl ether, 10 parts polyethylene glycol monomethyl etheramine (degree of polymerization 3), 0.3 parts triethylamine, and 0.3 parts antioxidant 1010. The preparation process is the same as in Example 9.

[0074] Comparative Example 1 This comparative example is a typical long-chain hydrophilic modified curing agent in the prior art.

[0075] Unlike Example 1, the hydrophilic end-capping agent was replaced with long-chain polyethylene glycol monomethyl etheramine, and no hydrophobic modified monomer was used; instead, a linear grafting structure was directly adopted.

[0076] A self-emulsifying polyetheramine curing agent, by weight: 50 parts polypropylene glycol (molecular weight 1000), 20 parts isophorone diamine, 19 parts polyethylene glycol monomethyl etheramine (degree of polymerization 15-20), 0.3 parts triethylamine, and 0.2 parts hindered phenolic antioxidant. Polyethylene glycol monomethyl etheramine (degree of polymerization 15-20, manufacturer: Huntsman, product model: JEFFAMINE M-2005).

[0077] Preparation process: Refer to the steps in Example 1, but omit the step of adding hydrophobic modified monomer in S102. Directly dehydrate polypropylene glycol and mix it with diamine and catalyst, and then add long-chain hydrophilic end-capping agent to react.

[0078] Comparative Example 2 This comparative example uses no hydrophobic modified monomers and only short-chain hydrophilic end-capping agents.

[0079] Description: Based on Example 1, the following conditions were changed: phenyl glycidyl ether (hydrophobic modified monomer) was not added, and the amount of polypropylene glycol was increased accordingly to maintain the total balance.

[0080] A self-emulsifying polyetheramine curing agent, by weight: 60 parts polypropylene glycol, 20 parts isophorone diamine, 10 parts polyethylene glycol monomethyl etheramine (degree of polymerization 3-4), 0.3 parts triethylamine, and 0.2 parts hindered phenolic antioxidant.

[0081] Preparation process: Same as in Example 1, but in step S102, phenyl glycidyl ether is not added dropwise, and the process proceeds directly to step S103 after being kept at a certain temperature for a period of time.

[0082] Comparative Example 3 This comparative example simulates the curing agent used in traditional zinc-rich coatings, without any interface isolation measures, and the hydrophilic chain segment is too long.

[0083] A commercially available conventional water-based polyamide curing agent was used as a comparison. This product is widely available in the market and represents the current level of technology.

[0084] Raw material source: Directly purchased commercially available product; manufacturer: Air Products; product model: Ancamide 350A (a typical water-dispersible polyamide curing agent). The specific formulation of this product is a trade secret, but its technical characteristics are consistent with the long-chain hydrophilic modification and lack of targeted hydrophobic core protection described in the background art.

[0085] Comparative Example 4 This comparative study investigated the effect of excessively high polymerization of the hydrophilic end-capping agent (beyond the scope of this invention) on its activity, even in the presence of hydrophobic monomers.

[0086] Description: Based on Example 1, the following conditions were changed: the hydrophilic end-capping agent was replaced with polyethylene glycol monomethyl etheramine (manufacturer: Huntsman, product model: JEFFAMINE M-1000) with a degree of polymerization of 8-10, while other conditions remained unchanged.

[0087] Preparation process: exactly the same as in Example 1.

[0088] Comparative Example 5 This comparative study investigated the effect of the absence of antioxidants on storage stability, particularly in zinc-rich environments.

[0089] Based on Example 1, the following conditions were changed: hindered phenolic antioxidants were not added, while other conditions and raw material ratios remained exactly the same.

[0090] Preparation process: exactly the same as in Example 1, but no antioxidant is added in step S104, and the mixture is directly homogenized and cooled.

[0091] Experimental Example 1 Experiment Title: Curing Kinetics and Physical and Mechanical Properties Testing of Coating Film at Room Temperature Experimental participants: Examples 1-10, Comparative Examples 1-5.

[0092] Experimental equipment: Electronic balance (manufacturer: Mettler Toledo, product model: XS205); Constant temperature and humidity curing chamber (manufacturer: Thermo Fisher Scientific, product model: Heraeus BBR); Pendulum hardness tester (manufacturer: BYK, product model: BYK-310, conforming to standard ISO 1522); Adhesion tester (manufacturer: Elcometer, product model: Elcometer 106, conforming to standard ASTM D3359); Impact tester (manufacturer: Q-Lab, product model: QI-10, conforming to standard ASTM D2794).

[0093] Experimental Methods: This experiment aims to evaluate the curing agents of each example and comparative example compared to standard epoxy resin (manufacturer: Olin, product model: [missing information]). Curing behavior and film-forming properties of EPI-REZ 3510-W-60 (60% solids content) after mixing. S1: Based on epoxy equivalent, each curing agent sample was mixed with epoxy resin in stoichiometric ratio, and deionized water was added to adjust... Adjust to the working viscosity (40-60s, Fort 4 cup), disperse at high speed for 5 minutes to prepare the varnish. S2: Apply the varnish to the tinplate, control the wet film thickness to 80-100μm, and place at a temperature of 23±2℃. Maintain in an environment with a humidity of 50±5%.

[0094] S3: Record the surface drying time (finger test, conforming to GB / T 1728) and complete drying time (cotton ball test, conforming to GB / T 1728); S4: After 7 days of curing, test the pendulum hardness, adhesion (cross-cut test), and forward and reverse impact strength of the paint film; S5: Repeat the test 3 times for each group of samples and take the average value. Record the surface drying time, complete drying time, pendulum hardness, adhesion grade, and impact strength data for each sample, as detailed in Table 1.

[0095] Experimental Example 2 Experiment title: Storage stability and gas production test of zinc-rich coatings Experimental participants: Examples 1-10, Comparative Examples 1-5.

[0096] Experimental equipment: High-pressure reactor (manufacturer: Parr Instrument, product model: Parr 4560); Gas pressure sensor (manufacturer: Honeywell, product model: ST 3000); Laser particle size analyzer (manufacturer: Malvern Panalytical, product model: Mastersizer 3000); Electrochemical workstation (manufacturer: Gamry Instruments, product model: Reference 600+).

[0097] Experimental Method: This experiment simulates the actual storage environment of zinc-rich primer to evaluate the inhibitory ability of the curing agent on the side reaction between zinc powder and water. S1: Preparation of Zinc-Rich Coating: Zinc powder (manufacturer: Umicore, product model: Zinc Dust Grade 3, content...) S1: Mix 99% zinc powder with epoxy resin emulsion and various curing agent samples in proportion, and set the zinc powder volume concentration (PVC) to 80%; S2: Put the prepared coating into a sealed container and place it in a 50°C oven for accelerated aging test; S3: Monitor the pressure change in the container every 24 hours and record the cumulative gas production (mainly hydrogen) over 7 days; S4: Test the viscosity change and sedimentation of the coating after 7 days, and measure the particle size distribution after redispersing; S5: Prepare the coating and conduct a salt spray test (compliant with ASTM B117), and record the percentage of rust area after 500 hours.

[0098] Record the gas production, viscosity growth rate, sedimentation rate, and corrosion area of ​​each sample during accelerated aging. See Table 2 for detailed data.

[0099] Experimental Example 3 Experiment title: Microstructure and water whitening resistance test of emulsion Experimental participants: Examples 1-10, Comparative Examples 1-5.

[0100] Experimental equipment: Transmission electron microscope (TEM, manufacturer: JEOL, product model: JEM-2100); Dynamic light scattering instrument (DLS, manufacturer: Brookhaven, product model: NanoBrook Omni); Gloss meter (manufacturer: BYK, product model: micro-TRI-gloss).

[0101] Experimental methods: S1: Dilute each curing agent sample into a 1% aqueous solution and determine the emulsion particle size and distribution index (PDI) using DLS; S2: Take a portion of the sample, freeze-dry it, and then observe it using TEM to analyze the microphase separation morphology; S3: Mix the curing agent with the epoxy emulsion to cure it into a film, immerse it in deionized water for 48 hours, observe whether the film turns white (water whitening phenomenon), and test the gloss retention rate before and after immersion; S4: Compare and analyze the correlation between microstructure and macroscopic performance. Record the average particle size of the emulsion, PDI value, TEM morphology description, appearance rating after water immersion, and gloss retention rate, as detailed in Table 3.

[0102] Table 1 As shown in Table 1, the surface drying time of Examples 1-10 was generally between 1-3 hours, and the actual drying time was between 12-24 hours, significantly better than Comparative Examples 1 and 3. Comparative Example 1, due to the shielding effect of the long-chain hydrophilic groups, had a surface drying time of over 6 hours and an actual drying time exceeding 48 hours. The pendulum hardness of Example 1 reached over 180s, while Comparative Example 2, lacking a hydrophobic core, had insufficient cross-linking density and a hardness of only around 120s. This indicates that the "core-shell" structure constructed in this invention effectively releases amino activity, promotes the epoxy ring-opening reaction, and simultaneously enhances the density and mechanical strength of the coating film through the hydrophobic core. The results of Comparative Example 4 show that even with hydrophobic monomers, if the hydrophilic segments are too long (degree of polymerization 8-10), the activity is still significantly inhibited, confirming the necessity of limiting the degree of polymerization of the hydrophilic segments to 2-5 in this invention.

[0103] Table 2 As shown in Table 2, the zinc-rich coatings of Examples 1-10 exhibited extremely low gas production after accelerated aging at 50°C for 7 days, averaging less than 5 mL / kg. In contrast, Comparative Examples 1 and 3 showed gas production as high as 50-80 mL / kg, even exhibiting can swelling. This is attributed to the microphase separation structure formed by the hydrophobic rigid segments in this invention, which constructs an effective physical barrier on the zinc powder surface, blocking direct contact between water molecules and zinc. Although Comparative Example 2 used a short-chain hydrophilic agent, its lack of a hydrophobic core resulted in poor isolation and a still high gas production. Furthermore, the coatings in the Example groups showed minimal viscosity increase and good redispersibility after aging, with a rust area of ​​less than 5% in the salt spray test, while the comparative examples generally showed severe blistering and rust. This fully demonstrates the originality and significant progress of this invention in solving the storage stability problem of zinc-rich systems.

[0104] Table 3 As shown in Table 3, DLS and TEM results show that Examples 1-10 formed uniform micelles with particle sizes between 50-150 nm. TEM images clearly show a light and dark alternating "core-shell" structure, confirming the successful construction of microphase separation. In contrast, Comparative Example 1 has a larger particle size and wider distribution, with no obvious core-shell structure. In the water whitening test, the paint film of the Example group remained transparent after immersion, with a gloss retention rate of over 90%, while the paint film of the Comparative Example group quickly whitened, with a gloss decrease of over 40%. This indicates that the microphase separation structure of the present invention not only improves activity but also optimizes the spatial arrangement of hydrophilic groups, enabling them to effectively retract or form a closed structure after film formation, reducing the retention channels of water molecules inside the paint film, thereby endowing the coating with excellent water whitening resistance. In summary, the superiority of the technical solution of the present invention can be seen through the data comparison in Tables 1-3. First, in terms of curing activity (Table 1), the surface drying and hard drying times of Examples 1-10 are significantly shorter than those of Comparative Examples 1, 3, and 4. In particular, Comparative Example 1 (long-chain hydrophilic) and Comparative Example 3 (commercially available product) had curing times that of Example 1, which were more than 4 times and 3 times longer, respectively. This directly proves that the present invention successfully eliminated steric hindrance and electronic shielding effects by limiting the length of the hydrophilic chain segments (degree of polymerization 2-5) and constructing a hydrophobic core, releasing the nucleophilic activity of the terminal amino groups. The data from Comparative Example 4 further corroborates the critical importance of controlling the length of the hydrophilic chain segments; once the degree of polymerization exceeds 5, the activity decreases significantly. Secondly, in terms of storage stability and corrosion resistance (Table 2), the gas production of the example groups was extremely low (<7 mL / kg), while the gas production of the comparative groups (especially Comparative Examples 3 and 1) was huge, even posing a safety hazard. This huge difference (10-20 times) strongly proves that the microphase separation structure formed by the hydrophobic rigid chain segments in the present invention constructs an efficient interfacial isolation layer on the zinc powder surface, effectively blocking the reaction between water and zinc. Although Comparative Example 2 used a short-chain hydrophilic agent, the isolation effect was significantly reduced due to the lack of a hydrophobic monomer core, yet the gas production rate remained as high as 42.1 mL / kg. This demonstrates that the integrity of the "core-shell" structure is crucial for functionality, and improvements to a single feature are insufficient to solve the problem. Finally, regarding microstructure and water resistance (Table 3), the example group exhibited uniform nanoscale particle size and a clear core-shell morphology, along with excellent water whitening resistance (gloss retention >85%). In contrast, Comparative Examples 1 and 3 had large particle sizes and wide distributions, resulting in poor water resistance. This indicates that the molecular design of this invention not only solved the problems of activity and stability but also optimized the microstructure of the emulsion, allowing the hydrophilic groups to be effectively "hidden" after film formation, avoiding the water-whitening defects of traditional water-based coatings. In summary, this invention achieves synergistic effects among various components through specific component selection and process control.

[0105] The above is a further detailed description of the present invention and should not be considered as a limitation on the specific implementation of the present invention. For those skilled in the art, simple deductions or substitutions without departing from the concept of the present invention are all within the protection scope of the present invention.

Claims

1. A self-emulsifying polyetheramine curing agent, characterized in that, The raw materials, by weight, consist of the following components: Component A 40-60 parts; Component B 15-25 parts; Component C 10-20 parts; Component D 5-15 parts; Component E 0.1-0.5 parts; Component F 0.1-0.3 parts; wherein, Component A is polypropylene glycol or polytetrahydrofuran glycol with a molecular weight range of 800-2000; Component B is selected from at least one of isophorone diamine, dicyclohexylmethane diamine, or phenylenediamine; Component C is at least one of epoxy derivatives containing long-chain alkyl or aromatic ring structures; Component D is polyethylene glycol monomethyl ether amine or an amine compound containing sulfonic acid groups with a degree of polymerization range of 2-5; Component E is a tertiary amine compound; and Component F is at least one of hindered phenolic antioxidants or phosphite antioxidants.

2. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, Component A is polypropylene glycol with a molecular weight range of 1000-1500, or polytetrahydrofuran glycol with a molecular weight range of 800-1200.

3. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, Component B is isophorone diamine, or a mixture of dicyclohexylmethane diamine and phenylenediamine in a mass ratio of 1:

1.

4. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, Component C is selected from one or more of phenyl glycidyl ether, dodecyl glycidyl ether, bisphenol A diglycidyl ether, or nonylphenol glycidyl ether.

5. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, The D component is polyethylene glycol monomethyl ether amine with a degree of polymerization between 3 and 4, or an amine compound containing sulfonic acid groups with a degree of polymerization between 3 and 4.

6. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, The E component is selected from one of triethylamine, N,N-dimethylethanolamine, or benzyldimethylamine.

7. The self-emulsifying polyetheramine curing agent according to claim 1, characterized in that, The F component is selected from a mixture of hindered phenolic antioxidants and phosphite antioxidants in a mass ratio of 1:

1.

8. A method for preparing a self-emulsifying polyetheramine curing agent as described in any one of claims 1-7, characterized in that, The process includes the following steps: Dehydration treatment: Dehydrating component A; Mixing and curing: Adding components B, E, and C to component A and mixing and curing to obtain a curing intermediate raw material; End-capping reaction: Adding component D to the curing intermediate raw material and performing an end-capping reaction to obtain a post-capped raw material; Homogenization treatment: Adding component F to the post-capped raw material and performing homogenization treatment, followed by cooling to obtain a curing agent.

9. The preparation method according to claim 8, characterized in that, The mixing and maturation step involves cooling the reaction system of component A to 60-90℃, adding components B and E, stirring and mixing evenly, and then slowly adding component C dropwise, controlling the dropwise addition time within the range of 2-4 hours. After the dropwise addition is completed, the mixture is kept warm and matured for 3-5 hours.

10. The application of the self-emulsifying polyetheramine curing agent according to any one of claims 1 to 9 in the preparation of waterborne epoxy coatings and waterborne anti-corrosion coatings containing metal fillers.

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