Composite flame-retardant waterborne epoxy resin, its preparation method and coating

Abstract

This invention relates to the field of waterborne coatings technology, and in particular to a composite flame-retardant waterborne epoxy resin, its preparation method, and coatings. The preparation method includes the following steps: (a) a halogenated anhydride reacts with glycidol under heat to obtain an intermediate, which is then reacted with epoxy resin A under heat to obtain a halogenated epoxy resin; (b) epoxy resin B, polyethylene glycol diglycidyl ether, and monoethanolamine phosphate are refluxed in a solvent, cooled, and then reacted with glacial acetic acid to obtain a phosphorus-containing emulsifier; (c) the halogenated epoxy resin, the phosphorus-containing emulsifier, and water are mixed and emulsified to obtain a composite flame-retardant waterborne epoxy resin; the mass ratio of epoxy resin A to the intermediate is (40-120):1. This invention, through the preparation of a phosphorus-containing emulsifier, can significantly reduce the amount of halogenated flame-retardant raw materials used, greatly reducing production costs while improving the compatibility of the matrix and enhancing the mechanical properties and storage stability of the matrix.

Description

Technical Field

[0001] This invention relates to the field of waterborne coatings technology, and in particular to a composite flame-retardant waterborne epoxy resin, its preparation method, and coating. Background Technology

[0002] Waterborne epoxy coatings possess excellent properties, exhibiting superior corrosion resistance and adhesion, particularly excelling as primers in industrial coating systems. Suitable for almost all substrate surfaces, they are an indispensable and important coating type. However, their high flammability, releasing significant heat and toxic fumes during combustion, poses a potential threat to life and property. The fire hazard of waterborne epoxy coatings limits their application in fields with high flame-retardant requirements, especially in aerospace, rail transportation, and electrical and electronic industries. Therefore, the development of flame-retardant epoxy resins is of great significance. Furthermore, with the development of the new energy vehicle industry, epoxy coatings for new energy vehicle motors have encountered opportunities. The stability and reliability of flame-retardant systems are crucial for the safe operation and use of motors. Because new energy vehicle drive motors typically experience frequent starts, speed changes, and torque variations during operation, resulting in high operating temperatures and strong mechanical vibrations, higher performance requirements are placed on coatings used in new energy vehicle motors, demanding higher mechanical strength, heat resistance, and thermal conductivity.

[0003] The application of novel phosphorus-containing flame retardants developed from DOPO and its derivatives in the field of flame retardancy has increased significantly in recent years. However, although they have significant characteristics such as low toxicity, low smoke, and environmental friendliness, they also have shortcomings such as low phosphorus content, high water absorption, and high cost, which greatly limit their application scope.

[0004] Furthermore, in practical applications, achieving good flame-retardant effects requires the introduction of a large amount of flame-retardant raw materials, which increases production costs and also results in poor compatibility with the resin system. Moreover, emulsions prepared via phase inversion exhibit poor fineness, deteriorated storage performance, and reduced mechanical properties, failing to meet the requirements of industrial production. Therefore, how to stably add flame-retardant raw materials to epoxy resins while meeting the needs of industrial production is a pressing problem to be solved in this field.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] One object of the present invention is to provide a method for preparing composite flame-retardant waterborne epoxy resin, so as to solve the problems of insufficient flame retardancy and stability of existing flame-retardant waterborne epoxy resins.

[0007] Another object of the present invention is to provide a composite flame-retardant waterborne epoxy resin.

[0008] Another object of the present invention is to provide a coating comprising a composite flame-retardant waterborne epoxy resin.

[0009] To achieve the above-mentioned objectives of the present invention, one aspect of the present invention provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0010] (a) After heating the halogenated anhydride and glycidol to obtain an intermediate, it is then heated to react with epoxy resin A to obtain a halogenated epoxy resin.

[0011] (b) After epoxy resin B, polyethylene glycol diglycidyl ether and monoethanolamine phosphate were refluxed in a solvent, glacial acetic acid was added after cooling to obtain a phosphorus-containing emulsifier.

[0012] (c) The halogen-containing epoxy resin, the phosphorus-containing emulsifier and water are mixed and phase-inverted emulsified to obtain the composite flame-retardant waterborne epoxy resin.

[0013] The mass ratio of epoxy resin A to the intermediate is (40-120):1.

[0014] In a specific embodiment of the present invention, in step (a), the molar ratio of the halogenated anhydride to the glycidol is 1:(0.8-1.2). Further, in the heating reaction of the halogenated anhydride and glycidol, the heating temperature is 60-80°C, and the reaction time is 3-4 hours.

[0015] In a specific embodiment of the present invention, in step (a), the heating temperature in the reaction with epoxy resin A is 100-120°C, and the reaction time is 2-3 hours.

[0016] In a specific embodiment of the present invention, the epoxy resin A includes bisphenol A type epoxy resin and / or phenolic epoxy resin.

[0017] In a specific embodiment of the present invention, the halogenated anhydride includes at least one of 1,4,5,6-tetrabromophthalic anhydride, tetrachlorophthalic anhydride, and chlorinated anhydride.

[0018] In a specific embodiment of the present invention, in step (b), the mass ratio of the epoxy resin B, the polyethylene glycol diglycidyl ether, and the monoethanolamine phosphate is (7-8):(6-7):(2-4).

[0019] In a specific embodiment of the present invention, in step (b), the amount of solvent used is 15% to 30% of the mass of epoxy resin B; the amount of glacial acetic acid used is 0.5 to 1.5 times the mass of monoethanolamine phosphate.

[0020] In a specific embodiment of the present invention, in step (b), the temperature of the reflux reaction is 80-90°C, and the time of the reflux reaction is 3-5 hours.

[0021] In a specific embodiment of the present invention, the epoxy resin B is a bisphenol A type epoxy resin.

[0022] In a specific embodiment of the present invention, the solvent includes at least one of propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol monobutyl ether, methyl isobutyl ketone, and ethylene glycol butyl ether.

[0023] In a specific embodiment of the present invention, in step (c), the mass ratio of the halogenated epoxy resin, the phosphorus-containing emulsifier and the water is (46-49):(3.8-5):(45-48).

[0024] In a specific embodiment of the present invention, the temperature of the system during the phase inversion emulsification is 50–70°C. Furthermore, high-speed stirring is performed during the phase inversion emulsification; the stirring rate is 2000–4000 r / min.

[0025] In another aspect, the present invention provides a composite flame-retardant waterborne epoxy resin prepared by any of the above-described methods.

[0026] In another aspect, the present invention provides a coating comprising any of the composite flame-retardant waterborne epoxy resins described above.

[0027] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0028] (1) The present invention modifies epoxy resin with halogen anhydride. Compared with the DOPO type epoxy resin currently widely used, the flame retardant elements are widely available, the raw material consumption is less, the preparation process is simple, and the cost performance is higher. At the same time, the preparation process of halogen anhydride modified epoxy resin does not add any solvent, which saves costs and meets the market demand for low VOC emissions.

[0029] (2) The present invention introduces monoethanolamine phosphate into the emulsifier, which has a good synergistic flame retardant effect with the halogen flame retardant elements in the halogen-containing epoxy resin, and the flame retardancy of the resin is significantly improved.

[0030] (3) By preparing phosphorus-containing emulsifiers, the present invention can greatly reduce the amount of halogen-type flame retardant raw materials used, thereby greatly reducing production costs while improving the compatibility of the matrix and improving the mechanical properties and storage stability of the matrix. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0032] This invention provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0033] (a) After heating the halogenated anhydride and glycidol to obtain an intermediate, it is then heated to react with epoxy resin A to obtain a halogenated epoxy resin.

[0034] (b) After epoxy resin B, polyethylene glycol diglycidyl ether and monoethanolamine phosphate were refluxed in a solvent, glacial acetic acid was added after cooling to obtain a phosphorus-containing emulsifier.

[0035] (c) A halogenated epoxy resin, a phosphorus-containing emulsifier and water are mixed and phase-inverted emulsified to obtain a composite flame-retardant waterborne epoxy resin.

[0036] The mass ratio of epoxy resin A to intermediate is (40-120):1.

[0037] This invention introduces monoethanolamine phosphate into an emulsifier to obtain a phosphorus-containing emulsifier, which exhibits excellent synergistic flame-retardant effect with halogens in halogenated epoxy resins, significantly improving the flame retardancy of the resin. Simultaneously, the introduction of the phosphorus-containing emulsifier reduces the amount of halogen-based flame-retardant raw materials used, significantly improving matrix compatibility, mechanical properties, and storage stability.

[0038] Meanwhile, the preparation of the halogenated epoxy resin of the present invention does not involve the addition of any solvent, which saves costs while meeting the market demand for low VOC emissions.

[0039] In different embodiments, the mass ratio of epoxy resin A to the intermediate can be 40:1, 50:1, 60:1, 70:1, 80:1, 90:1, 100:1, 110:1, 120:1, or any combination thereof, such as (45-95):1.

[0040] The present invention, through the introduction of phosphorus-containing emulsifiers, enables excellent flame retardant properties to be achieved in halogen-containing epoxy resins by introducing only a small amount of halogen.

[0041] In a specific embodiment of the present invention, in step (a), the molar ratio of halogenated anhydride to glycidol is 1:(0.8 to 1.2).

[0042] In different embodiments, in step (a), the molar ratio of the halogenated anhydride to the glycidol can be 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, or any combination thereof.

[0043] In a specific embodiment of the present invention, in the heating reaction of halogenated anhydride and glycidol, the heating temperature is 60-80°C and the reaction time is 3-4 hours.

[0044] In different embodiments, the heating temperature in the reaction of halogenated anhydride with glycidol can be 60°C, 65°C, 70°C, 75°C, 80°C or any combination thereof; the reaction time can be 3h, 3.5h or 4h, etc., and the specific reaction time can be adjusted according to the actual situation.

[0045] In a specific embodiment of the present invention, in step (a), the heating temperature for the reaction with epoxy resin A is 100-120°C, and the reaction time is 2-3 hours.

[0046] In different embodiments, in step (a), the heating temperature during the heating reaction of the intermediate with epoxy resin A can be 100°C, 105°C, 110°C, 115°C, 120°C or any combination thereof; the reaction time can be 2h, 2.5h or 3h, etc., and the specific reaction time can be adjusted according to the actual situation.

[0047] In a specific embodiment of the present invention, epoxy resin A includes bisphenol A type epoxy resin and / or phenolic epoxy resin. Further, the bisphenol A type epoxy resin has an epoxy equivalent of 180–350 g / eq; the phenolic epoxy resin has an epoxy equivalent of 170–180 g / eq, and the phenolic epoxy resin has a functionality of 2.5–3.5.

[0048] In different embodiments, the epoxy equivalent of the bisphenol A type epoxy resin in epoxy resin A can be in the range of 180 g / eq, 200 g / eq, 220 g / eq, 250 g / eq, 280 g / eq, 300 g / eq, 320 g / eq, 350 g / eq, or any combination thereof; the epoxy equivalent of the phenolic epoxy resin can be in the range of 170 g / eq, 172 g / eq, 175 g / eq, 178 g / eq, 180 g / eq, or any combination thereof; and the functionality of the phenolic epoxy resin can be 2.5, 3, 3.5, etc.

[0049] In a specific embodiment of the present invention, the halogenated anhydride includes at least one of 1,4,5,6-tetrabromophthalic anhydride, tetrachlorophthalic anhydride, and chlorinated anhydride.

[0050] In a specific embodiment of the present invention, in step (b), the mass ratio of epoxy resin B, polyethylene glycol diglycidyl ether, and monoethanolamine phosphate is (7-8):(6-7):(2-3).

[0051] In different embodiments, in step (b), the mass ratio of epoxy resin B, polyethylene glycol diglycidyl ether, and monoethanolamine phosphate can be 7:6:3, 7.5:6:3, 8:6:3, 7:6:2, 7:6.5:2, 7:7:2, 7:6:2.5, or any combination thereof.

[0052] In a specific embodiment of the present invention, in step (b), the amount of solvent used is 15wt% to 30wt% of the mass of epoxy resin B; the amount of glacial acetic acid used is 0.5 to 1.5 times the mass of monoethanolamine phosphate.

[0053] In different embodiments, in step (b), the amount of solvent can be 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, 28 wt%, 30 wt%, or any combination thereof, based on the mass of epoxy resin B; the amount of glacial acetic acid can be 0.5 times, 0.8 times, 1 time, 1.2 times, 1.5 times, or any combination thereof, based on the mass of monoethanolamine phosphate.

[0054] In a specific embodiment of the present invention, in step (b), the reflux reaction temperature is 80-90°C and the reflux reaction time is 3-5 hours.

[0055] In different embodiments, in step (b), the reflux reaction temperature can be 80°C, 82°C, 85°C, 88°C, 90°C, or any combination thereof; the reflux reaction time can be 3h, 4h, 5h, etc. The reflux reaction temperature can be adjusted conventionally according to different solvents and systems.

[0056] In a specific embodiment of the present invention, in step (b), epoxy resin B and polyethylene glycol diglycidyl ether are first dissolved in a solvent by stirring, and then monoethanolamine phosphate is added to react.

[0057] In a specific embodiment of the present invention, in step (b), the temperature is lowered to 45-50°C; glacial acetic acid is added to carry out the reaction, and the reaction time is 2-3 hours.

[0058] In different implementations, in step (b), the temperature can be lowered to 45°C, 48°C, or 50°C, etc.; after adding glacial acetic acid, the reaction time can be 2h, 2.5h, or 3h, etc.

[0059] In a specific embodiment of the present invention, epoxy resin B is a bisphenol A type epoxy resin. Further, the epoxy equivalent of epoxy resin B is 190–600 g / eq.

[0060] In different embodiments, the epoxy equivalent of the bisphenol A type epoxy resin in epoxy resin B can be a range of 190 g / eq, 200 g / eq, 250 g / eq, 300 g / eq, 350 g / eq, 400 g / eq, 450 g / eq, 500 g / eq, 550 g / eq, 600 g / eq, or any combination thereof.

[0061] In a specific embodiment of the present invention, the solvent includes at least one of propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol monobutyl ether, methyl isobutyl ketone, and ethylene glycol butyl ether.

[0062] In a specific embodiment of the present invention, in step (c), the mass ratio of halogenated epoxy resin, phosphorus-containing emulsifier and water is (46-49):(3.8-5):(45-48).

[0063] In different embodiments, in step (c), the mass ratio of the halogenated epoxy resin, the phosphorus-containing emulsifier, and water can be a range of 46:3.8:45, 47:3.8:45, 48:3.8:45, 49:3.8:45, 46:4:45, 46:5:45, 46:3.8:46, 46:3.8:47, 46:3.8:48, or any combination thereof.

[0064] In a specific embodiment of the present invention, the temperature of the system during phase inversion emulsification is 50–70°C. Furthermore, high-speed stirring is performed during phase inversion emulsification; the stirring rate is 2000–4000 r / min.

[0065] In different implementations, during step (c) of phase inversion emulsification, the temperature of the system can be controlled to be within a range of 50°C, 55°C, 60°C, 65°C, 70°C, or any combination thereof.

[0066] During phase inversion emulsification, high-speed stirring and shearing are performed. The stirring rate can be 2000 r / min, 2500 r / min, 3000 r / min, 3500 r / min, 4000 r / min or any combination thereof.

[0067] In actual operation, in step (c), water is added to the mixture of halogenated epoxy resin and phosphorus-containing emulsifier at a rate of 2 to 5 drops / s.

[0068] In another aspect, the present invention provides a composite flame-retardant waterborne epoxy resin prepared by any of the above-mentioned methods.

[0069] The composite flame-retardant waterborne epoxy resin prepared by the method of the present invention has a flame-retardant element content of about 1wt% to 5wt% in the emulsion, a fineness that can be maintained in the range of 20 to 35μm, a particle size of 300 to 430nm, a UL 94 rating of V-0, and an LOI of 25.2% to 28%.

[0070] In another aspect, the present invention provides a coating comprising any of the above-mentioned composite flame-retardant waterborne epoxy resins.

[0071] In a specific embodiment of the present invention, the coating is a two-component coating, comprising component A and component B; component A comprises a composite flame-retardant waterborne epoxy resin, pigments, and additives; component B comprises a curing agent.

[0072] In component A, the amount of composite flame-retardant waterborne epoxy resin is 38wt% to 42wt%, and the amount of pigment can be 54wt% to 58wt%. Additives may include one or more of solvents, wetting agents, defoamers, leveling agents, and rheology modifiers; the curing agent may include an epoxy curing agent. The pigments, additives, and curing agents can adopt conventional compositions of existing coatings.

[0073] In a specific embodiment of the present invention, the composite flame-retardant waterborne epoxy resin in component A and the curing agent in component B are formulated with a molar ratio of epoxy in the composite flame-retardant waterborne epoxy resin to amine hydrogen in the curing agent of 1:(0.75~0.85), such as 1:0.8.

[0074] In practice, the application method of the coating includes: mixing component A and component B, spraying under certain temperature and humidity conditions, leveling at room temperature for 30 to 40 minutes, and then baking at 75 to 85°C for 1.5 to 2.5 hours.

[0075] Example 1

[0076] This embodiment provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0077] (1) 59.34g of chlorine anhydride and 11.85g of glycidol were added to a 100mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 60℃ and kept for 3h to obtain a chlorine-containing flame retardant intermediate; then 3.84g of the chlorine-containing flame retardant intermediate and 360g of o-cresol epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) were added to a 500mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 110℃ and kept for 2h to obtain a chlorine-containing epoxy resin.

[0078] (2) Dissolve 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (molecular weight 330) in 13.75g of propylene glycol methyl ether, add them to a 250mL reaction vessel equipped with a stirrer and thermometer, heat to 60℃ and disperse for 30min; then add 23.9g of monoethanolamine phosphate, heat to 80℃ and reflux for 4h, cool to 50℃ and add 15.62g of glacial acetic acid, react at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0079] (3) Take 29.11g of the phosphorus-containing emulsifier obtained in step (2) and add it to the chlorine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min. Then cool down to 60℃ and slowly add 348.47g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain a phosphorus-containing and halogen-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 430nm, a fineness of 20μm, and the emulsion is milky white with a bluish tint.

[0080] Example 2

[0081] This embodiment provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0082] (1) 59.34g of chlorine anhydride and 11.85g of glycidol were added to a 100mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 60℃ and kept for 3h to obtain a chlorine-containing flame retardant intermediate; then 7.68g of the chlorine-containing flame retardant intermediate and 360g of o-cresin epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) were added to a 500mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 120℃ and kept for 2h to obtain a chlorine-containing epoxy resin.

[0083] (2) Dissolve 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (molecular weight 330) in 13.75g of propylene glycol methyl ether, add them to a 250mL reaction vessel equipped with a stirrer and thermometer, heat to 60℃ and disperse for 30min; then add 23.9g of monoethanolamine phosphate, heat to 80℃ and reflux for 4h, cool to 50℃ and add 15.62g of glacial acetic acid, react at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0084] (3) Take 29.42g of the phosphorus-containing emulsifier obtained in step (2) and add it to the chlorine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min. Then cool down to 60℃ and slowly add 352.15g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain a phosphorus-containing and halogen-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 320nm, a fineness of 20μm, and the emulsion is milky white with a bluish tint.

[0085] Example 3

[0086] This embodiment provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0087] (1) 74.18g of 1,4,5,6-tetrabromophthalic anhydride and 11.85g of glycidol were added to a 200mL reactor equipped with a stirrer and a thermometer. The mixture was heated to 65℃ and kept at that temperature for 3h to obtain a bromine-containing flame retardant intermediate. Subsequently, 4.64g of the bromine-containing flame retardant intermediate and 228g of epoxy resin E44 (molecular weight 456) were added to a 500mL reactor equipped with a stirrer and a thermometer. The mixture was heated to 110℃ and kept at that temperature for 2h to obtain a bromine-containing epoxy resin.

[0088] (2) Dissolve 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (molecular weight 330) in 13.75g of propylene glycol ethyl ether, add them to a 250mL reaction vessel equipped with a stirrer and thermometer, heat to 60℃ and disperse for 30min; then add 23.9g of monoethanolamine phosphate, heat to 80℃ and reflux for 4h, cool to 50℃ and add 15.62g of glacial acetic acid, react at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0089] (3) Take 18.61g of the phosphorus-containing emulsifier obtained in step (2) and add it to the bromine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min. Then cool down to 60℃ and slowly add 222.80g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain a phosphorus-containing and halogen-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 360nm, a fineness of 30μm, and the emulsion is milky white with a bluish tint.

[0090] Example 4

[0091] This embodiment provides a method for preparing a composite flame-retardant waterborne epoxy resin, comprising the following steps:

[0092] (1) 59.34g of chlorine anhydride and 11.85g of glycidol were added to a 100mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 60℃ and kept for 3h to obtain a chlorine-containing flame retardant intermediate; then 15.36g of the chlorine-containing flame retardant intermediate and 360g of o-cresol epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) were added to a 500mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 110℃ and kept for 2h to obtain a chlorine-containing epoxy resin.

[0093] (2) Dissolve 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (molecular weight 330) in 13.75g of propylene glycol methyl ether, add them to a 250mL reaction vessel equipped with a stirrer and thermometer, heat to 60℃ and disperse for 30min; then add 23.9g of monoethanolamine phosphate, heat to 80℃ and reflux for 4h, cool to 50℃ and add 15.62g of glacial acetic acid, react at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0094] (3) Take 37.54g of the phosphorus-containing emulsifier obtained in step (2) and add it to the chlorine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min, then cool down to 60℃ and slowly add 366.16g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain a phosphorus-containing and halogen-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 350nm, a fineness of 35μm, and an emulsion that is milky white with a bluish tint.

[0095] Comparative Example 1

[0096] Comparative Example 1 provides a method for preparing an aqueous epoxy resin, comprising the following steps:

[0097] (1) 59.34g of chlorine anhydride and 11.85g of glycidol were added to a 100mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 60℃ and kept for 3h to obtain a chlorine-containing flame retardant intermediate; then 7.68g of the chlorine-containing flame retardant intermediate and 360g of o-cresphenolic epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) were added to a 500mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 110℃ and kept for 2h to obtain a chlorine-containing epoxy resin.

[0098] (2) Take 22.06g of commercially available emulsifier (Nantong Xinbaoyuan LAE-4) and add it to the chlorine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min, then cool down to 60℃ and slowly add 345.62g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain halogen-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 490nm, a fineness of 40μm, and the emulsion is milky white.

[0099] Comparative Example 2

[0100] Comparative Example 2 provides a method for preparing an aqueous epoxy resin, comprising the following steps:

[0101] (1) 59.34g of chlorine anhydride and 11.85g of glycidol were added to a 100mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 60℃ and kept for 3h to obtain a chlorine-containing flame retardant intermediate; then 30.72g of the chlorine-containing flame retardant intermediate and 360g of o-cresin epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) were added to a 500mL reactor equipped with a stirrer and a thermometer, and the temperature was raised to 120℃ and kept for 2h to obtain a chlorine-containing epoxy resin.

[0102] (2) Dissolve 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (molecular weight 330) in 13.75g of propylene glycol methyl ether, add them to a 250mL reaction vessel equipped with a stirrer and thermometer, heat to 60℃ and disperse for 30min; then add 23.9g of monoethanolamine phosphate, heat to 80℃ and reflux for 4h, cool to 50℃ and add 15.62g of glacial acetic acid, react at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0103] (3) Take 50.79g of the phosphorus-containing emulsifier obtained in step (2) and add it to the chlorine-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min, then cool down to 60℃ and slowly add 390.99g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain waterborne epoxy resin with a solid content of 53%, an average particle size of 500nm, a fineness of 45μm, and the emulsion is milky white.

[0104] Comparative Example 3

[0105] Comparative Example 3 provides a method for preparing an aqueous epoxy resin, comprising the following steps:

[0106] (1) 360g of o-cresol epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) and 25.9g of DOPO were added to a 500mL reactor equipped with a stirrer and a thermometer. Then 23.15g of propylene glycol methyl ether was added, the temperature was raised to 120℃ to liquefy the mixed raw materials, and then the temperature was raised to 130℃ to add 1.16g of triphenylphosphine. The mixture was kept warm for 5h to obtain a phosphorus-containing epoxy resin.

[0107] (2) 50g of epoxy resin E51 and 43.55g of polyethylene glycol diglycidyl ether (dissolved in 13.75g of propylene glycol methyl ether) were added to a 250mL reactor equipped with a stirrer and a thermometer and heated to 60℃ for 30min. Then 23.9g of monoethanolamine phosphate was added, and the mixture was heated to 80℃ and refluxed for 4h. The mixture was then cooled to 50℃ and 15.62g of glacial acetic acid was added. The mixture was reacted at 50℃ for 2h to obtain a phosphorus-containing emulsifier.

[0108] (3) Take 30.87g of the phosphorus-containing emulsifier obtained in step (2) and add it to the phosphorus-containing epoxy resin obtained in step (1). Mix at 110℃ for 30min, then cool down to 60℃ and slowly add 370.36g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify and obtain a phosphorus-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 400nm, a fineness of 35μm, and the emulsion is milky white with a bluish tint.

[0109] Comparative Example 4

[0110] Comparative Example 4 provides a method for preparing an aqueous epoxy resin, comprising the following steps:

[0111] (1) 360g of o-cresol epoxy resin (molecular weight 1800, functionality 3.33, EEW: 180g / eq) and 65.41g of DOPO were added to a 500mL reactor equipped with a stirrer and a thermometer. Then 25.52g of propylene glycol methyl ether was added, the temperature was raised to 120℃ to liquefy the mixed raw materials, and then the temperature was raised to 130℃ to add 1.28g of tetramethylammonium bromide. The mixture was kept at this temperature for 5h to obtain a phosphorus-containing epoxy resin.

[0112] (2) Add 34.03g of commercially available waterborne epoxy film-forming emulsifier (Nantong Xinbaoyuan LAE-4) to the phosphorus-containing epoxy resin obtained in step (1) and mix at 110℃ for 30min. Then cool down to 60℃ and slowly add 407.43g of deionized water within 15min under high-speed stirring (3000rpm) to emulsify, and obtain a phosphorus-containing waterborne epoxy resin with a solid content of 53%, an average particle size of 500nm, a fineness of 40μm, and a milky white emulsion.

[0113] Experimental Example 1

[0114] The waterborne epoxy resins of Examples 1-4 and Comparative Examples 1-4 were tested, and the test results are shown in Table 1.

[0115] The following test results are based on the following test methods or standards:

[0116] The particle size of epoxy resin was tested using a PSS particle size analyzer from the United States, and the fineness of the emulsion was tested according to GB / T1724-1979.

[0117] The UL-94 value was tested using a CZF-6 vertical burning tester according to the ASTM D-3801 test standard.

[0118] The LOI value was measured using a JF-5 oxygen index meter according to the GB / T 2046 standard.

[0119] The test method for thermal storage stability includes: taking an appropriate amount of the prepared waterborne epoxy resin into a thermal storage bottle and placing it in an oven at 50°C for accelerated storage stability testing. Every two days, observe the emulsion in the thermal storage bottle for phenomena such as stratification, soft settling, coarsening, demulsification, and particle size enlargement. No abnormalities within 30 days are considered a pass.

[0120] Table 1 Test results of different waterborne epoxy resins

[0121]

[0122]

[0123] Experiment Example 2

[0124] The waterborne epoxy resins of Examples 1-4 and Comparative Examples 1-4 were respectively prepared into coatings, each coating comprising component A and component B. Component A was formulated according to the composition in Table 2, and component B was AQUAC-3126 epoxy curing agent (Jiangsu Fuqisen) diluted with a mixed solvent (propylene glycol methyl ether and water in a mass ratio of 1:1) to a solid content of 30%. The composition of the pigment and filler slurry is shown in Table 3.

[0125] Table 2 Composition of Component A

[0126] Raw material name Mass percentage (%) Waterborne epoxy resin 40.0 Pigment and filler slurry (specific formula as follows) 56.6 Cosolvent (TEGO902W (Germany)) 2.0 Defoamer BYK015 (BYK Chemicals) 0.3 Substrate wetting agent TEGO270 (Germany) 0.5 Rheology modifier XS-83 (Gorta, France) 0.4 Leveling agent BYK301 (BYK Chemicals) 0.2 Total 100

[0127] Table 3 Composition of Pigment and Filler Slurry

[0128]

[0129]

[0130] The coating preparation method includes: preparing component A according to the composition in Table 2, mixing it evenly, and then mixing it with component B at a molar ratio of 1:0.8 for the epoxy in the water-based epoxy resin and the amine hydrogen in the curing agent. The prepared paint is then sprayed onto polished tinplate and cold-rolled steel plate to prepare a paint film. After application, the paint film is allowed to stand and level for 30 minutes, then placed in an 80℃ oven for 2 hours to cure. Performance tests are conducted after 24 hours. The cold-rolled steel plate is used for hot water resistance and neutral salt spray resistance tests, while other tests are performed using the tinplate. The test results are shown in Table 4.

[0131] Table 4 Test results of different waterborne epoxy resin coatings

[0132] Test Project Adhesion hardness Flexibility / mm Impact resistance / cm Water resistant to 40℃ / d Resistance to neutral salt spray / h Example 1 Level 0 3H 2mm 50 ＞30d 408h Example 2 Level 0 2H 3mm 40 ＞30d 360h Example 3 Level 0 2H 2mm 40 ＞30d 360h Example 4 Level 0 2H 2mm 30 ＞30d 360h Comparative Example 1 Level 0 HB 2mm 30 20d 312h Comparative Example 2 Level 1 HB 2mm 30 15d 288h Comparative Example 3 Level 1 HB 2mm 30 20d 312h Comparative Example 4 Level 1 HB 2mm 30 20d 312h

[0133] The above test results are based on the following test methods or standards:

[0134] Adhesion determination by cross-cut test, GB / T 9286-1998;

[0135] Determination of pencil hardness of paint film, GB / T 6739-1996;

[0136] Determination of paint film flexibility, GB / T 1731-1993;

[0137] Determination of impact resistance of paint film GB / T 1973-1993;

[0138] Test for water resistance at 40℃, GB / T 1733-1993;

[0139] Test for resistance to neutral salt spray, GB / T 1771-2007.

[0140] The test results above show that the composite flame-retardant waterborne epoxy resin prepared by this invention, after using a suitable phosphorus-containing emulsifier, greatly reduces the amount of flame-retardant raw materials used, saves production costs, and improves the compatibility of the matrix. This results in excellent flame-retardant performance while achieving superior fineness and storage stability, and also improves the problem of poor mechanical properties. Comparison of Examples 1-4 shows that when the flame-retardant element content in the emulsion is 2.2%, the emulsion exhibits good flame retardancy, storage stability, and excellent mechanical properties. However, excessive or insufficient flame-retardant content in the emulsion will affect both flame retardancy and storage stability. Comparison of Examples 1-4 shows that achieving good flame-retardant performance using commercially available emulsifiers requires more flame-retardant raw materials, resulting in extremely high production costs and significant problems with poor compatibility and emulsion stability. Furthermore, compared with commonly available DOPO-type flame-retardant emulsions, this invention uses less flame-retardant raw material, has lower costs, and exhibits superior flame-retardant performance and durability compared to DOPO-type flame-retardant epoxy resins.

[0141] In summary, the composite flame-retardant waterborne epoxy resin prepared by this invention represents a new breakthrough in both epoxy resin modification and emulsifier modification. It reduces production costs, improves the flame-retardant properties of the emulsion while enhancing its storage stability and mechanical properties, thus meeting the requirements of industrial production.

[0142] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a composite flame-retardant waterborne epoxy resin, characterized in that, Includes the following steps: (a) After reacting halogenated anhydride with glycidol at 60-80°C for 3-4 hours to obtain an intermediate, it is reacted with epoxy resin A at 100-120°C for 2-3 hours to obtain halogenated epoxy resin. (b) After epoxy resin B, polyethylene glycol diglycidyl ether and monoethanolamine phosphate were refluxed in a solvent, glacial acetic acid was added after cooling to obtain a phosphorus-containing emulsifier. (c) The halogenated epoxy resin, the phosphorus-containing emulsifier and water are mixed and phase-inverted emulsified to obtain the composite flame-retardant waterborne epoxy resin; The mass ratio of epoxy resin A to the intermediate is (40-120):1; In step (a), the molar ratio of the halogenated anhydride to the glycidol is 1:(0.8-1.2); the halogenated anhydride includes at least one of 1,4,5,6-tetrabromophthalic anhydride, tetrachlorophthalic anhydride, and chlorohydrin. In step (c), the mass ratio of the halogenated epoxy resin, the phosphorus-containing emulsifier, and the water is (46-49): (3.8-5): (45-48).

2. The preparation method of the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, The epoxy resin A includes bisphenol A type epoxy resin and / or phenolic epoxy resin.

3. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the mass ratio of epoxy resin B, polyethylene glycol diglycidyl ether, and monoethanolamine phosphate is (7-8):(6-7):(2-4).

4. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the amount of solvent used is 15% to 30% of the mass of epoxy resin B.

5. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the amount of glacial acetic acid used is 0.5 to 1.5 times the mass of monoethanolamine phosphate.

6. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the temperature of the reflux reaction is 80-90°C, and the time of the reflux reaction is 3-5 hours.

7. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the epoxy resin B is a bisphenol A type epoxy resin.

8. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, In step (b), the solvent includes at least one of propylene glycol methyl ether, propylene glycol ethyl ether, propylene glycol monobutyl ether, methyl isobutyl ketone, and ethylene glycol butyl ether.

9. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, During the phase inversion emulsification, the temperature of the system is 50–70°C.

10. The method for preparing the composite flame-retardant waterborne epoxy resin according to claim 1, characterized in that, During the phase inversion emulsification, high-speed stirring is performed; the high-speed stirring rate is 2000-4000 r / min.

11. The composite flame-retardant waterborne epoxy resin prepared by the method of any one of claims 1 to 10.

12. A coating, characterized in that, Includes the composite flame-retardant waterborne epoxy resin as described in claim 11.

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