Sprayable flame-retardant polyurea coating and use thereof

Abstract

To solve the problems in the prior art, the application provides a spraying type flame-retardant polyurea coating, which comprises component A and component B, the component A is a semi-prepolymer prepared by reacting a first polyether polyol with an aromatic isocyanate.The component B comprises, in mass fractions, 30-50 parts of a second polyether polyol, 20-30 parts of an amine chain extender, 0.2-0.5 parts of a coupling agent, 0.2-0.5 parts of a catalyst and 35-37 parts of a composite flame retardant.The composite flame retardant comprises, in mass fractions, 34-35 parts of a first flame retardant and 1-2 parts of a second flame retardant.The first flame retardant is triphenyl phosphate coated aluminum hypophosphite, and the second flame retardant is zeolite imidazole framework-8 modified MXene.The application effectively improves the interfacial interaction between the flame retardant and PUA, and the mechanical properties of the flame-retardant coating are obviously improved.

Description

Technical Field

[0001] This invention relates to the field of polymer flame retardant modification technology, and in particular to a sprayable flame retardant polyurea coating and its application. Background Technology

[0002] Polyurea (PUA), as a high-performance elastomer, possesses excellent mechanical properties, corrosion resistance, abrasion resistance, and water resistance. Due to its superior shock absorption and protective properties, polyurea coatings have been widely used in national defense and military projects (such as tank chassis, bulletproof helmets, and protective armor coatings), concrete coatings, pipeline corrosion protection, tank linings, and building waterproofing. Sprayed polyurea technology, developed in the last decade abroad, is a new type of solvent-free and pollution-free green construction technology to meet environmental protection requirements, following low- (non-)pollution coating technologies such as high-solids coatings, water-based coatings, radiation-cured coatings, and powder coatings. Sprayed polyurea is an elastomer coating formed by the rapid reaction of isocyanate components (component A) and amino compound components (component B). Its tensile strength, tear strength, and weather resistance are superior to polyurethane waterproof coatings. It features rapid curing, can be sprayed onto any curved surface, does not produce sagging, is insensitive to moisture, and does not contain volatile organic solvents. It can be sprayed onto any substrate such as steel, wood, and concrete.

[0003] However, polyurea itself is extremely flammable, with a limiting oxygen index (LOI) of only around 21%, and produces a large amount of molten droplets and toxic fumes during combustion. Large amounts of flammable droplets can cause burns and rapid fire spread, while toxic fumes can cause asphyxiation. Therefore, improving the flame retardant properties of polyurea, suppressing droplets, and reducing smoke release are of great significance. Generally, adding flame retardants is the most economical and convenient way to improve the fire safety of PUA. Halogenated flame retardants have excellent flame retardant effects, but they release toxic gases during combustion, endangering human health. Inorganic phosphorus-based flame retardants such as aluminum hypophosphite (AHP) have widely available raw materials, are inexpensive, have high thermal stability, long-lasting flame retardancy, and good smoke suppression properties. However, these flame retardants often have poor compatibility with PUA, and their addition can lead to a significant deterioration in the mechanical properties of PUA. Microencapsulation is an effective method to improve the compatibility between flame retardants and the matrix. Meanwhile, nanofillers have been shown to enhance the flame retardancy and mechanical properties of polymers simultaneously at low addition levels. MXene, as a novel two-dimensional nanomaterial, has exhibited excellent mechanical strengthening and flame retardant properties in many polymer materials in recent years. However, due to the poor dispersibility of MXene in the PUA matrix and its tendency to agglomerate, the modification effect is not ideal. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a sprayable flame-retardant polyurea coating, comprising component A and component B. Component A is a semi-prepolymer obtained by reacting a first polyether polyol with an aromatic isocyanate. Component B, by mass parts, comprises: 30-50 parts of a second polyether polyol, 20-30 parts of an amine chain extender, 0.2-0.5 parts of a coupling agent, 0.2-0.5 parts of a catalyst, and 35-37 parts of a composite flame retardant.

[0005] The composite flame retardant comprises, by weight, 34-35 parts of a first flame retardant and 1-2 parts of a second flame retardant. The first flame retardant is triphenyl phosphate coated aluminum hypophosphite, and the second flame retardant is zeolite imidazole skeleton-8 modified MXene.

[0006] Furthermore, the first polyether polyol is at least one of polytetrahydrofuran ether polyol and polyoxypropylene ether polyol. The second polyether polyol is at least one of difunctional polyether polyol and trifunctional polyether polyol.

[0007] Furthermore, the molecular weight of the first polyether polyol is 1000-2000. The molecular weight of the second polyether polyol is 1000-4000.

[0008] Furthermore, both component A and component B are liquid phase components. The volume ratio of component A to component B is 1:1.

[0009] Furthermore, the semi-prepolymer is prepared by the following method:

[0010] In an inert environment, the first polyether polyol is heated to 100-120°C in a reaction vessel while stirring.

[0011] S102 creates a negative pressure environment in the reaction vessel and maintains this negative pressure environment for a preset time.

[0012] S103 maintains a negative pressure environment, reducing the temperature of the first polyether polyol in the reaction vessel to 50-60℃.

[0013] S104 adds the required amount of isocyanate to the reaction vessel and heats the reaction system of the first polyether polyol and isocyanate to 80-90°C.

[0014] The semi-prepolymer is obtained by reacting S105 for 2-3 hours. The NCO% content in the semi-prepolymer is 15-20%.

[0015] Furthermore, the first flame retardant is particulate matter with a particle size of 10-50 μm, and the second flame retardant is a sheet-like material with a sheet width of 20-50 μm and a thickness of 50-100 nm.

[0016] Furthermore, the first flame retardant is prepared by the following method:

[0017] S201 is expressed in parts by mass. 3-6 parts of triphenyl phosphate are dissolved in the first solvent to obtain the first reaction system.

[0018] S202 heats the first reaction system to 55-65℃ and adds 20-30 parts of aluminum hypophosphate to obtain the second reaction system.

[0019] After stirring the S203 second reaction system for 25-35 minutes, the first product was obtained by rotary evaporation at 55-65℃.

[0020] S204 dries the first product in an environment of 45-55℃, and after drying, the first flame retardant is obtained.

[0021] Furthermore, the second flame retardant is prepared by the following method:

[0022] S301, expressed in parts by mass, dissolves 2.5-3.5 parts of 2-methylimidazole and 0.5-2 parts of MXene in a second solvent and sonicates for 50-80 minutes to obtain a third reaction system.

[0023] S302 dissolves 1-2 parts of zinc nitrate hexahydrate in a second solvent to obtain a fourth reaction system.

[0024] S303 was slowly added dropwise to the third reaction system at room temperature, and the reaction was continued at room temperature for 20-40 hours to obtain the second product.

[0025] S304 centrifuges, filters, washes, and dries the second product to obtain the second flame retardant.

[0026] Furthermore, the MXene in the second flame retardant is prepared by the following method:

[0027] S401, by mass fraction, adds 1-3 parts of titanium aluminum carbide to a third solvent, which is composed of concentrated hydrochloric acid and lithium fluoride, and stirs at room temperature for 22-26 hours to obtain a third product.

[0028] S402 washes the third product with deionized water until the pH is neutral to obtain the fourth product.

[0029] S403 centrifuged the fourth product at 8000-12000 rpm for 8-12 min, collected the bottom precipitate, and obtained the fifth product.

[0030] S404 added the fifth product to deionized water and then subjected it to ultrasonic and centrifugation treatments to obtain an MXene aqueous suspension.

[0031] S405 freeze-drying the MXene aqueous suspension to obtain the MXene.

[0032] In addition, the present invention also provides an application of the above-mentioned sprayable flame-retardant polyurea coating in the fields of storage tank protection, bulletproof coating, vehicle body protection, building waterproofing, pipeline corrosion protection and ship hull protection.

[0033] The beneficial effects of this invention are as follows: This invention employs an interface control strategy to coat and surface-modify AHP and MXene, and then adds the resulting TPP@AHP and ZIF-8@MXene compounded into polyurea. This effectively enhances the interfacial interaction between the flame retardant and PUA, resulting in a significant improvement in the mechanical properties of the flame-retardant coating. When exposed to flame, the flame-retardant coating is more difficult to ignite, and the heat and smoke release during combustion are significantly reduced. The weight and mass of the char layer generated after combustion are also significantly improved, allowing the char layer to better block oxygen and heat, thus better protecting the matrix. Compared with existing flame-retardant systems, the advantage of this invention is that it achieves excellent flame-retardant and smoke-suppressing properties while essentially preserving the mechanical properties of the PUA itself, resulting in a high-performance PUA coating with excellent flame-retardant, smoke-suppressing, and mechanical properties. Attached Figure Description

[0034] Figure 1 The images show a comparison of electron microscopy and X-ray energy dispersive spectroscopy (EDS) of phosphorus elements in the cross-sections of the tensile specimens of Example 1 and Comparative Example 6 of this invention.

[0035] Figure 2 These are screenshots from videos of vertical combustion tests conducted in Embodiment 1, Comparative Example 4, and Comparative Example 6 of the present invention.

[0036] Figure 3 This is a comparison chart of the total heat release and total smoke release of the pure PUA of the present invention, Example 1, and some comparative examples.

[0037] Figure 4 The thermogravimetric curves of Embodiment 1 of the present invention and pure PUA are shown. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0039] Unless otherwise specified, the reagents used in this invention are all conventional test reagents or commercially available reagents, and the processing methods such as stirring, heating, washing, and drying are all conventional processing methods.

[0040] Unless otherwise specified, the weight parts mentioned in this invention refer to uniform mass parts, such as 1g, 10g, or 100g. The specific mass number corresponding to one mass part can be determined as needed and is not limited to the examples of 1g, 10g, or 100g mentioned above.

[0041] This invention provides an exemplary sprayable flame-retardant polyurea coating, comprising component A and component B. Component A is a semi-prepolymer obtained by reacting a first polyether polyol with an aromatic isocyanate. Component B, by mass parts, comprises: 30-50 parts of a second polyether polyol, 20-30 parts of an amine chain extender, 0.2-0.5 parts of a coupling agent, 0.2-0.5 parts of a catalyst, and 35-37 parts of a composite flame retardant.

[0042] The composite flame retardant comprises, by weight, 34-35 parts of a first flame retardant and 1-2 parts of a second flame retardant. The first flame retardant is triphenyl phosphate coated aluminum hypophosphite, and the second flame retardant is zeolite imidazole skeleton-8 modified MXene.

[0043] The present invention provides, by way of example, a first polyether polyol, which is at least one of polytetrahydrofuran ether polyol and polyoxypropylene ether polyol.

[0044] The present invention provides, by way of example, a second polyether polyol, which is at least one of difunctional polyether polyol and trifunctional polyether polyol.

[0045] The present invention provides, by way of example, a first polyether polyol with a molecular weight of 1000-2000.

[0046] The present invention provides, by way of example, a second polyether polyol with a molecular weight of 1000-4000.

[0047] This invention provides, by way of example, a component A and a component B, both of which are liquid phase components. The volume ratio of component A to component B is 1:1.

[0048] This invention provides an exemplary semi-prepolymer corresponding to component A, which is prepared by the following method:

[0049] In an inert environment, the first polyether polyol is heated to 100-120°C in a reaction vessel while stirring.

[0050] S102 creates a negative pressure environment in the reaction vessel and maintains this negative pressure environment for a preset time.

[0051] S103 maintains a negative pressure environment, reducing the temperature of the first polyether polyol in the reaction vessel to 50-60℃.

[0052] S104 adds the required amount of isocyanate to the reaction vessel and heats the reaction system of the first polyether polyol and isocyanate to 80-90°C.

[0053] The semi-prepolymer is obtained by reacting S105 for 2-3 hours. The NCO% content in the semi-prepolymer is 15-20%.

[0054] The present invention provides a first flame retardant, which is particulate matter with a particle size of 10-50 μm.

[0055] The present invention provides a second flame retardant, which is a sheet with a sheet width of 20-50 μm and a thickness of 50-100 nm.

[0056] This invention provides, by way of example, a first flame retardant, which is prepared by the following method:

[0057] S201 is expressed in parts by mass. 3-6 parts of triphenyl phosphate are dissolved in the first solvent to obtain the first reaction system.

[0058] S202 heats the first reaction system to 55-65℃ and adds 20-30 parts of aluminum hypophosphate to obtain the second reaction system.

[0059] After stirring the S203 second reaction system for 25-35 minutes, the first product was obtained by rotary evaporation at 55-65℃.

[0060] S204 dries the first product in an environment of 45-55℃, and after drying, the first flame retardant is obtained.

[0061] This invention provides an exemplary second flame retardant, which is prepared by the following method:

[0062] S301, expressed in parts by mass, dissolves 2.5-3.5 parts of 2-methylimidazole and 0.5-2 parts of MXene in a second solvent and sonicates for 50-80 minutes to obtain a third reaction system.

[0063] S302 dissolves 1-2 parts of zinc nitrate hexahydrate in a second solvent to obtain a fourth reaction system.

[0064] S303 was slowly added dropwise to the third reaction system at room temperature, and the reaction was continued at room temperature for 20-40 hours to obtain the second product.

[0065] S304 centrifuges, filters, washes, and dries the second product to obtain the second flame retardant.

[0066] This invention provides an exemplary embodiment of MXene in a second flame retardant, which is prepared by the following method:

[0067] S401, by mass fraction, adds 1-3 parts of titanium aluminum carbide to a third solvent, which is composed of concentrated hydrochloric acid and lithium fluoride, and stirs at room temperature for 22-26 hours to obtain a third product.

[0068] S402 washes the third product with deionized water until the pH is neutral to obtain the fourth product.

[0069] S403 centrifuged the fourth product at 8000-12000 rpm for 8-12 min, collected the bottom precipitate, and obtained the fifth product.

[0070] S404 added the fifth product to deionized water and then subjected it to ultrasonic and centrifugation treatments to obtain an MXene aqueous suspension.

[0071] S405 freeze-drying the MXene aqueous suspension to obtain the MXene.

[0072] This invention employs an interface control strategy to coat and surface-modify AHP and MXene, and then combines the resulting TPP@AHP and ZIF-8@MXene into polyurea. This interface control effectively enhances the interfacial interaction between the flame retardant and PUA, resulting in a significant improvement in the mechanical properties of the flame-retardant coating.

[0073] In addition, the present invention also provides an application of the above-mentioned sprayable flame-retardant polyurea coating in the fields of storage tank protection, bulletproof coating, vehicle body protection, building waterproofing, pipeline corrosion protection and ship hull protection.

[0074] The technical effects of the present invention will be further explained below with reference to specific embodiments.

[0075] Example 1

[0076] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0077] (1) Preparation of component A:

[0078] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0079] (2) Preparation of component B:

[0080] Component B is obtained by dispersing and stirring 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 34 parts of TPP@AHP, 2 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst evenly and filtering.

[0081] (3) Preparation of flame-retardant polyurea coatings:

[0082] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0083] Example 2

[0084] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0085] (1) Preparation of component A:

[0086] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0087] (2) Preparation of component B:

[0088] Component B is obtained by dispersing and stirring 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 35 parts of TPP@AHP, 1 part of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst evenly and filtering.

[0089] (3) Preparation of flame-retardant polyurea coatings:

[0090] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0091] Comparative Example 1

[0092] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0093] (1) Preparation of component A:

[0094] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0095] (2) Preparation of component B:

[0096] Component B is obtained by dispersing and stirring 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 34 parts of TPP@AHP, 2 parts of MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst evenly, and then filtering.

[0097] (3) Preparation of flame-retardant polyurea coatings:

[0098] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0099] Comparative Example 2

[0100] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0101] (1) Preparation of component A:

[0102] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0103] (2) Preparation of component B:

[0104] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 34 parts of AHP, 2 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0105] (3) Preparation of flame-retardant polyurea coatings:

[0106] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0107] Comparative Example 3

[0108] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0109] (1) Preparation of component A:

[0110] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0111] (2) Preparation of component B:

[0112] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 34 parts of AHP, 2 parts of MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0113] (3) Preparation of flame-retardant polyurea coatings:

[0114] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0115] Comparative Example 4

[0116] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0117] (1) Preparation of component A:

[0118] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0119] (2) Preparation of component B:

[0120] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of TPP@AHP, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0121] (3) Preparation of flame-retardant polyurea coatings:

[0122] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0123] Comparative Example 5

[0124] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0125] (1) Preparation of component A:

[0126] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0127] (2) Preparation of component B:

[0128] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of TPP, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0129] (3) Preparation of flame-retardant polyurea coatings:

[0130] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0131] Comparative Example 6

[0132] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0133] (1) Preparation of component A:

[0134] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0135] (2) Preparation of component B:

[0136] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of AHP, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0137] (3) Preparation of flame-retardant polyurea coatings:

[0138] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0139] Comparative Example 7

[0140] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0141] (1) Preparation of component A:

[0142] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0143] (2) Preparation of component B:

[0144] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0145] (3) Preparation of flame-retardant polyurea coatings:

[0146] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0147] Comparative Example 8

[0148] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0149] (1) Preparation of component A:

[0150] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0151] (2) Preparation of component B:

[0152] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0153] (3) Preparation of flame-retardant polyurea coatings:

[0154] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0155] Comparative Example 9

[0156] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0157] (1) Preparation of component A:

[0158] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0159] (2) Preparation of component B:

[0160] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 36 parts of ZIF-8, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0161] (3) Preparation of flame-retardant polyurea coatings:

[0162] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0163] Comparative Example 10

[0164] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0165] (1) Preparation of component A:

[0166] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0167] (2) Preparation of component B:

[0168] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 40.8 parts of TPP@AHP, 2.4 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0169] (3) Preparation of flame-retardant polyurea coatings:

[0170] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0171] Comparative Example 11

[0172] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0173] (1) Preparation of component A:

[0174] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0175] (2) Preparation of component B:

[0176] Component B is obtained by dispersing and stirring 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 27.2 parts of TPP@AHP, 1.6 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst evenly and filtering.

[0177] (3) Preparation of flame-retardant polyurea coatings:

[0178] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0179] Comparative Example 12

[0180] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0181] (1) Preparation of component A:

[0182] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0183] (2) Preparation of component B:

[0184] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 35.8 parts of TPP@AHP, 0.2 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0185] (3) Preparation of flame-retardant polyurea coatings:

[0186] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0187] Comparative Example 13

[0188] A sprayable flame-retardant polyurea coating is prepared by the following method:

[0189] (1) Preparation of component A:

[0190] Under inert conditions, 48 ​​parts of polyoxypropylene ether polyol with a molecular weight of 2000 are heated to 100-120°C and dehydrated under vacuum pressure (-0.1MPa) for at least 1 hour until no bubbles are generated. Then, the temperature is lowered to 50-60°C and 26 parts of isocyanate MDI-50 and 26 parts of isocyanate MDI-100 are added. The mixture is reacted at 80-90°C for 2-3 hours to obtain semi-prepolymer component A.

[0191] (2) Preparation of component B:

[0192] 41 parts of polyoxypropylene ether polyol with a molecular weight of 2000, 22 parts of 3,5-dimethylthiotoluene diamine, 4 parts of N,N-dialkyltoluene diamine, 18 parts of TPP@AHP, 18 parts of ZIF-8@MXene, 0.5 parts of coupling agent and 0.5 parts of catalyst were dispersed and stirred evenly, and then filtered to obtain component B.

[0193] (3) Preparation of flame-retardant polyurea coatings:

[0194] The flame-retardant polyurea coating can be prepared by spraying the above components A and B in a volume ratio of 1:1 using a high-pressure airless spraying device.

[0195] Performance testing and results

[0196] The conventional mechanical properties and combustion performance tests of flame-retardant polyurea coatings were conducted according to the following standards, and the results are shown in Table 1.

[0197] Tensile strength: Tested according to ASTM D 638-2010 standard at a test speed of 500 mm / min.

[0198] Combustion performance: LOI standard test according to ASTM D2863, UL-94 standard test according to ASTM D3801. Cone calorimetry test at 35 kW / m² power according to ISO 5660–1.

[0199] Thermal stability: Thermogravimetric analysis was performed in accordance with the provisions of GB / T 27761-2011.

[0200] Figure 1 The images show a comparison of electron microscopy and X-ray energy dispersive spectroscopy (EDS) of phosphorus in the cross-sections of the tensile specimens of Example 1 and Comparative Example 6. It can be seen that in Comparative Example 6, AHP exhibits poor dispersion and severe agglomeration in PUA, indicating poor compatibility between AHP and PUA. This is the main reason for the significant deterioration of the mechanical properties of PUA after the addition of AHP. In Example 1, the modified TPP@AHP shows more uniform dispersion in PUA and the agglomeration phenomenon disappears. This demonstrates that microencapsulation of AHP with TPP significantly improves its dispersibility in PUA, thereby enhancing its mechanical and flame-retardant properties.

[0201] Figure 2 These are screenshots from videos of the vertical combustion tests conducted in Example 1, Comparative Examples 4 and 6. Figure 2 It can be seen that Comparative Example 6 used uncoated modified AHP, which produced molten droplets and ignited the degreased cotton during the test, achieving only a V-2 rating. In contrast, Example 1 and Comparative Example 4 used coated TPP@AHP, which showed better flame retardant effect due to the more uniform dispersion of TPP@AHP in PUA, and both achieved a V-0 rating.

[0202] Figure 3 This is a comparison chart of the total heat release (THR) and total smoke release (TSP) of pure PUA, Example 1, and some comparative examples. Pure PUA is an extremely flammable polymer with a THR and TSP as high as 121.3 MJ / m³. 2 and 13.4m 2 In the remaining samples, as the proportion of ZIF-8@MXene increased, the THR and TSP of the samples showed a decreasing trend, indicating that ZIF-8@MXene can effectively suppress the release of PUA heat and smoke. However, if the proportion of ZIF-8@MXene is too high, it will also have a negative impact on the vertical combustion results. As can be seen from the results in Table 1, although the THR and TSP of Comparative Examples 8 and 13 are low, they can only reach the V-2 level in the vertical combustion test. Therefore, the formulation in Example 1 has better overall performance.

[0203] Figure 4 The thermogravimetric curves (TGA) for pure PUA and Example 1 under nitrogen atmosphere are shown. For pure PUA, decomposition mainly occurs in the temperature range of 300°C to 450°C. At 800°C, the residual carbon content is only 4.2%, indicating that PUA is a polymer that is difficult to char. Compared with pure PUA, the residual carbon content of Example 1 at 800°C is significantly increased to 17.7%, indicating that the addition of the composite flame retardant significantly improves the thermal stability of the flame-retardant PUA material.

[0204] The test results of mechanical properties and flame retardant properties of Examples 1-2 and Comparative Examples 1-13 are shown in Table 1:

[0205] Table 1. Test results of mechanical and flame retardant properties of Examples 1-2 and Comparative Examples 1-13

[0206]

[0207]

[0208] As can be seen from the performance comparison in Table 1:

[0209] 1. Compared to Comparative Example 6, Comparative Example 4, which used AHP coating, showed significant improvements in tensile strength and elongation at break. This is because in Comparative Example 6, AHP exhibited poor dispersion and severe agglomeration in PUA, resulting in uneven stress distribution in the coating. In Comparative Example 4, TPP@AHP was more uniformly dispersed in PUA, thus improving mechanical properties. In Example 1, the addition of ZIF-8@MXene further enhanced the mechanical properties of the coating. This is because the modified ZIF-8@MXene is uniformly dispersed in PUA, allowing external stress to be transferred from the matrix to the rigid two-dimensional ZIF-8@MXene nanosheets during tensile testing, thereby dissipating a significant amount of fracture energy and improving the material's mechanical properties.

[0210] 2. Examples 1 and 2, and Comparative Examples 4 and 12 all achieved the UL-94V-0 rating, but the heat and smoke release of Comparative Examples 4 and 12 were worse than those of Examples 1 and 2. This is because ZIF-8@MXene in Examples 1 and 2 has excellent synergistic flame retardant effect. Its layered structure can play a barrier role, and the Zn and Ti elements can catalyze the formation of a denser char layer, thereby effectively protecting the matrix. Therefore, Examples 1 and 2 have better flame retardant effect. Comparative Example 10 also achieved the UL-94V-0 rating, but its mechanical properties were reduced due to the increased amount of flame retardant compared to Example 1.

[0211] The above results show that the flame-retardant polyurea coatings of the present invention, specifically Examples 1 and 2, have significantly better overall performance than the comparative examples. The polyurea coatings prepared using the raw materials and proportions provided in the embodiments of the present invention have excellent flame retardant, smoke suppression, and mechanical properties. The final flame-retardant polyurea material properties can achieve tensile strength > 17 MPa, elongation at break > 220%, oxygen index > 27%, and reach V-0 rating in vertical burning tests. It also exhibits low heat release and minimal smoke release during combustion, demonstrating strong application prospects.

[0212] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A sprayable flame-retardant polyurea coating, comprising component A and component B, characterized in that, Component A is a semi-prepolymer prepared by reacting a first polyether polyol with an aromatic isocyanate. By mass, component B comprises: 30-50 parts of second polyether polyol, 20-30 parts of amine chain extender, 0.2-0.5 parts of coupling agent, 0.2-0.5 parts of catalyst, and 35-37 parts of composite flame retardant; The composite flame retardant comprises 34-35 parts of a first flame retardant and 1-2 parts of a second flame retardant by weight; the first flame retardant is triphenyl phosphate coated aluminum hypophosphite, and the second flame retardant is zeolite imidazole skeleton-8 modified MXene. The first flame retardant is prepared by the following method: S201, expressed as parts by mass, involves dissolving 3-6 parts of triphenyl phosphate in the first solvent to obtain the first reaction system; S202 Heat the first reaction system to 55-65℃ and add 20-30 parts of aluminum hypophosphate to obtain the second reaction system; After stirring the S203 second reaction system for 25-35 minutes, the first product was obtained by rotary evaporation at 55-65℃. S204 The first product is dried in an environment of 45-55℃, and the first flame retardant is obtained after drying.

2. The sprayable flame-retardant polyurea coating according to claim 1, characterized in that, The first polyether polyol is at least one of polytetrahydrofuran ether polyol and polyoxypropylene ether polyol; the second polyether polyol is at least one of difunctional polyether polyol and trifunctional polyether polyol.

3. The sprayable flame-retardant polyurea coating according to claim 2, characterized in that, The molecular weight of the first polyether polyol is 1000-2000; the molecular weight of the second polyether polyol is 1000-4000.

4. The sprayable flame-retardant polyurea coating according to any one of claims 1-3, characterized in that, Both component A and component B are liquid phase components; the volume ratio of component A to component B is 1:

1.

5. The sprayable flame-retardant polyurea coating according to claim 1, characterized in that, The semi-prepolymer was prepared by the following method: S101 In an inert environment, the first polyether polyol is heated to 100-120°C in a reaction vessel while maintaining stirring; S102 creates a negative pressure environment in the reaction vessel and maintains this negative pressure environment for a preset time; S103 maintains a negative pressure environment to reduce the temperature of the first polyether polyol in the reaction vessel to 50-60℃; S104 Add the required amount of isocyanate to the reaction vessel and heat the reaction system of the first polyether polyol and isocyanate to 80-90°C; The semi-prepolymer is obtained by reacting S105 for 2-3 hours; the NCO% content in the semi-prepolymer is 15-20%.

6. The sprayable flame-retardant polyurea coating according to claim 1, characterized in that, The first flame retardant is particulate matter with a particle size of 10-50 μm, and the second flame retardant is a sheet with a sheet width of 20-50 μm and a thickness of 50-100 nm.

7. The sprayable flame-retardant polyurea coating according to any one of claims 1 or 6, characterized in that, The second flame retardant is prepared by the following method: S301: Dissolve 2.5-3.5 parts of 2-methylimidazole and 0.5-2 parts of MXene in a second solvent, and sonicate for 50-80 minutes to obtain a third reaction system. S302 Dissolves 1-2 parts of zinc nitrate hexahydrate in a second solvent to obtain a fourth reaction system; S303 was slowly added dropwise to the third reaction system at room temperature, and the reaction was continued at room temperature for 20-40 hours to obtain the second product. S304 The second product is centrifuged, filtered, washed and dried to obtain the second flame retardant.

8. The sprayable flame-retardant polyurea coating according to any one of claims 1 or 6, characterized in that, The MXene in the second flame retardant is prepared by the following method: S401: Add 1-3 parts by mass of titanium aluminum carbide to a third solvent, which is composed of concentrated hydrochloric acid and lithium fluoride, and stir at room temperature for 22-26 hours to obtain a third product. S402 Wash the third product with deionized water until the pH is neutral to obtain the fourth product; S403 Centrifuge the fourth product at 8000-12000 rpm for 8-12 min, collect the bottom precipitate, and obtain the fifth product; S404 The fifth product was added to deionized water and subjected to ultrasonic and centrifugation treatments in sequence to obtain an MXene aqueous suspension. S405 The MXene aqueous suspension is freeze-dried to obtain the MXene.

9. The application of a sprayable flame-retardant polyurea coating according to any one of claims 1-8 in the fields of storage tank protection, bulletproof coating, vehicle body protection, building waterproofing, pipeline corrosion protection and ship hull protection.

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