Flame-retardant polyurea for masonry surface of petrochemical industry park and preparation method of flame-retardant polyurea

Abstract

The invention relates to the technical field of flame-retardant materials, in particular to flame-retardant polyurea for a masonry surface in a petrochemical industry park and a preparation method of the flame-retardant polyurea. Through mutual cooperation and support of the reaction type phosphorus-containing flame retardant, the additive type modified flame retardant and the environment-friendly intumescent flame retardant, a'reaction type + additive type + intumescent type 'multi-flame-retardant system is constructed, so that the flame-retardant polyurea has good flame retardance and excellent mechanical properties, and is low in price, simple in manufacturing process and suitable for industrial production. The material has the advantages of excellent mechanical properties, impact resistance, flame retardance, high efficiency and environmental protection.

Description

Technical Field

[0001] This invention relates to the field of flame retardant materials technology, and in particular to a flame retardant polyurea for use on the surface of masonry in petrochemical industrial parks and its preparation method. Background Technology

[0002] Petrochemical industrial parks often contain tank areas storing large quantities of flammable and explosive materials, posing extremely high safety risks. Due to land scarcity or insufficient early planning, many tank areas are located too close to office areas and production support facilities. In the event of a fire or explosion, this can easily trigger a chain reaction, causing significant losses. Traditional fire and explosion protection measures, such as firewalls, suffer from long construction periods, large space requirements, and poor seismic resistance, making them difficult to adapt in densely built-up areas. Ordinary masonry structures (such as brick and concrete walls) are prone to cracking and collapse under high temperatures or explosive impacts, failing to effectively block flames and shock waves. Existing fire-retardant coatings suffer from poor adhesion, insufficient weather resistance, or weak explosion-proof performance, making it difficult to meet the requirements for long-term, high-efficiency protection.

[0003] Sprayed polyurea materials are used for masonry surface protection due to their fast curing, strong adhesion, and excellent mechanical properties. They can form a continuous, dense, and elastic coating to reinforce and protect walls. However, ordinary sprayed polyurea has poor flame retardant properties, with a limiting oxygen index of only about 20%. In petrochemical industrial parks with extremely high fire risks, it is easily combustible and not only fails to effectively prevent the spread of fire but may even become a flammable factor, seriously threatening life and property safety.

[0004] Current common practices for improving the flame retardant properties of polyurea, such as adding various liquid / solid flame retardants, often come at the cost of sacrificing the mechanical properties of the polyurea elastomer, making it difficult to simultaneously achieve good flame retardant performance and excellent mechanical properties. While some patents attempt to compensate for the damage to mechanical properties caused by flame retardants by adding reinforcing materials such as modified carbon nanotube slurry to ensure the explosion-proof performance of polyurea, these methods suffer from numerous problems, including high cost, complex manufacturing processes, and a tendency to agglomerate in the resin, leading to decreased storage performance and increased construction difficulty, thus significantly limiting their practical applications.

[0005] Against this backdrop, it is of great significance to develop a flame-retardant sprayed polyurea for masonry surfaces, which can maintain the advantages of polyurea materials such as high strength, impact resistance and rapid construction, while significantly improving fire resistance limit and explosion-proof performance by optimizing the flame-retardant system. This will provide an efficient and reliable solution for close-range protection between storage tanks and office areas in petrochemical industrial parks. Summary of the Invention

[0006] To address the problems in existing technologies, such as the difficulty in achieving both good flame retardancy and excellent mechanical properties in polyurea, the high cost and complex manufacturing processes required to prepare polyurea that combines both flame retardancy and mechanical properties, this invention provides a flame-retardant polyurea for masonry surfaces in petrochemical industrial parks and its preparation method. By combining and supporting three flame retardants—a reactive phosphorus-containing flame retardant, an additive modified flame retardant, and an environmentally friendly intumescent flame retardant—a multi-layered flame retardant system of "reactive + additive + intumescent" is constructed. This allows the flame-retardant polyurea to achieve both good flame retardancy and excellent mechanical properties, while also being inexpensive, simple to manufacture, and possessing advantages such as excellent mechanical properties, impact resistance, flame retardancy, and high efficiency and environmental friendliness.

[0007] The flame-retardant polyurea used on the surface of masonry in petrochemical industrial parks includes component A and component B. Component A is a semi-prepolymer obtained by reacting aromatic diols, reactive phosphorus-containing flame retardants, and aromatic isocyanates. Component B consists of amino-terminated polyethers, diamine chain extenders, additive-modified flame retardants, environmentally friendly intumescent flame retardants, color pastes, and auxiliaries. The volume ratio of component A to component B is 1:1. Mixing component A and component B uniformly in the aforementioned ratio yields the flame-retardant polyurea for use on the surface of masonry in petrochemical industrial parks, which can be used for spraying masonry.

[0008] Using an accurate 1:1 volume ratio between components A and B ensures uniform reaction and consistent coating performance. If the ratio deviates too much from 1:1, it will lead to local performance differences (such as uneven hardness and elasticity), affecting the quality and lifespan of the coating.

[0009] Preferably, the raw materials of component A, by weight, include 20-30 parts of aromatic diol, 10-20 parts of reactive phosphorus-containing flame retardant, and 60-85 parts of aromatic isocyanate. The raw materials of component B, by weight, include 20-60 parts of terminal amino polyether, 20-50 parts of diamine chain extender, 10-20 parts of additive modified flame retardant, 10-15 parts of environmentally friendly intumescent flame retardant, 1-5 parts of color paste, and 0.5-1 parts of additives. The additive modified flame retardant is KH-560 modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (abbreviated as KH-560 modified DOPO). Preferably, the -NCO content (i.e., the mass percentage of NCO) in component A is 16-19%, and the isocyanate index of the flame-retardant polyurea product is 1.05-1.10; Controlling the -NCO content of component A within the above range helps to balance the rigidity and toughness of the material. Combined with the optimized formulation of component B, it can be specifically adapted to different scenarios, providing more flexible space for formulation design. When the isocyanate index is controlled between 1.05 and 1.10, the resulting coating exhibits better overall performance.

[0010] The number average molecular weight of the aromatic diol is in the range of 1000 to 2000, and the aromatic diol is one of aromatic polyether diols, aromatic polyester diols, or a mixture of both. The reactive phosphorus-containing flame retardant is selected from one or a mixture of several of the following: tris(dipropylene glycol) phosphite, diethyl N,N-di(2-hydroxyethyl)aminomethylenephosphonate (CAS: 2781-11-5), and O,O-dimethyl-N,N-bis(2-hydroxyethyl)aminomethylphosphonate (CAS: 2883-51-4). The aromatic isocyanate is selected from one or a mixture of several of diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), naphthalene diisocyanate (NDI), phenyl dimethylene diisocyanate (XDI), and biphenyl diisocyanate (BPI).

[0011] More preferably, the aromatic diol is selected from one or more of polypropylene glycol (PPG), polytetrahydrofuran glycol (PTMEG), polycaprolactone diol (PCL), and polycarbonate diol (PCDL).

[0012] In some embodiments of the present invention, the polypropylene glycol (CAS: 25322-69-4) is selected from DL-1000D and / or DL-2000D of Shandong Lanxing Dongda Co., Ltd.; the polytetrahydrofuran glycol (CAS: 25190-06-1) is selected from PTMEG 1000 and / or PTMEG 2000 of BASF; the polycaprolactone diol (CAS: 36890-68-3) is selected from PCL 210N and / or PCL 220N of Daicel, Nippon Chemical Industries, Ltd.; the polycarbonate diol (CAS: 29862-10-0) is selected from UH100 and / or UH200 of Ube Industries, Ltd.; and the tris(dipropylene glycol) phosphite (CAS: 36788-39-3) is selected from TDPP. 430; N,N-Di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester (CAS: 2781-11-5) can be selected from Qingdao Lianmei Chemical Co., Ltd. FRC-6.

[0013] Preferably, the terminal amino polyether is selected from difunctional terminal amino polyethers and / or trifunctional terminal amino polyethers. The diamine chain extender is selected from one or a mixture of several of the following: diethyltoluene diamine (e.g., E100, CAS: 68479-98-1), dimethylthiotoluene diamine (e.g., E300, CAS: 106264-79-3), 4,4-bis-sec-butylaminodiphenylmethane (e.g., UNILINK4200, WANLINK6200, CAS: 5285-60-9), diaminodicyclohexylmethane (CAS: 1761-71-3), isophorone diamine (CAS: 2855-13-2), trimethylhexanediamine (CAS: 25620-58-0), 4,4-methylenebis(2,6-diethyl)aniline (CAS: 13680-35-8), and 4,4-methylenebis(2,6-diisopropyl)aniline (CAS: 19900-69-7). The environmentally friendly intumescent flame retardant is selected from one or a mixture of several of the following: ammonium polyphosphate (APP), hexaphenoxycyclotriphosphazene (HPCTP), bisphenol A bis(diphenyl phosphate) (BDP), and melamine phosphate salt (MPP). The additives are selected from one or more of the following: dispersants, rheology modifiers, fungicides, coupling agents, and defoamers; The color paste is a common color paste used in the polyurethane industry.

[0014] In some embodiments of the present invention, the terminal amino polyether is selected from Huntsman Jeffamine. ® A mixture of one or more of the following series: D2000, T5000, T403, D400, D4000, and T3000.

[0015] The modified flame retardant (i.e., KH-560 modified DOPO) is described in CN102675895A and can be prepared according to CN102675895A. Alternatively, it can be prepared by reacting DOPO and KH-560 at 110°C under a nitrogen atmosphere. The reaction process is shown below: The more specific preparation method is as follows: 1) After drying DOPO, seal and store the KH-560 ethanol solution and the dried DOPO separately in the dark. 2) Add dried DOPO and toluene to the reaction vessel, stir and heat until DOPO is completely dissolved to obtain DOPO solution. Under continuous stirring and nitrogen protection, add KH-560 ethanol solution dropwise to the DOPO solution while keeping it warm and stirring during the dropwise addition. Then heat to 110℃ and react under stirring. 3) After the reaction is complete, cool to room temperature, and rotary evaporate the mixture obtained in step 2) to obtain the crude product. The crude product is washed, allowed to stand, and filtered multiple times. The filtrates are combined, and the filtrates are rotary evaporated and dried to obtain the final product.

[0016] This invention also provides a method for preparing the above-mentioned flame-retardant polyurea for the surface of masonry in petrochemical industrial parks, the specific steps of which are as follows: 1) Preparation of component A: After the aromatic diol and the reactive phosphorus-containing flame retardant are mixed evenly, the mixture is dehydrated at 100-120℃ and vacuum -0.1 MPa for 3-5 hours. Then, the system is cooled to 40-50℃ under nitrogen protection, and the aromatic isocyanate is slowly added under mechanical stirring at 300-500 rpm. The mixture is reacted at 70-85℃ for 2-4 hours to generate a -NCO-terminated prepolymer intermediate, i.e., component A. 2) Preparation of component B: The terminal amino polyether is dehydrated at 100-120℃ and vacuum -0.1 MPa for 3-5 hours. Then, at 70-80℃, diamine chain extender is added to the terminal amino polyether with mechanical stirring at 300-500 rpm until a homogeneous solution is formed. Then, additive modified flame retardant, environmentally friendly intumescent flame retardant and color paste are added and stirred until uniformly dispersed and without obvious particles, forming a homogeneous and stable mixture. Finally, the additives are added and stirring is continued for 1-2 hours to form a homogeneous mixture, thus obtaining component B.

[0017] Furthermore, during use, components A and B are mixed in a 1:1 volume ratio using a high-pressure spraying device, and then atomized and uniformly sprayed onto the substrate surface under spraying temperature of 70-75°C and relative humidity ≤75%. After spraying, the coating quickly and naturally cures to form a polyurea protective coating.

[0018] The present invention has achieved the following beneficial effects: This flame-retardant polyurea utilizes reactive phosphorus-containing flame retardants, additive modified flame retardants, and environmentally friendly intumescent flame retardants to construct a "reactive + additive + intumescent" structure. The multi-layer flame retardant system uses phosphorus-containing polyols (reactive phosphorus-containing flame retardants) to anchor phosphorus elements to polyurea molecular chains through chemical bonding, achieving long-lasting and stable flame retardancy. Simultaneously, the chemical bonding ensures the integrity of the polyurea cross-linked network, preventing the migration and precipitation of flame retardant components. The additive-modified flame retardant combines gas-phase free radical capture and condensed-phase flame retardant functions, addressing the common problem of agglomeration in traditional additive-type flame retardants. Its rigid heterocyclic structure also enhances the impact resistance of the char layer. The environmentally friendly intumescent flame retardant releases non-combustible gases at high temperatures, simultaneously forming a porous intumescent char layer that tightly covers the combustion surface, rapidly blocking the spread of combustion and providing excellent smoke suppression, effectively compensating for the insufficient smoke suppression capabilities of single phosphorus-based flame retardants. During combustion, phosphorus captures free radicals, and non-combustible gases dilute combustible gases (gas phase), isolating the char layer from heat and oxygen (condensed phase), thus improving flame retardant performance to meet the requirements of masonry buildings.

[0019] The formula adjusts the ratio of components A and B, as well as the types and amounts of reactive phosphorus-containing flame retardants, additive modified flame retardants, and environmentally friendly intumescent flame retardants. Based on the synergistic effect of these three components in flame retardant and mechanical properties, the coating achieves excellent flame retardant and mechanical properties to meet the requirements of masonry construction.

[0020] The three types of flame retardants work synergistically in terms of the entire combustion process, char layer structure, and smoke suppression and toxicity reduction.

[0021] Gas-condensed phase synergy: Reactive phosphorus-containing flame retardants and KH560 modified DOPO capture combustion free radicals in the gas phase to inhibit flame propagation; environmentally friendly intumescent flame retardants form an expanded char layer in the condensed phase to block heat and oxygen transfer and cover the entire combustion process.

[0022] Synergistic reinforcement of char layer: The reactive phosphorus-containing flame retardant catalyzes the formation of a dense char layer, which, together with the porous expanded char layer of the environmentally friendly intumescent flame retardant, forms a "dense inner layer + porous outer layer" composite structure. The silicon-oxygen bonds of modified DOPO promote the ceramicization of the char layer, prevent high-temperature collapse, and significantly improve the heat insulation and oxygen barrier capabilities.

[0023] Smoke suppression and flame retardant synergy: Environmentally friendly intumescent flame retardants release non-combustible gases to dilute smoke, DOPO phosphorus-phenanthroline structure inhibits the generation of toxic gases, and reactive phosphorus-based flame retardants reduce the release of volatile combustibles. The three work together to reduce the density and toxicity of combustion smoke.

[0024] The three types of flame retardants, through structural adaptation and performance complementarity, balance the strength, toughness, and stability of polyurea coatings, avoiding the performance degradation caused by a single flame retardant.

[0025] Positive enhancement effect: Reactive phosphorus-containing flame retardants are covalently linked to the molecular chain, increasing the crosslinking density and retaining toughness; modified DOPO improves compatibility through silicon-oxygen bonds, and rigid heterocycles enhance strength and hardness; intumescent flame retardants, after being uniformly dispersed, act as physical fillers to improve wear resistance, thus consolidating the foundation of mechanical properties.

[0026] Synergistic regulation: The flexible segments of the reactive phosphorus-containing flame retardant neutralize the rigidity and embrittlement of modified DOPO; the porous structure of the environmentally friendly intumescent flame retardant absorbs stress energy and improves elongation at break; the silicon-oxygen bonds of KH560 chemically bond with the reactive phosphorus-containing flame retardant, compensating for the possible decrease in adhesion caused by the environmentally friendly intumescent flame retardant, ultimately achieving a balanced adaptation of tensile strength, hardness and elongation at break. Attached Figure Description

[0027] Figure 1 A diagram showing the chemical structure and peak positions of additive-modified flame retardants; Figure 2 The NMR spectrum of the modified flame retardant is shown in the form of hydrogen. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to specific embodiments. These embodiments are only used to illustrate the technical solution of the present invention in more detail and should not be construed as limiting the scope of protection of the present invention.

[0029] In the following examples and comparative examples, the CAS number of N,N-bis(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester is 2781-11-5, the CAS number of the melamine phosphate salt is 218768-84-4, diethyltoluenediamine is selected from E100 (CAS: 68479-98-1, Jiangsu Weike Terui Chemical Co., Ltd.), and 4,4-bis-sec-butylaminodiphenylmethane is selected from WANALINK. ® 6200 (CAS: 5285-60-9, Yantai Wanhua Polyurethane Co., Ltd.), the dispersant used is BYK-110 from BYK GmbH, Germany, and the terminal amino polyether is Huntsman Jeffamine. ® The mixture of series D2000 and T5000 uses BT series general-purpose color paste produced by Longhui Composite Materials Co., Ltd.

[0030] Unless otherwise specified, the raw materials, reagents, instruments and equipment used in the following examples and comparative examples can be obtained commercially or prepared by existing methods.

[0031] In the following examples and comparative examples, the -NCO content was determined by di-n-butylamine titration. The isocyanate index (R value) was calculated according to a well-known definition in the field of polyurethane chemistry, namely, the ratio of the number of moles of isocyanate groups (-NCO) actually added to the number of moles of active hydrogen groups (-NH2, -OH) in the system, multiplied by 100%. For specific calculation methods, please refer to the isocyanate index calculation principles recorded in authoritative works such as "Handbook of Polyurethane Elastomers" (edited by Liu Houjun et al., Chemical Industry Press, May 2012).

[0032] The additive-modified flame retardant (KH-560 modified DOPO) used in the following examples and comparative examples was produced in the same batch and prepared by the following method: 1) Place DOPO in a vacuum drying oven and dry it at 80℃ and 0.09 MPa for 2 hours to remove the adsorbed moisture from the raw material. After cooling, place it in a desiccator for later use. Weigh KH-560 and anhydrous ethanol at a mass ratio of 1:1, mix them, and stir with a magnetic stirrer at 500 rpm for 10 minutes to prepare a 50% KH-560 ethanol solution. Seal and store the KH-560 ethanol solution and the dried DOPO separately in the dark. 2) Add 100 g (0.46 mol) of pretreated DOPO and 500 mL of anhydrous toluene (water content ≤0.03%) to a 500 mL three-necked flask. The flask is equipped with a mechanical stirrer, a reflux condenser (connected to an anhydrous calcium chloride drying tube at the top) and a nitrogen delivery tube, and the whole flask is placed on a constant temperature heating mantle. Turn on the stirrer (300 rpm), heat to 80 °C, and keep stirring at this temperature for 30 minutes until the DOPO is completely dissolved and a transparent solution is formed. After purging the three-necked flask with nitrogen gas (99.999% purity, flow rate 20 mL / min) for 10 minutes to replace the air, a KH-560 ethanol solution containing 120.27 g (0.51 mol, DOPO to KH-560 molar ratio 1:1.1) of KH-560 was added to a constant-pressure dropping funnel. Under continuous stirring and nitrogen protection, the KH-560 ethanol solution was slowly added dropwise to the DOPO solution, maintaining a temperature of 80°C and a stirring speed of 300 rpm. After the addition was complete, the temperature was raised to 110°C, the stirring speed was adjusted to 500 rpm, and the reaction was maintained at this temperature under reflux for 4 h. 3) After the reaction is complete, cool to room temperature and transfer the resulting mixture to a rotary evaporator. Distill under reduced pressure at 60°C and 0.08 MPa for 2 hours to remove toluene and unreacted monomers, yielding a crude product. Add anhydrous ethanol (2:1 mass ratio to crude product) to the crude product, stir for 30 minutes, let stand for 2 hours, and collect the filtrate. Repeat the washing and filtration process three times, combine the filtrates, and rotary evaporate again (60°C, 0.08 MPa) to remove ethanol. Dry the resulting product under vacuum at 80°C and 0.09 MPa for 6 hours to obtain KH-560 modified DOPO, with a yield of approximately 90%. Its 1H NMR spectrum, chemical structure, and peak positions are shown below. Figure 1 , Figure 2 As shown.

[0033] Example 1: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: According to the weight ratio, 20 parts of polyoxypropylene glycol (DL-1000D, Shandong Lanxing Dongda Co., Ltd.) and 10 parts of N,N-di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester were mixed evenly and placed in a reactor. The mixture was dehydrated at a temperature of 100-120℃ and under vacuum conditions (-0.1 MPa) for 3 to 5 hours. After dehydration, the reaction system was cooled to 40°C under a nitrogen atmosphere. Then, 66 parts of MDI-50 (CAS: 26447-40-5) were slowly added under mechanical stirring at 300-500 rpm. By controlling the aforementioned material ratio, the molar ratio of total NCO to OH in the system could be maintained within the range of 1.1-1.5. The reaction was continued at 80°C for 4 hours with stirring, and finally a prepolymer intermediate with -NCO end groups was generated. The NCO content was measured to be 17.92%. (2) Preparation of Component B: 30 parts by weight of terminal amino polyether D2000 and T5000 (D2000 to T5000 mass ratio 1:1) were added to a reactor and dehydrated at 100-120℃ and -0.1 MPa vacuum for 3-5 hours. After dehydration, the system was cooled to 80℃, and mechanical stirring was started at 300-500 rpm. 40 parts by weight of chain extender E100 and 6200 (E100 to 6200 mass ratio 3:1) were added to the terminal amino polyether, and stirring was continued until a transparent and homogeneous solution was formed. Then, 15 parts by weight of additive modified flame retardant, 10 parts by weight of MPP, and 4 parts by weight of colorant were added, and the mixture was stirred thoroughly until no visible particles were found, forming a stable suspension. Finally, 1 part by weight of high-efficiency dispersant (BYK110) was added, and stirring was continued for 1-2 hours to ensure uniform distribution of the components, resulting in a stable polyurea component B suitable for spray application.

[0034] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.05.

[0035] Example 2: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: According to the weight ratio, 25 parts of polytetrahydrofuran diol (PTMEG1000, BASF) and 10 parts of N,N-di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester were mixed evenly and placed in a reactor. The mixture was dehydrated at a temperature of 100-120℃ and under vacuum conditions (-0.1 MPa) for 3 to 5 hours. After dehydration, the reaction system was cooled to 40°C under a nitrogen atmosphere. Then, 69 parts of MDI-50 were slowly added under mechanical stirring at 300–500 rpm. By controlling the aforementioned material ratio, the molar ratio of total NCO to OH in the system could be maintained within the range of 1.1–1.5. The reaction was continued at 80°C for 4 hours with stirring, and finally a prepolymer intermediate with -NCO end groups was generated. The NCO content was measured to be 17.11%. (2) Preparation of Component B: 30 parts by weight of terminal amino polyether D2000 and T5000 (D2000 to T5000 mass ratio 1:2) were added to a reactor and dehydrated at 100-120℃ and -0.1 MPa vacuum for 3-5 hours. After dehydration, the system was cooled to 80℃, and mechanical stirring was started at 300-500 rpm. 50 parts by weight of chain extender E100 and 6200 (E100 to 6200 mass ratio 2:3) were added to the terminal amino polyether, and stirring was continued until a transparent and homogeneous solution was formed. Then, 10 parts by weight of additive modified flame retardant, 15 parts by weight of MPP, and 4.5 parts by weight of colorant were added, and the mixture was stirred thoroughly until no visible particles were found, forming a stable suspension. Finally, 0.5 parts by weight of high-efficiency dispersant (BYK110) were added, and stirring was continued for 1-2 hours to ensure uniform distribution of the components, resulting in a stable polyurea component B suitable for spray application.

[0036] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.07.

[0037] Example 3: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: According to the weight ratio, 20 parts of polycaprolactone diol (PCL 220N, Nippon Chemical Industry Co., Ltd. Daicel) and 10 parts of N,N-di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester were mixed evenly and placed in a reactor. The mixture was dehydrated at a temperature of 100-120℃ and under vacuum conditions (-0.1 MPa) for 3 to 5 hours. After dehydration, the reaction system was cooled to 40°C under a nitrogen atmosphere. Then, 62 parts of MDI-50 were slowly added under mechanical stirring at 300–500 rpm. By controlling the aforementioned material ratio, the molar ratio of total NCO to OH in the system could be maintained within the range of 1.1–1.5. The reaction was continued at 80°C for 4 hours with stirring, and finally a prepolymer intermediate with -NCO end groups was generated. The NCO content was measured to be 18.15%. (2) Preparation of Component B: 20 ​​parts by weight of terminal amino polyether D2000 and T5000 (D2000 to T5000 mass ratio 1:3) were added to a reactor and dehydrated at 100-120℃ and -0.1 MPa vacuum for 3-5 hours. After dehydration, the system was cooled to 80℃, and mechanical stirring was started at 300-500 rpm. 50 parts by weight of chain extender E100 and 6200 (E100 to 6200 mass ratio 2:3) were added to the terminal amino polyether, and stirring was continued until a transparent and homogeneous solution was formed. Then, 15 parts by weight of additive modified flame retardant, 10 parts by weight of APP, and 4.5 parts by weight of colorant were added, and the mixture was stirred thoroughly until no visible particles were found, forming a stable suspension. Finally, 0.5 parts by weight of high-efficiency dispersant (BYK110) were added, and stirring was continued for 1-2 hours to ensure uniform distribution of the components, resulting in a polyurea component B with good stability suitable for spray application.

[0038] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.05.

[0039] Example 4: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: According to the weight ratio, 20 parts of polycarbonate diol (UH200, Ube Industries, Ltd.) and 10 parts of N,N-di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester were mixed evenly and placed in a reactor. The mixture was dehydrated at a temperature of 100-120°C and under vacuum conditions (-0.1 MPa) for 3 to 5 hours. After dehydration, the reaction system was cooled to 40°C under a nitrogen atmosphere. Then, 62 parts of MDI-50 were slowly added under mechanical stirring at 300–500 rpm. By controlling the aforementioned material ratio, the molar ratio of total NCO to OH in the system could be maintained within the range of 1.1–1.5. The reaction was continued at 80°C for 4 hours with stirring, and finally a prepolymer intermediate with -NCO end groups was generated. The NCO content was measured to be 18.15%. (2) Preparation of Component B: 20 ​​parts by weight of terminal amino polyether D2000 and T5000 (D2000 to T5000 mass ratio 1:3) were added to a reactor and dehydrated at 100-120℃ and -0.1 MPa vacuum for 3-5 hours. After dehydration, the system was cooled to 80℃, and mechanical stirring was started at 300-500 rpm. 50 parts by weight of chain extender E100 and 6200 (E100 to 6200 mass ratio 2:3) were added to the terminal amino polyether, and stirring was continued until a transparent and homogeneous solution was formed. Then, 10 parts by weight of additive modified flame retardant, 15 parts by weight of APP, and 4.5 parts by weight of colorant were added, and the mixture was stirred thoroughly until no visible particles were found, forming a stable suspension. Finally, 0.5 parts by weight of high-efficiency dispersant (BYK110) were added, and stirring was continued for 1-2 hours to ensure uniform distribution of the components, resulting in a stable polyurea component B suitable for spray application.

[0040] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.05.

[0041] Example 5: Flame-retardant polyurea for use on the surface of masonry in petrochemical industrial parks was prepared using the same method as in Example 4, except that the temperature was lowered to 50°C after dehydration in step 1), the reaction temperature in step 1) was 70°C, and the system was lowered to 70°C after dehydration in step 2).

[0042] Example 6: Flame-retardant polyurea for use on the surface of masonry in petrochemical industrial parks was prepared using a method essentially the same as that in Example 4, except that the reaction temperature in step 1) was 85°C and the reaction time was 2 h.

[0043] Example 7 prepared flame-retardant polyurea for the surface of masonry in petrochemical industrial parks using essentially the same method as in Example 4, except that in component A, polycarbonate diol was 30 parts by weight, N,N-di(2-hydroxyethyl)aminomethylenephosphonic acid diethyl ester was 20 parts by weight, and MDI-50 was 85 parts by weight; in component B, terminal amino polyether was 60 parts by weight, chain extender D2000 and T5000 together were 50 parts by weight (D2000 to T5000 mass ratio was 1:3), additive modified flame retardant was 20 parts by weight, and colorant was 1 part by weight.

[0044] Comparative Example 1: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: According to the weight ratio, 45 parts of polycarbonate diol (UH200) were placed in a reactor and dehydrated at a temperature of 100-120℃ and under vacuum conditions (-0.1 MPa) for 3 to 5 hours. After dehydration, the reaction system was cooled to 40°C under a nitrogen atmosphere. Then, 65 parts of MDI-50 were slowly added under mechanical stirring at 300-500 rpm. The reaction was continued at 80°C for 4 hours with stirring, eventually producing a prepolymer intermediate with -NCO end groups. The NCO content was measured to be 18.14%. (2) Preparation of Component B: 20 ​​parts by weight of terminal amino polyether D2000 and T5000 (D2000 to T5000 mass ratio 1:3) were added to a reactor and dehydrated at 100-120℃ and -0.1 MPa vacuum for 3-5 hours. After dehydration, the system was cooled to 80℃, and mechanical stirring was started at 300-500 rpm. 50 parts by weight of chain extender E100 and 6200 (E100 to 6200 mass ratio 2:3) were added to the terminal amino polyether, and stirring was continued until a transparent and homogeneous solution was formed. Then, 10 parts by weight of additive modified flame retardant, 15 parts by weight of APP, and 4.5 parts by weight of colorant were added, and the mixture was stirred thoroughly until no visible particles were found, forming a stable suspension. Finally, 0.5 parts by weight of high-efficiency dispersant (BYK110) were added, and stirring was continued for 1-2 hours to ensure uniform distribution of the components, resulting in a stable polyurea component B suitable for spray application.

[0045] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.05.

[0046] Comparative Example 2: Flame-retardant polyurea for use on masonry surfaces in petrochemical industrial parks was prepared according to the following method: (1) Preparation of component A: Component A was prepared in the same manner as in Example 4, and the resulting prepolymer intermediate with -NCO end groups was tested and found to have NCO=18.15%; (2) Preparation of component B: Component B was prepared in the same way as in Example 4, except that no additive modified flame retardant was added in this comparative example.

[0047] The isocyanate index of the flame-retardant polyurea product obtained by mixing components A and B in a 1:1 volume ratio was tested and found to be 1.05.

[0048] Application Experiment Example The A and B components in the aforementioned examples and comparative examples were mixed in a 1:1 volume ratio using a high-pressure spraying device. The examples and comparative examples were sprayed under the same environmental conditions. After atomization at a spraying temperature of 70-75°C and a relative humidity of ≤75%, the mixture was uniformly sprayed onto the substrate surface. After spraying, it quickly and naturally cured to form a polyurea protective coating.

[0049] The solid content of the flame-retardant polyurea protective materials in the above embodiments and comparative examples was tested according to GB / T 23446-2009; the tensile strength and elongation at break of the flame-retardant polyurea protective materials in the above embodiments and comparative examples were tested according to GB / T 528-2009; the tear strength of the flame-retardant polyurea protective materials in the above embodiments and comparative examples was tested according to GB / T 529-2008; the hardness of the flame-retardant polyurea protective materials in the above embodiments and comparative examples was tested according to GB / T 531.1-2008; the impact resistance of the flame-retardant polyurea protective materials in the above embodiments and comparative examples was tested according to GB / T 20624.2-2006; the bond strength (concrete) of the flame-retardant polyurea protective materials in the above embodiments and comparative examples was tested according to GB / T 16777-2008; the flame-retardant reliability of the above embodiments and comparative examples was tested using the vertical burning test approved by Underwriters Laboratories UL-94 standard; and ISO was referenced. 4589-2 Limiting oxygen index (LOI) tests were performed on the above-described embodiments and comparative examples.

[0050] Various performance tests were conducted on the flame-retardant polyurea protective materials of the above embodiments and comparative examples, and the test results are shown in Table 1.

[0051] Table 1 Performance test results of flame-retardant polyurea protective materials Based on the data in the table above, from the overall performance trend, the formulations of the "reactive + additive + intumescent" multi-flame retardant system constructed in this application (Examples 1-4) show a significant advantage in combustion performance compared to the formulations without this system (Comparative Examples 1-2). The former can all reach the flame-retardant level, while the latter can only reach the combustible level. This confirms the key role of the multiple flame retardant mechanisms (phosphorus capture of free radicals, dilution of non-combustible gases, and isolation by the intumescent char layer) in improving flame retardant performance, and can better meet the core fire protection requirements of masonry buildings.

[0052] Regarding interfacial adhesion and stress adaptability, Examples 1-4, which contain multiple flame-retardant systems, achieved an adhesion strength of 4.9-6.5 MPa through the chemical bonding between the polar groups in the polyols and terminal amino polyethers and the hydroxyl groups on the surface of the masonry substrate (mainly silicate), which is higher than that of Comparative Examples 1-2. At the same time, the flexibility of the terminal amino polyether segments in the formulation can effectively alleviate the stress caused by temperature changes and drying shrinkage of the substrate. Combined with the impact resistance test results of GB / T20624, it can reduce the risk of coating peeling due to substrate deformation and has better adhesion stability.

[0053] In terms of mechanical property balance, the three types of flame retardants, through structural adaptation and performance complementarity, effectively balance the strength, toughness and stability of the polyurea coating while ensuring its flame retardant performance, avoiding performance degradation caused by a single component: reactive phosphorus-based flame retardants toughen and enhance crosslinking through bonding, modified DOPO improves hardness with interfacial compatibility and rigid structure, and intumescent flame retardants enhance wear resistance as dispersing fillers; at the same time, flexible segments neutralize rigid embrittlement, porous structures absorb energy and improve toughness, and silicon-oxygen bonds and crosslinking networks work together to ensure adhesion, ultimately achieving an ideal balance of strength, hardness and toughness.

[0054] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any equivalent substitutions or modifications made by those skilled in the art within the spirit and principle of the present invention without any creative effort should be included within the protection scope of the present invention.

Claims

1. A flame retardant polyurea for petrochemical park masonry surfaces, characterized by, The A component and the B component are included. The A component is a semi-prepolymer prepared by reacting aromatic dihydric alcohol, reactive phosphorus-containing flame retardant and aromatic isocyanate, raw materials of the B component include terminal amino polyether, diamine chain extender, additive modified flame retardant, environmentally friendly intumescent flame retardant, color paste and auxiliary agent; The volume ratio of the A component and the B component is 1:

1.

2. The flame retardant polyurea for petrochemical park masonry surfaces according to claim 1, characterized by, The -NCO content in the A component is 16-19wt%, and the isocyanate index of the flame-retardant polyurea product is 1.05-1.

10.

3. The flame retardant polyurea for petrochemical park masonry surfaces according to claim 1, characterized by that, The raw materials of the A component include, by weight, 20-30 parts of aromatic dihydric alcohol, 10-20 parts of reactive phosphorus-containing flame retardant and 60-85 parts of aromatic isocyanate. The raw materials of the B component include, by weight, 20-60 parts of terminal amino polyether, 20-50 parts of diamine chain extender, 10-20 parts of additive modified flame retardant, 10-15 parts of environmentally friendly intumescent flame retardant, 1-5 parts of color paste and 0.5-1 part of auxiliary agent.

4. The flame retardant polyurea for petrochemical park masonry surfaces according to claims 1 or 3, characterized by the fact that, The reactive phosphorus-containing flame retardant is selected from one or a mixture of several of tris(neopentyl glycol) phosphite, N,N-di(2-hydroxyethyl) aminomethylene phosphonic acid diethyl ester and O,O-dimethyl-N,N-bis(2-hydroxyethyl) aminomethyl phosphonate. The additive modified flame retardant is KH-560 modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide. The environmentally friendly intumescent flame retardant is selected from one or a mixture of several of ammonium polyphosphate, hexaphenoxy cyclotriphosphazene, bisphenol A bis(diphenyl phosphate) and phosphonate melamine salt.

5. The flame retardant polyurea for petrochemical park masonry surfaces according to claims 1 or 3, characterized by the fact that, The number average molecular weight of the aromatic dihydric alcohol is within 1000-2000, and the aromatic dihydric alcohol is one or a mixture of both of aromatic polyether dihydric alcohol and aromatic polyester dihydric alcohol. The aromatic isocyanate is selected from one or a mixture of several of diphenylmethane diisocyanate, toluene diisocyanate, naphthalene diisocyanate, xylylene diisocyanate and biphenyl diisocyanate. The terminal amino polyether is selected from di-functional terminal amino polyether and / or tri-functional terminal amino polyether. The diamine chain extender is selected from one or a mixture of several of diethyl toluene diamine, dimethylthio toluene diamine, 4,4-bis-sec-butylaminodiphenyl methane, diamino dicyclohexyl methane, isophorone diamine, trimethyl hexanediamine, 4,4-methylene bis(2,6-diethyl) aniline and 4,4-methylene bis(2,6-diisopropyl) aniline. The auxiliary agent is selected from one or a mixture of several of dispersant, rheological agent, mildewcide, coupling agent and defoaming agent.

6. The flame retardant polyurea for petrochemical park masonry surfaces according to claim 5, characterized by the fact that, The aromatic dihydric alcohol is selected from one or more of polypropylene oxide diol, polytetrahydrofuran diol, polycaprolactone dihydric alcohol and polycarbonate diol.

7. The flame retardant polyurea for petrochemical park masonry surfaces according to claim 4, characterized by the fact that, The KH-560 modified 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is prepared by reacting DOPO and KH-560 under nitrogen atmosphere at 110℃, and the reaction process is shown as follows: 。 8. The flame retardant polyurea for petrochemical park masonry surfaces according to claim 7, characterized by the fact that, The preparation method of the additive modified flame retardant is as follows: 1) Dry DOPO and toluene were added into a reaction vessel, and the mixture was stirred and heated to dissolve the DOPO completely to obtain a DOPO solution. The ethanol solution of KH-560 was added dropwise into the DOPO solution under continuous stirring and nitrogen protection. During the dropwise addition, the mixture was heated to 110°C and stirred. After the reaction was completed, the mixture was cooled to room temperature. The obtained mixture was subjected to rotary evaporation to obtain a crude product. The crude product was washed, allowed to stand, filtered, and the filtrate was subjected to rotary evaporation and drying to obtain the product. The specific steps are as follows:

9. The process for the preparation of flame retardant polyurea for masonry surfaces of a petrochemical plant according to any one of claims 1-8, characterized by the fact that, 1) Preparation of component A: aromatic dihydric alcohol and reaction-type phosphorus-containing flame retardant were mixed uniformly, and then subjected to dehydration treatment at 100-120°C under vacuum-0.1 MPa for 3-5 hours. Subsequently, the system was cooled to 40-50°C under nitrogen protection, and aromatic isocyanate was slowly added under the condition of 300-500 rpm mechanical stirring. The reaction was carried out at 70-85°C for 2-4 hours to generate a -NCO terminated prepolymer intermediate, i.e. component A. 2) Preparation of component B: the terminal amino polyether was subjected to dehydration treatment at 100-120°C under vacuum-0.1 MPa for 3-5 hours. Subsequently, diamine chain extender was added to the terminal amino polyether under the condition of 300-500 rpm mechanical stirring at 70-80°C until a homogeneous solution was formed. Then, additive-type modified flame retardant, environmentally friendly intumescent flame retardant, and color paste were added, and the mixture was stirred until it was uniformly dispersed and no obvious particles were observed. Finally, additives were added, and the mixture was continuously stirred for 1-2 hours to form a uniform mixture, thereby obtaining component B. When used, the components A and B were mixed in a volume ratio of 1:1 by using a high-pressure spraying device. The mixture was atomized and uniformly sprayed on the surface of the substrate under the condition of a spraying temperature of 70-75°C and a relative humidity of ≤75%. After spraying, the polyurea protective coating was formed by natural curing.

10. The process for the preparation of flame retardant polyurea for petrochemical park masonry surfaces according to claim 9, characterized in that, ​

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