Flame-retardant polyurea protective coating as well as preparation method and application thereof

Abstract

The invention provides a flame-retardant polyurea protective paint and a preparation method and application thereof, and belongs to the technical field of polyurea protective paints.The flame-retardant polyurea protective paint is prepared by mixing a component A and a component B according to the volume ratio of 1: 1, the component A is a prepolymer obtained by reacting a reactive flame retardant, a solvent, MDI and polyhydric alcohol, and the component B is a polyhydric alcohol prepolymer obtained by reacting the reactive flame retardant, the solvent, the MDI and the polyhydric alcohol; the reactive flame retardant is prepared from at least one of melamine, cyanuric acid and tris (2-hydroxyethyl) isocyanurate; and the component B comprises polyol, an amine chain extender, an antioxidant, a catalyst and an auxiliary agent. According to the invention, the reactive flame retardant is embedded into the main chain of the isocyanate prepolymer by using a block copolymerization method, so that the triazine nitrogen-containing heterocyclic ring is fixed on the main chain and forms a three-dimensional network structure with the isocyanate group, the crosslinking density of the system is improved, the flame retardance of the polyurea coating is improved, and the mechanical property of the coating is enhanced.

Description

Technical Field

[0001] The present application relates to the technical field of polyurea protective coatings, and in particular to a flame retardant polyurea protective coating and a preparation method and application thereof. Background Art

[0002] Polyurea coating is a new type of solvent-free, pollution-free green coating developed and researched by foreign countries to meet environmental protection needs after high-solid coatings, water-based coatings, radiation-cured coatings, powder coatings and other low (no) pollution coatings. Compared with traditional environmentally friendly coatings, polyurea coatings have the following advantages: ① Rapid curing, can be sprayed on any curved surface, inclined surface and vertical surface without sagging; ② Insensitive to water and moisture, construction is not affected by ambient temperature and humidity; ③ 100% solid content, does not contain any volatile organic compounds (VOC), and is environmentally friendly; ④ Can be sprayed or poured at a 1:1 volume ratio, and the design thickness requirement can be achieved in one construction, overcoming the drawbacks of previous multi-layer construction; ⑤ Excellent theoretical ⑥ It has good thermal stability, can be used for a long time at 120℃, and can withstand short-term thermal shock at 150℃; ⑦ The color of the coating is adjustable; ⑧ The formula system is arbitrarily adjustable, and the feel ranges from soft rubber (Shore A20) to hard elastomer (Shore D75); ⑨ The prototype has good reproducibility, the coating is continuous, dense, seamless, pinhole-free, beautiful and practical; ⑩ The use of complete sets of equipment makes the construction convenient and the efficiency is extremely high.

[0003] Commonly used polyurea coatings have high resin content and poor flame retardant properties. In the fields of new energy battery explosion-proof polyurea products and military explosion-proof polyurea products, polyurea coatings are often required to have certain flame retardant properties on the basis of high physical and chemical properties. However, when preparing polyurea coatings, in order to achieve a certain flame retardant effect of the cured polyurea coating, a large amount of flame retardant is often needed, which leads to a cliff-like drop in the strength of the polyurea coating. Summary of the invention

[0004] In view of the technical problems existing in the background technology, the present application provides a flame retardant polyurea protective coating and a preparation method and application thereof, aiming to solve the technical problem that adding flame retardants to polyurea coatings leads to a decrease in the strength of polyurea coatings.

[0005] In the first aspect, the composition is prepared by mixing component A and component B in a volume ratio of 1:1, wherein component A is a prepolymer obtained by reacting a reactive flame retardant, a solvent, MDI and a polyol, and the reactive flame retardant includes at least one of melamine, cyanuric acid and trihydroxyethyl isocyanurate; component B includes a polyol, an amine chain extender, an antioxidant, a catalyst and an additive.

[0006] In the prior art, reactive flame retardants are added directly into polyurea coatings as additive flame retardants, which will block the resin crosslinking of components A and B of the polyurea coatings during the polymerization process, causing a sharp drop in the tensile strength, tear strength and other mechanical properties of the polyurea coating.

[0007] The reactive flame retardant in this embodiment is dissolved in a solvent and can react with diphenylmethane diisocyanate (MDI) to fix the reactive flame retardant on the main chain of the prepolymer synthesized by the reaction of MDI and polyol. The reactive flame retardant includes melamine, cyanuric acid and tris(hydroxyethyl)isocyanurate. The reaction mechanism of the three with MDI is as follows: Melamine has three amino groups. When melamine is directly added to MDI, it does not react with MDI. However, when melamine is dissolved in a solvent and then added to MDI, the three amino groups of melamine can react with MDI to form polyurea. When the melamine solution and polyol are simultaneously added to MDI, the polyol and MDI form isocyanate prepolymers. Melamine reacts with MDI at the same time, fixing the triazine nitrogen-containing heterocyclic ring of melamine on the main chain of the isocyanate prepolymer. Since melamine contains three amino groups, it can form a three-dimensional network structure with the isocyanate group, thereby increasing the crosslinking density of the system and enhancing the mechanical properties of the coating. After cyanuric acid is dissolved in the solvent, the three hydroxyl groups in cyanuric acid react with MDI to form polyurethane. When the melamine solution and the polyol are simultaneously added to MDI, the polyol and MDI form isocyanate prepolymers. Cyanuric acid reacts with MDI at the same time, so that the triazine nitrogen-containing heterocyclic ring of cyanuric acid is fixed on the main chain of the isocyanate prepolymer. Cyanuric acid contains three hydroxyl groups, which can form a three-dimensional network structure with the isocyanate group. After trihydroxyethyl isocyanurate is dissolved in a solvent, it reacts with MDI. The isocyanate group of MDI can react with the hydroxyl group of trihydroxyethyl isocyanurate to generate a carbamate bond (-NHCOO-), so that the triazine nitrogen-containing heterocycle of trihydroxyethyl isocyanurate is fixed on the main chain of the isocyanate prepolymer. Trihydroxyethyl isocyanurate contains three hydroxyl groups, thereby constructing a cross-linked network structure to generate a three-dimensional polyurethane.

[0008] The reactive flame retardant, diphenylmethane diisocyanate (MDI) and polyol are reacted to synthesize a prepolymer, so that the triazine nitrogen-containing heterocyclic ring of the reactive flame retardant is fixed on the main chain of the prepolymer and forms a three-dimensional network structure with the isocyanate group, thereby improving the crosslinking density of the system, thereby improving the flame retardancy of the polyurea coating, improving the crosslinking density of the system, and enhancing the mechanical properties of the coating.

[0009] The reactive flame retardant, MDI and polyol in component A react to generate an isocyanate-based prepolymer containing triazine nitrogen-containing heterocyclic rings. Component B contains an amine chain extender. When preparing a flame-retardant polyurea coating, component A and component B are mixed and heated in a volume ratio of 1:1. The isocyanate (R-NCO) in component A reacts with the amino group (R'-NH2) of the amine chain extender in component B to generate a polymer material with a urea bond (RNHCONHR'), and a polyurea coating is obtained after curing. The polyol in component B can play a role in plasticization and cross-linking.

[0010] Preferably, the solvent includes at least one of pyridine, dimethylformamide, dimethyl sulfoxide and N,N-dimethylpyrrolidone.

[0011] Preferably, by weight, component A includes 25-45 parts of polyol, 5-20 parts of reactive flame retardant and 40-50 parts of MDI.

[0012] In this embodiment, when the amount of reactive flame retardant added in component A is 10% to 15%, the flame retardant properties and mechanical properties of the coating are optimal. If the amount of reactive flame retardant added is too high, the viscosity of component A becomes large, which is not conducive to construction. If the amount added is too low, the flame retardant effect is poor.

[0013] Preferably, by weight, component B includes 55-65 parts of polyol, 15-30 parts of amine chain extender, 0.1-0.5 parts of antioxidant, 0.05-0.2 parts of catalyst and 4.6-7.6 parts of auxiliary agent, and the auxiliary agent includes 1-2 parts of coupling agent, 0.05-0.15 parts of defoaming agent, 0.1-0.3 parts of leveling agent, 3-5 parts of dewatering agent and 0.2-0.4 parts of dispersant.

[0014] Preferably, the coupling agent includes at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a bimetallic coupling agent, a phosphate coupling agent, and a borate coupling agent.

[0015] The defoaming agent includes at least one of BYK-066N, BYK-054 and BYK-057.

[0016] The leveling agent includes at least one of BYK-306, BYK-307, and BYK-310.

[0017] The dispersant includes at least one of BYK-161, BYK-163, BYK-164, and BYK-170.

[0018] Preferably, the polyol includes at least two of polyether diol, polyester diol, polyether triol, polytetramethylene glycol, conventional polyester polyol, polycaprolactone polyol, and polycarbonate diol.

[0019] Preferably, the polyol includes at least two of TEP-330N, PPG4000, PPG2000, PPG1000, MN3050, MN1000, MN700, MN500, PTMG-1000, PTMG-2000, PCL-1200, PCL-2044, PCL-2053, PCL-3057, PCL-2200A, and PCL-2200C.

[0020] Preferably, the catalyst includes at least one of stannous octoate, dibutyltin dilaurate and dibutyltin oxide, bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, bismuth cycloalkaneate, and oxazolidinone.

[0021] Preferably, the amine chain extender includes at least one of diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-bis-sec-butylaminodiphenylmethane, and 3,3'-dichloro-4,4'-diaminodiphenylmethane.

[0022] In a second aspect, the present application provides a method for preparing a flame retardant polyurea protective coating, comprising the following steps: The reactive flame retardant and the solvent are mixed and stirred to completely dissolve the reactive flame retardant to obtain a reactive flame retardant solution; the polyol is dehydrated in a reactor at 70-80°C under vacuum conditions for 2-3 hours, and then the vacuum is removed and the temperature is lowered to below 70°C to obtain a dehydrated polyol; a calculated amount of liquid MDI is added to another reactor, and the temperature is raised to 40-60°C, the reactive flame retardant solution and the dehydrated polyol are added to the liquid MDI, the temperature is raised to 70-80°C, and the solvent is removed and filtered after reacting for 2-3 hours to obtain component A; The polyol and the auxiliary agent are stirred evenly at high speed, and then the amine chain extender, antioxidant and catalyst are added and stirred evenly, and after dehydration, component B is obtained.

[0023] Preferably, the reactive flame retardant solution and the dehydrated polyol are simultaneously added dropwise into the MDI within 1 to 2 hours.

[0024] In a third aspect, an embodiment of the present application provides an application of a flame-retardant polyurea protective coating, comprising the following steps: adding 5 to 10 parts of propylene carbonate (PC) solvent to component A and component B, respectively, so that the viscosity of component A and component B is less than 2000 mPa·s, and the viscosity difference between component A and component B does not exceed 50 mPa·s, using a special polyurea sprayer to evenly mix the diluted component A and component B in a volume ratio of 1:1, and then spraying, and placing at room temperature for curing to obtain a flame-retardant polyurea protective coating.

[0025] Different from the existing technical solutions, the beneficial effects of this application include: In this application, a reactive flame retardant solution and a polyol are simultaneously added to MDI, and the polyol reacts with MDI to generate an isocyanate prepolymer. At the same time, a reactive flame retardant is embedded in the main chain of the isocyanate prepolymer by a block copolymerization method, so that the triazine nitrogen-containing heterocyclic ring of the reactive flame retardant is fixed on the main chain and forms a three-dimensional network structure with the isocyanate group, thereby improving the crosslinking density of the system, improving the flame retardancy of the polyurea coating, and enhancing the mechanical properties of the coating; when 10% to 20% of the reactive flame retardant is added, the flame retardancy of the coating can reach an oxygen index of 26 to 32, the tensile strength can reach 19MPa, and the tear strength can reach 78KN / m. The high-performance flame-retardant polyurea coating prepared by this method not only meets the user's requirements for the flame retardancy of the material, but also has increased mechanical properties, and has good application prospects.

[0026] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. DETAILED DESCRIPTION

[0027] The following is a detailed description of the embodiments of the technical solution of the present application. The following embodiments are only used to more clearly illustrate the technical solution of the present application, and are therefore only used as examples, and cannot be used to limit the scope of protection of the present application.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the description and claims of this application and any variations thereof are intended to cover non-exclusive inclusions.

[0029] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0030] At present, when preparing polyurea coatings, in order to make the cured polyurea coating achieve a certain flame retardant effect, it is often necessary to add a large amount of flame retardants, which causes a cliff-like drop in the strength of the polyurea coating.

[0031] In order to solve the technical problem that the addition of flame retardants leads to a decrease in the strength of polyurea coatings, the present application provides a flame-retardant polyurea protective coating, which includes component A and component B, component A is a prepolymer obtained by the reaction of a reactive flame retardant, MDI and a polyol, the reactive flame retardant includes at least one of melamine, cyanuric acid and trihydroxyethyl isocyanurate; component B includes a polyol, an amine chain extender, an antioxidant, a catalyst and an additive, and the volume ratio of component A to component B is 1:1.

[0032] Furthermore, in some embodiments, component A includes 25-45 parts of polyol, 5-20 parts of reactive flame retardant and 40-50 parts of MDI.

[0033] Further, in some embodiments, component B includes 55-65 parts of polyol, 15-30 parts of amine chain extender, 0.1-0.5 parts of antioxidant, 0.05-0.2 parts of catalyst and 4.6-7.6 parts of auxiliary agent, and the auxiliary agent includes 1-2 parts of coupling agent, 0.05-0.15 parts of defoaming agent, 0.1-0.3 parts of leveling agent, 3-5 parts of dewatering agent and 0.2-0.4 parts of dispersant.

[0034] In this embodiment, the coupling agent includes at least one of a silane coupling agent, a titanate coupling agent, an aluminate coupling agent, a bimetallic coupling agent, a phosphate coupling agent, and a borate coupling agent.

[0035] The defoaming agent includes at least one of BYK-066N, BYK-054 and BYK-057.

[0036] The leveling agent includes at least one of BYK-306, BYK-307, and BYK-310.

[0037] The dispersant includes at least one of BYK-161, BYK-163, BYK-164, and BYK-170.

[0038] Further, in some embodiments, the polyol includes at least two of polyether diol, polyester diol, polyether triol, polytetramethylene glycol, conventional polyester polyol, polycaprolactone polyol, and polycarbonate diol.

[0039] In this embodiment, the polyol includes at least two of TEP-330N, PPG4000, PPG2000, PPG1000, MN3050, MN1000, MN700, MN500, PTMG-1000, PTMG-2000, PCL-1200, PCL-2044, PCL-2053, PCL-3057, PCL-2200A, and PCL-2200C.

[0040] Further, in some embodiments, the catalyst includes at least one of stannous octoate, dibutyltin dilaurate and dibutyltin oxide, bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, bismuth cyclohexaneate, and oxazolidinone.

[0041] Further, in some embodiments, the amine chain extender includes at least one of diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-bis-sec-butylaminodiphenylmethane, and 3,3'-dichloro-4,4'-diaminodiphenylmethane.

[0042] In a second aspect, the present invention provides a method for preparing a flame retardant polyurea protective coating, comprising the following steps: The reactive flame retardant and the solvent are mixed and stirred to completely dissolve the reactive flame retardant to obtain a reactive flame retardant solution; the polyol is dehydrated in a reactor at 70-80°C under vacuum conditions for 2-3 hours, and then the vacuum is removed and the temperature is lowered to below 70°C to obtain a dehydrated polyol; a calculated amount of liquid MDI is added to another reactor, and the temperature is raised to 40-60°C, and the reactive flame retardant solution and the dehydrated polyol are added to the liquid MDI, and the temperature is raised to 70-80°C, and the reaction is carried out for 2-3 hours; the temperature is raised to 100°C, and the solvent is removed in vacuum; the vacuum is removed, the temperature is lowered to below 60°C, and the component A is obtained by filtering; The polyol and the auxiliary agent are stirred evenly at high speed, and then the amine chain extender, the antioxidant and the catalyst are added and stirred evenly, and dehydrated at 105° C. under vacuum conditions for 2 hours, and then the vacuum is removed and cooled to room temperature to obtain component B.

[0043] Furthermore, in some embodiments, the reactive flame retardant solution and the dehydrated polyol are simultaneously added dropwise into the MDI within 1 to 2 hours.

[0044] In a third aspect, an embodiment of the present application provides an application of a flame retardant polyurea protective coating, comprising the following steps: adding PC solvent to component A and component B respectively, so that the viscosity of component A and component B is less than 2000 mPa·s, and the viscosity difference between component A and component B does not exceed 50 mPa·s, using a special polyurea sprayer to evenly mix the diluted component A and component B in a volume ratio of 1:1 and then spray them, and place them at room temperature for curing for 7 days to obtain a flame retardant polyurea protective coating.

[0045] Some specific embodiments are listed below. It should be noted that the embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. If specific techniques or conditions are not specified in the embodiments, the techniques or conditions described in the literature in this area or the product specifications are used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be obtained commercially.

[0046] 1. Preparation method Example 1 Embodiment 1 provides a reactive high-performance flame-retardant polyurea coating, and a method for preparing the reactive high-performance flame-retardant polyurea coating comprises the following steps: (1) Add 20 parts of reactive flame retardant melamine and 20 parts of N,N-dimethylpyrrolidone (NMP) into a dispersion tank and stir to completely dissolve the melamine; add 27 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 53 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum and cool to below 60°C, detect the NCO content to be 15.88%, filter and package.

[0047] (2) 42 parts of polyol PPG2000, 20 parts of polyol MN700, 0.4 parts of UV stabilizer UV-24, 0.3 parts of dispersant BYK-163, 0.2 parts of leveling agent BYK-306, 0.1 parts of defoamer BYK-054, 1 part of coupling agent KH-560, 4 parts of molecular sieve A4, 1 part of bentonite BP127, 1.9 parts of black pulp, and 8.6 parts of white pulp were stirred at high speed, and then 20 parts of E-100 amine chain extender, 0.4 parts of antioxidant 245, and 0.1 parts of T18 catalyst were added and stirred evenly, and dehydrated at 105°C under vacuum for 2 hours, and then the vacuum was removed, and the mixture was cooled to room temperature and packaged.

[0048] (3) Add 5-10 parts of PC solvent to adjust the viscosity of components A and B. At a working temperature of 65°C, the viscosity of component A is 98 mPa·s and that of component B is 89 mPa·s. Use a special polyurea sprayer to transport components A and B separately through a heated pipe in a volume ratio of 1:1 to the spray gun mixing chamber. Under high temperature and high pressure, they are instantly collided and mixed evenly. After passing through the nozzle, they are atomized and sprayed on test panels and samples, and then placed at room temperature for curing for 7 days.

[0049] Example 2 The difference between the reactive high-performance flame-retardant polyurea coating in this embodiment and that in Embodiment 1 is only that the amount of raw material added to component A is different, and the other steps are the same. The preparation method of component A includes the following steps: Add 15 parts of reactive flame retardant melamine and 20 parts of NMP into a dispersion tank and stir to completely dissolve the melamine; add 31 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 54 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum, cool to below 60°C, detect the NCO content to be 16.02%, and filter and package.

[0050] Example 3 The difference between the reactive high-performance flame-retardant polyurea coating in this embodiment and that in Embodiment 1 is only that the amount of raw material added to component A is different, and the other steps are the same. The preparation method of component A includes the following steps: Add 10 parts of reactive flame retardant melamine and 20 parts of NMP into a dispersion tank and stir to completely dissolve the melamine; add 36 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 54 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 dropwise into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum, cool to below 60°C, detect the NCO content to be 15.64%, and filter and package.

[0051] Example 4 The difference between the reactive high-performance flame-retardant polyurea coating in this embodiment and that in Embodiment 1 is only that the raw material type and addition amount of component A are different, and the other steps are the same. The preparation method of component A includes the following steps: Add 15 parts of reactive flame retardant cyanuric acid and 20 parts of NMP to the dispersion tank, stir to completely dissolve melamine; add 31 parts of polyol PPG2000 to the reactor, dehydrate at 70~80℃ and vacuum for 2~3h, then remove the vacuum and cool to below 70℃ for standby; add 54 parts of liquid MDI to another reactor. Heat to 40~60℃, drop reactive flame retardant solution and dehydrated polyol PPG2000 to the reactor at the same time within 1~2h, heat to 70~80℃, react for 2~3h; then heat to 100℃, vacuum remove NMP; remove vacuum, cool to below 60℃, detect NCO content of 15.92%, filter and package.

[0052] Example 5 The difference between the reactive high-performance flame-retardant polyurea coating in this embodiment and that in Embodiment 1 is only that the raw material type and addition amount of component A are different, and the other steps are the same. The preparation method of component A includes the following steps: Add 15 parts of reactive flame retardant trihydroxyethyl isocyanate and 20 parts of NMP into a dispersion tank and stir to completely dissolve melamine; add 31 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 54 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 dropwise into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum, cool to below 60°C, detect the NCO content to be 15.76%, and filter and package.

[0053] Comparative Example 1 Comparative Example 1 provides a reactive high-performance flame-retardant polyurea coating, which differs from Example 1 in that no flame retardant is added. The preparation method of the reactive high-performance flame-retardant polyurea coating in Comparative Example 1 comprises the following steps: (1) Add 48 parts of polyol PPG2000 into a reactor, dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 52 parts of liquid MDI into another reactor, heat it to 40-60°C, add the dehydrated polyol PPG2000 dropwise within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; remove the vacuum, cool it to below 60°C, detect the NCO content and find it is 15.68%, filter and package.

[0054] (2) 42 parts of polyol PPG2000, 20 parts of polyol MN700, 0.4 parts of UV stabilizer UV-24, 0.3 parts of dispersant BYK-163, 0.2 parts of leveling agent BYK-306, 0.1 parts of defoamer BYK-054, 1 part of coupling agent KH-560, 4 parts of molecular sieve A4, 1 part of bentonite BP127, 1.9 parts of black pulp, and 8.6 parts of white pulp were stirred at high speed, and then 20 parts of E-100 amine chain extender, 0.4 parts of antioxidant 245, and 0.1 parts of T18 catalyst were added and stirred evenly, and dehydrated at 105°C under vacuum for 2 hours, and then the vacuum was removed, and the mixture was cooled to room temperature and packaged.

[0055] (3) Add 5-10 parts of PC solvent to adjust the viscosity of components A and B. At a working temperature of 65°C, the viscosity of component A is 98 mPa·s and that of component B is 89 mPa·s. Use a special polyurea sprayer to transport components A and B separately through a heated pipe in a volume ratio of 1:1 to the spray gun mixing chamber. Under high temperature and high pressure, they are instantly collided and mixed evenly. After passing through the nozzle, they are atomized and sprayed on test panels and samples, and then placed at room temperature for curing for 7 days.

[0056] Comparative Example 2 Compared with Example 1, the only difference in this comparative example is that the reactive flame retardant in step (1) is directly added without being dissolved: (1) Add 48 parts of polyol PPG2000 into a reactor, dehydrate at 70-80°C and vacuum for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 52 parts of liquid MDI into another reactor, heat it to 40-60°C, add the dehydrated polyol PPG2000 dropwise within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; remove the vacuum, cool it to below 60°C, then add 20 parts of melamine and disperse it evenly; detect the NCO content to be 15.73%, filter and package.

[0057] Comparative Example 3 Compared with Example 1, the only difference is that 20 parts of reactive flame retardant melamine are directly added to step (2) without being dissolved. The preparation method of the reactive high-performance flame retardant polyurea coating in Comparative Example 3 comprises the following steps: (1) Add 48 parts of polyol PPG2000 into a reactor, dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 52 parts of liquid MDI into another reactor, heat to 40-60°C, add the dehydrated polyol PPG2000 dropwise within 1-2 hours, heat to 70-80°C, react for 2-3 hours; remove the vacuum, cool to below 60°C, detect the NCO content to be 15.85%, filter and package.

[0058] (2) 42 parts of polyol PPG2000, 20 parts of polyol MN700, 20 parts of melamine, 0.4 parts of UV stabilizer UV-24, 0.3 parts of dispersant BYK-163, 0.2 parts of leveling agent BYK-306, 0.1 parts of defoamer BYK-054, 1 part of coupling agent KH-560, 4 parts of molecular sieve A4, 1 part of bentonite BP127, 1.9 parts of black pulp, and 8.6 parts of white pulp were stirred at high speed, and then 20 parts of E-100 amine chain extender, 0.4 parts of antioxidant 245, and 0.1 parts of T18 catalyst were added and stirred evenly, and dehydrated at 105°C under vacuum for 2 hours, and then the vacuum was removed, cooled to room temperature and packaged.

[0059] (3) Add 5-10 parts of PC solvent to adjust the viscosity of components A and B. At a working temperature of 65°C, the viscosity of component A is 98 mPa·s and that of component B is 89 mPa·s. Use a special polyurea sprayer to transport components A and B separately through a heated pipe in a volume ratio of 1:1 to the spray gun mixing chamber. Under high temperature and high pressure, they are instantly collided and mixed evenly. After passing through the nozzle, they are atomized and sprayed on test panels and samples, and then placed at room temperature for curing for 7 days.

[0060] Comparative Example 4 Compared with Example 1, the only difference is that step (1) is: (1) Add 5 parts of reactive flame retardant melamine and 20 parts of NMP into a dispersion tank and stir to completely dissolve the melamine; add 41 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 54 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum and cool to below 60°C, detect the NCO content to be 15.91%, filter and package.

[0061] Comparative Example 5 Compared with Example 1, the only difference is that step (1) is: (1) Add 30 parts of reactive flame retardant cyanuric acid and 20 parts of NMP into a dispersion tank and stir to completely dissolve melamine; add 16 parts of polyol PPG2000 into a reactor and dehydrate at 70-80°C and vacuum conditions for 2-3 hours, then remove the vacuum and cool to below 70°C for standby use; add 54 parts of liquid MDI into another reactor and heat it to 40-60°C, and simultaneously add the reactive flame retardant solution and the dehydrated polyol PPG2000 into the reactor within 1-2 hours, heat it to 70-80°C, and react for 2-3 hours; then heat it to 100°C and remove NMP in vacuum; remove the vacuum and cool to below 60°C, detect the NCO content to be 15.74%, filter and package.

[0062] 2. Test Method 1. Adhesion test method: GB / T 5210 Paint and varnish adhesion test by pull-off method.

[0063] 2. Tensile strength and elongation at break test method: GB / T 528-2009 Determination of tensile stress-strain properties of vulcanized rubber or thermoplastic rubber.

[0064] 3. Tear strength test method: GB / T 529-2008 Determination of tear strength of vulcanized rubber or thermoplastic rubber (trouser-shaped, right-angled and crescent-shaped specimens).

[0065] 4. Oxygen index test method: GB / T 2406.2-2009 Plastics oxygen index method for determining combustion behavior.

[0066] 5. Shore hardness (SHD) test method: Use Shore hardness tester for testing.

[0067] III. Analysis of test results of various embodiments and comparative examples According to the methods of Examples 1 to 5 and Comparative Examples 1 to 5, polyurea coatings were prepared, and the adhesion of the polyurea coatings, the tensile strength, tear strength, elongation at break and flame retardancy of the polyurea samples were tested at room temperature. The test data are shown in Table 1 below: Table 1 Performance test data of polyurea coating in various embodiments and comparative examples

[0068] The reactive flame retardant added in Examples 1 to 3 and Comparative Examples 4 to 5 is melamine. As can be seen from Table 1 above, in Examples 1 to 3, the amount of melamine added is 10 to 20 parts, accounting for 10% to 20% of component A. Within this percentage range, as the amount of melamine added increases, the tensile strength, tear strength and flame retardant oxygen index of the polyurea sample gradually increase, and the elongation at break gradually decreases. The flame retardant property of the coating can reach an oxygen index of 24 to 32, the tensile strength increases from 16 MPa to 19 MPa, and the tear strength increases from 75 KN / m to 78 KN / m. The polyurea samples prepared in Examples 1 to 3 have good flame retardant properties and mechanical properties. In Comparative Example 4, the amount of melamine added is 5 parts, accounting for 5% of component A. It can be seen from Table 1 that the tensile strength, tear strength and flame retardant oxygen index of the polyurea sample prepared in Comparative Example 4 are greatly reduced, the oxygen index is 15.4, and the coating is flammable. It can be seen that the amount of flame retardant added is too low and the flame retardant effect cannot be achieved; the amount of melamine added in Comparative Example 5 accounts for 30% of component A. It can be seen from Table 1 that the elongation at break in Comparative Example 5 is greatly reduced, the Shore hardness SHD is increased, and the amount of reactive flame retardant added is too high, the viscosity of component A becomes large, which is not conducive to construction, indicating that the amount of reactive flame retardant added is preferably 10 to 20 parts.

[0069] In Example 4 and Example 5, cyanuric acid and trihydroxyethyl isocyanate are used as reactive flame retardants respectively, and the obtained polyurea coatings have good flame retardant properties and mechanical properties.

[0070] In Comparative Example 1, no flame retardant was added, and the oxygen index of the obtained polyurea coating was 14, which was less than 21, and it was a flammable material; in Comparative Example 2, melamine was not dissolved by solvent, but was directly added to component A, and the oxygen index of the obtained polyurea coating was 18, which was less than 21, and it was a flammable material, and the tensile strength, tear strength and adhesion were greatly reduced compared with Examples 1 to 5; in Comparative Example 3, melamine was not dissolved by solvent, but was directly added to component A, and the oxygen index of the obtained polyurea coating was 17.6, which was less than 21, and it was a flammable material, and the tensile strength, tear strength and adhesion were greatly reduced compared with Examples 1 to 5. It can be seen from this that adding the reactive flame retardant directly to the polyurea coating without dissolving it cannot achieve the ideal flame retardant performance, and will cause the mechanical properties of the polyurea coating to decrease.

[0071] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and the embodiments having the same structure as the technical idea and exerting the same effect within the scope of the technical solution of the present application are all included in the technical scope of the present application. In addition, within the scope of the subject matter of the present application, various modifications that can be thought of by those skilled in the art to the embodiments and other methods of combining some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A flame retardant polyurea protective coating, characterized in that: The invention is prepared by mixing component A and component B in a volume ratio of 1:1, wherein component A is a prepolymer obtained by reacting a reactive flame retardant, a solvent, MDI and a polyol, and the reactive flame retardant comprises at least one of melamine, cyanuric acid and trishydroxyethyl isocyanurate; and component B comprises a polyol, an amine chain extender, an antioxidant, a catalyst and an additive.

2. The flame retardant polyurea protective coating according to claim 1, characterized in that: The solvent includes at least one of pyridine, dimethylformamide dimethyl sulfoxide and N,N-dimethylpyrrolidone.

3. The flame retardant polyurea protective coating according to claim 1, characterized in that: Calculated by weight, the component A includes 25-45 parts of polyol, 5-20 parts of reactive flame retardant and 40-50 parts of MDI.

4. The flame retardant polyurea protective coating according to claim 1, characterized in that: In parts by mass, the B component includes 55-65 parts of polyol, 15-30 parts of amine chain extender, 0.1-0.5 parts of antioxidant, 0.05-0.2 parts of catalyst and 4.6-7.6 parts of auxiliary agent, and the auxiliary agent includes 1-2 parts of coupling agent, 0.05-0.15 parts of defoaming agent, 0.1-0.3 parts of leveling agent, 3-5 parts of dewatering agent and 0.2-0.4 parts of dispersant.

5. The flame retardant polyurea protective coating according to claim 1, characterized in that: The polyol comprises at least two of polyether diol, polyester diol, polyether triol, polytetrahydrofuran diol, conventional polyester polyol, polycaprolactone polyol and polycarbonate diol.

6. The flame retardant polyurea protective coating according to claim 1, characterized in that: The catalyst comprises at least one of stannous octoate, dibutyltin dilaurate and dibutyltin oxide, bismuth neodecanoate, bismuth laurate, bismuth isooctanoate, bismuth cyclohexaneate and oxazolidinone.

7. The flame retardant polyurea protective coating according to claim 1, characterized in that: The amine chain extender includes at least one of diethyltoluenediamine, dimethylthiotoluenediamine, 4,4'-bis-sec-butylaminodiphenylmethane, and 3,3'-dichloro-4,4'-diaminodiphenylmethane.

8. A method for preparing a flame retardant polyurea protective coating according to any one of claims 1 to 7, characterized in that: The steps include: The reactive flame retardant and the solvent are mixed and stirred to completely dissolve the reactive flame retardant to obtain a reactive flame retardant solution; the polyol is dehydrated in a reactor at 70-80°C under vacuum conditions for 2-3 hours, and then the vacuum is removed and the temperature is lowered to below 70°C to obtain a dehydrated polyol; a calculated amount of liquid MDI is added to another reactor, and the temperature is raised to 40-60°C, the reactive flame retardant solution and the dehydrated polyol are added to the liquid MDI, the temperature is raised to 70-80°C, and the solvent is removed and filtered after reacting for 2-3 hours to obtain component A; The polyol and the auxiliary agent are stirred evenly at high speed, and then the amine chain extender, antioxidant and catalyst are added and stirred evenly, and after dehydration, component B is obtained.

9. The method for preparing the flame retardant polyurea protective coating according to claim 8, characterized in that: Add the reactive flame retardant solution and the dehydrated polyol into MDI simultaneously within 1 to 2 hours.

10. The use of a flame retardant polyurea protective coating according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: adding 5 to 10 parts of PC solvent to component A and component B respectively, so that the viscosity of component A and component B is less than 2000 mPa·s, and the difference in viscosity between component A and component B does not exceed 50 mPa·s, uniformly mixing the diluted component A and component B in a volume ratio of 1:1, spraying, and curing at room temperature to obtain a flame retardant polyurea protective coating.

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