Intelligent self-healing, flame-retardant, light-resistant water-based polyurethane coating

Abstract

The present invention relates to a preparation method of an intelligent self-repairing, flame-retardant and light-resistant water-based polyurethane coating. The method comprises the following steps: preparing a self-made hyperbranched flame retardant and using it in the synthesis of a polyurethane prepolymer; cooling the mixture to 58° C., adding 2,2-dimethylolpropionic acid, reacting the mixture for 1 to 2 hours, adding 1 to 2 parts of a disulfide compound, reacting the mixture for 1 to 2 hours at 60 to 80° C., adding 1 to 2 parts of a hydrogen bonding agent, reacting the mixture for 1 hour at 60 to 80° C., adding 0.5 to 1.5 parts of a coumarin derivative, and reacting the mixture for 60 to 90° C. The mixture was stirred for 1-2 hours, and then spiropyran, diethanol monoisopropanolamine, and 0.01 parts of p-toluenesulfonamide were added, and the mixture was reacted at 50°C for 30 minutes. The temperature was lowered to 40-45°C, and 1-2 parts of triethylamine were added, and the mixture was reacted for 1-2 hours. The mixture was cooled to room temperature, and 60-65 parts of water were added. The mixture was stirred at a speed of 1800-2000 r / min for 0.5-1 hour to obtain an intelligent self-healing, flame-retardant, and light-resistant water-based polyurethane coating. The flame retardancy and self-healing properties of the obtained water-based polyurethane were significantly improved.

Description

[0001] This invention is a divisional of invention patent 202311129132X applied for on September 4, 2023. Technical Field

[0002] The present invention relates to a method for preparing a polyurethane coating, and in particular to a method for preparing an intelligent self-repairing, flame-retardant and light-resistant water-based polyurethane coating. Background Art

[0003] Polyurethane is formed by the addition polymerization of diisocyanates or polyisocyanates with dihydroxy or polyhydroxy compounds. Its backbone consists of flexible and rigid segments, resulting in excellent physical and mechanical properties, heat resistance, and weather resistance. Compared to metals, polyurethane materials offer advantages such as light weight, good processability, low density, and high production yields. They are widely used in leather finishing, coatings, and adhesives. As a film-forming agent in leather processing, polyurethane not only beautifies leather but also extends the life of leather products, increasing their value. However, polyurethane is highly flammable, with a combustion oxygen index of only 14% to 16%. During combustion and heating, depolymerization and cracking produce numerous complex low-molecular-weight and gaseous toxic substances (such as HCN and CO). These substances can continue to burn, releasing significant heat that accelerates the decomposition of the polyurethane, forming a positive feedback loop that significantly limits its use. To improve its flame retardancy, inorganic flame retardants are often added to enhance the flame retardancy of resin materials. Currently, commonly used small-molecule flame retardants include halogenated flame retardants, phosphorus-based flame retardants, silicon-based flame retardants, nitrogen-based flame retardants, and composite flame retardants. Due to their poor compatibility with other materials, small-molecule flame retardants can reduce the mechanical properties of resin materials and degrade the viscosity, compatibility, and flexibility of polymer materials. Therefore, to address the various drawbacks of small-molecule flame retardants, it is imperative to develop new flame retardants that can enhance the flame retardancy of materials without compromising their mechanical properties. Hyperbranched flame retardants have attracted widespread attention from researchers due to their excellent rheological properties and processing properties.

[0004] Phosphorus-based hyperbranched flame retardants are synthesized using phosphorus compounds as core molecules. These compounds primarily include phosphonates, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and phosphazenes. The flame retardant mechanisms of phosphorus-based hyperbranched (HB) flame retardant systems are characterized by acid, carbon, and gas sources. The acid source is the generation of inorganic acids such as phosphoric acid when the HB flame retardant comes into contact with an external heat source. These phosphorus-containing inorganic acids are important flame retardant intermediates and accelerate the formation of a dense carbon layer within the system. The gas source is primarily the large amount of incombustible gases released by the HB flame retardant upon contact with an external heat source, blocking oxygen from entering the system. The carbon-forming agent is primarily the polyhydroxy moiety within the HB flame retardant, which forms the carbon-containing skeleton of the hyperbranched carbon layer, insulating it from combustion. From the above three parts, it can be concluded that the phosphorus-containing hyperbranched flame retardant has a flame retardant hyperbranched polymer, and no halogen atoms are added to the flame retardant, so it is an environmentally friendly and low-toxic hyperbranched flame retardant.

[0005] Hyperbranched flame retardants with silicon compounds as core molecules are based on inorganic silica or organic polysilicon oxides. These flame retardants offer advantages such as high efficiency, environmental friendliness, excellent thermal stability, and good processability. They also contribute to char formation and smoke suppression. These flame retardants not only improve the flame retardancy of resins but also enhance their processability and flowability, making them more suitable for polymer processing. However, these flame retardants suffer from low oxygen index, poor self-healing properties, and minimal impact on polyurethane droplets.

[0006] Nitrogen-based hyperbranched flame retardants are based on melamine as the core molecule. They offer advantages such as heat insulation, oxygen isolation, smoke suppression, and dripping prevention, making them highly effective and low-toxic. These hyperbranched flame retardants address a number of drawbacks associated with traditional nitrogen-based melamine flame retardants, including the potential release of toxic cyanide gases at high temperatures, poor thermal stability, a short service life, easy phase separation after mixing, difficulty in mixing uniformly, easy migration with the matrix, and poor water resistance. However, these hyperbranched flame retardants offer minimal improvement in the oxygen index of the resulting polyurethane.

[0007] Yuan Xiaoxue et al. used tetraethyl orthosilicate as a silicon source and ammonia as an alkaline medium to prepare silica microspheres using the Stober method, mesoporous silica using the sol-gel method, and hollow silica using the hard template method. They modified the three nano-silica spheres by introducing epoxy groups onto their surfaces. Subsequently, hexachlorocyclotriphosphazene was reacted with 4,4'-diaminodiphenylmethane and m-phenylenediamine via nucleophilic substitution to prepare two hyperbranched polymers. These were then used to prepare polyurethane foam using a water-blown method. Limiting oxygen index (LOI) and vertical burning tests showed that the LOI value increased with increasing flame retardant dosage. At a 20% addition, some flame retardants achieved LOI values ​​approaching flame retardancy levels, reaching UL-94 V-0. However, the polyurethane foam studied was not water-based polyurethane, and the flame retardant oxygen index was low. Furthermore, the effects of droplets were not investigated.

[0008] Wang Xiang prepared hyperbranched waterborne polyurethane using 2,4-toluene diisocyanate (TDI), polypropylene glycol (PPG-1000), diethanolamine (DEOA), and dimethylolpropionic acid (DMPA) as the basic raw materials, following the A2+CB2 synthesis route. By optimizing the formula, he determined that when the R value (-NCO / -OH) was 1.4 and the mass fractions of DMPA and DEOA were both 5%, the resulting emulsion had excellent properties and good film-forming properties. Infrared and 13C NMR characterization of the product confirmed that it was the target hyperbranched waterborne polyurethane. Based on these experiments, he studied the flame retardant chemical modification of hyperbranched waterborne polyurethane. Using an organophosphorus diol (flame retardant FR6), hyperbranched waterborne polyurethanes with FR6 contents of 5%, 10%, 15%, and 20%, respectively, were synthesized. Characterization and testing of the resulting samples revealed successful incorporation of the flame retardant into the molecular chain. The properties of the sample emulsions were correlated with the FR6 content: as the FR6 content increased, the emulsion's color gradually shifted from milky white to yellow, and its stability, film-forming properties, freeze-thaw cycle resistance, and toughness gradually deteriorated. The viscosity of the emulsions initially decreased and then increased, while the pH range of acid and alkaline resistance continued to expand. Films prepared from the emulsions were tested, and the oxygen indexes of the samples containing 15% and 20% FR6 were 28.4% and 33.3%, respectively, reaching flame retardancy levels. However, the method's drawbacks include the high amount of flame retardant required, a decrease in the emulsion's film-forming properties, stability, and toughness, and the lack of research into the waterborne polyurethane's drip resistance.

[0009] Polyurethane will suffer irreversible damage when stimulated by external light or mechanical strength, which will greatly affect its service life. Therefore, the self-healing performance of water-based polyurethane becomes the key to solving this problem. At present, the main repair methods of water-based polyurethane in the industry are divided into external self-healing and intrinsic self-healing.

[0010] Externally assisted self-healing materials incorporate external components containing a healing system, such as microcapsules, microcapsules, and nanoparticles, into the coating matrix. This method requires the pre-application of various healing agents and their thorough mixing within the matrix. When the material is subjected to significant stress, it may be damaged. These external stimuli (such as mechanical stress, acid-base conditions, and temperature) release the healing agent from the damaged area, which then reaches the crack surface through capillary action and, under certain conditions, undergoes polymerization, enabling the material to self-heal. Microcapsule self-healing is currently the most widely used method in the field of self-healing coatings. Externally assisted self-healing of waterborne polyurethane is achieved by adding additional components such as microcapsules, microcapsules, and nanoparticles containing the healing system to the matrix. Currently, externally assisted self-healing is less widely used than intrinsically assisted self-healing. Intrinsically assisted self-healing materials achieve self-healing through reversible chemical reactions within specific molecular bonds within the material. Compared to externally assisted self-healing methods, this method does not require the addition of additional substances, does not affect the material's performance and thermal stability, and may even be beneficial to its use. Therefore, the intrinsic self-repair method has more research value and broader prospects than the external aid method. This paper focuses on the intrinsic self-repair method.

[0011] There are different types of waterborne polyurethane self-healing through reversible chemical reactions, divided into dynamic covalent bond chemical reactions and dynamic non-covalent bond chemical reactions. Currently, mature methods for the application of self-healing waterborne polyurethanes include self-healing waterborne polyurethanes based on DA (Diels-Alder) bonds, self-healing waterborne polyurethanes based on disulfide bonds, self-healing waterborne polyurethanes based on diselenide bonds, and self-healing waterborne polyurethanes based on hydrogen bonds. Disulfide bonds are characterized by their strong dynamic reversibility, which makes their activation energy extremely low and allows them to be broken and reconstructed multiple times, thereby achieving more efficient structural adjustment. Due to the dynamic reversibility of disulfide bonds, they are applied to waterborne PUR to achieve self-healing by utilizing the interaction between them under low activation energy environments, thereby improving its functionality and stability.

[0012] By introducing dynamic disulfide bonds into waterborne polyurethane (PUR), Ye et al. successfully prepared a self-healing waterborne PUR material (WPU) using polytetramethylene glycol (PTMEG) as a soft segment, IPDI as a hard segment, and DMPA as a hydrophilic chain extender, effectively modifying PUR. The material was cut and then stretched, and the recovery effect was determined by the ratio of the elongation before and after cutting. After cutting, the WPU sample was heat-treated at 70°C for 4 hours. It maintained tensile strength and self-healing efficiency of 96.14%. The repaired sample at 25°C had a repair efficiency of 84.21%. This method uses heat to further enhance the repair efficiency, considering the self-healing properties in flame-retardant environments.

[0013] Zhang et al. used polyurethane diol (PCDL), DMPA, fluorocarbon amide (DFU), and methylguanamine (AGM) to obtain polyurethane elastomers (WPU-FMs) with a hexahydrogen-bonded structure. The structure consists of two triple hydrogen bonds formed by self-assembly of DFU and AGM side groups as hydrogen bond donors / acceptors. The dynamic cross-linked network generated by the hexahydrogen bonds not only consumes elastic strain energy but also promotes rapid remodeling of hydrogen bonds after rupture, resulting in excellent self-healing properties (104.32% self-healing efficiency at 90°C for 24 hours) and good mechanical properties (tensile strength of 22.19 MPa and elongation at break of 493.98%). This solves the self-healing problem of polyurethane elastomers, which has not been considered in waterborne polyurethanes.

[0014] The team's previous Chinese invention patent ZL202111473297.X self-repairing flame retardant, molten droplet and wear resistant polyurethane coating preparation and application method uses isocyanate loaded on vacuum glass microspheres HGB-DI, in a nitrogen-protected reaction vessel

[0015] In the reaction mixture, polypropylene glycol, polytetramethylene glycol, isophorone diisocyanate and HGB-DI were added, the system temperature was raised to 80°C, dibutyltin dilaurate, chain extender 2,2-dithiodiethanol and nitrogen-phosphorus intumescent flame retardant were added, the temperature was lowered to 50-70°C, and the viscosity reducer N,N-diethylformamide was added; the temperature was then lowered to 40°C, and triethylamine was added to obtain a transparent viscous liquid, which was cooled to room temperature, and deionized water, epoxy resin E51, trimethylolpropane trimethacrylate and 3,4'-diaminodiphenyl ether were added to finally obtain a polyurethane emulsion. The obtained polyurethane emulsion was significantly superior in flame retardancy, self-repairing, dripping resistance and wear resistance. However, the stability of the polyurethane emulsion modified with vacuum glass microspheres as an inorganic substance was less than 1 day, which affected its usability and required heating at 80°C for repair.

[0016] In view of the shortcomings of the existing technology, such as low oxygen index, flammability, poor droplet resistance, and poor repairability after wear, in order to expand the application field of waterborne polyurethane coatings, it is urgent to improve the above-mentioned defects of waterborne polyurethane film formation. Summary of the Invention

[0017] The present invention mainly solves the technical difficulties of Shandong Province's small and medium-sized enterprise promotion project "Research and Industrialization of Flame-retardant, Light-resistant, Low-VOC Polyurethane Coatings 2022TSGC1354". The technical problems to be solved are the low oxygen index, flammability, and easy wear of polyurethane. A hyperbranched nitrogen-phosphorus-silicon flame retardant is designed and prepared for flame retardant treatment of polyurethane to make up for the flammable defects of polyurethane and the problem of releasing a large amount of molten droplets and large smoke generation during combustion. It provides a new flame retardant option for flame retardant modification of polyurethane, and adopts a combination of disulfide bonds, coumarin derivatives (photorepair) and multiple dynamic hydrogen bonds, and uses spiropyran compounds to absorb light and release energy, so that coumarin derivatives (photorepair) and disulfide bonds can improve the self-repairing durability of polyurethane at room temperature.

[0018] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant waterborne polyurethane coating is characterized by comprising the preparation of a hyperbranched nitrogen-phosphorus-silicon flame retardant and its use in the prepolymerization of waterborne polyurethane, wherein the preparation process of the hyperbranched nitrogen-phosphorus-silicon is as follows:

[0019] (1) Weigh 18-22 parts of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, 30-35 parts of isocyanatepropyltriethoxysilane, 0.8-1 part of catalyst dibutyltin dilaurate and 15-2 parts of tetrahydrofuran, add them to a reaction vessel, and stir and react at 60-65°C for 2-3 hours; add nitric acid to the system to adjust the pH value of the system to 4-5, add 3-5 parts of deionized water to the system, stir and react at 60-65°C for 2-3 hours, add 10-12 parts of tetrahydrofuran, and mix with 40-45 parts of triglycidyl isocyanurate, and stir and react at 60-70°C for 2-3 hours to obtain material A;

[0020] (2) Add 0.03-0.05 parts of phosphorylation reagent and material A in step (1) and stir to react at 70-80°C for 2-3 hours. Filter the reactant with a suction filtration device, pour the lower layer of liquid into a rotary evaporator, and perform rotary evaporation at 60-65°C for 15-20 minutes. Place it in an oven at 60-65°C and dry it for 3-4 hours to obtain a gel-like hyperbranched flame retardant.

[0021] In the preparation method of the flame-retardant, self-repairing waterborne polyurethane coating, the phosphorylation reagent is any one of phosphorus pentachloride, phosphorus trichloride, and phenylphosphonium dichloride.

[0022] The preparation method of the flame-retardant, self-repairing waterborne polyurethane coating is as follows:

[0023] (1) Raw material pretreatment: vacuum drying polytetramethylene glycol and polypropylene glycol for 18 to 24 hours;

[0024] (2) Prepolymerization: Weigh 20-25 parts of polyol and 6-9 parts of isocyanate into a flask, drop 0.1-0.3 parts of dibutyltin dilaurate into it, insert a thermometer, a glass stopper, a stirring paddle, and a nitrogen tube, heat to 80-85°C, set the speed to 200-250 r / min, react for 1-2 hours, add 2-5 parts of the above-mentioned hyperbranched flame retardant into the reaction system, and react for 1-2 hours;

[0025] (3) Chain extension: Cool down to 58°C, add 1~2 parts of 2,2-dihydroxymethylpropionic acid, react for 1~2 hours, then add 1~2 parts of disulfide compound, react at 60~80°C for 1~2 hours, then add 1~2 parts of hydrogen bonding reagent, react at 60~80°C for 1 hour, then add 0.5~1.5 parts of coumarin derivative, react at 60~90°C for 1~2 hours, then add 0.0.2~0.04 parts of spiropyran, 0.01 parts of diethanol monoisopropanolamine, and 0.01 parts of p-toluenesulfonamide, react at 50°C for 30 minutes, cool down to 40~45°C, add 1~2 parts of triethylamine, and react for 1~2 hours;

[0026] (4) Emulsification: cool to room temperature, add 60-65 parts of water, stir and react at a speed of 1800-2000 r / min for 0.5-1 h, adjust the pH of the system to 7-8, and obtain a flame-retardant, self-healing waterborne polyurethane coating.

[0027] The polyol is any one of polytetramethylene glycol and polypropylene glycol.

[0028] As the isocyanate, any one of IPDI, HDI, and MDI can be used.

[0029] The disulfide compound is either 2,2'-dithiodiethanol or 2,2-diaminodiphenyl disulfide.

[0030] The hydrogen bonding agent is either 2-amino-4-hydroxy-6-methylpyrimidine or 4-methylumbelliferone.

[0031] The preparation method of the coumarin derivative is as follows: 11.0 parts of resorcinol, 13-15 parts of ethyl acetoacetate, and 0.25-0.4 parts of p-toluenesulfonic acid are added to a three-necked flask, and the mixture is heated to 85-90°C with stirring at 220 r / min. As the reaction proceeds, the reactant changes from a colorless transparent liquid to a light yellow liquid and gradually becomes a yellow viscous substance. After reacting for 2 hours, the heating is stopped, the three-necked flask is removed, and the mixture in the flask is transferred to a Buchner funnel for suction filtration and washed with ice water to obtain a yellow solid crude product. The crude product is recrystallized with 67% ethanol to obtain white needle-shaped crystals, which are dried in a vacuum drying oven to obtain the coumarin derivative.

[0032] The preparation method of the spiropyran:

[0033] (1) Preparation of 1-hydroxyethyl-2,3,3-trimethylindoline iodide: 3.8 parts of 2,3,3-trimethyl-3H-indole and 4.1-4.5 parts of 2-iodoethanol are reacted at 80°C for 30-60 minutes. During the reaction, 10-15 parts of anhydrous ethanol are added dropwise to obtain a crystalline product, 1-hydroxyethyl-2,3,3-trimethylindoline iodide.

[0034] (2) Take 1.7 parts of 5-nitrosalicylicylaldehyde and 3 parts of 1-hydroxyethyl-2,3,3-trimethylindoline iodide, use piperidine as a catalyst, dissolve them in 15 parts of anhydrous ethanol, react at 80°C for 10-12 hours, dry under reduced pressure, dissolve in chloroform, and perform column chromatography to obtain spiropyran.

[0035] The positive effects of the present invention are:

[0036] (1) The present invention uses isocyanatepropyl triethoxysilane as the carbon source and silicon source, which is the basis for forming a silicon carbon layer. When heated, it decomposes, removes water molecules, and forms a dense silicon carbon layer on the surface of the substrate, reducing the occurrence of mass transfer and heat transfer during the combustion process, and protecting the substrate from damage by fire. In the present invention, the addition of 1,3,5-tris(2-hydroxyethyl)cyanuric acid and triglycidyl isocyanurate can supplement the carbon source and nitrogen source. The nitrogen source decomposes after heating to produce non-combustible and flame-retardant gas. On the one hand, the non-combustible and flame-retardant gas covers the surface of the polyurethane, which can isolate the substrate from the contact with the external combustible gas, delaying or hindering the spread of the fire. On the other hand, the released flame-retardant gas can dilute the concentration of the combustible and combustion-supporting gas in the system, delaying the combustion, which is the gas dilution effect.

[0037] (2) The triglycidyl isocyanurate in the present invention can not only supplement the carbon source and nitrogen source, but also undergo a ring-opening reaction when it comes into contact with water, and then the flame retardant forms a branched structure, thereby generating a hyperbranched flame retardant. At the same time, it is modified with a chlorophosphorus compound and reacts with the hydroxyl group of the branched product to increase the phosphorus content of the hyperbranched flame retardant, thereby enhancing its carbonization ability.

[0038] (3) The present invention is based on the fact that disulfide bonds are dynamic weak covalent bonds with lower thermal effect response conditions than reversible covalent bonds, and can achieve low-temperature self-repair of polyurethane. The repair method is based on the fact that disulfide bonds are easily broken to form sulfur anions or sulfur free radicals, and self-repair is achieved through the recombination process between different sulfur anions or sulfur free radicals or the reversible reaction between disulfide bonds and thiol groups. By introducing disulfide bonds into waterborne polyurethane, when the polyurethane is worn or damaged, the disulfide bonds are first broken to form free sulfur free radicals. Under sunlight, the sulfur free radicals combine with each other to form disulfide bonds again, thereby achieving self-repair. Multiple hydrogen bonds are used after chain extension. Coumarin derivatives are used. Due to the unique optical properties of the coumarin functional group, it can undergo photodimerization and photodepolymerization under ultraviolet light of different wavelengths without the addition of any catalyst. Since the parent core structure of coumarin is reversible, its derivative structure also has self-repairing properties. The synthesized coumarin-based polyurethane exhibits the property of reversible photodimerization due to the addition of coumarin groups. When used in polyurethane coatings, it can achieve reversible repair of the coating under ultraviolet light, thus forming a smart coating with self-healing capabilities.

[0039] (4) The present invention utilizes resorcinol and ethyl acetoacetate in the presence of p-toluenesulfonic acid as a catalyst to generate a hydroxyphenol with a double bond and an ester bond on the right side to obtain an inner six-membered ring. Under ultraviolet light conditions exceeding 300 nm, the intermolecular double bond forms an inner four-ring buffer, which makes it have strong self-repairing properties under light conditions. At the same time, the spiropyran compounds absorb light under light conditions and can release energy when the light source disappears, thereby compensating for the self-repairing properties of the coumarin-based compounds.

[0040] (5) The present invention adopts the reaction of polyol and isocyanate. A hyperbranched flame retardant is introduced into the prepolymer chain segment of polyurethane, and 2,2-dimethylol propionic acid, disulfide compounds and multiple hydrogen bond compounds are added to react, and then react with coumarin derivatives. The reaction is self-repaired under light conditions, while the spiropyran absorbs energy. The hydroxyl group of diethanol monoisopropanolamine and the amino group of p-toluenesulfonamide help to increase the energy absorption of the spiropyran and improve the self-repair of the coumarin. The present invention adopts the multiple effects of disulfide bonds, multiple hydrogen bonds and light absorption to carry out the repair, exerting the above-mentioned synergistic effect.

[0041] (6) The present invention reacts 2,3,3-trimethyl-3H-indole with 2-iodoethanol to convert nitrogen into N+, which reacts with 5-nitrosalicylicylaldehyde and is grafted onto the 2,3,3-trimethyl-3H-indole substance to form a cyclic compound composed of two benzene rings, a five-membered ring and a six-membered heterocycle, which has a certain light absorption property. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 SEM images of the PU of the present invention (b) and PU without hyperbranched flame retardant (d);

[0043] Figure 2 Polarizing microscope photos; Figure a: Before restoration without adding restoration agent; Figure b: After restoration without adding restoration agent;

[0044] Figure c: Example 1 before self-repair. Figure d: Example 1 after self-repair. No repair agent was added, that is, no disulfide compound and hydrogen bonding agent were added. DETAILED DESCRIPTION

[0045] The present invention is further described below with reference to examples.

[0046] The chemical materials of unspecified manufacturers involved in the embodiments of the present invention can be replaced with similar products of Shanghai MacLean Biochemical Co., Ltd.

[0047] Example 1

[0048] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant waterborne polyurethane coating is characterized by comprising the preparation of a hyperbranched nitrogen-phosphorus-silicon flame retardant and its use in the prepolymerization of waterborne polyurethane, wherein the preparation process of the hyperbranched nitrogen-phosphorus-silicon flame retardant is as follows:

[0049] (1) Weigh 18 parts of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, 30 parts of isocyanatepropyltriethoxysilane, 0.8 parts of catalyst dibutyltin dilaurate and 15 parts of tetrahydrofuran, add them to a reaction vessel, and stir and react at 60°C for 2 hours; add nitric acid to the system to adjust the pH value of the system to 4-5, add 3 parts of deionized water to the system, stir and react at 60°C for 2 hours, add 10 parts of tetrahydrofuran, and mix with 40 parts of triglycidyl isocyanurate, and stir and react at 60°C for 2-3 hours to obtain material A;

[0050] (2) Add 0.03 parts of phosphorus pentachloride and material A in step (1) and stir to react at 70°C for 2 hours. Filter the reactant with a suction filtration device, pour the lower layer of liquid into a rotary evaporator, and perform rotary evaporation at 60°C for 15 minutes. Place it in a 60°C oven and dry it for 3 hours to obtain a gel-like hyperbranched flame retardant.

[0051] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant water-based polyurethane coating is as follows:

[0052] (1) Raw material pretreatment: vacuum drying polytetramethylene ether glycol (molecular weight 2000 g / mol) for 18 h;

[0053] (2) Prepolymerization: Weigh 20 parts of polytetramethylene glycol and 6 parts of IPDI into a flask, add 0.1 parts of dibutyltin dilaurate, insert a thermometer, a glass stopper, a stirring paddle, and a nitrogen tube, heat to 80°C, rotate at 200 r / min, react for 1 hour, add 2 parts of the above-mentioned hyperbranched flame retardant to the reaction system, react at 80°C for 1 hour, and obtain a polyurethane prepolymer;

[0054] (3) Chain extension: in step (2), the polyurethane prepolymer system was cooled to 58°C, 1 part of 2,2-dihydroxymethylpropionic acid was added, the reaction time was 1 hour, 1 part of 2,2'-dithiodiethanol was added, the reaction time was 60°C for 1 hour, 1 part of 2-amino-4-hydroxy-6-methylpyrimidine was added, the reaction time was 60°C for 1 hour, 0.5 parts of coumarin derivatives were added, the reaction time was 60°C for 1 hour, 0.02 parts of spiropyran, 0.01 parts of diethanol monoisopropanolamine and 0.01 parts of p-toluenesulfonamide were added, the reaction time was 50°C for 30 minutes, the temperature was cooled to 40°C, 1 part of triethylamine was added and the reaction time was 1 hour;

[0055] (4) Emulsification: The system in step (3) was cooled to room temperature, 60 parts of water was added, and the reaction was stirred at a speed of 1800 r / min for 0.5 h. The pH of the system was adjusted to 7-8 to obtain an intelligent self-repairing, flame-retardant, and light-resistant water-based polyurethane coating.

[0056] The preparation method of the coumarin derivative is as follows: 11.0 parts of resorcinol, 13 parts of ethyl acetoacetate, and 0.25 parts of p-toluenesulfonic acid are added to a three-necked flask, and the mixture is heated to 85°C with stirring at 220 r / min. As the reaction proceeds, the reactant changes from a colorless transparent liquid to a light yellow liquid and gradually becomes a yellow viscous substance. After reacting for 2 hours, the heating is stopped, the three-necked flask is removed, and the mixture in the flask is transferred to a Buchner funnel for suction filtration and washed with ice water to obtain a yellow solid crude product. The crude product is recrystallized with 67% ethanol to obtain white needle-shaped crystals, which are dried in a vacuum drying oven to obtain the coumarin derivative.

[0057] The preparation method of the spiropyran:

[0058] (1) Preparation of 1-hydroxyethyl-2,3,3-trimethylindoline iodide: 3.8 parts of 2,3,3-trimethyl-3H-indole and 4.1 parts of 2-iodoethanol were reacted at 80°C for 30 minutes. During the reaction, 10 parts of anhydrous ethanol was added dropwise to obtain a crystalline product, 1-hydroxyethyl-2,3,3-trimethylindoline iodide.

[0059] (2) Take 1.7 parts of 5-nitrosalicylicylaldehyde and 3 parts of 1-hydroxyethyl-2,3,3-trimethylindoline iodide, use 0.05 parts of piperidine as a catalyst, dissolve them in 15 parts of anhydrous ethanol, react at 80°C for 10 hours, dry under reduced pressure, dissolve in chloroform, and perform column chromatography to obtain spiropyran.

[0060] Example 2

[0061] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant waterborne polyurethane coating is characterized by comprising the preparation of a hyperbranched nitrogen-phosphorus-silicon flame retardant and its use in the prepolymerization of waterborne polyurethane, wherein the preparation process of the hyperbranched nitrogen-phosphorus-silicon flame retardant is as follows:

[0062] (1) Weigh 22 parts of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, 35 parts of isocyanatepropyltriethoxysilane, 1 part of catalyst dibutyltin dilaurate and 20 parts of tetrahydrofuran, add them into a reaction vessel, stir and react at 65°C for 3 hours; add nitric acid to the system to adjust the pH value of the system to 4-5, add 5 parts of deionized water to the system, stir and react at 65°C for 3 hours, add 45 parts of triglycidyl isocyanurate dissolved in 12 parts of tetrahydrofuran, stir and react at 70°C for 3 hours to obtain material A;

[0063] (2) Add 0.05 parts of phosphorus trichloride and material A obtained in step (1) and stir to react at 80°C for 3 hours. Filter the reactant with a suction filtration device, pour the lower layer of liquid into a rotary evaporator, and perform rotary evaporation at 65°C for 20 minutes. Place it in a 65°C oven and dry it for 4 hours to obtain a gel-like hyperbranched flame retardant.

[0064] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant water-based polyurethane coating is as follows:

[0065] (1) Raw material pretreatment: Polypropylene glycol (molecular weight 2000 g / mol) was vacuum dried for 24 h;

[0066] (2) Prepolymerization: Weigh 25 parts of polypropylene glycol and 9 parts of HDI into a flask, add 0.3 parts of dibutyltin dilaurate, insert a thermometer, a glass stopper, a stirring paddle, and a nitrogen tube, heat to 85°C, rotate at 250 r / min, react for 2 hours, add 5 parts of the above-mentioned hyperbranched flame retardant into the reaction system, react at 85°C for 2 hours, and obtain a polyurethane prepolymer;

[0067] (3) Chain extension: in step (2), the polyurethane prepolymer system was cooled to 58°C, 2 parts of 2,2-dihydroxymethylpropionic acid were added, and the reaction time was 2 h. Then, 2 parts of 2,2-diaminodiphenyl disulfide were added, and the reaction was carried out at 80°C for 2 h. Then, 2 parts of 4-methylumbelliferone were added, and the reaction time was 1 h at 80°C. Then, 1.5 parts of coumarin derivatives were added, and the reaction was carried out at 90°C for 2 h. Then, 0.04 parts of spiropyran, 0.01 parts of diethanol monoisopropanolamine, and 0.01 parts of p-toluenesulfonamide were added, and the reaction was carried out at 50°C for 30 min. The system was cooled to 45°C, and 2 parts of triethylamine were added and the reaction was carried out for 2 h.

[0068] (4) Emulsification: Cool to room temperature, add 65 parts of water, stir at a speed of 2000 r / min for 1 hour, adjust the pH of the system to 7-8, and obtain an intelligent self-repairing, flame-retardant, and light-resistant water-based polyurethane coating.

[0069] The preparation method of the coumarin derivative is as follows: 11.0 parts of resorcinol, 15 parts of ethyl acetoacetate, and 0.4 parts of p-toluenesulfonic acid are added to a three-necked flask, and the mixture is heated to 90°C with stirring at 220 r / min. As the reaction proceeds, the reactant changes from a colorless transparent liquid to a light yellow liquid and gradually becomes a yellow viscous substance. After reacting for 2 hours, the heating is stopped, the three-necked flask is removed, and the mixture in the flask is transferred to a Buchner funnel for suction filtration and washed with ice water to obtain a yellow solid crude product. The crude product is recrystallized with 67% ethanol to obtain white needle-shaped crystals, which are dried in a vacuum drying oven to obtain the coumarin derivative.

[0070] The preparation method of the spiropyran:

[0071] (1) Preparation of 1-hydroxyethyl-2,3,3-trimethylindoline iodide: 3.8 parts of 2,3,3-trimethyl-3H-indole and 4.5 parts of 2-iodoethanol were reacted at 80°C for 60 minutes. During the reaction, 15 parts of anhydrous ethanol was added dropwise to obtain a crystalline product, 1-hydroxyethyl-2,3,3-trimethylindoline iodide.

[0072] (2) Take 1.7 parts of 5-nitrosalicylicylaldehyde and 3 parts of 1-hydroxyethyl-2,3,3-trimethylindoline iodide, use 0.05 parts of piperidine as a catalyst, dissolve them in 15 parts of anhydrous ethanol, react at 80°C for 12 hours, dry under reduced pressure, dissolve them in chloroform, and perform column chromatography to obtain spiropyran.

[0073] Example 3

[0074] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant waterborne polyurethane coating is characterized by comprising the preparation of a hyperbranched nitrogen-phosphorus-silicon flame retardant and its use in the prepolymerization of waterborne polyurethane, wherein the preparation process of the hyperbranched nitrogen-phosphorus-silicon flame retardant is as follows:

[0075] (1) Weigh 20 parts of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, 7.5 parts of isocyanatepropyltriethoxysilane, 0.9 parts of catalyst dibutyltin dilaurate and 17.5 parts of tetrahydrofuran, add them to a reaction vessel, and stir at 60°C for 2.5 hours; add nitric acid to the system to adjust the pH value of the system to 4-5, add 4 parts of deionized water to the system, stir at 60°C for 2.5 hours, add 11 parts of tetrahydrofuran, and mix with 42.5 parts of triglycidyl isocyanurate, and stir at 65°C for 2.5 hours to obtain material A;

[0076] (2) Add 0.04 parts of phenyl dichlorophosphine and material A in step (1) and stir to react at 75°C for 2.5 hours. Filter the reactant with a suction filtration device, pour the lower layer of liquid into a rotary evaporator, and perform rotary evaporation at 60°C for 15 minutes. Place it in a 60°C oven and dry it for 3.5 hours to obtain a gel-like hyperbranched flame retardant.

[0077] A method for preparing an intelligent self-repairing, flame-retardant, and light-resistant water-based polyurethane coating is as follows:

[0078] (1) Raw material pretreatment: vacuum drying polypropylene glycol for 21 hours;

[0079] (2) Prepolymerization: Weigh 22.5 parts of polytetramethylene glycol and 37.5 parts of MDI into a flask, drop 0.2 parts of dibutyltin dilaurate into it, insert a thermometer, a glass stopper, a stirring paddle, and a nitrogen tube, heat to 80°C, set the speed to 225 r / min, react for 1.5 hours, add 2.5 parts of the above-mentioned hyperbranched flame retardant into the reaction system, react for 1.5 hours, and obtain a polyurethane prepolymer;

[0080] (3) Chain extension: Cool the polyurethane prepolymer to 58°C, add 1.5 parts of 2,2-dihydroxymethylpropionic acid, react for 1.5 hours, then add 1.5 parts of 2,2'-dithiodiethanol, react at 70°C for 1.5 hours, then add 1.5 parts of 2-amino-4-hydroxy-6-methylpyrimidine, react at 70°C for 1 hour, then add 1.0 parts of coumarin derivative, react at 75°C for 1.5 hours, then add 0.03 parts of spiropyran, 0.01 parts of diethanol monoisopropanolamine, and 0.01 parts of p-toluenesulfonamide, react at 50°C for 30 minutes, cool to 40°C, add 1.5 parts of triethylamine, and react for 1.5 hours;

[0081] (4) Emulsification: cool to room temperature, add 62.5 parts of water, stir and react at a speed of 1900 r / min for 0.5 h, adjust the pH of the system to 7-8, and obtain an intelligent self-healing, flame-retardant, and light-resistant water-based polyurethane coating.

[0082] The preparation method of the coumarin derivative is as follows: 11.0 parts of resorcinol, 14 parts of ethyl acetoacetate, and 0.3 parts of p-toluenesulfonic acid are added to a three-necked flask, and the mixture is heated to 85°C with stirring at 220 r / min. As the reaction proceeds, the reactant changes from a colorless transparent liquid to a light yellow liquid and gradually becomes a yellow viscous substance. After reacting for 2 hours, the heating is stopped, the three-necked flask is removed, and the mixture in the flask is transferred to a Buchner funnel for suction filtration and washed with ice water to obtain a yellow solid crude product. The crude product is recrystallized with 67% ethanol to obtain white needle-shaped crystals, which are dried in a vacuum drying oven to obtain the coumarin derivative.

[0083] The preparation method of the spiropyran:

[0084] (1) Preparation of 1-hydroxyethyl-2,3,3-trimethylindoline iodide: 3.8 parts of 2,3,3-trimethyl-3H-indole and 4.3 parts of 2-iodoethanol were reacted at 80°C for 45 minutes. During the reaction, 12.5 parts of anhydrous ethanol was added dropwise to obtain a crystalline product, 1-hydroxyethyl-2,3,3-trimethylindoline iodide.

[0085] (2) Take 1.7 parts of 5-nitrosalicylicylaldehyde and 3 parts of 1-hydroxyethyl-2,3,3-trimethylindoline iodide, use piperidine as a catalyst, dissolve them in 15 parts of anhydrous ethanol, react at 80°C for 11 hours, dry under reduced pressure, dissolve in chloroform, and perform column chromatography to obtain spiropyran.

[0086] SEM: Add about 1g of flame retardant-free polyurethane and flame retardant polyurethane to two crucibles respectively, put them into a muffle furnace, and calcine at 300℃ for 30 minutes. Then take the upper expanded carbon layer and analyze the carbon layer of the calcined polyurethane using a scanning electron microscope to observe whether the polyurethane with added flame retardant has a dense expanded carbon layer.

[0087] Raman analysis: Raman spectroscopy instrument was used for analysis.

[0088] Preparation of polyurethane film: The prepared intelligent self-healing, flame-retardant, light-resistant water-based polyurethane coating was poured into a polytetrafluoroethylene mold with a thickness of 3 mm, and the carbon residue rate, expansion height, molten droplet test and polarized fiber were carried out.

[0089] Carbon residue rate and expansion height:

[0090] The muffle furnace samples were used to measure the residual carbon rate and expansion height at 500°C. About 1g of different flame retardant samples were placed in each crucible and placed in the muffle furnace. The initial test temperature was set to 100°C, the holding temperature was 500°C, and the holding time was 10 minutes. After the time was up, the crucible was taken out and placed in a drying oven to cool to room temperature. The sample was weighed, the expansion height was measured, the data was recorded, and a table of the residual carbon rate and expansion height of the flame retardant at different holding times was drawn.

[0091] Emulsion stability: Use a high-speed rotating centrifuge to simulate the 36-month storage stability of the emulsion. Spin the emulsion at a speed of 3500 r / min for 20 minutes and observe the situation. If there is no precipitation in the emulsion, it means that the emulsion is stable.

[0092] The test was carried out using ASTM E1354-1990 (2004 standard) and a cone calorimeter 2000 from FTT, UK. The sample was 10 cm × 10 cm, 3 mm thick, and the thermal radiation power was 12 kw / m 2 , determine the maximum heat release rate pkHHR kW / m 2, THR total heat release MJ / m².

[0093] Droplet test

[0094] (1) Sample preparation: Place the prepared PU film in a constant temperature and humidity chamber set at 23℃±0.5℃ and 50%±5% humidity for 48 hours. Then take it out and cut it into 110cm×10cm×3mm samples. Prepare two sets of samples, with 5 samples in each group.

[0095] (2) Parameters: Clamp the sample about 5 mm from the top, so that it is facing vertically downward. Place a rosin board under the sample, and pad about 0.3 g of absorbent cotton on the board, evenly placed on the board. Adjust the gas flow rate to 105 ± 5 mL / min so that the flame height reaches 20 ± 1 mm. Set the combustion time to 10 s.

[0096] (3) Flame recording: After setting the parameters, start the flame ignition. After the 10s ignition is over, press the afterflame time start button. When the sample combustion is finished and only sparks are left, press the afterflame combustion end button and enter the afterburning time. When the sample is completely extinguished, press the afterburning time end button and record the burning afterflame time and afterburning time.

[0097] (4) Melt droplet observation: During the combustion process, pay attention to whether the combustion produces melt droplets, and whether the melt droplets falling on the absorbent cotton below will cause secondary combustion, and record the observation results.

[0098] Cone calorimetry test was performed according to ISO55660-1 standard. The sample was cut into 100 mm × 100 mm × 3 mm, and the heat flux density was 35 KW / m 3 , measure the pkHHR and THR produced by combustion.

[0099] Light resistance is measured by observing the color change under ultraviolet light under simulated sunlight for 48 hours.

[0100] The spectrophotometer was Gretag Macbeth Coloreye (D65 illuminant, 10 degree observer, including UV).

[0101] Compare to Example 2 with patent 202111473297.X;

[0102] Raman spectroscopy revealed that the -1 There is no obvious peak in the blank group near the 1% sample, while there is a significant convex peak compared to the blank. It can be judged that disulfide bonds are introduced into the polyurethane. -1 There are obvious characteristic peaks on the left and right, which is considered to be composed of aromatic molecules.

[0103] Table 1 Data of hyperbranched flame retardants

[0104] Example 1 Example 2 Example 3 Comparative Patents Residual carbon rate / % 75.7 76.1 75.8 73.7 Expansion height / cm 5.86 5.88 5.91 5.81

[0105] The comparative invention of the present invention uses Example 2 of 202111473297.X for comparison. The experiment found that the residual carbon rate and expansion height of the hyperbranched flame retardant of the present invention are better than those of the comparative document (corresponding flame retardant).

[0106] Table 2 Effects of some materials on the performance of hyperbranched flame retardants (based on Example 2)

[0107] Example 2 No added material Residual carbon rate / % (expansion height / cm) 63.4 / 4.25 Triglycidyl isocyanurate Residual carbon rate / % (expansion height / cm) 54.6 / 3.62 Phosphorus trichloride

[0108] It can be found from Table 2 that triglycidyl isocyanurate and phosphorus trichloride have a relatively large influence on the carbon residue rate and expansion height of the hyperbranched flame retardant, and both play a significant role.

[0109] Table 3 Comprehensive properties of the intelligent self-repairing, flame retardant and light-resistant waterborne polyurethane coatings of the present invention

[0110] Example 1 Example 2 Example 3 Comparative Patents Emulsion stability Stablize Stablize Stablize Easy to layer Burning droplet phenomenon No melting and no dripping No melting and no dripping No melting and no dripping No melting and no dripping pkH 53.24 52.14 51.32 68.24 THR 152.23 154.35 154.78 186.15 Self-repair rate (%) 88.61 89.45 88.82 62.15

[0111] Example 2 of 202111473297X was tested, and the test standard was consistent with the test of the present invention (the self-healing rate was tested based on a film size of 0.8-1 mm thick and 5 mm wide, and other factors were tested in accordance with GB / T1040.3-2006. A horizontal line was drawn in the middle of the film with a blade, and the film was cut. The film was irradiated at a wavelength of 365-400 nm at 30°C for 6 h, and an electronic universal testing machine (UTM2502HB) was used at room temperature to perform tensile tests on the uncut original specimens and the specimens after the self-healing test. The tensile rate was 50 mm / min, and the comparison of the maximum strain ratio before and after repair was the self-healing rate.

[0112] It can be found from Table 3 that the polyurethane emulsion of the present invention has good stability, and its film combustion does not produce droplets and dripping, the heat of combustion such as pkHHR and THR are lower than those of the comparative patents, and the self-repair rate is stronger than that of the comparative documents.

[0113] Table 4 Influence of some materials on the comprehensive performance of intelligent self-repairing, flame retardant and light-resistant waterborne polyurethane coatings (taking Example 1 as an example)

[0114] Performance or phenomenon No added material Burning droplet phenomenon Large amount of molten droplets No hyperbranched nitrogen-phosphorus-silicon flame retardant added Burning droplet phenomenon A small amount of molten droplets Added hyperbranched nitrogen phosphorus silicon flame retardant, without phosphorus pentachloride Burning droplet phenomenon Very small amount of droplets Add hyperbranched nitrogen-phosphorus-silicon flame retardant, triglycidyl isocyanurate THR 213.68 No hyperbranched nitrogen-phosphorus-silicon flame retardant added THR 178.56 Added hyperbranched nitrogen phosphorus silicon flame retardant, without phosphorus pentachloride THR 182.39 Add hyperbranched nitrogen-phosphorus-silicon flame retardant, triglycidyl isocyanurate pkH 78.45 No hyperbranched nitrogen-phosphorus-silicon flame retardant added pkH 65.23 Added hyperbranched nitrogen phosphorus silicon flame retardant, without phosphorus pentachloride pkH 66.49 Add hyperbranched nitrogen-phosphorus-silicon flame retardant, triglycidyl isocyanurate Self-repair rate (%) 82.38 No 2,2'-dithiodiethanol added Self-repair rate (%) 82.15 No 2-amino-4-hydroxy-6-methylpyrimidine added Self-repair rate (%) 66.45 No coumarin derivatives added Self-repair rate (%) 84.21 Monoisopropanolamine without diethanol added Self-repair rate (%) 78.36 No toluenesulfonamide added Self-repair rate (%) 63.52 No spiropyran added Self-repair rate (%) 68.42 Spiropyran was added, but 1-hydroxyethyl-2,3,3-trimethylindoline iodide was not added

[0115] Taking Example 1 as an example, some materials such as hyperbranched nitrogen-phosphorus-silicon flame retardants, coumarin derivatives and diethanol monoisopropanolamine have played a role in flame retardancy and self-healing.

[0116] Scanning electron microscopy (SEM)

[0117] Size 10 μm (magnification 1000), by SEM Figure 1As can be seen: (b) The char layer obtained after calcination with the addition of a flame retardant is very smooth and has a large number of pores. This is because the flame retardant contains a large amount of phosphorus and silicon. When heated, phosphorus decomposes into inflammable gases and phosphorus-containing inorganic acids. Phosphorus free radicals are expelled from the system, causing pores. The phosphorus-containing inorganic acids accelerate the formation of carbon and make the carbon layer more dense. When heated, silicon forms a silicon-carbon insulation layer with carbon, isolating the system from further thermal decomposition. Nitrogen is completely converted into non-flammable gases such as nitrogen and ammonia and is expelled. In contrast, the char layer surface of PU calcined without the addition of a flame retardant (d) is a rough, fluffy structure.

[0118] Polarizing microscope observation results

[0119] From the above Figure 2 It can be clearly seen in the polarizing microscope photos a and b of Example 1 without adding coumarin derivatives and spiropyran, and photos c and d with adding coumarin derivatives and spiropyran. Compared with photos b and d, photo d has much better repairability.

[0120] The branching degrees of Examples 1 to 3 obtained by crude determination of separation and purification of hyperbranched nitrogen-phosphorus-silicon flame retardants were 0.68, 0.63, and 0.65, respectively.

[0121] Table 5 Film light resistance test

[0122] Example 1 Example 2 Example 3 Comparative Example Burning droplet phenomenon 4.0 4.0 4.0 4.0

[0123] The comparative example uses 202011498616.8 to obtain Example 2. The light resistance effect of the present invention is comparable to that of the comparative example, and is better than the light resistance of ordinary polyurethane (202111473297.X) (level 2.5), showing that the coumarin derivatives and spiropyran in the present invention play a role. The light resistance without adding coumarin derivatives is level 2.0, and the light resistance without adding spiropyran is level 2.5.

Claims

1. Intelligent self-repairing, flame-retardant, light-resistant water-based polyurethane coating, characterized by: These include hyperbranched nitrogen-phosphorus-silicon flame retardants, spiropyrans, coumarin derivatives, and disulfide compounds; The disulfide compounds are 2,2'-dithiodiethanol and 2,2-diaminodiphenyl disulfide; The preparation method of the hyperbranched nitrogen-phosphorus-silicon flame retardant is: (1) Weigh 18-22 parts of 1,3,5-tris(2-hydroxyethyl)cyanuric acid, 30-35 parts of isocyanatepropyltriethoxysilane, 0.8-1 part of catalyst dibutyltin dilaurate and 15-20 parts of tetrahydrofuran, add them into a reaction vessel, and stir and react at 60-65°C for 2-3 hours; add nitric acid to the system to adjust the pH value of the system to 4-5, add 3-5 parts of deionized water to the system, stir and react at 60-65°C for 2-3 hours, add 40-45 parts of triglycidyl isocyanurate mixed with 10-12 parts of tetrahydrofuran, and stir and react at 60-70°C for 2-3 hours to obtain material A; (2) Add 0.03-0.05 parts of phosphorylation reagent and material A in step (1) and stir the reaction at 70-80°C for 2-3 hours. Filter the reactant with a suction filtration device, pour the lower layer of liquid into a rotary evaporator, and perform rotary evaporation at 60-65°C for 15-20 minutes. Place it in an oven at 60-65°C and dry it for 3-4 hours to obtain a gel-like hyperbranched nitrogen-phosphorus-silicon flame retardant.

2. The intelligent self-repairing, flame-retardant, light-resistant waterborne polyurethane coating according to claim 1, characterized in that: The phosphorylation reagent is any one of phosphorus pentachloride, phosphorus trichloride and phenylphosphonium dichloride.

3. The intelligent self-repairing, flame-retardant, light-resistant waterborne polyurethane coating according to claim 1, characterized in that: The preparation method of the coumarin derivative is as follows: 11.0 parts of resorcinol, 13-15 parts of ethyl acetoacetate, and 0.25-0.4 parts of p-toluenesulfonic acid are added to a three-necked flask, and the mixture is heated to 85-90°C with stirring at 220 r / min. As the reaction proceeds, the reactant changes from a colorless transparent liquid to a light yellow liquid and gradually becomes a yellow viscous substance. After reacting for 2 hours, heating is stopped, the three-necked flask is removed, and the mixture in the flask is transferred to a Buchner funnel for suction filtration and washed with ice water to obtain a yellow solid crude product. The crude product is recrystallized with 67% ethanol to obtain white needle-shaped crystals, which are dried in a vacuum drying oven to obtain the coumarin derivative.

4. The intelligent self-repairing, flame-retardant, light-resistant waterborne polyurethane coating according to claim 1, wherein the preparation method of the spiropyran is: (1) Preparation of 1-hydroxyethyl-2,3,3-trimethylindoline iodide: 3.8 parts of 2,3,3-trimethyl-3H-indole and 4.1-4.5 parts of 2-iodoethanol are reacted at 80°C for 30-60 minutes. During the reaction, 10-15 parts of anhydrous ethanol are added dropwise to obtain a crystalline product, namely 1-hydroxyethyl-2,3,3-trimethylindoline iodide. (2) Take 1.7 parts of 5-nitrosalicylicylaldehyde and 3 parts of 1-hydroxyethyl-2,3,3-trimethylindoline iodide of step (1), dissolve them in 15 parts of anhydrous ethanol and react at 80°C for 10-12 hours using piperidine as a catalyst, dry them under reduced pressure, dissolve them in chloroform and perform column chromatography to obtain spiropyran.

Images