Scratch repair coating and preparation method thereof

Abstract

The invention discloses a scratch repair coating and a preparation method thereof, and relates to the technical field of high polymer materials. When the scratch repair coating is prepared, hydroxylated boron nitride reacts with 1-(3-triethoxysilylpropyl)-2-imidazoline to prepare pre-modified boron nitride, and then the pre-modified boron nitride and 4-chloro-1-butene are subjected to quaternization to prepare modified boron nitride; the preparation method comprises the following steps: reacting styryl phosphonic dichloride with 4, 4, 5, 5, 6, 6, 7, 7, 7-nonafluoro-1, 2-heptanediol to prepare a hydroxyl-terminated phosphorus-fluorine-containing polymer; the preparation method comprises the following steps: reacting isophorone diisocyanate with a hydroxyl-terminated phosphorus and fluorine-containing polymer to prepare a polyurethane prepolymer; reacting the polyurethane prepolymer with hydroxyl-terminated coumarin to generate modified polyurethane; and uniformly mixing the modified polyurethane, the modified boron nitride and a photoinitiator to prepare the scratch repair coating. The scratch repairing coating prepared by the invention has good self-repairing performance, flame retardant property, corrosion resistance and mechanical property.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to a scratch repair coating and a preparation method thereof. Background Art

[0002] During use, coatings are susceptible to environmental influences, often developing cracks or localized damage, which can affect the coating's aesthetics and even directly impact its lifespan. Therefore, timely measures are necessary to repair damaged coatings. However, passive repair methods alone are no longer sufficient to meet the multifunctional demands placed on modern coatings. The development of intelligent coatings that can restore cracks or localized damage to their original state without external influence has become a trend in the coatings industry.

[0003] The coumarin functional group is highly optically active, capable of reversible photodimerization and photodepolymerization under ultraviolet light of varying wavelengths, without the need for any catalyst. The reversible photodimerization of the coumarin core structure imbues its derivatives with reversible self-healing properties. Consequently, the present invention produces a scratch-repair coating with excellent self-healing, flame-retardant, corrosion-resistant, and mechanical properties. Summary of the Invention

[0004] The purpose of the present invention is to provide a scratch repair coating and a preparation method thereof to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A scratch repair coating is prepared by mixing modified polyurethane, modified boron nitride and a photoinitiator.

[0006] As an optimization, the modified polyurethane is prepared by reacting a polyurethane prepolymer with terminal hydroxy coumarin.

[0007] As an optimization, the polyurethane prepolymer is prepared by reacting isophorone diisocyanate with a hydroxyl-terminated phosphorus-containing fluoropolymer.

[0008] As an optimization, the terminal hydroxy coumarin is prepared by a Schiff base reaction of 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde and 2-(aminomethyl)-1,3-diol.

[0009] As an optimization, the hydroxyl-terminated phosphorus-containing fluoropolymer is prepared by reacting styrylphosphonic acid dichloride with 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol.

[0010] As an optimization, the modified boron nitride is prepared by quaternization reaction of pre-modified boron nitride with 4-chloro-1-butene.

[0011] As an optimization, the pre-modified boron nitride is prepared by reacting hexagonal boron nitride with acetone and 1-(3-triethoxysilylpropyl)-2-imidazoline in sequence.

[0012] A method for preparing a scratch repair coating comprises the following steps: (1) Hexagonal boron nitride and acetone are mixed evenly, stirred for reaction, centrifuged, and vacuum dried to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95 wt% ethanol aqueous solution are mixed evenly, hydroxylated boron nitride is added, stirred for reaction, centrifuged, washed, and dried to obtain pre-modified boron nitride; pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide are mixed evenly, stirred for reaction, vacuum distilled, and dried to obtain modified boron nitride; (2) Under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine, and tetrahydrofuran were mixed evenly, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol was added, stirred for reaction, filtered, and rotary evaporated to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; (3) Under a nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide were mixed evenly, stirred for reaction, cooled to room temperature, rotary evaporated, washed, and dried to obtain terminal hydroxy coumarin; (4) Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated phosphorus-containing fluoropolymer, dibutyltin dilaurate, and N,N-dimethylformamide are mixed uniformly, stirred for reaction, and a polyurethane prepolymer is obtained; under a nitrogen atmosphere, a polyurethane prepolymer and terminal hydroxy coumarin are mixed uniformly, stirred for reaction, and subjected to reduced pressure distillation and drying to obtain a modified polyurethane; (5) The modified polyurethane, modified boron nitride and photoinitiator are mixed evenly, stirred and dispersed to prepare a scratch repair coating.

[0013] As an optimization, the preparation steps of the modified boron nitride in step (1) are as follows: hexagonal boron nitride and acetone are uniformly mixed in a mass ratio of 1: (15~20), stirred at 40~60℃, 200~300r / min, reacted for 2~3h, centrifuged at a speed of 1200~1400rpm for 10~12min, and the obtained precipitate is vacuum dried at 75~85℃ for 10~12h to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95wt% ethanol aqueous solution are uniformly mixed in a mass ratio of 1: (30~50), stirred at room temperature, 200~300r / min for 20~40min, and 1-(3-triethoxysilylpropyl)-2-imidazoline is added. 8-10 times the amount of hydroxylated boron nitride is stirred and reacted at 55-65°C and 200-300 r / min for 2-3 hours, and centrifuged at a speed of 10000-12000 rpm for 10-12 minutes. The resulting precipitate is washed 2-4 times with anhydrous ethanol and vacuum-dried at 100-120°C for 10-12 hours to obtain pre-modified boron nitride. Pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide are uniformly mixed in a mass ratio of 1:(0.6-0.8):(15-20), stirred and reacted at 60-70°C and 200-300 r / min for 2-4 hours, N,N-dimethylformamide is removed by reduced pressure distillation, and vacuum-dried at 50-60°C for 10-12 hours to obtain modified boron nitride.

[0014] As an optimization, the preparation steps of the hydroxyl-terminated phosphorus-containing fluoropolymer in step (2) are as follows: under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine and tetrahydrofuran are uniformly mixed in a mass ratio of 1: (1.2~1.4): (15~20), and the mixture is stirred at 0~4°C and 200~300r / min for 20~40min, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol (1.5~2 times the mass of styrylphosphonic acid dichloride) is added, and the mixture is stirred at 20~30°C and 200~300r / min for 8~10h, the triethylamine hydrochloride precipitate is removed by filtration, and the tetrahydrofuran is removed by rotary evaporation to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer.

[0015] As an optimization, the preparation steps of the terminal hydroxy coumarin in step (3) are as follows: under a nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide are uniformly mixed in a mass ratio of 1: (0.5~0.6): (0.004~0.006): (10~12), stirred at 100~120℃ and 200~300r / min for 8~10h, cooled to room temperature, rotary evaporated to remove N,N-dimethylformamide, washed with anhydrous ethanol 2~4 times, and vacuum dried at 50~60℃ for 10~12h to obtain terminal hydroxy coumarin.

[0016] As an optimization, the preparation steps of the modified polyurethane in step (4) are as follows: under a nitrogen atmosphere, isophorone diisocyanate and a hydroxyl-terminated phosphorus-containing fluoropolymer are uniformly mixed at a molar ratio of isocyanate group to hydroxyl group of 1: (0.6-0.7), dibutyltin dilaurate (0.006-0.008 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (15-20 times the mass of isophorone diisocyanate) are added, and the mixture is stirred at 80-90°C for 2 h. ℃, 200~300r / min, stirring and reacting for 6~8h to obtain a polyurethane prepolymer; under a nitrogen atmosphere, the polyurethane prepolymer and the terminal hydroxy coumarin are uniformly mixed according to the molar ratio of isocyanate group to hydroxyl group of 1: (1~1.02), and the mixture is stirred and reacted at 80~90℃, 200~300r / min for 2~3h, and N,N-dimethylformamide is removed by distillation under reduced pressure. The mixture is vacuum dried at 60~70℃ for 8~10h to obtain a modified polyurethane.

[0017] As an optimization, the preparation steps of the scratch repair coating in step (5) are as follows: the modified polyurethane, modified boron nitride, and photoinitiator are uniformly mixed in a mass ratio of 1: (0.06~0.08): (0.02~0.04), and the mixture is stirred and dispersed at a speed of 800~1000r / min for 30~50min to prepare the scratch repair coating.

[0018] As an optimization, the average particle size of the hexagonal boron nitride is 80 nm, which is purchased from Shanghai Xiaohuang Nanotechnology Co., Ltd.

[0019] As an optimization, the photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

[0020] As an optimization, the reaction process of the modified boron nitride in step (1) is as follows: .

[0021] As an optimization, the reaction process of the hydroxyl-terminated phosphorus-containing fluoropolymer in step (2) is as follows: .

[0022] As an optimization, the reaction process of the hydroxy-terminated coumarin in step (3) is as follows: .

[0023] Compared with the prior art, the present invention has the following beneficial effects: In the preparation of the scratch repair coating, the present invention comprises the following steps: reacting hexagonal boron nitride with acetone to obtain hydroxylated boron nitride, which is then reacted with 1-(3-triethoxysilylpropyl)-2-imidazoline to obtain pre-modified boron nitride; reacting the pre-modified boron nitride with 4-chloro-1-butene to obtain a quaternary ammonium-modified boron nitride; reacting styrylphosphonic acid dichloride with 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to obtain a hydroxylated boron nitride; and reacting the styrylphosphonic acid dichloride with 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to obtain a hydroxylated boron nitride. The invention relates to a method for preparing a modified polyurethane by reacting a hydroxyl-terminated phosphorus-containing fluoropolymer with a hydroxyl group; reacting 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde with 2-(aminomethyl)-1,3-diol to produce a Schiff base to produce a terminal hydroxyl coumarin; reacting isophorone diisocyanate with a hydroxyl-terminated phosphorus-containing fluoropolymer to produce a polyurethane prepolymer, which is then reacted with the terminal hydroxyl coumarin to produce a modified polyurethane; and mixing the modified polyurethane, modified boron nitride and a photoinitiator to produce a scratch repair coating.

[0024] First, hexagonal boron nitride is reacted with acetone to obtain hydroxylated boron nitride, which is then reacted with 1-(3-triethoxysilylpropyl)-2-imidazoline to obtain pre-modified boron nitride. Hexagonal boron nitride is introduced into the polyurethane matrix due to its unique lamellar structure and large specific surface area, which can improve the mechanical properties of the coating. Hexagonal boron nitride can also promote the formation of a dense carbon layer, thereby reducing heat transfer and the diffusion of combustible gases, and plays a role in isolating oxygen, thereby improving flame retardancy. At the same time, hexagonal boron nitride has excellent anti-permeability properties, which can effectively prevent corrosive media from entering the coating, improving Anti-corrosion performance: Boron nitride is modified with 1-(3-triethoxysilylpropyl)-2-imidazoline to improve the dispersibility of boron nitride in polyurethane and introduce imidazoline groups into the coating; the pre-modified boron nitride is reacted with 4-chloro-1-butene to undergo a quaternization reaction to produce modified boron nitride, and the imidazoline groups on the pre-modified boron nitride undergo a quaternization reaction with the chlorine on the 4-chloro-1-butene to form an imidazoline quaternary ammonium salt, thereby improving the anti-corrosion performance of the coating; at the same time, double bonds are introduced into the boron nitride, which react with the double bonds on the modified polyurethane to form a cross-linked network structure, thereby improving the mechanical properties of the coating; Secondly, styrylphosphonic acid dichloride is reacted with 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde is reacted with 2-(aminomethyl)-1,3-diol to produce a Schiff base reaction to obtain a terminal hydroxyl coumarin; isophorone diisocyanate is reacted with a hydroxyl-terminated phosphorus-containing fluoropolymer to obtain a polyurethane prepolymer, which is then reacted with the terminal hydroxyl coumarin to obtain a modified polyurethane; the P-Cl on styrylphosphonic acid dichloride reacts with the hydroxyl group on 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to produce a hydroxyl-terminated phosphorus-containing fluoroblock polymer, which is used as the soft segment of the polyurethane. The fluorine element is introduced into the coating to improve the hydrophobicity of the material, thereby improving the coating's waterproofing. Corrosion resistance; at the same time, phosphorus is introduced into the coating, which can promote the formation of a carbon layer and block the combustion reaction by capturing free radicals, further improving the flame retardant properties. At the same time, double bonds are introduced into the coating to react with the double bonds on the modified boron nitride to form a cross-linked network structure, thereby improving the mechanical properties of the coating; the aldehyde group on 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde reacts with the amino group on 2-(aminomethyl)-1,3-diol to produce a Schiff base reaction, and the generated terminal hydroxy coumarin is used as a chain extender to introduce coumarin functional groups into the polyurethane. The coumarin functional group can undergo a cycloaddition reaction (λ>300nm) or a cleavage reaction (λ<260nm) within a specific light wave range. The reversible photodimerization of coumarin gives coumarin self-healing properties, thereby improving the self-healing properties of the coating.

[0025] Finally, the modified polyurethane, modified boron nitride, and photoinitiator were mixed to prepare a scratch repair coating. The double bonds on the modified polyurethane reacted with the double bonds on the modified boron nitride to form a cross-linked network structure, which improved the mechanical properties of the coating. At the same time, the coumarin group underwent a cycloaddition reaction under the irradiation of ultraviolet light, further improving the mechanical properties of the coating. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. Example 1:

[0027] A method for preparing a scratch repair coating comprises the following steps: (1) Hexagonal boron nitride and acetone were mixed in a mass ratio of 1:15, stirred at 40 ° C, 200 r / min, reacted for 2 h, centrifuged at 1200 rpm for 10 min, and the resulting precipitate was vacuum dried at 75 ° C for 10 h to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95wt% ethanol aqueous solution were mixed in a mass ratio of 1:30, stirred at room temperature, 200 r / min for 20 min, and 8 times the mass of 1-(3-triethoxysilylpropyl)-2-imidazoline was added. The hydroxylated boron nitride was stirred and reacted at 55°C and 200 r / min for 2 hours, and the mixture was centrifuged at a speed of 10000 rpm for 10 minutes. The resulting precipitate was washed twice with anhydrous ethanol and dried in vacuum at 100°C for 10 hours to obtain pre-modified boron nitride; the pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide were mixed uniformly in a mass ratio of 1:0.6:15, stirred and reacted at 60°C and 200 r / min for 2 hours, and N,N-dimethylformamide was removed by vacuum distillation under reduced pressure, and the mixture was dried in vacuum at 50°C for 10 hours to obtain modified boron nitride; (2) Under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:1.2:15, stirred at 0°C and 200 r / min for 20 min, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol (1.5 times the mass of styrylphosphonic acid dichloride) was added, and stirred at 20°C and 200 r / min for 8 h. The triethylamine hydrochloride precipitate was removed by filtration, and tetrahydrofuran was removed by rotary evaporation to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; (3) Under nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide were mixed uniformly in a mass ratio of 1:0.5:0.004:10, stirred at 100°C and 200 r / min for 8 h, cooled to room temperature, and rotary evaporated to remove N,N-dimethylformamide. The product was washed twice with anhydrous ethanol and dried in vacuum at 50°C for 10 h to obtain terminal hydroxycoumarin. (4) Under nitrogen atmosphere, isophorone diisocyanate and hydroxyl-terminated phosphorus-containing fluoropolymer were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.6, dibutyltin dilaurate (0.006 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (15 times the mass of isophorone diisocyanate) were added, and the mixture was stirred at 80°C and 200 r / min for 6 h to obtain a polyurethane prepolymer; under nitrogen atmosphere, polyurethane prepolymer and terminal hydroxyl coumarin were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:1, and the mixture was stirred at 80°C and 200 r / min for 2 h, and N,N-dimethylformamide was removed by reduced pressure distillation, and the mixture was vacuum dried at 60°C for 8 h to obtain a modified polyurethane; (5) The modified polyurethane, modified boron nitride and photoinitiator were mixed evenly in a mass ratio of 1:0.06:0.02, and stirred and dispersed at a speed of 800 r / min for 30 minutes to prepare a scratch repair coating. Example 2:

[0028] A method for preparing a scratch repair coating comprises the following steps: (1) Hexagonal boron nitride and acetone were mixed in a mass ratio of 1:18, stirred at 50 ° C, 250 r / min, reacted for 2.5 hours, centrifuged at 1300 rpm for 11 minutes, and the resulting precipitate was vacuum dried at 80 ° C for 11 hours to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95wt% ethanol aqueous solution were mixed in a mass ratio of 1:40, stirred at room temperature, 250 r / min for 30 minutes, and 9 times the mass of 1-(3-triethoxysilylpropyl)-2-imidazoline was added. The hydroxylated boron nitride was stirred at 60°C and 250 r / min for 2.5 hours, centrifuged at 11000 rpm for 11 minutes, and the resulting precipitate was washed three times with anhydrous ethanol and dried in vacuum at 110°C for 11 hours to obtain pre-modified boron nitride; the pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide were uniformly mixed in a mass ratio of 1:0.7:18, stirred at 65°C and 250 r / min for 3 hours, N,N-dimethylformamide was removed by distillation under reduced pressure, and the modified boron nitride was obtained by vacuum drying at 55°C for 11 hours; (2) Under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:1.3:18, stirred at 2°C and 250 r / min for 30 min, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol (1.8 times the mass of styrylphosphonic acid dichloride) was added, and stirred at 25°C and 250 r / min for 9 h. The triethylamine hydrochloride precipitate was removed by filtration, and tetrahydrofuran was removed by rotary evaporation to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; (3) Under nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide were mixed uniformly in a mass ratio of 1:0.55:0.005:11, stirred at 110°C and 250 r / min for 9 h, cooled to room temperature, and rotary evaporated to remove N,N-dimethylformamide. The mixture was washed with anhydrous ethanol three times and vacuum dried at 55°C for 11 h to obtain terminal hydroxycoumarin. (4) Under nitrogen atmosphere, isophorone diisocyanate and hydroxyl-terminated phosphorus-containing fluoropolymer were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.65, dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) were added, and the mixture was stirred at 85°C and 250 r / min for 7 h to obtain a polyurethane prepolymer; under nitrogen atmosphere, polyurethane prepolymer and terminal hydroxyl coumarin were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:1.01, and the mixture was stirred at 85°C and 250 r / min for 2.5 h, and N,N-dimethylformamide was removed by reduced pressure distillation, and the mixture was vacuum dried at 65°C for 9 h to obtain a modified polyurethane; (5) The modified polyurethane, modified boron nitride, and photoinitiator were mixed evenly in a mass ratio of 1:0.07:0.03, and stirred and dispersed at a speed of 900 r / min for 40 minutes to prepare a scratch repair coating. Example 3:

[0029] A method for preparing a scratch repair coating comprises the following steps: (1) Hexagonal boron nitride and acetone were mixed in a mass ratio of 1:20, stirred at 60 ° C, 300 r / min for 3 h, centrifuged at 1400 rpm for 12 min, and the resulting precipitate was vacuum dried at 85 ° C for 12 h to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95wt% ethanol aqueous solution were mixed in a mass ratio of 1:50, stirred at room temperature, 300 r / min for 40 min, and 10wt% 1-(3-triethoxysilylpropyl)-2-imidazoline was added. times of hydroxylated boron nitride, stirred and reacted at 65°C, 300 r / min for 3 hours, centrifuged at 12000 rpm for 12 minutes, washed the obtained precipitate with anhydrous ethanol 4 times, and dried in vacuum at 120°C for 12 hours to obtain pre-modified boron nitride; pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide were uniformly mixed in a mass ratio of 1:0.8:20, stirred and reacted at 70°C, 300 r / min for 4 hours, N,N-dimethylformamide was removed by reduced pressure distillation, and vacuum dried at 60°C for 12 hours to obtain modified boron nitride; (2) Under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine, and tetrahydrofuran were mixed in a mass ratio of 1:1.4:20, stirred at 4°C and 300 r / min for 40 min, and 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol (2 times the mass of styrylphosphonic acid dichloride) was added, and stirred at 30°C and 300 r / min for 10 h. The triethylamine hydrochloride precipitate was removed by filtration, and tetrahydrofuran was removed by rotary evaporation to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; (3) Under nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide were mixed uniformly in a mass ratio of 1:0.6:0.006:12, stirred at 120°C and 300 r / min for 10 h, cooled to room temperature, and rotary evaporated to remove N,N-dimethylformamide. The product was washed with anhydrous ethanol 4 times and dried in vacuum at 60°C for 12 h to obtain terminal hydroxycoumarin. (4) Under nitrogen atmosphere, isophorone diisocyanate and hydroxyl-terminated phosphorus-containing fluoropolymer were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:0.7, dibutyltin dilaurate (0.008 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (20 times the mass of isophorone diisocyanate) were added, and the mixture was stirred at 90°C and 300 r / min for 8 h to obtain a polyurethane prepolymer; under nitrogen atmosphere, polyurethane prepolymer and terminal hydroxyl coumarin were mixed evenly at a molar ratio of isocyanate group to hydroxyl group of 1:1.02, and the mixture was stirred at 90°C and 300 r / min for 3 h, and N,N-dimethylformamide was removed by reduced pressure distillation, and the mixture was vacuum dried at 70°C for 10 h to obtain a modified polyurethane; (5) The modified polyurethane, modified boron nitride and photoinitiator were mixed evenly in a mass ratio of 1:0.08:0.04, and stirred and dispersed at a speed of 1000 r / min for 50 minutes to prepare a scratch repair coating.

[0030] Comparative Example 1: The preparation method of the scratch repair coating of Comparative Example 1 is different from that of Example 2 in that step (1) is different. Step (1) is modified as follows: hexagonal boron nitride and acetone are uniformly mixed in a mass ratio of 1:18, stirred at 50°C and 250r / min for 2.5h, centrifuged at a speed of 1300rpm for 11min, and the obtained precipitate is vacuum dried at 80°C for 11h to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline, A 95 wt % ethanol aqueous solution was uniformly mixed at a mass ratio of 1:40, stirred at 250 rpm at room temperature for 30 minutes, and hydroxylated boron nitride (9 times the mass of 1-(3-triethoxysilylpropyl)-2-imidazoline) was added. The mixture was stirred at 60°C and 250 rpm for 2.5 hours, and centrifuged at 11,000 rpm for 11 minutes. The resulting precipitate was washed three times with anhydrous ethanol and dried in vacuo at 110°C for 11 hours to produce modified boron nitride. The remaining steps were the same as in Example 2.

[0031] Comparative Example 2: The preparation method of the scratch repair coating of Comparative Example 2 differs from that of Example 2 in that step (1) is omitted and step (5) is modified as follows: the modified polyurethane and the photoinitiator are uniformly mixed in a mass ratio of 1:0.03, and the mixture is stirred and dispersed at a speed of 900 r / min for 40 min to prepare the scratch repair coating. The remaining steps are the same as those of Example 2.

[0032] Comparative Example 3: The preparation method of the scratch repair coating of Comparative Example 3 differs from that of Example 2 in that step (2) is omitted and step (4) is modified as follows: under a nitrogen atmosphere, isophorone diisocyanate and polytetramethylene glycol are uniformly mixed at a molar ratio of isocyanate group to hydroxyl group of 1:0.65, dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) are added, and the mixture is stirred at 85°C and 250 r / min for 7 hours to obtain a polyurethane prepolymer; under a nitrogen atmosphere, the polyurethane prepolymer and terminal hydroxyl coumarin are uniformly mixed at a molar ratio of isocyanate group to hydroxyl group of 1:1.01, and the mixture is stirred at 85°C and 250 r / min for 2.5 hours, N,N-dimethylformamide is removed by reduced pressure distillation, and the mixture is vacuum dried at 65°C for 9 hours to obtain a modified polyurethane. The remaining steps are the same as those of Example 2.

[0033] Comparative Example 4: The preparation method of the scratch repair coating of Comparative Example 4 differs from that of Example 2 in that step (3) is omitted and step (4) is modified as follows: under a nitrogen atmosphere, isophorone diisocyanate and a hydroxyl-terminated phosphorus-containing fluoropolymer are uniformly mixed at a molar ratio of isocyanate group to hydroxyl group of 1:0.65, dibutyltin dilaurate (0.007 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (18 times the mass of isophorone diisocyanate) are added, and the mixture is stirred at 85°C and 250 r / min for 7 hours to obtain a polyurethane prepolymer; under a nitrogen atmosphere, the polyurethane prepolymer and 1,3-propylene glycol are uniformly mixed at a molar ratio of isocyanate group to hydroxyl group of 1:1.01, and the mixture is stirred at 85°C and 250 r / min for 2.5 hours, N,N-dimethylformamide is removed by reduced pressure distillation, and the mixture is vacuum dried at 65°C for 9 hours to obtain a modified polyurethane. The remaining steps are the same as those of Example 2.

[0034] Test Example 1: Flame retardant performance test: Preparation of samples: Pour the scratch repair coating prepared in each embodiment and comparative example into a polytetrafluoroethylene mold, cure it in a UV lamp box with a wavelength of 365nm for 15 minutes, open the mold and take it out. Select the mold or cut it according to the relevant standard documents to prepare the scratch repair coating light-cured specimen.

[0035] The light-cured specimens of the scratch repair coatings obtained in the examples and comparative examples were tested for limiting oxygen index according to GB / T2406.2-2009.

[0036] The results are shown in Table 1.

[0037] Table 1

[0038] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 1, it can be found that the scratch repair coating prepared by the present invention has good flame retardant properties.

[0039] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that hexagonal boron nitride is reacted with acetone to prepare hydroxylated boron nitride, which is then reacted with 1-(3-triethoxysilylpropyl)-2-imidazoline to prepare pre-modified boron nitride. Hexagonal boron nitride can promote the formation of a dense carbon layer, thereby reducing heat transfer and diffusion of combustible gases, and plays a role in isolating oxygen, thereby improving the flame retardant properties of the scratch repair coating.

[0040] By comparison, the limiting oxygen index of Examples 1 to 3 is greater than that of Comparative Example 3, indicating that the P-Cl on the styrylphosphonic dichloride reacts with the hydroxyl group on 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to generate a hydroxyl-terminated phosphorus-fluorine block polymer, which serves as the soft segment of the polyurethane. Phosphorus is introduced into the coating, and phosphorus can promote the formation of a carbon layer and block the combustion reaction by capturing free radicals, thereby improving the flame retardant properties of the scratch repair coating.

[0041] Test Example 2: Mechanical properties and self-repair performance tests: Preparation of samples: Pour the scratch repair coating prepared in each embodiment and comparative example into a polytetrafluoroethylene mold, cure it in a UV lamp box with a wavelength of 365nm for 15 minutes, open the mold and take it out. Select the mold or cut it according to the relevant standard documents to prepare the scratch repair coating light-cured specimen.

[0042] Tensile Strength Test Method: 30 mm × 4 mm × 2 mm test specimens of the scratch repair coatings prepared in each example and comparative example were prepared. The tensile strength was tested at room temperature using an AGS-X tensile tester at a speed of 100 mm / min. Three measurements were taken, and the average tensile strength of the specimens was calculated, denoted as M.

[0043] Self-repair performance testing method: Use a blade to cut the light-cured scratch repair coating strips prepared in each example and comparative example in the middle, re-align them to ensure full contact between the cut surfaces, and then heat them in a 60°C constant temperature oven for 1 hour. Irradiate them under a 254nm UV lamp for 5 minutes, followed by irradiation under a 365nm mercury lamp for 120 minutes. The tensile strength of the repaired strips is then measured using an AGS-X tensile tester at a speed of 100mm / min. Three measurements are taken, and the average value is used to obtain the tensile strength of the repaired strips, recorded as N. The self-repair efficiency is calculated as N / M × 100%.

[0044] The results are shown in Table 2.

[0045] Table 2

[0046] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 2, it can be found that the scratch repair coating prepared by the present invention has good mechanical properties and self-repairing properties.

[0047] By comparison, the tensile strength of Examples 1 to 3 is greater than that of Comparative Examples 1 and 3, indicating that the scratch repair coating is prepared by mixing the modified polyurethane, modified boron nitride, and photoinitiator, and the double bonds on the modified polyurethane react with the double bonds on the modified boron nitride to form a cross-linked network structure, thereby improving the mechanical properties of the scratch repair coating.

[0048] By comparison, the tensile strength of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that hexagonal boron nitride is reacted with acetone to prepare hydroxylated boron nitride, which is then reacted with 1-(3-triethoxysilylpropyl)-2-imidazoline to prepare pre-modified boron nitride. Hexagonal boron nitride is introduced into the polyurethane matrix due to its unique lamellar structure and large specific surface area, further improving the mechanical properties of the scratch repair coating.

[0049] By comparison, the tensile strengths of Examples 1 to 3 are greater than that of Comparative Example 4, indicating that the coumarin group undergoes a cycloaddition reaction under the irradiation of 365 nm ultraviolet light, thereby improving the mechanical properties of the scratch repair coating.

[0050] By comparison, the self-repair efficiency of Examples 1 to 3 is greater than that of Comparative Example 4, indicating that the aldehyde group on 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde reacts with the amino group on 2-(aminomethyl)-1,3-diol to produce a Schiff base reaction. The generated terminal hydroxy coumarin acts as a chain extender to introduce coumarin functional groups into the polyurethane. The coumarin functional groups can undergo cycloaddition reactions (λ>300nm) or cleavage reactions (λ<260nm) within a specific light wavelength range. The reversible photodimerization of coumarin gives coumarin self-repairing properties, thereby improving the self-repairing performance of the scratch repair coating.

[0051] Test Example 3: Corrosion test: Sample preparation: A Q235 steel substrate (model: Q235, quality grade: B, C≤0.20%, Si≤0.35%, Mn≤1.4%, S≤0.045%, P≤0.045%, 60 mm × 60 mm × 1.5 mm) was polished using 1000-grit sandpaper and ultrasonically cleaned using 99.5% ethanol for 10 minutes. The scratch repair coating prepared in each embodiment and test example was evenly applied to the Q235 steel substrate using a scraper and placed in a UV lamp box with a wavelength of 365 nm for curing for 15 minutes to prepare a sample.

[0052] According to GB / T6458-1986 “Neutral Salt Spray Test for Metal Coverings”, the samples prepared in the examples and comparative examples were subjected to corrosion resistance tests in a salt spray test chamber to test the corrosion resistance duration.

[0053] The results are shown in Table 3.

[0054] Table 3

[0055] From the comparison of the experimental data of Examples 1 to 3 and Comparative Examples 1 to 4 in Table 3, it can be found that the scratch repair coating prepared by the present invention has good anti-corrosion performance.

[0056] By comparison, the corrosion resistance time of Examples 1 to 3 is greater than that of Comparative Example 1, indicating that the pre-modified boron nitride is subjected to a quaternization reaction with 4-chloro-1-butene to obtain modified boron nitride, and the imidazoline group on the pre-modified boron nitride undergoes a quaternization reaction with the chlorine on 4-chloro-1-butene to generate an imidazoline quaternary ammonium salt with anti-corrosion properties, thereby improving the anti-corrosion performance of the scratch repair coating.

[0057] By comparison, the corrosion resistance time of Examples 1 to 3 is greater than that of Comparative Example 2, indicating that hexagonal boron nitride is reacted with acetone to obtain hydroxylated boron nitride, which is then reacted with 1-(3-triethoxysilylpropyl)-2-imidazoline to obtain pre-modified boron nitride. Hexagonal boron nitride has excellent anti-penetration properties and can effectively prevent corrosive media from entering the interior of the coating, further improving the anti-corrosion performance of the scratch repair coating.

[0058] By comparison, the corrosion resistance time of Examples 1 to 3 is longer than that of Comparative Example 3, which shows that the P-Cl on the styrylphosphonic dichloride reacts with the hydroxyl group on 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol to generate a hydroxyl-terminated phosphorus-fluorine block polymer, which serves as the soft segment of the polyurethane. The introduction of fluorine element into the coating improves the hydrophobicity of the material, thereby improving the anti-corrosion performance of the scratch repair coating.

[0059] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A scratch repair coating, characterized in that: The scratch repair coating is prepared by mixing modified polyurethane, modified boron nitride and a photoinitiator; The modified polyurethane is prepared by reacting a polyurethane prepolymer with a terminal hydroxy coumarin; The polyurethane prepolymer is prepared by reacting isophorone diisocyanate with a hydroxyl-terminated phosphorus-containing fluoropolymer; The terminal hydroxy coumarin is prepared by a Schiff base reaction between 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde and 2-(aminomethyl)-1,3-diol; The hydroxyl-terminated phosphorus-containing fluoropolymer is prepared by reacting styrylphosphonic acid dichloride with 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol; The modified boron nitride is prepared by a quaternization reaction between pre-modified boron nitride and 4-chloro-1-butene; The pre-modified boron nitride is prepared by sequentially reacting hexagonal boron nitride with acetone and 1-(3-triethoxysilylpropyl)-2-imidazoline.

2. A method for preparing a scratch repair coating, characterized in that: The method comprises the following preparation steps: (1) Hexagonal boron nitride and acetone are mixed evenly, stirred for reaction, centrifuged, and vacuum dried to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95 wt% ethanol aqueous solution are mixed evenly, hydroxylated boron nitride is added, stirred for reaction, centrifuged, washed, and dried to obtain pre-modified boron nitride; pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide are mixed evenly, stirred for reaction, vacuum distilled, and dried to obtain modified boron nitride; (2) Under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine, and tetrahydrofuran were mixed evenly, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol was added, stirred for reaction, filtered, and rotary evaporated to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer; (3) Under a nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide were mixed evenly, stirred for reaction, cooled to room temperature, rotary evaporated, washed, and dried to obtain terminal hydroxy coumarin; (4) Under a nitrogen atmosphere, isophorone diisocyanate, hydroxyl-terminated phosphorus-containing fluoropolymer, dibutyltin dilaurate, and N,N-dimethylformamide are mixed uniformly, stirred for reaction, and a polyurethane prepolymer is obtained; under a nitrogen atmosphere, a polyurethane prepolymer and terminal hydroxy coumarin are mixed uniformly, stirred for reaction, and subjected to reduced pressure distillation and drying to obtain a modified polyurethane; (5) The modified polyurethane, modified boron nitride and photoinitiator are mixed evenly, stirred and dispersed to prepare a scratch repair coating.

3. The method for preparing a scratch repair coating according to claim 2, wherein: The preparation steps of the modified boron nitride in step (1) are as follows: hexagonal boron nitride and acetone are uniformly mixed in a mass ratio of 1: (15~20), stirred at 40~60℃, 200~300r / min, reacted for 2~3h, centrifuged at a speed of 1200~1400rpm for 10~12min, and the obtained precipitate is vacuum dried at 75~85℃ for 10~12h to obtain hydroxylated boron nitride; 1-(3-triethoxysilylpropyl)-2-imidazoline and 95wt% ethanol aqueous solution are uniformly mixed in a mass ratio of 1: (30~50), stirred at room temperature, 200~300r / min for 20~40min, and 1-(3-triethoxysilylpropyl)-2-imidazoline with a mass of 8~ 10 times of hydroxylated boron nitride is stirred and reacted at 55-65°C and 200-300 r / min for 2-3 hours, and centrifuged at a speed of 10000-12000 rpm for 10-12 minutes. The resulting precipitate is washed with anhydrous ethanol 2-4 times and vacuum-dried at 100-120°C for 10-12 hours to obtain pre-modified boron nitride. Pre-modified boron nitride, 4-chloro-1-butene, and N,N-dimethylformamide are uniformly mixed in a mass ratio of 1:(0.6-0.8):(15-20), stirred and reacted at 60-70°C and 200-300 r / min for 2-4 hours, N,N-dimethylformamide is removed by reduced pressure distillation, and vacuum-dried at 50-60°C for 10-12 hours to obtain modified boron nitride.

4. The method for preparing a scratch repair coating according to claim 2, wherein: The preparation steps of the hydroxyl-terminated phosphorus-containing fluoropolymer in step (2) are as follows: under a nitrogen atmosphere, styrylphosphonic acid dichloride, triethylamine and tetrahydrofuran are uniformly mixed in a mass ratio of 1: (1.2~1.4): (15~20), and the mixture is stirred at 0~4°C and 200~300r / min for 20~40min, 4,4,5,5,6,6,7,7,7-nonafluoro-1,2-heptanediol in an amount of 1.5~2 times the mass of styrylphosphonic acid dichloride is added, and the mixture is stirred at 20~30°C and 200~300r / min for 8~10h, the triethylamine hydrochloride precipitate is removed by filtration, and the tetrahydrofuran is removed by rotary evaporation to obtain a hydroxyl-terminated phosphorus-containing fluoropolymer.

5. The method for preparing a scratch repair coating according to claim 2, wherein: The preparation step of the terminal hydroxy coumarin in step (3) is as follows: under a nitrogen atmosphere, 4-methyl-2-oxo-2H-benzopyran-7-carboxaldehyde, 2-(aminomethyl)-1,3-diol, glacial acetic acid, and N,N-dimethylformamide are uniformly mixed in a mass ratio of 1: (0.5~0.6): (0.004~0.006): (10~12), stirred at 100~120°C and 200~300r / min for 8~10h, cooled to room temperature, rotary evaporation to remove N,N-dimethylformamide, washed with anhydrous ethanol 2~4 times, and vacuum dried at 50~60°C for 10~12h to obtain the terminal hydroxy coumarin.

6. The method for preparing a scratch repair coating according to claim 2, wherein: The preparation steps of the modified polyurethane in step (4) are as follows: in a nitrogen atmosphere, isophorone diisocyanate and a hydroxyl-terminated phosphorus-containing fluoropolymer are uniformly mixed according to a molar ratio of isocyanate group to hydroxyl group of 1: (0.6-0.7), dibutyltin dilaurate (0.006-0.008 times the mass of isophorone diisocyanate) and N,N-dimethylformamide (15-20 times the mass of isophorone diisocyanate) are added, and the mixture is heated at 80-90°C for 2 The polyurethane prepolymer was stirred at 00-300 r / min for 6-8 hours to obtain a polyurethane prepolymer; under a nitrogen atmosphere, the polyurethane prepolymer and the terminal hydroxy coumarin were evenly mixed according to the molar ratio of isocyanate group to hydroxyl group of 1: (1-1.02), and the mixture was stirred at 80-90 ° C and 200-300 r / min for 2-3 hours, and N, N-dimethylformamide was removed by vacuum distillation. The mixture was vacuum dried at 60-70 ° C for 8-10 hours to obtain a modified polyurethane.

7. The method for preparing a scratch repair coating according to claim 2, wherein: The preparation steps of the scratch repair coating in step (5) are as follows: the modified polyurethane, the modified boron nitride, and the photoinitiator are uniformly mixed in a mass ratio of 1: (0.06-0.08): (0.02-0.04), and the mixture is stirred and dispersed at a speed of 800-1000 r / min for 30-50 minutes to prepare the scratch repair coating.

8. The method for preparing a scratch repair coating according to claim 2 or 3, characterized in that: The average particle size of the hexagonal boron nitride is 80 nm.

9. The method for preparing a scratch repair coating according to claim 2 or 7, characterized in that: The photoinitiator is 2-hydroxy-2-methyl-1-phenylpropanone.

Images