High-performance low-temperature curing powder coating for vehicle surface and preparation method of high-performance low-temperature curing powder coating

Abstract

The invention relates to the technical field of powder coatings, in particular to a high-performance low-temperature curing powder coating for a vehicle surface and a preparation method. The high-performance low-temperature curing powder coating for the vehicle surface comprises the following components in parts by weight: 45-65 parts of carboxyl-terminated polyester resin, 30-45 parts of epoxy resin, 2-5 parts of a curing agent, 0.2-0.5 part of a curing accelerator, 0.5-1.5 parts of a flatting agent, 2-6 parts of an amino-terminated flame retardant and 3-8 parts of modified carbon nanotubes. The high-performance low-temperature curing powder coating for the vehicle surface has excellent ultraviolet aging resistance and flame retardance, can protect the integrity and attractiveness of a coating, and has wide application prospects in the field of automobile coating.

Description

Technical Field

[0001] The invention relates to the technical field of powder coatings, and in particular to a high-performance, low-temperature curing powder coating for vehicle surfaces and a preparation method thereof. Background Art

[0002] With the development of automobile industry technology and the upgrading of consumer demand, vehicle surface coatings not only need to have good decorative and protective properties, but also need to meet higher functional requirements. Especially for new energy vehicles, for the sake of driving safety, their surface coatings must have excellent flame retardant properties to effectively reduce the risk of fire. However, the method of improving the flame retardant properties of coatings by adding flame retardants in the prior art has obvious shortcomings: flame retardants are easy to migrate or even precipitate from the coating system, which not only reduces the durability of the flame retardant effect, but also affects the overall performance of the coating. At the same time, as a means of transportation exposed to the outdoor environment for a long time, the surface coating of the automobile must be able to withstand continuous ultraviolet radiation. This harsh use environment places extremely high demands on the UV aging resistance of the coating. Therefore, it is necessary to improve the powder coating formula to solve the above problems. Summary of the invention

[0003] In order to overcome the shortcomings of the prior art, one of the purposes of the present invention is to provide a high-performance low-temperature curing powder coating for vehicle surfaces. The powder coating has excellent UV aging resistance and flame retardancy, can protect the integrity and aesthetics of the coating, and has broad application prospects in the field of automotive coating.

[0004] The second object of the present invention is to provide a method for preparing a high-performance low-temperature curing powder coating for vehicle surfaces, which has strong operability and is conducive to industrial production.

[0005] One of the purposes of the present invention is achieved by the following technical solution: A high-performance low-temperature curing powder coating for vehicle surface, comprising, by weight: 45-65 parts of carboxyl-terminated polyester resin, 30-45 parts of epoxy resin, 2-5 parts of curing agent, 0.2-0.5 parts of curing accelerator, 0.5-1.5 parts of leveling agent, 2-6 parts of amino-terminated flame retardant, and 3-8 parts of modified carbon nanotubes; the preparation process of the modified carbon nanotubes is as follows: (1) dissolving chrysoprazole, 4-(chloromethyl)benzaldehyde and acid-binding agent A in solvent A, reacting under inert gas, and purifying to obtain an intermediate; (2) Add the amino-modified carbon nanotubes to solvent B, add the intermediate to carry out reflux reaction, and obtain the modified carbon nanotubes by filtering, washing and drying.

[0006] Furthermore, the molar ratio of the chrysoprazole, 4-(chloromethyl)benzaldehyde and the acid-binding agent A is 1:(1-1.5):(1.75-2.25), the concentration of the chrysoprazole in the solvent A is 0.025-0.04 mol / L, the solvent A is N,N-dimethylformamide, and the acid-binding agent A is anhydrous potassium carbonate.

[0007] Furthermore, the mass ratio of the amino carbon nanotubes to the intermediate is 1:2.5-7.0, the concentration of the amino carbon nanotubes in solvent B is 0.015-0.025 g / mL, and the solvent B is chloroform.

[0008] Furthermore, in step (1), the reaction time is 10-12 hours; in step (2), the reflux reaction temperature is 60-65° C., and the reaction time is 2-4 hours.

[0009] Furthermore, the preparation process of the amino-terminated flame retardant is as follows: Diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridine-3-amine and acid-binding agent B are added to solvent C and refluxed to obtain the product.

[0010] Furthermore, the molar ratio of the diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridine-3-amine, and the acid-binding agent B is 1:(2-2.2):(2-3), and the acid-binding agent B is anhydrous potassium carbonate; the concentration of the diphenyldihydroxysilane in the solvent C is 0.2-0.4 mol / L, and the solvent C is N,N-dimethylformamide.

[0011] Furthermore, the reflux reaction temperature is 105-135° C. and the time is 8-10 h.

[0012] Furthermore, the acid value of the terminal carboxyl polyester resin is 40-60 mgKOH / g; the epoxy resin is bisphenol A epoxy resin or phenolic epoxy resin; the curing agent is dicyandiamide; the curing accelerator is at least one of 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, heptadecylimidazole, and isopropylimidazole; and the leveling agent is isophorone or diacetone alcohol.

[0013] The second object of the present invention is achieved by adopting the following technical solution: The method for preparing the above-mentioned high-performance low-temperature curing powder coating for vehicle surface comprises the following steps: According to the weight parts, the carboxyl-terminated polyester resin, epoxy resin, curing agent, curing accelerator, leveling agent, amino-terminated flame retardant and modified carbon nanotubes are mixed uniformly, added into a twin-screw extruder for melt extrusion, and then crushed, ground and sieved to obtain a high-performance low-temperature curing powder coating for vehicle surface.

[0014] Furthermore, the extrusion temperature is 95-105°C.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a high-performance low-temperature curing powder coating for vehicle surface, which has excellent UV aging resistance and flame retardancy, can protect the integrity and aesthetics of the coating, and has broad application prospects in the field of automobile painting.

[0016] Specifically, the modified carbon nanotubes added to the coating enhance the coating's anti-ultraviolet aging performance. Carbon nanotubes, with their unique conjugated structure, can efficiently absorb and disperse ultraviolet light energy, playing a good ultraviolet shielding role; at the same time, the active phenolic hydroxyl groups in the golden purple base molecules can effectively quench ultraviolet-induced free radicals and inhibit the occurrence of oxidation reactions. The two work synergistically to construct a multi-level protection system that can reflect and scatter part of the ultraviolet radiation and block oxygen penetration, thereby significantly enhancing the coating's anti-ultraviolet aging performance.

[0017] The high-performance, low-temperature curing powder coating for vehicle surface of the present invention is further added with an amino-terminated flame retardant, which has a flame retardant structure in the middle and is connected to an amino group at each end. The flame retardant structure relies on the silicon-oxygen structure to form a heat-insulating protective layer at high temperature. At the same time, the nitrogen-containing heterocycle decomposes to produce non-flammable gas and promotes carbonization, and realizes dual flame retardancy in gas phase and condensed phase through the silicon-nitrogen synergistic effect. The two amino groups at both ends can react with the carboxyl-terminated polyester resin and the epoxy resin to form a strong chemical bond, so that it can be firmly bonded in the coating system. It is not easy to migrate or precipitate in the coating after long-term use, which affects the coating performance.

[0018] 2. The amino groups at both ends of the amino-terminated flame retardant added to the high-performance low-temperature curing powder coating for the vehicle surface of the present invention can not only firmly bond the flame retardant structure in the system, but also act as a curing agent, thereby reducing the amount of curing agent used.

[0019] 3. The present invention also provides a method for preparing a high-performance low-temperature curing powder coating for vehicle surface, which has strong operability and is conducive to industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the modified carbon nanotubes of the present invention. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, under the premise of no conflict, the embodiments described below or the technical features can be arbitrarily combined to form new embodiments. The specific conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used, unless otherwise specified, are conventional products obtained through commercial channels.

[0022] The aminated carbon nanotubes of the present invention are aminated multi-walled carbon nanotubes with a purity greater than 95%, a pH value greater than 7, and -NH 2 The content is 0.45wt%, the length is 55µm, the inner diameter is 2-4nm, and the outer diameter is 8-15nm.

[0023] The acid value of the carboxyl-terminated polyester resin of the present invention is 40-60 mgKOH / g; the model of the bisphenol A epoxy resin of the present invention is E-20; and the model of the phenolic epoxy resin of the present invention is F44.

[0024] Example 1 A high-performance, low-temperature curing powder coating for a vehicle surface comprises, by weight, 55 parts of a carboxyl-terminated polyester resin, 40 parts of a bisphenol A epoxy resin, 3 parts of dicyandiamide, 0.3 parts of 2,4-dimethylimidazole, 1 part of isophorone, 4 parts of an amino-terminated flame retardant, and 5 parts of modified carbon nanotubes.

[0025] The preparation process of modified carbon nanotubes is as follows: (1) Chrysopridine, 4-(chloromethyl)benzaldehyde and anhydrous potassium carbonate were added to N,N-dimethylformamide in a molar ratio of 1:1.2:2 to fully dissolve, wherein the concentration of chrysopridine in N,N-dimethylformamide was 0.03 mol / L; under nitrogen protection, the reaction was stirred at room temperature for 11 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure and purified by column chromatography (chloroform / methanol, volume ratio 30:1) to obtain an intermediate (yield 61.3%); the intermediate 1 HNMR: (C 22 H 14 O 7 , 400MHz, DMSO-d6) δ: 5.85 (s, H), 6.71 (s, H), 7.0-7.02 (d, 2H), 7.35-7.37 (d, 2H), 7. 60-7.62 (d, 2H), 8.01-8.03 (d, 2H), 8.73 (s, H), 9.48 (s, H), 9.89 (s, H), 19.98 (s, H). MS (ESI) m / z=390.07 [M].

[0026] (2) Ultrasonic dispersion of the amino carbon nanotubes in chloroform, adding the intermediate, wherein the mass ratio of the amino carbon nanotubes to the intermediate is 1:5, and the concentration of the amino carbon nanotubes in chloroform is 0.02 g / mL; react at 62 °C under reflux conditions for 3 h, filter to obtain a solid product, wash with deionized water, and vacuum dry to obtain modified carbon nanotubes.

[0027] The preparation process of the amino-terminated flame retardant is as follows: Diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridin-3-amine and anhydrous potassium carbonate were added into N,N-dimethylformamide in a molar ratio of 1:2.1:2.5 to fully dissolve, wherein the concentration of diphenyldihydroxysilane in N,N-dimethylformamide was 0.3 mol / L; after reacting at 125°C for 9 h under nitrogen protection, the reaction solution was filtered, and then the filtrate was subjected to reduced pressure distillation to remove the solvent, the remaining product was added to a 5 wt% hydrochloric acid solution for precipitation, and a solid product was obtained by filtration, and the filtrate was washed with deionized water until the filtrate was neutral, and then vacuum dried to obtain an amino-terminated flame retardant (yield 74.6%); 1 HNMR: (C 26 H 22 N 6 O 2 Si, 400MHz, DMSO-d6) δ: 5.82 (s, 4H), 6.86 (s, 2H), 7.04-7.08 (d, 2H), 7.35-7.40 (m, 6H), 7.44-7.48 (m, 4H), 7.50 (s, 2H), 9.50 (s, 2H). MS (ESI) m / z=478.16[M].

[0028] This embodiment also provides a method for preparing a high-performance low-temperature curing powder coating for a vehicle surface, comprising the following steps: According to the above weight parts, the carboxyl-terminated polyester resin, bisphenol A epoxy resin, dicyandiamide, 2,4-dimethylimidazole, isophorone, amino-terminated flame retardant and modified carbon nanotubes are mixed uniformly, added into a twin-screw extruder for melt extrusion, and the extrusion temperature is controlled at 100° C. After extrusion, it is crushed and ground, and then passed through a 150-mesh sieve to obtain a high-performance low-temperature curing powder coating for vehicle surface.

[0029] Example 2 A high-performance, low-temperature curing powder coating for a vehicle surface comprises, by weight, 45 parts of a carboxyl-terminated polyester resin, 30 parts of a phenolic epoxy resin, 2 parts of dicyandiamide, 0.2 parts of 2-ethyl-4-methylimidazole, 0.5 parts of diacetone alcohol, 2 parts of an amino-terminated flame retardant, and 3 parts of modified carbon nanotubes.

[0030] The preparation process of modified carbon nanotubes is as follows: (1) Chrysopurine, 4-(chloromethyl)benzaldehyde and anhydrous potassium carbonate were added to N,N-dimethylformamide in a molar ratio of 1:1:1.75 to fully dissolve, wherein the concentration of chrysopurine in N,N-dimethylformamide was 0.03 mol / L; under nitrogen protection, the reaction was stirred at room temperature for 10 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure and purified by column chromatography (chloroform / methanol, volume ratio 30:1) to obtain an intermediate (yield 60.7%); the intermediate 1 The results of HNMR and MS are the same as those of Example 1; (2) Ultrasonic dispersion of the amino carbon nanotubes in chloroform, adding the intermediate, wherein the mass ratio of the amino carbon nanotubes to the intermediate is 1:2.5, and the concentration of the amino carbon nanotubes in chloroform is 0.02 g / mL; react at 60 ° C under reflux conditions for 4 hours, filter to obtain a solid product, wash with deionized water, and vacuum dry to obtain modified carbon nanotubes.

[0031] The preparation process of the amino-terminated flame retardant is as follows: Diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridin-3-amine and anhydrous potassium carbonate were added to N,N-dimethylformamide in a molar ratio of 1:2:2 to fully dissolve, wherein the concentration of diphenyldihydroxysilane in N,N-dimethylformamide was 0.3 mol / L; under nitrogen protection, after reacting at 105°C for 10 h, the reaction solution was filtered, and then the filtrate was subjected to reduced pressure distillation to remove the solvent, the remaining product was added to a 5 wt% hydrochloric acid solution for precipitation, and a solid product was obtained by filtration, and the filtrate was washed with deionized water until the filtrate was neutral, and then vacuum dried to obtain an amino-terminated flame retardant (yield 73.8%); 1 The results of HNMR and MS were the same as those in Example 1.

[0032] This embodiment also provides a method for preparing a high-performance low-temperature curing powder coating for a vehicle surface, comprising the following steps: According to the above weight parts, the carboxyl-terminated polyester resin, phenolic epoxy resin, dicyandiamide, 2-ethyl-4-methylimidazole, diacetone alcohol, amino-terminated flame retardant and modified carbon nanotubes are mixed uniformly, added into a twin-screw extruder for melt extrusion, and the extrusion temperature is controlled at 95° C. After extrusion, it is crushed and ground, and then passed through a 150-mesh sieve to obtain a high-performance low-temperature curing powder coating for vehicle surface.

[0033] Example 3 A high-performance, low-temperature curing powder coating for a vehicle surface comprises, by weight, 65 parts of a carboxyl-terminated polyester resin, 45 parts of a bisphenol A epoxy resin, 5 parts of dicyandiamide, 0.5 parts of 2,4-dimethylimidazole, 1.5 parts of isophorone, 6 parts of an amino-terminated flame retardant, and 8 parts of modified carbon nanotubes.

[0034] The preparation process of modified carbon nanotubes is as follows: (1) Chrysopurine, 4-(chloromethyl)benzaldehyde and anhydrous potassium carbonate were added to N,N-dimethylformamide in a molar ratio of 1:1.5:2.25 to fully dissolve, wherein the concentration of chrysopurine in N,N-dimethylformamide was 0.03 mol / L; under nitrogen protection, the reaction was stirred at room temperature for 12 h. After the reaction was completed, the reaction solution was concentrated under reduced pressure and purified by column chromatography (chloroform / methanol, volume ratio 30:1) to obtain an intermediate (yield 61.0%); the intermediate 1 The results of HNMR and MS are the same as those of Example 1; (2) Ultrasonic dispersion of the amino carbon nanotubes in chloroform, adding the intermediate, wherein the mass ratio of the amino carbon nanotubes to the intermediate is 1:7.0, and the concentration of the amino carbon nanotubes in chloroform is 0.02 g / mL; react at 65 °C under reflux conditions for 2 h, filter to obtain a solid product, wash with deionized water, and vacuum dry to obtain modified carbon nanotubes.

[0035] The preparation process of the amino-terminated flame retardant is as follows: Diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridine-3-amine and anhydrous potassium carbonate were added into N,N-dimethylformamide in a molar ratio of 1:2.2:3 to fully dissolve, wherein the concentration of diphenyldihydroxysilane in N,N-dimethylformamide was 0.3 mol / L; after reacting at 135°C for 8 h under nitrogen protection, the reaction solution was filtered, and then the filtrate was subjected to reduced pressure distillation to remove the solvent, the remaining product was added to a 5 wt% hydrochloric acid solution for precipitation, and a solid product was obtained by filtration, and the filtrate was washed with deionized water until the filtrate was neutral, and then vacuum dried to obtain an amino-terminated flame retardant (yield 74.5%); 1 The results of HNMR and MS were the same as those in Example 1.

[0036] This embodiment also provides a method for preparing a high-performance low-temperature curing powder coating for a vehicle surface, comprising the following steps: According to the above weight parts, the carboxyl-terminated polyester resin, bisphenol A epoxy resin, dicyandiamide, 2,4-dimethylimidazole, isophorone, amino-terminated flame retardant, and modified carbon nanotubes are mixed uniformly, added to a twin-screw extruder for melt extrusion, and the extrusion temperature is controlled at 105° C. After extrusion, it is crushed and ground, and then passed through a 200-mesh sieve to obtain a high-performance low-temperature curing powder coating for vehicle surface.

[0037] Comparative Example 1 This comparative example 1 is substantially the same as the example 1, except that the modified carbon nanotubes are replaced by amino-treated carbon nanotubes.

[0038] Comparative Example 2 This comparative example 2 is substantially the same as the example 1, except that the amino-terminated flame retardant is omitted.

[0039] Test Example 1 The structure of modified carbon nanotubes was characterized by infrared. Figure 1 shown.

[0040] Depend on Figure 1 It can be seen that the infrared spectrum of modified carbon nanotubes is between 3200-3600 cm -1 The characteristic absorption peak of hydroxyl group appears at 1680 cm -1 The characteristic absorption peak of C=O appears at 1564 cm -1 The characteristic absorption peak of the benzene ring skeleton appears at , indicating that the carbon nanotubes have been successfully grafted with goldenrod.

[0041] Test Example 2 The coatings obtained in Examples 1-3 and Comparative Examples 1-2 were electrostatically sprayed on steel plates, and then cured at 120° C. for 30 min to form a coating with a thickness of 60 μm. After standing at room temperature for 20 h, the performance indicators of the coating of the present invention were tested. The specific method is as follows: (1) Adhesion is tested according to the test standard of GB / T 9286-2021.

[0042] (2) The flame retardant properties of the coating were tested according to GB / T2406.2-2009 "Determination of Combustion Behavior of Plastics by Oxygen Index Method" 8.2.3 Method B - Diffusion Ignition Method, using Type I specimens.

[0043] (3) The specific test steps for the UV resistance of the coating of the present invention are as follows: Set the UV light intensity to 200 W / m 2, the temperature is 65℃, and the coating is aged for 2000h in an accelerated UV aging tester. The changes in the coating surface are observed. The glossiness of the coating before and after UV aging is measured with a gloss meter, and the gloss retention rate (%) is recorded. The color difference (ΔE) of the coating before and after UV aging is calculated according to the standard of GB / T11186.3-1898. The above test results are recorded in Table 1.

[0044] Table 1 It can be seen from Table 1 that the coatings formed by the coatings of Examples 1-3 of the present invention have good adhesion, and after being subjected to ultraviolet accelerated aging treatment, there is basically no blistering, cracking, rusting and powdering, the light retention rate is maintained at more than 90%, the color difference (ΔE) is less than 3.0, and the discoloration level is 0. The light retention rate of Comparative Example 1 is reduced to 72%, and the ΔE is 5.8. Its light retention rate is much lower than that of Example 1, and the ΔE is higher than that of Example 1. This is because the modified carbon nanotubes introduced enhance the anti-ultraviolet aging performance of the coating. It is attributed to the unique conjugated structure of carbon nanotubes, which can efficiently absorb and disperse ultraviolet light energy and play a good ultraviolet shielding role; at the same time, the active phenolic hydroxyl group in the golden purple alkaloid molecule can effectively quench ultraviolet-induced free radicals and inhibit the occurrence of oxidation reactions. The two work synergistically to construct a multi-level protection system that can reflect and scatter part of the ultraviolet radiation and block oxygen penetration, thereby significantly enhancing the anti-ultraviolet aging performance of the coating.

[0045] In addition, the coatings formed in Examples 1-3 also have excellent flame retardant properties, with an oxygen index of up to 44.6%. After the amino-terminated flame retardant is omitted in Comparative Example 2, the oxygen index is reduced to 24.3%. This phenomenon may be attributed to the special flame retardant structure of the amino-terminated flame retardant, which relies on the silicon-oxygen structure to form a dense Si-OC thermal insulation protective layer at high temperatures to isolate the transfer of oxygen and heat. At the same time, the nitrogen-containing heterocycle decomposes to produce non-flammable gas and promotes carbonization, and realizes dual flame retardancy in the gas phase and condensed phase through the silicon-nitrogen synergistic effect. The two amino groups at both ends can react with the carboxyl-terminated polyester resin and epoxy resin in the coating to form a strong chemical bond, so that it can be firmly bonded in the coating system. It is not easy to migrate or precipitate in the coating after long-term use, which affects the performance of the coating.

[0046] The above-mentioned embodiments are only preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by technicians in this field on the basis of the present invention shall fall within the scope of protection required by the present invention.

Claims

1. A high-performance low-temperature curing powder coating for vehicle surface, characterized in that: The high-performance low-temperature curing powder coating for vehicle surface comprises, by weight: 45-65 parts of carboxyl-terminated polyester resin, 30-45 parts of epoxy resin, 2-5 parts of curing agent, 0.2-0.5 parts of curing accelerator, 0.5-1.5 parts of leveling agent, 2-6 parts of amino-terminated flame retardant, and 3-8 parts of modified carbon nanotubes; The preparation process of the modified carbon nanotubes is as follows: (1) dissolving chrysoprazole, 4-(chloromethyl)benzaldehyde and acid-binding agent A in solvent A, reacting under inert gas, and purifying to obtain an intermediate; (2) Add the amino-modified carbon nanotubes to solvent B, add the intermediate to carry out reflux reaction, and obtain the modified carbon nanotubes by filtering, washing and drying.

2. The high-performance low-temperature curing powder coating for vehicle surface according to claim 1, characterized in that: The molar ratio of the chrysoprazole, 4-(chloromethyl)benzaldehyde and the acid-binding agent A is 1:(1-1.5):(1.75-2.25), the concentration of the chrysoprazole in the solvent A is 0.025-0.04 mol / L, the solvent A is N,N-dimethylformamide, and the acid-binding agent A is anhydrous potassium carbonate.

3. The high-performance low-temperature curing powder coating for vehicle surface according to claim 1, characterized in that: The mass ratio of the amino carbon nanotubes to the intermediate is 1:2.5-7.0, the concentration of the amino carbon nanotubes in solvent B is 0.015-0.025 g / mL, and the solvent B is chloroform.

4. The high-performance low-temperature curing powder coating for vehicle surface according to claim 1, characterized in that: In step (1), the reaction time is 10-12 hours; in step (2), the reflux reaction temperature is 60-65° C. and the reaction time is 2-4 hours.

5. The high performance low temperature curing powder coating for vehicle surface according to claim 1, characterized in that: The preparation process of the amino-terminated flame retardant is as follows: Diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridine-3-amine and acid-binding agent B are added to solvent C and refluxed to obtain the product.

6. The high-performance low-temperature curing powder coating for vehicle surface according to claim 5, characterized in that: The molar ratio of the diphenyldihydroxysilane, 7-chloro-1H-pyrrolo[2,3-C]pyridine-3-amine and the acid-binding agent B is 1:(2-2.2):(2-3), and the acid-binding agent B is anhydrous potassium carbonate; the concentration of the diphenyldihydroxysilane in the solvent C is 0.2-0.4 mol / L, and the solvent C is N,N-dimethylformamide.

7. The high performance low temperature curing powder coating for vehicle surface according to claim 5, characterized in that: The temperature of the reflux reaction is 105-135° C. and the time is 8-10 h.

8. The high performance low temperature curing powder coating for vehicle surface according to claim 1, characterized in that: The acid value of the carboxyl-terminated polyester resin is 40-60 mgKOH / g; the epoxy resin is bisphenol A epoxy resin or phenolic epoxy resin; the curing agent is dicyandiamide; the curing accelerator is at least one of 2,4-dimethylimidazole, 2-ethyl-4-methylimidazole, heptadecylimidazole, and isopropylimidazole; and the leveling agent is isophorone or diacetone alcohol.

9. The method for preparing a high-performance low-temperature curing powder coating for vehicle surface according to any one of claims 1 to 8, characterized in that: The following steps are involved: According to the weight parts, the carboxyl-terminated polyester resin, epoxy resin, curing agent, curing accelerator, leveling agent, amino-terminated flame retardant and modified carbon nanotubes are mixed uniformly, added into a twin-screw extruder for melt extrusion, and then crushed, ground and sieved to obtain a high-performance low-temperature curing powder coating for vehicle surface.

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