A stone chip resistant anticorrosive powder coating and a method of preparation

Abstract

The application belongs to the technical field of powder coatings, and specifically provides an anti-stone-impact anticorrosive powder coating and a preparation method. The anti-stone-impact anticorrosive powder coating comprises the following components: polyester resin, epoxy resin E-12, precipitated barium sulfate, titanium white, functional additive, 2-methyl imidazole, leveling agent, benzoin; the functional additive is prepared by compounding palygorskite and modified hyperbranched polyester; the modified hyperbranched polyester is prepared by reacting hydroxamic acid with carboxyl-terminated hyperbranched polyester; and the carboxyl-terminated hyperbranched polyester is prepared by reacting trimethylolpropane with 2,2-dimethylol propionic acid and then reacting with phthalic anhydride. The anti-stone-impact anticorrosive powder coating prepared by the application has good corrosion resistance and impact resistance.

Description

Technical Field

[0001] This application belongs to the field of powder coating technology, and in particular relates to an anti-stone impact and anti-corrosion powder coating and its preparation method. Background Technology

[0002] Powder coatings are widely used in home appliances, building profiles, construction machinery, automotive parts, and steel structure protection due to their characteristics such as being solvent-free, having high utilization rates, being environmentally friendly, and having excellent coating performance. Among them, epoxy resin powder coatings have excellent adhesion, chemical resistance, and corrosion resistance, but poor weather resistance; polyester powder coatings have good weather resistance and decorative properties, but due to the presence of many ester bonds in their molecular chains, their water resistance, alkali resistance, and long-term corrosion resistance are somewhat limited. Therefore, in industry, epoxy resin and polyester resin are commonly compounded to form epoxy-polyester powder coating systems.

[0003] Epoxy-polyester powder coating systems exhibit good adhesion, flexibility, impact strength, and film appearance. However, after curing, these powder coatings inevitably contain free volume and microscopic defects. Corrosive media such as moisture, oxygen, and chloride ions can gradually diffuse to the metal interface along the resin free volume, filler interface, and microcracks, thereby reducing the long-term corrosion resistance of the coating. In addition, under service conditions such as sand and gravel impact, the coating is also prone to developing microcracks and forming channels for corrosive media penetration.

[0004] To address these issues, the addition of sheet-like fillers and inorganic nanoparticles is commonly used to improve the barrier properties of coatings. However, traditional particulate fillers primarily reduce porosity through filling, offering limited control over the diffusion path of corrosive media. While some high aspect ratio sheet materials can improve barrier properties, their high rigidity reduces coating toughness and impact resistance. Furthermore, fillers often exhibit a tendency to agglomerate and insufficient interfacial bonding, making it difficult to simultaneously achieve corrosion resistance, hydrolysis resistance, and stone chip resistance. Summary of the Invention

[0005] To address the aforementioned issues and further improve the stone impact resistance and corrosion resistance of powder coatings, this application provides a stone impact resistant and corrosion resistant powder coating and its preparation method.

[0006] This application first provides an anti-stone chip and anti-corrosion powder coating, comprising the following components by weight: 35-40 parts polyester resin, 25-30 parts epoxy resin E-12, 16-18 parts precipitated barium sulfate, 8-10 parts titanium dioxide, 3-5 parts functional additives, 0.2-0.4 parts 2-methylimidazole, 0.6-0.8 parts leveling agent, and 0.1-0.3 parts benzoin; The functional additive is prepared by combining palygorskite@zirconium α-phosphate with modified hyperbranched polyester; The modified hyperbranched polyester was prepared by reacting isohydroxyoxime acid with carboxyl-terminated hyperbranched polyester. The end-carboxyl hyperbranched polyester is prepared by reacting trimethylolpropane with 2,2-dimethylolpropionic acid and then with phthalic anhydride.

[0007] Furthermore, the preparation method of the functional additive includes the following steps: dispersing and stirring modified hyperbranched polyester with palygorskite@α-zirconium phosphate to obtain the functional additive.

[0008] Furthermore, the preparation method of palygorskite@α-zirconium phosphate includes the following steps: A1, palygorskite is acidified with hydrochloric acid at a certain material-liquid ratio to obtain acidified palygorskite; A2, ZrOCl2·8H2O, NaF, and acidified palygorskite are mixed, and H3PO4 is slowly added dropwise to obtain palygorskite@α-zirconium phosphate through hydrothermal reaction.

[0009] Furthermore, in A1, the ratio of palygorskite to hydrochloric acid solution is 1g: 8-10mL.

[0010] Furthermore, the isohydroxamic acid is 6-aminohexylhydroxamic acid.

[0011] Furthermore, the preparation method of the 6-aminohexylhydroxamic acid includes the following steps: 6-aminohexylhydroxamic acid is obtained by reacting caprolactam with hydroxylamine hydrochloride and then neutralizing with triethylamine.

[0012] Furthermore, the preparation method of the modified hyperbranched polyester includes the following steps: B1, trimethylolpropane and 2,2-dimethylolpropionic acid are reacted with p-toluenesulfonic acid as a catalyst, and then reacted with phthalic anhydride, washed and dried to obtain a carboxyl-terminated hyperbranched polyester; B2, 6-aminohexylhydroxamic acid and the carboxyl-terminated hyperbranched polyester are reacted with the carboxyl-terminated hyperbranched polyester under the catalysis of EDC·HCl and NHS, and the pH is adjusted to obtain the modified hyperbranched polyester.

[0013] Furthermore, in B2, the reaction is adjusted to pH 4-4.5.

[0014] Furthermore, this application provides a method for preparing an anti-stone impact and anti-corrosion powder coating, comprising the following steps: premixing all components by hand in a torque rheometer for melt mixing, cooling to room temperature after mixing, pulverizing by a pulverizer, and sieving to obtain the anti-stone impact and anti-corrosion powder coating.

[0015] Furthermore, the melt mixing temperature is 100-105℃, and the time is 4-6 minutes.

[0016] Compared with the prior art, this application has the following beneficial effects: This application uses palygorskite as a framework, with α-zirconium phosphate lamellars grown on its periphery, forming a stable one-dimensional and two-dimensional heterogeneous structure. This reduces the agglomeration problem of the two-dimensional α-zirconium phosphate lamellars, forms a barrier pathway in the resin, and improves the diffusion resistance of corrosive media. Through the esterification of the amino group of 6-aminohexyl hydroxamic acid with the carboxyl group of the hyperbranched polyester, and the stable coordination of its hydroxamic acid group with the zirconium active sites in α-zirconium phosphate, the hyperbranched organic layer and the inorganic filler palygorskite@α-zirconium phosphate are stably bonded, reducing the interfacial energy between the inorganic filler and the epoxy-polyester resin and improving wetting and dispersibility. Simultaneously, the branched structure of the hyperbranched polymer effectively buffers curing shrinkage stress and external impact forces, alleviates interfacial stress concentration, and improves coating toughness. Through the synergistic effect of these functions, the anti-corrosion and impact resistance of the stone-impact anti-corrosion powder coating are improved. Attached Figure Description

[0017] Figure 1 This is a TEM image of palygorskite@α-zirconium phosphate from Example 3.

[0018] Figure 2 The figures show the cathode stripping test results of Examples 1-3 and Comparative Examples 1-2. Detailed Implementation

[0019] To make the inventive objectives, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. Obviously, the described embodiments are only a portion of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0021] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only” is used, in which case another component may be added.

[0022] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0023] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0024] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0025] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0026] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0027] Example 1 The anti-stone chip and anti-corrosion powder coating in this embodiment comprises the following components by weight: 35g polyester resin, 25g epoxy resin E-12, 18g precipitated barium sulfate, 8g titanium dioxide, 3g functional additives, 0.4g 2-methylimidazole, 0.8g leveling agent, and 0.3g benzoin.

[0028] The preparation method of the anti-stone impact and anti-corrosion powder coating in this embodiment is as follows: After manually premixing each component, the mixture is melt-mixed at 105°C for 4 minutes using a torque rheometer, then discharged, cooled to room temperature, pulverized by a pulverizer, and passed through a 180-mesh standard sieve to obtain the anti-stone impact and anti-corrosion powder coating.

[0029] The preparation method of the functional additive in this embodiment is as follows: Modified hyperbranched polyester and palygorskite@zirconium phosphate are dispersed in 300 mL of mixed solution (DMF:ethanol = 1:1), wherein the molar ratio of hydroxamic acid groups in the modified hyperbranched polyester to Zr sites in palygorskite@zirconium phosphate is 1.5:1. The pH is adjusted to 5.5, and the reaction is carried out at 80 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature, filtered and dried to obtain the functional additive.

[0030] The preparation method of palygorskite@α-zirconium phosphate in this embodiment is as follows: A1. Add palygorskite to hydrochloric acid with a concentration of 1 mol / L, with a material-to-liquid ratio (g: mL) of 1:8. After stirring for 6 hours, wash with deionized water until neutral, centrifuge, dry at 105℃, pulverize, and pass through a 100-mesh sieve to obtain acidified palygorskite. A2, 4.5g ZrOCl2·8H2O, 0.06g NaF, and 5mL H2O were mixed with 8g of acidified palygorskite, and 3.2g H3PO4 was slowly added dropwise. The mixture was sealed in a hydrothermal reactor lined with polytetrafluoroethylene and hydrothermally reacted at 180℃ for 12h. After the reaction was completed, the mixture was washed and dried to obtain palygorskite@α-zirconium phosphate.

[0031] The preparation method of 6-aminohexylhydroxamic acid in this embodiment is as follows: 0.1 mol caprolactam and 0.1 mol hydroxylamine hydrochloride were added to a reactor, followed by 39.8 mL of toluene. The mixture was stirred at 105 °C for 3 h. After the reaction was completed, excess solvent was distilled off, and after cooling, DMF was added to dissolve the solvent. Triethylamine was then added to neutralize the hydrochloride to obtain 6-aminohexylhydroxamic acid.

[0032] The method for preparing the modified hyperbranched polyester in this embodiment is as follows: B1. Weigh 0.2 mol of trimethylolpropane and 0.6 mol of 2,2-dimethylolpropionic acid and add them to a 500 mL round-bottom flask equipped with a mechanical stirrer, thermometer, water separator, and nitrogen inlet. Then add 0.4 g of p-toluenesulfonic acid. Under N2 protection, heat to 140 °C for melt polycondensation and react for 3 h. Then add 1.2 mol of 2,2-dimethylolpropionic acid and 0.8 g of p-toluenesulfonic acid and continue reacting under N2 protection for 3 h. After the reaction is complete, stop the N2 flow and react under reduced pressure for 2 h to obtain a hydroxyl-terminated hyperbranched polyester. Take 30 g of the hydroxyl-terminated hyperbranched polyester and add it to a three-necked flask. Heat to 135 °C and melt completely. Then add 45 g of phthalic anhydride and react for 2 h. After cooling, add acetone to dissolve and then add a large amount of deionized water. Centrifuge to collect the precipitate and dry it under vacuum at 60 °C for 24 h to obtain a carboxyl-terminated hyperbranched polyester.

[0033] B2, 20g of terminal carboxyl hyperbranched polyester (acid value 195.1mgKOH / g) was added to the reactor, 200mL of DMF was added, and after stirring and mixing, EDC·HCl and NHS were added (EDC·HCl: NHS = 1: 1.2) to adjust the pH to 4.5. Then 5g of 6-aminohexylhydroxamic acid was added, and the reaction was carried out at 25°C for 24h. After the reaction was completed, the product was washed and dried to obtain the modified hyperbranched polyester.

[0034] Example 2 The anti-stone chip and anti-corrosion powder coating in this embodiment comprises the following components by weight: 38g polyester resin, 28g epoxy resin E-12, 18g precipitated barium sulfate, 9g titanium dioxide, 4g functional additives, 0.4g 2-methylimidazole, 0.7g leveling agent, and 0.2g benzoin.

[0035] The preparation method of the anti-stone impact and anti-corrosion powder coating in this embodiment is as follows: After manually premixing each component, the mixture is melt-mixed at 100°C for 6 minutes using a torque rheometer, then discharged, cooled to room temperature, pulverized by a pulverizer, and passed through a 180-mesh standard sieve to obtain the anti-stone impact and anti-corrosion powder coating.

[0036] The preparation method of the functional additive in this embodiment is as follows: Modified hyperbranched polyester and palygorskite@zirconium phosphate are dispersed in 300 mL of mixed solution (DMF:ethanol = 1:1), wherein the molar ratio of hydroxamic acid groups in the modified hyperbranched polyester to Zr sites in palygorskite@zirconium phosphate is 1.5:1. The pH is adjusted to 5.5, and the reaction is carried out at 80 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature, filtered and dried to obtain the functional additive.

[0037] The preparation method of palygorskite@α-zirconium phosphate in this embodiment is as follows: A1. Add palygorskite to hydrochloric acid with a concentration of 1 mol / L, with a material-to-liquid ratio (g: mL) of 1:10. After stirring for 6 hours, wash with deionized water until neutral, centrifuge, dry at 105℃, pulverize, and pass through a 100-mesh sieve to obtain acidified palygorskite. A2, 4.5g ZrOCl2·8H2O, 0.06g NaF, and 5mL H2O were mixed with 8g of acidified palygorskite, and 3.2g H3PO4 was slowly added dropwise. The mixture was sealed in a hydrothermal reactor lined with polytetrafluoroethylene and hydrothermally reacted at 180℃ for 12h. After the reaction was completed, the mixture was washed and dried to obtain palygorskite@α-zirconium phosphate.

[0038] The preparation method of 6-aminohexylhydroxamic acid in this embodiment is as follows: 0.1 mol caprolactam and 0.1 mol hydroxylamine hydrochloride were added to a reactor, followed by 39.8 mL of toluene. The mixture was stirred at 105 °C for 3 h. After the reaction was completed, excess solvent was distilled off, and after cooling, DMF was added to dissolve the solvent. Triethylamine was then added to neutralize the hydrochloride to obtain 6-aminohexylhydroxamic acid.

[0039] The method for preparing the modified hyperbranched polyester in this embodiment is as follows: B1. Weigh 0.2 mol of trimethylolpropane and 0.6 mol of 2,2-dimethylolpropionic acid and add them to a 500 mL round-bottom flask equipped with a mechanical stirrer, thermometer, water separator, and nitrogen inlet. Then add 0.4 g of p-toluenesulfonic acid. Under N2 protection, heat to 140 °C for melt polycondensation and react for 3 h. Then add 1.2 mol of 2,2-dimethylolpropionic acid and 0.8 g of p-toluenesulfonic acid and continue reacting under N2 protection for 3 h. After the reaction is complete, stop the N2 flow and react under reduced pressure for 2 h to obtain a hydroxyl-terminated hyperbranched polyester. Take 30 g of the hydroxyl-terminated hyperbranched polyester and add it to a three-necked flask. Heat to 135 °C and melt completely. Then add 45 g of phthalic anhydride and react for 2 h. After cooling, add acetone to dissolve and then add a large amount of deionized water. Centrifuge to collect the precipitate and dry it under vacuum at 60 °C for 24 h to obtain a carboxyl-terminated hyperbranched polyester.

[0040] B2. Take 20g of carboxyl-terminated hyperbranched polyester (acid value 195.1mgKOH / g) and add it to the reactor. Add 200mL of DMF, stir and mix, then add EDC·HCl and NHS (EDC·HCl: NHS = 1: 1.2) to adjust the pH to 4. Then add 5g of 6-aminohexylhydroxamic acid and react at 25°C for 24h. After the reaction is completed, wash and dry to obtain the modified hyperbranched polyester.

[0041] Example 3 The anti-stone chip and anti-corrosion powder coating in this embodiment comprises the following components by weight: 40g polyester resin, 30g epoxy resin E-12, 16g precipitated barium sulfate, 10g titanium dioxide, 5g functional additives, 0.2g 2-methylimidazole, 0.8g leveling agent, and 0.1g benzoin.

[0042] The preparation method of the anti-stone impact and anti-corrosion powder coating in this embodiment is as follows: After manually premixing each component, the mixture is melt-mixed at 100°C for 5 minutes using a torque rheometer, then discharged, cooled to room temperature, pulverized by a pulverizer, and passed through a 180-mesh standard sieve to obtain the anti-stone impact and anti-corrosion powder coating.

[0043] The preparation method of the functional additive in this embodiment is as follows: Modified hyperbranched polyester and palygorskite@zirconium phosphate are dispersed in 300 mL of mixed solution (DMF:ethanol = 1:1), wherein the molar ratio of hydroxamic acid groups in the modified hyperbranched polyester to Zr sites in palygorskite@zirconium phosphate is 1.5:1. The pH is adjusted to 5.5, and the reaction is carried out at 80 °C for 12 h. After the reaction is completed, the mixture is cooled to room temperature, filtered and dried to obtain the functional additive.

[0044] The preparation method of palygorskite@α-zirconium phosphate in this embodiment is as follows: A1. Add palygorskite to hydrochloric acid with a concentration of 1 mol / L, with a material-to-liquid ratio (g: mL) of 1:9. After stirring for 6 hours, wash with deionized water until neutral, centrifuge, dry at 105℃, pulverize, and pass through a 100-mesh sieve to obtain acidified palygorskite. A2, 4.5g ZrOCl2·8H2O, 0.06g NaF, and 5mL H2O were mixed with 8g of acidified palygorskite, and 3.2g H3PO4 was slowly added dropwise. The mixture was sealed in a hydrothermal reactor lined with polytetrafluoroethylene and hydrothermally reacted at 180℃ for 12h. After the reaction was completed, the mixture was washed and dried to obtain palygorskite@α-zirconium phosphate.

[0045] The preparation method of 6-aminohexylhydroxamic acid in this embodiment is as follows: 0.1 mol caprolactam and 0.1 mol hydroxylamine hydrochloride were added to a reactor, followed by 39.8 mL of toluene. The mixture was stirred at 105 °C for 3 h. After the reaction was completed, excess solvent was distilled off, and after cooling, DMF was added to dissolve the solvent. Triethylamine was then added to neutralize the hydrochloride to obtain 6-aminohexylhydroxamic acid.

[0046] The method for preparing the modified hyperbranched polyester in this embodiment is as follows: B1. Weigh 0.2 mol of trimethylolpropane and 0.6 mol of 2,2-dimethylolpropionic acid and add them to a 500 mL round-bottom flask equipped with a mechanical stirrer, thermometer, water separator, and nitrogen inlet. Then add 0.4 g of p-toluenesulfonic acid. Under N2 protection, heat to 140 °C for melt polycondensation and react for 3 h. Then add 1.2 mol of 2,2-dimethylolpropionic acid and 0.8 g of p-toluenesulfonic acid and continue reacting under N2 protection for 3 h. After the reaction is complete, stop the N2 flow and react under reduced pressure for 2 h to obtain a hydroxyl-terminated hyperbranched polyester. Take 30 g of the hydroxyl-terminated hyperbranched polyester and add it to a three-necked flask. Heat to 135 °C and melt completely. Then add 45 g of phthalic anhydride and react for 2 h. After cooling, add acetone to dissolve and then add a large amount of deionized water. Centrifuge to collect the precipitate and dry it under vacuum at 60 °C for 24 h to obtain a carboxyl-terminated hyperbranched polyester.

[0047] B2, 20g of terminal carboxyl hyperbranched polyester (acid value 195.1mgKOH / g) was added to the reactor, 200mL of DMF was added, and after stirring and mixing, EDC·HCl and NHS were added (EDC·HCl: NHS = 1: 1.2) to adjust the pH to 4.5. Then 5g of 6-aminohexylhydroxamic acid was added, and the reaction was carried out at 25°C for 24h. After the reaction was completed, the product was washed and dried to obtain the modified hyperbranched polyester.

[0048] Comparative Example 1 The anti-stone chip corrosion powder coating in this comparative example comprises the following components by weight: 38g polyester resin, 28g epoxy resin E-12, 18g precipitated barium sulfate, 9g titanium dioxide, 2.5g palygorskite@zirconium phosphate, 0.4g 2-methylimidazole, 0.7g leveling agent, and 0.2g benzoin.

[0049] The preparation method of the anti-stone chip corrosion powder coating in this comparative example is the same as that in Example 2.

[0050] The preparation method of palygorskite@α-zirconium phosphate in this comparative example is the same as that in Example 2.

[0051] Comparative Example 2 The anti-stone chip and anti-corrosion powder coating in this comparative example comprises the following components by weight: 38g polyester resin, 28g epoxy resin E-12, 18g precipitated barium sulfate, 9g titanium dioxide, 4g functional additives, 0.4g 2-methylimidazole, 0.7g leveling agent, and 0.2g benzoin.

[0052] The preparation method of the anti-stone chip corrosion powder coating in this comparative example is the same as that in Example 2.

[0053] The functional additive in this comparative example was prepared as follows: 6-aminohexylhydroxamic acid and palygorskite@zirconium phosphate were dispersed in 300 mL of a mixed solution (DMF:ethanol = 1:1), wherein the molar ratio of the hydroxamic acid group in 6-aminohexylhydroxamic acid to the Zr site in palygorskite@zirconium phosphate was 1.5:1. The pH was adjusted to 5.5, and the reaction was carried out at 80 °C for 12 h. After the reaction was completed, the mixture was cooled to room temperature, filtered, and dried to obtain the functional additive.

[0054] The preparation method of palygorskite@α-zirconium phosphate in this comparative example is the same as that in Example 2.

[0055] The preparation method of 6-aminohexylhydroxamic acid in this comparative example is the same as that in Example 2.

[0056] Performance testing Corrosion resistance test: The anti-stone chip corrosion powder coating was electrostatically sprayed onto a Q235 steel plate, and cured at 150℃ for 20 minutes. Cathodic disbondment test: The steel plate was 100×100×6mm, and the coating thickness was 300±50μm. The test was conducted according to the standard SY / T 0315-2013. Water absorption test: The steel plate was 50×50×3mm, and the coating thickness was 500±50μm. The initial mass m0 of the sample was recorded, and then it was placed in a container filled with distilled water and sealed. After soaking at a constant temperature of 80℃ for 28 days, the sample was removed, the surface moisture was wiped off, and its mass m1 was measured. The water absorption rate Wm = (m1 - m0) / m0.

[0057] Impact resistance test: The anti-stone impact and anti-corrosion powder coating was electrostatically sprayed onto a tinplate sheet with dimensions of 120×50×0.2 mm. The curing conditions were 150℃×20min, and the coating thickness was 350±50μm. The test was conducted according to the standard GB / T 1732-2020.

[0058] Adhesion test: The anti-stone chip and anti-corrosion powder coating was electrostatically sprayed onto Q235 steel plate with a size of 100×100×6mm. The curing conditions were 150℃×30min and the coating thickness was 300±50μm. The test was conducted according to the standard GB / T 5210-2006.

[0059] Analyze Examples 1-3 and Comparative Examples 1-2, in conjunction with Table 1 and Figures 1-2 It can be seen that by grafting modified hyperbranched polyester onto the surface of palygorskite@α-zirconium phosphate, an organic-inorganic composite structure was constructed, which improved the dispersibility and interfacial compatibility of palygorskite@α-zirconium phosphate in epoxy-polyester powder coatings, and enhanced the mechanical and anti-corrosion properties of the coating.

[0060] Table 1. Performance test results of anti-stone chip and anti-corrosion powder coatings in Examples 1-3 and Comparative Examples 1-2 Analysis Table 1 and Figure 1 Compared to Examples 1-3, Comparative Example 1 did not use modified hyperbranched polyester, resulting in weakened interfacial compatibility of palygorskite@zirconium phosphate and reduced barrier effect. Consequently, Comparative Example 1 had increased water absorption, increased peel distance, and weakened anti-corrosion performance. Compared to Examples 1-3, Comparative Example 2 was modified with 6-aminohexyl hydroxamic acid but did not add hyperbranched polyester. This improved the compatibility of palygorskite@zirconium phosphate to some extent, but it could not exert the toughening and impact dispersion effects of hyperbranched polyester. Therefore, Comparative Example 2 had reduced impact resistance, decreased adhesion, and weakened mechanical properties.

[0061] analyze Figure 1 The red arrows indicate the palygorskite structure, and the yellow arrows indicate the α-zirconium phosphate structure. It can be seen that the rod-shaped structure of palygorskite is uniformly coated with a layered structure, proving that palygorskite@α-zirconium phosphate was successfully synthesized.

[0062] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A stone chip resistant anticorrosive powder coating, characterized in that, The product comprises the following components by weight: 35-40 parts polyester resin, 25-30 parts epoxy resin E-12, 16-18 parts precipitated barium sulfate, 8-10 parts titanium dioxide, 3-5 parts functional additives, 0.2-0.4 parts 2-methylimidazole, 0.6-0.8 parts leveling agent, and 0.1-0.3 parts benzoin. The functional additive is prepared by combining palygorskite@zirconium α-phosphate with modified hyperbranched polyester; The preparation method of palygorskite@α-zirconium phosphate includes the following steps: A1, palygorskite is acidified with hydrochloric acid at a certain material-liquid ratio to obtain acidified palygorskite; A2, ZrOCl2·8H2O, NaF, and acidified palygorskite are mixed, and H3PO4 is slowly added dropwise to obtain palygorskite@α-zirconium phosphate through hydrothermal reaction. The modified hyperbranched polyester is prepared by reacting isohydroxamic acid with carboxyl-terminated hyperbranched polyester; the isohydroxamic acid is 6-aminohexylhydroxamic acid; The end-carboxyl hyperbranched polyester is prepared by reacting trimethylolpropane with 2,2-dimethylolpropionic acid and then with phthalic anhydride.

2. The anti-stone chip corrosion powder coating according to claim 1, characterized in that, The preparation method of the functional additive includes the following steps: dispersing and stirring modified hyperbranched polyester with palygorskite@α-zirconium phosphate to obtain the functional additive.

3. The anti-stone chip corrosion powder coating according to claim 1, characterized in that, In A1, the ratio of palygorskite to hydrochloric acid solution is 1g: 8-10mL.

4. The anti-stone chip corrosion powder coating according to claim 1, characterized in that, The preparation method of the 6-aminohexylhydroxamic acid includes the following steps: 6-aminohexylhydroxamic acid is obtained by reacting caprolactam with hydroxylamine hydrochloride and then neutralizing with triethylamine.

5. The anti-stone chip corrosion powder coating according to claim 1, characterized in that, The method for preparing the modified hyperbranched polyester includes the following steps: B1, trimethylolpropane and 2,2-dimethylolpropionic acid are reacted with p-toluenesulfonic acid as a catalyst, and then reacted with phthalic anhydride, washed and dried to obtain a carboxyl-terminated hyperbranched polyester; B2, 6-aminohexylhydroxyoxime acid and the carboxyl-terminated hyperbranched polyester are reacted with the carboxyl-terminated hyperbranched polyester under the catalysis of EDC·HCl and NHS, and the pH is adjusted to obtain the modified hyperbranched polyester.

6. The anti-stone chip corrosion powder coating according to claim 5, characterized in that, In the B2 reaction, the pH is adjusted to 4-4.

5.

7. A method for preparing an anti-stone chip corrosion powder coating as described in any one of claims 1-6, characterized in that, The process includes the following steps: all components are premixed by hand and melted in a torque rheometer. After mixing, the mixture is cooled to room temperature, pulverized by a pulverizer, and sieved to obtain an anti-stone chip and anti-corrosion powder coating.

8. The method for preparing an anti-stone chip corrosion powder coating according to claim 7, characterized in that, The melting and mixing temperature is 100-105℃, and the time is 4-6 minutes.

Images