High-toughness super-weather-resistant powder coating for aluminum veneer and preparation method and application thereof

Abstract

The application belongs to the technical field of paint, and particularly relates to high-toughness super-weather-resistant powder coating for aluminum veneer, a preparation method and application thereof. The preparation raw materials of the high-toughness super-weather-resistant powder coating for aluminum veneer include polyester resin, fluorocarbon resin, curing agent and additive. The curing agent includes isocyanuric acid triglycidyl ester and caprolactam blocked isocyanate. The additive includes curing accelerator. The curing accelerator includes organic tin accelerator and imidazole accelerator. The application uses the combination of polyester resin and fluorocarbon resin, and the synergistic effect of the curing accelerator, i.e. isocyanuric acid triglycidyl ester and caprolactam blocked isocyanate, and the organic tin accelerator and imidazole accelerator, so that the coating system can have a fast reaction speed, realize fast curing, and the coating can have good high toughness and super weather resistance, thereby meeting the use requirements of the aluminum veneer.

Description

Technical Field

[0001] This invention belongs to the field of powder coating technology, and specifically relates to a high-toughness and ultra-weather-resistant powder coating for aluminum single-panel, its preparation method and application. Background Technology

[0002] Aluminum single-layer panels are building decoration materials that have undergone pretreatment such as chromating, followed by fluorocarbon paint spraying or roller coating. They can be used for curtain walls, ceilings, etc. Currently, solvent-based or water-based paints are commonly used for coating aluminum single-layer panels, which involves complex and environmentally unfriendly processes. In contrast, powder coating is a simpler and more environmentally friendly process.

[0003] Aluminum single-layer panel coatings require high weather resistance and toughness, demanding both ultra-weather resistance and high toughness. While powder coatings for coil aluminum sheets can meet the hardness, impact, and bending performance requirements of ordinary coil aluminum sheets (0.3-0.8mm thickness), their weather resistance is insufficient for the use of aluminum single-layer panels. Therefore, fluorocarbon resins are often blended with coil-grade polyester resins to achieve a balance between ultra-weather resistance and high toughness. However, fluorocarbon resins and polyester resins have poor compatibility and poor pigment wetting properties, resulting in poor leveling and low gloss after melt extrusion. Furthermore, while adding fluorocarbon resin improves weather resistance, it lacks active groups and has numerous carbon-fluorine bonds, leading to a significant shielding effect and slow coating curing speed, failing to meet the requirements for rapid curing of coil materials. Therefore, a suitable catalyst is needed to improve the coating's reaction rate. The coating formed by fluorocarbon resin powder coatings is less tough than that formed by polyester resin powder coatings. Although the toughness of the polyester resin powder coating for coils is sufficient, its weather resistance does not meet the requirements for aluminum single panels. Furthermore, although increasing the proportion of fluorocarbon resin improves weather resistance, it also reduces flexibility to some extent. Therefore, it is difficult for powder coatings to simultaneously achieve both ultra-weather resistance and high toughness.

[0004] In addition, the common substrate thickness of aluminum single panels is 1.5-3mm. Compared with the coating thickness of coil aluminum sheets (40-60μm), the coating thickness of aluminum single panels has increased (i.e. 60-100μm). The increase in coating thickness and aluminum substrate thickness also increases the toughness requirements of powder coating products, making development more difficult.

[0005] Therefore, it is of great significance to provide a powder coating for aluminum panels that can be cured quickly and has high toughness and ultra-weather resistance. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial solution. Specifically, the present invention provides a high-toughness, ultra-weather-resistant powder coating for aluminum panels, which can achieve rapid curing, and the prepared coating has both good toughness and weather resistance, thus meeting the application requirements of aluminum panels.

[0007] The inventive concept of this invention: The raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum single-panel panels of this invention include polyester resin, fluorocarbon resin, curing agent, and additives; the curing agent includes triglycidyl isocyanate and caprolactam-blocked isocyanate; the additives include curing accelerators; the curing accelerators include organotin accelerators and imidazole accelerators. This invention, through the compounding of polyester resin and fluorocarbon resin, combined with specific combinations of curing agents and curing accelerators, ensures a sufficiently fast reaction rate in the coating system, achieving rapid curing, and giving the coating high toughness and ultra-weather resistance, perfectly meeting the application requirements of aluminum single-panel panels.

[0008] Therefore, a first aspect of the present invention provides a high-toughness, ultra-weather-resistant powder coating for aluminum panels.

[0009] Specifically, the raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum panels include polyester resin, fluorocarbon resin, curing agent, and additives.

[0010] The curing agent includes triglycidyl isocyanurate (TGIC) and caprolactam-blocked isocyanate;

[0011] The additives include curing accelerators;

[0012] The curing accelerators include organotin accelerators and imidazole accelerators.

[0013] Preferably, the polyester resin is a carboxyl-terminated polyester resin, and the acid value of the polyester resin is 25-60 mgKOH / g; more preferably, the acid value of the polyester resin is 30-50 mgKOH / g.

[0014] Preferably, the glass transition temperature of the polyester resin is 40-65°C; more preferably, the TG of the polyester resin is 45-60°C.

[0015] Preferably, the melt high shear viscosity (ICI) of the polyester resin at 200°C is 2500-7000 mPa·s; more preferably, the melt ICI of the polyester resin at 200°C is 3000-6000 mPa·s.

[0016] Specifically, the polyester resin is a roll high-toughness polyester resin.

[0017] Preferably, the high-toughness, ultra-weather-resistant powder coating for aluminum panels further includes fillers, and the raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum panels include 160-280 parts of polyester resin, 10-100 parts of fluorocarbon resin, 15-65 parts of curing agent, 10-150 parts of filler, and 1-20 parts of additives, by weight.

[0018] More preferably, the high-toughness, ultra-weather-resistant powder coating for aluminum panels further includes fillers, and the raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum panels include 180-260 parts of polyester resin, 20-80 parts of fluorocarbon resin, 25-55 parts of curing agent, 20-120 parts of filler, and 2-18 parts of additives, by weight.

[0019] Preferably, the raw materials for preparing the polyester resin include polyols, polyacids, acid hydrolysants, and catalysts.

[0020] Preferably, the raw materials for preparing the polyester resin also include an ultraviolet absorber.

[0021] Preferably, the raw materials for preparing the polyester resin, by mass parts, include 23-60 parts of polyol, 23-65 parts of polyacid, 9-22 parts of acid hydrolysate, 0.9-3.3 parts of catalyst and 0.9-3.3 parts of ultraviolet absorber.

[0022] More preferably, the raw materials for preparing the polyester resin, by weight, include 25-55 parts of polyol, 25-60 parts of polyacid, 10-20 parts of acid hydrolysate, 1-3 parts of catalyst, and 1-3 parts of ultraviolet absorber.

[0023] Preferably, the polyol includes at least one selected from neopentyl glycol, 1,6-hexanediol, trimethylolpropane, trimethylpentanediol, ethylene glycol, 2,2-dimethyl-1,3-propanediol, and 1,4-cyclohexanediethanol.

[0024] Preferably, the polybasic acid includes at least one selected from isophthalic acid, terephthalic acid, adipic acid, succinic acid, trimellitic anhydride, 1,4-cyclohexanedicarboxylic acid, and sebacic acid.

[0025] Preferably, the acid hydrolysate includes at least one of sebacic acid and octadecanoic acid.

[0026] Preferably, the catalyst comprises monobutyltin oxide.

[0027] Preferably, the ultraviolet absorber includes a triazine-based ultraviolet absorber.

[0028] Preferably, the method for preparing the polyester resin includes the following steps:

[0029] (1) Mix the polyol, polyacid and catalyst to carry out the first reaction, then add the acid hydrolysis agent to carry out the second reaction to obtain material A;

[0030] (2) The material A obtained in step (1) is subjected to pre-condensation and vacuum condensation to obtain polyester resin.

[0031] Preferably, step (1) involves mixing polyol, polyacid, catalyst, and ultraviolet absorber under nitrogen protection to carry out a first reaction, and then adding the acid hydrolysate to carry out a second reaction to obtain material A.

[0032] Preferably, in step (1), the temperature of the first reaction is 160-280℃ and the time of the first reaction is 1.5-6.5h; more preferably, in step (1), the temperature of the first reaction is 180-260℃ and the time of the first reaction is 2-6h.

[0033] Preferably, in step (1), the second reaction takes 1.5-5.5 hours; more preferably, in step (1), the second reaction takes 2-5 hours.

[0034] Preferably, the acid value of material A is 40-50 mg KOH / g.

[0035] Preferably, in step (2), the pressure of the prepolymerization is 900-6500 Pa and the prepolymerization time is 0.5-2.5 h; more preferably, in step (2), the pressure of the prepolymerization is 1000-6000 Pa and the prepolymerization time is 1-2 h.

[0036] Preferably, in step (2), the pressure of vacuum polycondensation is 1400-5500 Pa, and the pre-polycondensation time is 0.5-3.5 h; more preferably, in step (2), the pressure of vacuum polycondensation is 1500-5000 Pa, and the pre-polycondensation time is 1-3 h.

[0037] Preferably, in step (2), after vacuum polycondensation, the acid value is measured by sampling, and the acid value is 30-50 mg KOH / g.

[0038] Preferably, after vacuum polycondensation, the material is cooled and discharged, then sliced ​​and crushed to obtain polyester resin.

[0039] Preferably, the fluorocarbon resin includes at least one of trifluorochloroethylene and vinyl ether copolymer (FEVE) and polyvinylidene fluoride (PVDF).

[0040] Preferably, the additives further include at least one of leveling agents, degassing agents, ultraviolet absorbers, antioxidants, wax powders, and toughening agents.

[0041] Preferably, the leveling agent comprises an acrylate polymer; more preferably, the leveling agent is GLP588.

[0042] Preferably, the degassing agent includes at least one of benzoin, polypropylene wax, and stearic acid; more preferably, the degassing agent is benzoin.

[0043] Preferably, the ultraviolet absorber is a benzophenone-based ultraviolet absorber.

[0044] Preferably, the antioxidant includes at least one of organophosphate antioxidants, amine antioxidants, and hindered phenolic antioxidants; more preferably, the antioxidant includes hindered phenolic antioxidants and organophosphate antioxidants.

[0045] Preferably, the wax powder includes at least one of polytetrafluoroethylene wax and polyethylene wax; more preferably, the wax powder is polytetrafluoroethylene wax.

[0046] Preferably, the toughening agent includes at least one of nitrile rubber, polyamide, chlorinated polyethylene, and polybutadiene; more preferably, the toughening agent is polyamide.

[0047] Preferably, the high-toughness, ultra-weather-resistant powder coating for the aluminum single panel also includes pigments.

[0048] Preferably, the raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum panels, by weight, include 160-280 parts of polyester resin, 10-100 parts of fluorocarbon resin, 15-65 parts of curing agent, 10-150 parts of filler, 1-20 parts of additives, and more than 0 parts and less than 10 parts of pigment.

[0049] More preferably, by weight, the raw materials for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum panels include 180-260 parts of polyester resin, 20-80 parts of fluorocarbon resin, 25-55 parts of curing agent, 20-120 parts of filler, 2-18 parts of additives, and 1-8 parts of pigment.

[0050] Preferably, the filler comprises at least one of precipitated barium, calcium carbonate, and matting barium sulfate; more preferably, the filler is matting barium sulfate.

[0051] Preferably, the pigment comprises an inorganic pigment.

[0052] Preferably, the inorganic pigment is at least one of outdoor weather-resistant general-purpose pigments; more preferably, the pigment includes at least one of rutile titanium dioxide, iron oxide red, and iron oxide yellow.

[0053] Preferably, the D of the powder coating 50The particle size is 20-45 μm; more preferably, the D of the powder coating is... 50 The particle size is 35-45μm.

[0054] A second aspect of the present invention provides a method for preparing the high-toughness, ultra-weather-resistant powder coating for aluminum single-panel as described in the first aspect of the present invention.

[0055] Specifically, the preparation method of the high-toughness, ultra-weather-resistant powder coating for aluminum single panels includes the following steps:

[0056] The raw material components are mixed, melt-extruded, and the high-toughness, ultra-weather-resistant powder coating for aluminum panels is obtained.

[0057] Preferably, the melt extrusion is performed using an extruder, wherein the temperature of the first temperature zone of the extruder is 90-110°C and the temperature of the second temperature zone of the extruder is 95-110°C.

[0058] More preferably, the temperature of the first temperature zone of the extruder is 95-105°C, and the temperature of the second temperature zone of the extruder is 100-105°C.

[0059] Preferably, the extruder is a twin-screw extruder.

[0060] A third aspect of the present invention provides an aluminum single-panel.

[0061] Specifically, the aluminum panel includes the coating formed by the high-toughness, ultra-weather-resistant powder coating of the aluminum panel as described in the first aspect of the present invention.

[0062] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0063] (1) By using polyester resin and fluorocarbon resin in combination, and combining specific curing agent combination and curing accelerator combination, the present invention can ensure that the coating system has a fast reaction speed, achieve rapid curing, and make the coating have high toughness and super weather resistance, which can well meet the use requirements of aluminum single panel.

[0064] (2) The high-toughness polyester resin of this invention has a certain weather resistance and is also a fast-curing polyester resin. When used in combination with fluorocarbon resin, it can improve the weather resistance of the coating while ensuring that the coating process is not affected, thus ensuring fast coating and fast curing. In addition, organotin accelerators catalyze the reaction rate of fluorocarbon resin, and imidazole accelerators catalyze the reaction rate of polyester resin. The combined use of the two ensures that the reaction rate of the coating system is fast enough to meet the requirements of the fast coating process for coils.

[0065] (3) The ultraviolet absorber and antioxidant in the additives of this invention are combined, and the hindered phenolic antioxidant and organophosphate antioxidant work synergistically to inhibit the coating aging caused by ultraviolet radiation and the oxidation and yellowing under high temperature environment, so as to ensure the coating is durable and extend the service life of the coating to a certain extent.

[0066] (4) In this invention, a specific thermoplastic resin toughening agent is used. This material is continuously integrated into the main resin network to form a semi-interpenetrating network polymer, which improves the toughness of the aluminum single panel coating and meets the performance requirements of 90° right angle stamping of aluminum single panels with a substrate thickness of 1.5-3mm and a coating thickness of 60-100mm.

[0067] (5) The powder coating in this invention can be cured by infrared light. The process is simple, efficient and low cost. There is no solvent in the entire production and coating process, which is green and environmentally friendly. It can form an ultra-weather-resistant and high-toughness powder coating on aluminum single-panel workpieces, thereby improving the service life of aluminum single-panel workpieces. Detailed Implementation

[0068] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0069] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0070] The raw material composition and dosage of the high-toughness and ultra-weather-resistant powder coatings for aluminum single panels in Examples 1-3 and Comparative Examples 1-7 of this invention are shown in Table 1.

[0071] Table 1: Raw material composition and dosage (parts by mass) of high-toughness, ultra-weather-resistant powder coatings for aluminum single-panel aluminum panels in Examples 1-3 and Comparative Examples 1-7

[0072]

[0073]

[0074] In Table 1, "-" indicates that no addition was made.

[0075] Example 1

[0076] A high-toughness, ultra-weather-resistant powder coating for aluminum single-panel is shown in Table 1, with its raw material composition and dosage.

[0077] A method for preparing a high-toughness, ultra-weather-resistant powder coating for aluminum composite panels includes the following steps:

[0078] (1) Place each raw material component in a mixing tank, mix thoroughly and crush to obtain a mixture;

[0079] (2) The mixture obtained in step (1) is melt-mixed in a twin-screw extruder, uniformly dispersed and extruded. The temperature of zone I of the extruder is 100℃ and the temperature of zone II is 105℃. After being pressed into tablets, cooled and crushed by a tablet press, it is then crushed by a special pulverizer and sieved to obtain a powder coating with a D50 particle size of 35-45μm.

[0080] The method for preparing high-toughness polyester resin for roll materials includes the following steps:

[0081] (1) Under nitrogen protection, 40 parts of neopentyl glycol, 50 parts of isophthalic acid, 3 parts of monobutyltin oxide catalyst, and 3 parts of triazine-based ultraviolet absorber were mixed and esterified. The reaction temperature was 220℃ and the reaction time was 4h. Then, 15 parts of sebacic acid were added as an acid hydrolysate and the reaction was carried out for 3h to obtain the esterified product. The acid value of the esterified product was measured to be 49mgKOH / g.

[0082] (2) Under 3000Pa conditions, the esterified product obtained in step (1) was pre-condensed for 1.5h, and then vacuum-condensed for 2h under 3000Pa vacuum conditions. The product was sampled and tested, and the acid value of the product was measured to be 42mgKOH / g. Then the product was cooled and discharged, sliced ​​and crushed to obtain the high-toughness polyester resin for rolls.

[0083] Example 2

[0084] A high-toughness, ultra-weather-resistant powder coating for aluminum single-panel is shown in Table 1, with its raw material composition and dosage.

[0085] A method for preparing a high-toughness, ultra-weather-resistant powder coating for aluminum composite panels includes the following steps:

[0086] (1) Place each raw material component in a mixing tank, mix thoroughly and crush to obtain a mixture;

[0087] (2) The mixture obtained in step (1) is melt-mixed in a twin-screw extruder, uniformly dispersed and extruded. The temperature of zone I of the extruder is 100℃ and the temperature of zone II is 105℃. After being pressed into tablets, cooled and crushed by a tablet press, it is then crushed by a special pulverizer and sieved to obtain a powder coating with a D50 particle size of 35-45μm.

[0088] The method for preparing high-toughness polyester resin for roll materials includes the following steps:

[0089] (1) Under nitrogen protection, 20 parts of trimethylolpropane, 20 parts of terephthalic acid, 1 part of monobutyltin oxide catalyst, and 1 part of triazine-based ultraviolet absorber were mixed and esterified. The reaction temperature was 220℃ and the reaction time was 4h. Then, 10 parts of octadecanoic acid were added as acid hydrolysate and the reaction was carried out for 3h to obtain the esterified product. The acid value of the esterified product was measured to be 49mgKOH / g.

[0090] (2) Under 3000Pa conditions, the esterified product obtained in step (1) was pre-condensed for 1.5h, and then vacuum-condensed for 2h under 3000Pa vacuum conditions. The product was sampled and tested, and the acid value of the product was measured to be 42mgKOH / g. Then the product was cooled and discharged, sliced ​​and crushed to obtain the high-toughness polyester resin for rolls.

[0091] Example 3

[0092] A high-toughness, ultra-weather-resistant powder coating for aluminum single-panel is shown in Table 1, with its raw material composition and dosage.

[0093] A method for preparing a high-toughness, ultra-weather-resistant powder coating for aluminum composite panels includes the following steps:

[0094] (1) Place each raw material component in a mixing tank, mix thoroughly and crush to obtain a mixture;

[0095] (2) The mixture obtained in step (1) is melt-mixed in a twin-screw extruder, uniformly dispersed and extruded. The temperature of zone I of the extruder is 100℃ and the temperature of zone II is 105℃. After being pressed into tablets, cooled and crushed by a tablet press, it is then crushed by a special pulverizer and sieved to obtain a powder coating with a D50 particle size of 35-45μm.

[0096] The method for preparing high-toughness polyester resin for roll materials includes the following steps:

[0097] (1) Under nitrogen protection, 60 parts of trimethylolpropane, 70 parts of terephthalic acid, 5 parts of monobutyltin oxide catalyst, and 5 parts of triazine-based ultraviolet absorber were mixed and esterified. The reaction temperature was 220℃ and the reaction time was 4h. Then, 25 parts of octadecanoic acid were added as acid hydrolysate and the reaction was carried out for 3h to obtain the esterified product. The acid value of the esterified product was measured to be 49mgKOH / g.

[0098] (2) Under 3000Pa conditions, the esterified product obtained in step (1) was pre-condensed for 1.5h, and then vacuum-condensed for 2h under 3000Pa vacuum conditions. The product was sampled and tested, and the acid value of the product was measured to be 42mgKOH / g. Then the product was cooled and discharged, sliced ​​and crushed to obtain the high-toughness polyester resin for rolls.

[0099] Comparative Example 1

[0100] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses an equal amount of hydroxyalkylamide to replace TGIC, while the rest is the same as Example 1.

[0101] Comparative Example 2

[0102] The only difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses an equal amount of hydroxyalkylamide to replace caprolactam-blocked isocyanate, while the rest is the same as Example 1.

[0103] Comparative Example 3

[0104] The only difference between Comparative Example 3 and Example 1 is that Comparative Example 3 uses an equal amount of imidazole salt accelerator 5-amino-4,5,6,7-tetrahydrobenzimidazole dihydrochloride to replace the 2-methylimidazole accelerator; otherwise, it is the same as Example 1.

[0105] Comparative Example 4

[0106] The only difference between Comparative Example 4 and Example 1 is that Comparative Example 4 uses an equal amount of imidazole salt accelerator 5-amino-4,5,6,7-tetrahydrobenzimidazole dihydrochloride to replace dibutyltin diacetate accelerator, while the rest is the same as Example 1.

[0107] Comparative Example 5

[0108] The only difference between Comparative Example 5 and Example 1 is that Comparative Example 5 uses an equal amount of high-toughness polyester resin to replace the fluorocarbon resin FEVE, and the amount of TGIC is 25 parts. It does not contain caprolactam-blocked isocyanate and dibutyltin diacetate accelerator. Otherwise, it is the same as Example 1.

[0109] Comparative Example 6

[0110] The only difference between Comparative Example 6 and Example 1 is that Comparative Example 6 uses an equal amount of fluorocarbon resin FEVE to replace the high-toughness polyester resin of the roll material, and the amount of caprolactam blocked isocyanate is 60 parts. It does not contain TGIC and 2-methylimidazole accelerator. Otherwise, it is the same as Example 1.

[0111] Comparative Example 7

[0112] Comparative Example 7 is the powder coating of Example 1 in the prior art CN115746678A.

[0113] Performance testing

[0114] A one-coat, one-bake coating process was used to spray the powder coatings prepared in Examples 1-3 and Comparative Examples 1-7 onto aluminum panels, respectively, and cure them at 230°C. The performance of the coatings was then measured, and the test items and methods are as follows:

[0115] Appearance: Evaluated based on visual inspection;

[0116] Pencil hardness: Tested according to GB / T 23443-2009;

[0117] Impact performance: Tested according to GB / T 23443-2009;

[0118] 2000h xenon lamp aging: Tested according to GB / T 23443-2009;

[0119] 90° right-angle stamping: Tested according to GB / T13448-2019;

[0120] Resistance to neutral salt spray: Tested according to GB / T 23443-2009.

[0121] The performance test results of the powder coatings obtained in Examples 1-3 and Comparative Examples 1-7 are shown in Table 2.

[0122] Table 2: Performance test results of the coatings obtained from the powder coatings of Examples 1-3 and Comparative Examples 1-7

[0123]

[0124] In Table 2, "-" indicates that the test was not conducted.

[0125] As can be seen from Table 2, the coating obtained by the powder coating of the present invention has good toughness and weather resistance, and has a fast curing speed, which can meet the coating process requirements of coil powder coating and the coating performance requirements of aluminum single panel.

[0126] Comparative Example 1, which did not contain TGIC in its curing agent, exhibited inferior impact resistance and 90° right-angle punching performance compared to Example 1, meaning its toughness was also inferior. Comparative Example 2, which did not contain caprolactam-blocked isocyanate, also showed inferior impact resistance, 90° right-angle punching performance, and pencil hardness compared to Example 1, meaning its toughness was also inferior. Comparative Examples 1 and 2 demonstrate that both TGIC and blocked isocyanate are indispensable in the curing agent of this invention; their combined use is necessary to achieve a coating that possesses both good weather resistance and good toughness.

[0127] Comparative Example 3 did not contain 2-methylimidazole accelerator, and Comparative Example 4 did not contain dibutyltin diacetate accelerator. This resulted in the coatings of Comparative Examples 3 and 4 exhibiting inferior impact resistance and 90° right-angle punching performance compared to Example 1, meaning their toughness was inferior. Comparative Examples 3 and 4 demonstrate that both 2-methylimidazole accelerator and dibutyltin diacetate accelerator are indispensable in the curing accelerator; their combined use is necessary to achieve a coating with both good weather resistance and good toughness.

[0128] Comparative Example 5, lacking fluorocarbon resin, exhibited inferior impact resistance, pencil hardness, xenon lamp aging performance, 90° right-angle punching performance, and neutral salt spray resistance compared to Example 1; specifically, its toughness and weather resistance were also inferior. Comparative Example 6, lacking polyester resin, resulted in significantly slower curing time, severe appearance defects, and its coating also exhibited inferior impact resistance, 90° right-angle punching performance, and neutral salt spray resistance compared to Example 1; furthermore, its toughness and weather resistance were also inferior. Comparative Examples 5 and 6 demonstrate that the combined action of fluorocarbon resin and polyester resin is necessary for the coating to simultaneously possess good toughness, weather resistance, and rapid curing performance.

[0129] Comparative Example 7 is a coating obtained by powder coating in the prior art, and its xenon lamp aging and neutral salt spray resistance are worse than those of Example 1.

[0130] In summary, this invention, through the combined use of polyester resin and fluorocarbon resin, and the synergistic effect of curing agents triglycidyl isocyanate and caprolactam-blocked isocyanate, and curing accelerators organotin accelerators and imidazole accelerators, can ensure a fast reaction rate of the coating system, achieve rapid curing, and enable the coating to simultaneously possess high toughness and ultra-weather resistance, thus well meeting the application requirements of aluminum single-panel panels.

[0131] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A powder coating, characterized in that, The powder coating is prepared by means of 160-280 parts polyester resin, 10-100 parts fluorocarbon resin, 15-65 parts curing agent, 10-150 parts filler, and 1-20 parts additives, by weight. The curing agent includes triglycidyl isocyanurate and caprolactam-blocked isocyanate; The additives include curing accelerators, and also include at least one of leveling agents, degassing agents, ultraviolet absorbers, antioxidants, wax powders, and toughening agents; The curing accelerator includes organotin accelerators and imidazole accelerators; The polyester resin is a carboxyl-terminated polyester resin, and the acid value of the polyester resin is 25-60 mgKOH / g; The glass transition temperature of the polyester resin is 40-65℃; The high shear viscosity of the polyester resin at 200°C is 2500-7000 mPa·s.

2. The powder coating according to claim 1, characterized in that, The raw materials for preparing the polyester resin include polyols, polyacids, acid hydrolysants, and catalysts.

3. The powder coating according to claim 1, characterized in that, The fluorocarbon resin includes at least one of trifluorochloroethylene and vinyl ether copolymer and polyvinylidene fluoride.

4. The powder coating according to claim 1, characterized in that, The powder coating also includes pigments.

5. The powder coating according to claim 1, characterized in that, The powder coating's D 50 The particle size is 20-45μm.

6. The method for preparing powder coating according to any one of claims 1-5, characterized in that, Includes the following steps: The raw material components are mixed, melt-extruded, and the powder coating is obtained.

7. The preparation method according to claim 6, characterized in that, The melt extrusion is performed using an extruder, wherein the temperature of the first temperature zone of the extruder is 90-110°C and the temperature of the second temperature zone of the extruder is 95-110°C.

8. The preparation method according to claim 6, characterized in that, The method for preparing the polyester resin includes the following steps: (1) Mix polyol, polyacid and catalyst to carry out the first reaction, then add acid hydrolysis agent to carry out the second reaction to obtain material A; (2) The material A obtained in step (1) is subjected to pre-condensation and vacuum condensation to obtain the polyester resin.

9. An aluminum single-layer panel, characterized in that, The coating formed by the powder coating as described in any one of claims 1-5.

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