A high wear-resistant powder coating, its preparation method and application

Abstract

This invention provides a high-wear-resistant powder coating, its preparation method, and its application, relating to the field of coating technology. The high-wear-resistant powder coating of this invention comprises the following raw materials: modified epoxy resin, modified carboxyl-terminated saturated polyester resin, polytetrafluoroethylene wax micropowder, calcined kaolin, titanium dioxide, quartz powder, and additives; wherein, the modified epoxy resin is obtained by first reacting bisphenol A epoxy resin with phytic acid, then adding cinnamic acid and heptanoic acid, and finally neutralizing with amine. The resulting coating exhibits excellent wear resistance and strength, good weather resistance, and will not peel or break after prolonged use, resulting in a long service life.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and in particular to a high wear-resistant powder coating, its preparation method, and its application. Background Technology

[0002] Powder coatings are pure solid coatings that do not contain volatile organic solvents. Their formulations mainly include resins, curing agents, pigments, fillers, and additives. Powder coatings generally contain a main resin, fillers, additives, and pigments, and are typically classified into thermoplastic powder coatings and thermosetting powder coatings. The main resins of thermoplastic powder coatings are generally polyethylene, polyvinyl chloride, polyester, nylon, polyphenylene sulfide, and polyvinyl fluoride, etc. Thermoplastic powder coatings melt and level to form a film when heated, but will remelt at high temperatures. The main resins of thermosetting powder coatings are generally epoxy resin, epoxy-polyester, polyurethane, and acrylic, etc. Thermosetting powder coatings undergo a curing and cross-linking reaction during melting, forming a strong film that will not remelt at high temperatures. Powder coatings are characterized by being solvent-free, pollution-free, recyclable, environmentally friendly, energy-saving, and having high mechanical strength. They are currently widely used in many fields, including building materials, home appliances, electronic products, automobiles, and ship decks.

[0003] As powder coatings become increasingly widely used, consumers are placing higher demands on them. For example, powder coatings are easily subjected to airflow, water flow, and mechanical friction during application, resulting in significant wear and tear that can cause them to lose their original protective or aesthetic functions. Therefore, improving the wear resistance of powder coatings is essential.

[0004] Currently, methods to improve the wear resistance of powder coatings mainly include selecting a base resin with high wear resistance, adding wear-resistant inorganic fillers and additives. However, in practical applications, it is difficult to achieve uniform dispersion of inorganic fillers in the coating, the bonding force between the resin and inorganic fillers is weak, making it difficult to exert their wear-enhancing properties, and they can easily affect other properties of the coating, thus failing to meet market demands.

[0005] Therefore, it is necessary to develop a new type of high wear-resistant powder coating. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies by providing a high-wear-resistant powder coating, its preparation method, and its application. This coating not only has high wear resistance and strength but also excellent weather resistance, effectively preventing the coating from peeling or breaking after long-term use and ensuring a long service life.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A high wear-resistant powder coating comprises the following raw materials: modified epoxy resin, modified carboxyl-terminated saturated polyester resin, polytetrafluoroethylene wax powder, calcined kaolin, titanium dioxide, quartz powder, and additives.

[0009] The modified epoxy resin is obtained by first reacting bisphenol A epoxy resin with phytic acid, then adding cinnamic acid and heptanoic acid, and finally neutralizing with amine.

[0010] This invention uses modified epoxy resin and modified carboxyl-terminated saturated polyester resin as the main resins, and adds polytetrafluoroethylene wax powder and calcined kaolin as functional additives, along with other auxiliary components to prepare powder coatings. The components work synergistically to produce powder coatings that not only have high wear resistance and strength, but also excellent weather resistance, effectively preventing the coating from peeling off and breaking after long-term use, and thus have a long service life.

[0011] Furthermore, in the preparation process of the modified epoxy resin, the amount of phytic acid used is 8-12% of the weight of the bisphenol A epoxy resin; the amount of cinnamic acid used is 10-18% of the weight of the bisphenol A epoxy resin; and the amount of heptanoic acid used is 20-30% of the weight of the bisphenol A epoxy resin.

[0012] Preferably, in the preparation process of the modified epoxy resin, the amount of phytic acid is 10% of the weight of the bisphenol A epoxy resin; the amount of cinnamic acid is 15% of the weight of the bisphenol A epoxy resin; and the amount of heptanoic acid is 26% of the weight of the bisphenol A epoxy resin.

[0013] Preferably, the modified epoxy resin is prepared by the following method:

[0014] Bisphenol A epoxy resin is dissolved in anhydrous ethanol. After complete dissolution, the solution is heated to 70-80°C, phytic acid is added and reacted for 3-4 hours, then cinnamic acid and heptanoic acid are added, the temperature is raised to 190-200°C and the reaction continues for 1.5-2 hours, then the temperature is lowered to 60-70°C, amine is added for neutralization, and finally the solution is dried to obtain the modified epoxy resin.

[0015] More preferably, in the preparation process of the modified epoxy resin, the mass ratio of the bisphenol A epoxy resin to anhydrous ethanol is 0.5-1:1.

[0016] More preferably, in the preparation of the modified epoxy resin, the amine is at least one of triethylamine, N,N-dimethylethanolamine, and ammonia.

[0017] This invention employs a stepwise reaction method. First, the phosphate groups in phytic acid react with epoxy resin to inoculate the epoxy resin with phytic acid. Then, cinnamic acid and heptanoic acid are grafted onto the epoxy resin to complete the modification. The modified epoxy resin introduces a long-chain structure, exhibiting ideal toughness. It can also increase the degree of cross-linking and density of the coating, thereby improving wear resistance and strength. Furthermore, controlling the amount of phytic acid, cinnamic acid, and heptanoic acid, especially the amount of phytic acid and cinnamic acid, can not only further enhance the strength and wear resistance of the coating, reduce the coefficient of friction of the coating surface, and improve slip properties, but also provide good aging resistance and weather resistance, maintaining good covering and protective capabilities even after long-term use.

[0018] Furthermore, the average particle size of the calcined kaolin is 1-2 μm.

[0019] Furthermore, the average particle size of the polytetrafluoroethylene wax micropowder is 2-5 μm.

[0020] Further, the modified carboxyl-terminated saturated polyester resin is prepared by the following method: diatomaceous earth is dispersed in concentrated sulfuric acid, stirred, filtered, and the filter residue is dried and calcined to obtain refined diatomaceous earth powder; bamboo fiber is added to an alkaline solution for activation treatment, washed with water until neutral, and dried to obtain activated bamboo fiber powder; then the activated bamboo fiber powder is added to the carboxyl-terminated saturated polyester resin, a coupling agent is added, the temperature is raised to 60-80℃, and the refined diatomaceous earth powder is added to react, thus obtaining the modified carboxyl-terminated saturated polyester resin.

[0021] Preferably, the mass ratio of diatomaceous earth to concentrated sulfuric acid is 1:1-2; and the mass concentration of the concentrated sulfuric acid is 60-80%.

[0022] Preferably, the calcination temperature is 600-800℃ and the time is 30-40 minutes.

[0023] Preferably, the stirring operation involves stirring at 1000-1500 r / min for 10 minutes, then reducing the speed to 500-600 r / min and continuing to stir for 30-40 minutes, and then repeating the operation once more.

[0024] Preferably, the volume ratio of bamboo fiber to alkaline solution is 1:1.5-2; the alkaline solution is a sodium hydroxide solution with a mass fraction of 5-10%.

[0025] Preferably, the mass ratio of the carboxyl-terminated saturated polyester resin, activated bamboo fiber powder, and refined diatomaceous earth powder is 1:0.3-0.5:0.2-0.4.

[0026] Preferably, the coupling agent is an organosilicon coupling agent selected from silane or titanate coupling agents, including but not limited to at least one of KH550, KH560, KH570, and triisostearoyl titanate isopropyl ester; the amount of the silane coupling agent is 0.5-1% of the weight of the carboxyl-terminated saturated polyester resin.

[0027] Furthermore, the additive is selected from at least one of curing agents, leveling agents, accelerators, antioxidants, and coupling agents.

[0028] Preferably, the curing agent is a substance that can accelerate the curing of powder coating, and the curing agent includes, but is not limited to, at least one of 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, dibutyltin dilaurate, triglycidyl isocyanurate, β-hydroxyalkylamide, and phenolic curing agents; the amount of curing agent added is 0.1-3% of the total weight of powder coating.

[0029] Preferably, the leveling agent enables the coating to form a smooth, uniform film during the drying process, effectively reducing the surface tension of the coating liquid and improving its leveling and uniformity. The leveling agent includes, but is not limited to, at least one of polydimethylsiloxane, polymethylphenylsiloxane, alkyl-modified organosiloxane, end-group modified organosilicon, acrylic resin, urea-formaldehyde resin, and melamine-formaldehyde resin. The amount of the leveling agent added is 0.1-3% of the total weight of the powder coating.

[0030] Preferably, the accelerator comprises, but is not limited to, at least one of methylimidazole, dimethylimidazole, fumed silica, and alumina; the amount of the accelerator added is 0.1-3% of the total weight of the powder coating.

[0031] Preferably, the antioxidant can improve the anti-aging properties and durability of the coating, and the antioxidant can be a phosphite antioxidant, wherein the amount of antioxidant added is 0.5-2% of the total weight of the powder coating.

[0032] Preferably, the coupling agent is a silane coupling agent and / or a titanate coupling agent; the amount of the coupling agent added is 0.1-1% of the total weight of the powder coating.

[0033] Furthermore, pigments can be added to the high-abrasion-resistant powder coating according to customer requirements. These pigments can impart color to the powder coating and simultaneously improve its relevant mechanical properties. The powder coating according to the present invention may include high-temperature resistant metal-based composite pigments. "High-temperature resistant" refers to pigments whose physicochemical properties do not change at 250°C. For example, pigments suitable for use in the powder coating of the present invention may include titanium dioxide, carbon black, copper chromium black, and any mixture thereof; the amount of pigment added is 0.5-10% of the total weight of the powder coating.

[0034] Furthermore, fillers may be added to the high wear-resistant powder coating. Fillers suitable for use in the powder coating of the present invention include, but are not limited to, at least one of mica powder, wollastonite, glass powder, and talc powder; the amount of filler added is 0.5-5% of the total weight of the powder coating.

[0035] Furthermore, the above-mentioned high abrasion-resistant powder coating, by weight, contains the following raw materials: 25-35 parts modified epoxy resin, 28-32 parts modified carboxyl-terminated saturated polyester resin, 5-8 parts polytetrafluoroethylene wax powder, 16-20 parts calcined kaolin, 5-6 parts titanium dioxide, 6-8 parts quartz powder, and 1-4 parts additives.

[0036] Preferably, the above-mentioned high wear-resistant powder coating comprises, by weight, the following raw materials: 32 parts modified epoxy resin, 30 parts modified carboxyl-terminated saturated polyester resin, 7.5 parts polytetrafluoroethylene wax powder, 16.6 parts calcined kaolin, 5.2 parts titanium dioxide, 7 parts quartz powder, and 1.7 parts additives.

[0037] On the other hand, the present invention also provides a method for preparing a high wear-resistant powder coating, comprising the following steps: mixing modified epoxy resin and modified carboxyl-terminated saturated polyester resin to obtain a mixed resin; adding polytetrafluoroethylene wax powder, calcined kaolin, titanium dioxide, quartz powder and additives to the mixed resin under stirring, mixing, extruding, pulverizing and sieving to obtain the high wear-resistant powder coating.

[0038] Furthermore, the stirring rate is 500-800 r / min.

[0039] Furthermore, the sieving refers to passing through a 150-200 mesh sieve.

[0040] Preferably, to further improve the wear resistance of the powder coating, the present invention first adds polytetrafluoroethylene wax micropowder to 5-8 times its weight of isopropanol at room temperature and disperses it evenly. Then, calcined kaolin is added under stirring, dispersed evenly, and then cooled to 5-10°C and kept at that temperature for 20-50 minutes. Then, the temperature is raised to 60-70°C and kept at that temperature for 60-100 minutes, while stirring is maintained during the holding process. Finally, it is dried, pulverized, and then added to the mixed resin. The present invention first treats the polytetrafluoroethylene wax micropowder and calcined kaolin, allowing the polytetrafluoroethylene micropowder to be adsorbed onto the surface of the calcined kaolin. Then, it is added to the resin, which improves the binding with the resin, thereby better exerting the characteristic of enhancing wear resistance. Moreover, compared with directly adding the two materials to the resin, mixing the two materials before adding them to the resin can also improve the weather resistance of the powder coating.

[0041] This invention also provides the application of the above-mentioned high wear-resistant powder coating in the preparation of wear-resistant materials.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] 1. This invention uses modified epoxy resin and modified carboxyl-terminated saturated polyester resin as base resins, and then adds and combines various fillers and additives to prepare powder coatings. The resulting powder coatings, while ensuring the coverage of the coating, also have excellent wear resistance, good toughness and weather resistance, effectively extending the service life and preventing peeling and damage during long-term use.

[0044] 2. This invention adds modified epoxy resin to powder coatings. Compared with unmodified epoxy resin, the addition of modified epoxy resin effectively improves the strength of the coating, also helps to significantly improve the wear resistance of the coating, reduce the coefficient of friction of the coating surface, improve the smoothness, and improve the weather resistance of the coating, thus greatly extending its service life.

[0045] 3. The present invention adds polytetrafluoroethylene wax powder and calcined kaolin to the powder coating, which helps to improve the wear resistance and strength of the material; in addition, mixing the two materials before adding them to the powder coating can also improve the weather resistance of the powder coating.

[0046] 4. This invention is characterized by its simple operation, strong safety, high practicality, and suitability for widespread use. Attached Figure Description

[0047] Figure 1 This is the infrared spectrum of modified epoxy resin; in the figure, A represents unmodified epoxy resin and B represents modified epoxy resin. Detailed Implementation

[0048] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following description is merely an exemplary illustration of the scope of protection of the present invention, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection of the present invention.

[0049] In the following specific embodiments, the modified carboxyl-terminated saturated polyester resin is prepared by the following method:

[0050] (1) Add 1.5 times its weight of concentrated sulfuric acid with a mass fraction of 70% to diatomaceous earth powder, stir and filter. Add 1.5 times its weight of concentrated sulfuric acid with a mass fraction of 80% to diatomaceous earth powder, stir and filter. After drying, calcine at 800℃ for 30 min to obtain refined diatomaceous earth powder. The stirring operation is to stir at 1000 r / min for 10 min, then reduce the speed to 500 r / min and continue stirring for 40 min, and repeat the operation once.

[0051] (2) Add bamboo fiber to a sodium hydroxide aqueous solution with a mass fraction of 8% and a volume of 2 times its weight, stir at 1000 r / min for 1 h, then wash with water until neutral, filter and dry to obtain activated bamboo fiber powder.

[0052] (3) The activated bamboo fiber powder obtained in step (2) is added to the carboxyl-terminated saturated polyester resin. After stirring for 30 minutes under inert gas conditions, 1% of the amount of carboxyl-terminated saturated polyester resin is added, and the temperature is raised to 80°C. Then, diatomaceous earth refined powder is added, and stirring is continued for 2 hours. The mixture is then cooled and discharged to obtain the modified carboxyl-terminated saturated polyester resin. The mass ratio of the carboxyl-terminated saturated polyester resin, activated bamboo fiber powder and diatomaceous earth refined powder is 1:0.5:0.4.

[0053] In this invention, unless otherwise stated, the numerical range “ab” represents a shortened representation of any combination of real numbers between a and b, and is intended to include all subranges thereof. For example, the numerical range “1-10” represents all real numbers between “1-10” listed herein, such as 1.1, 1.2, 1.5, 2…N, where N is a real number, and is intended to include all subranges between the minimum value 1 and the maximum value 10, i.e., a minimum value equal to or greater than 1 and a maximum value equal to or less than 10.

[0054] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0055] Example 1:

[0056] This embodiment provides a method for preparing a high-wear-resistant powder coating, including the following steps:

[0057] 25 kg of modified epoxy resin and 32 kg of modified carboxyl-terminated saturated polyester resin were mixed to obtain a mixed resin. Under stirring, 8 kg of polytetrafluoroethylene wax powder (average particle size 5 μm), 20 kg of calcined kaolin (average particle size 2 μm), 6 kg of titanium dioxide, 8 kg of quartz powder, and 1 kg of additives (0.5 kg of triglycidyl isocyanate and 0.5 kg of polydimethylsiloxane) were added to the mixed resin. After mixing, the mixture was extruded, pulverized, and sieved through a 200-mesh sieve to obtain the high wear-resistant powder coating.

[0058] The modified epoxy resin was prepared by the following method: 25 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 70°C, 2 kg of phytic acid was added and reacted for 4 h, then 2.5 kg of cinnamic acid and 7.5 kg of heptanoic acid were added, the temperature was raised to 190°C and the reaction continued for 2 h, then the temperature was lowered to 60°C, ammonia was added for neutralization, and finally the solution was dried to obtain the modified epoxy resin.

[0059] The infrared spectrum of the modified epoxy resin is as follows: Figure 1 As shown in the figure, curve A represents unmodified epoxy resin, and curve B represents modified epoxy resin. It can be seen that, compared to curve A, curve B has a lower viscosity at 1040 cm⁻¹. -1 A characteristic peak of COP appeared nearby, at 1953 cm⁻¹. -1 The presence of absorption peaks near the C=C double bond indicates that the modified epoxy resin was successfully prepared.

[0060] Example 2

[0061] This embodiment provides another method for preparing a high-wear-resistant powder coating, including the following steps:

[0062] 32 kg of modified epoxy resin and 30 kg of modified carboxyl-terminated saturated polyester resin were mixed to obtain a mixed resin. Under stirring, 7.5 kg of polytetrafluoroethylene wax micro powder (average particle size 2 μm), 16.6 kg of calcined kaolin (average particle size 1 μm), 5.2 kg of titanium dioxide, 7 kg of quartz powder, and 1.7 kg of additives (1 kg of β-hydroxyalkylamide and 0.7 kg of polymethylphenylsiloxane) were added to the mixed resin. After mixing, the mixture was extruded, pulverized, and sieved through a 180-mesh sieve to obtain the high wear-resistant powder coating.

[0063] The modified epoxy resin was prepared by the following method: 32 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, 3.2 kg of phytic acid was added and reacted for 3 h, then 4.8 kg of cinnamic acid and 8.32 kg of heptanoic acid were added, the temperature was raised to 200°C and the reaction continued for 1.5 h, then the temperature was lowered to 70°C, triethylamine was added for neutralization, and finally the solution was dried to obtain the modified epoxy resin.

[0064] Example 3

[0065] This embodiment provides another method for preparing a high-wear-resistant powder coating, including the following steps:

[0066] 35 kg of modified epoxy resin and 28 kg of modified carboxyl-terminated saturated polyester resin were mixed to obtain a mixed resin. Under stirring, 5 kg of polytetrafluoroethylene wax powder (average particle size 2 μm), 16 kg of calcined kaolin (average particle size 1 μm), 5 kg of titanium dioxide, 7 kg of quartz powder, and 4 kg of additives (2 kg of dibutyltin β-dilaurate and 2 kg of polydimethylsiloxane) were added to the mixed resin. After mixing, the mixture was extruded, pulverized, and sieved through a 180-mesh sieve to obtain the high wear-resistant powder coating.

[0067] The modified epoxy resin was prepared by the following method: 35 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, 4.2 kg of phytic acid was added and reacted for 3 h, then 6.3 kg of cinnamic acid and 7 kg of heptanoic acid were added, the temperature was raised to 200°C and the reaction continued for 1.5 h, then the temperature was lowered to 70°C, triethylamine was added for neutralization, and finally the solution was dried to obtain the modified epoxy resin.

[0068] Example 4

[0069] This embodiment provides another method for preparing a high-wear-resistant powder coating, including the following steps:

[0070] 32 kg of modified epoxy resin and 30 kg of modified carboxyl-terminated saturated polyester resin were mixed to obtain a mixed resin. 7.5 kg of polytetrafluoroethylene wax micro powder (average particle size 2 μm) was added to 8 times its weight of isopropanol and dispersed evenly at room temperature. Then, 16.6 kg of calcined kaolin (average particle size 1 μm) was added while stirring. After being evenly dispersed, the mixture was cooled to 5°C and kept at that temperature for 50 min. Then, the temperature was raised to 60°C and kept at that temperature for 100 min, while stirring was maintained during the holding period. Finally, the mixture was dried, pulverized, and then added to the mixed resin and mixed evenly. 5.2 kg of titanium dioxide, 7 kg of quartz powder, and 1.7 kg of additives (1 kg of β-hydroxyalkylamide and 0.7 kg of polymethylphenylsiloxane) were added, mixed evenly, extruded, pulverized, and sieved through a 180-mesh sieve to obtain the high-wear-resistant powder coating.

[0071] The preparation method of the modified epoxy resin is the same as that in Example 2.

[0072] Comparative Example 1

[0073] This comparative example provides another method for preparing a high-wear-resistant powder coating. The difference from Example 2 is that an equal amount of bisphenol A epoxy resin is used to replace the modified epoxy resin in this comparative example.

[0074] Comparative Example 2

[0075] This comparative example provides another method for preparing a high-abrasion-resistant powder coating. The difference from Example 2 is that the modified epoxy resin in this comparative example is prepared by the following method:

[0076] 32 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, and 2 kg of phytic acid was added and reacted for 3 hours. Then, 3 kg of cinnamic acid and 10 kg of heptanoic acid were added, and the temperature was raised to 200°C and the reaction continued for 1.5 hours. The temperature was then lowered to 70°C, and triethylamine was added for neutralization. Finally, the solution was dried to obtain the modified epoxy resin.

[0077] Comparative Example 3

[0078] This comparative example provides another method for preparing a high-abrasion-resistant powder coating. The difference from Example 2 is that the modified epoxy resin in this comparative example is prepared by the following method:

[0079] 32 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, and 4 kg of phytic acid was added and reacted for 3 hours. Then, 6 kg of cinnamic acid and 6 kg of heptanoic acid were added, and the temperature was raised to 200°C and the reaction continued for 1.5 hours. The temperature was then lowered to 70°C, and triethylamine was added for neutralization. Finally, the solution was dried to obtain the modified epoxy resin.

[0080] Comparative Example 4

[0081] This comparative example provides another method for preparing a high-abrasion-resistant powder coating. The difference from Example 2 is that the modified epoxy resin in this comparative example is prepared by the following method:

[0082] 32 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, and 3.2 kg of phytic acid was added and reacted for 3 hours. Then, 8.32 kg of heptanoic acid was added, and the temperature was raised to 200°C and the reaction continued for 1.5 hours. The temperature was then lowered to 70°C, and triethylamine was added for neutralization. Finally, the solution was dried to obtain the modified epoxy resin.

[0083] Comparative Example 5

[0084] This comparative example provides another method for preparing a high-abrasion-resistant powder coating. The difference from Example 2 is that the modified epoxy resin in this comparative example is prepared by the following method:

[0085] 32 kg of bisphenol A epoxy resin was dissolved in anhydrous ethanol at a weight ratio of 0.5:1. After complete dissolution, the solution was heated to 80°C, and 4.8 kg of cinnamic acid and 8.32 kg of heptanoic acid were added. The solution was then heated to 200°C and reacted for 1.5 h. The solution was then cooled to 70°C, and triethylamine was added for neutralization. Finally, the solution was dried to obtain the modified epoxy resin.

[0086] Comparative Example 6

[0087] This comparative example provides another method for preparing a highly wear-resistant powder coating. The difference from Example 2 is that polytetrafluoroethylene wax powder was not added in this comparative example, but the composition remains unchanged.

[0088] Comparative Example 7

[0089] This comparative example provides another method for preparing a highly wear-resistant powder coating. The difference from Example 2 is that calcined kaolin was not added in this comparative example, but its composition remains unchanged.

[0090] Comparative Example 8

[0091] This comparative example provides another method for preparing a high-wear-resistant powder coating, comprising the following steps: 28 kg of epoxy resin and 34 kg of modified carboxyl-terminated saturated polyester resin are mixed evenly, and then 0.5 kg of hydroxyalkylamide, 20 kg of Al2O3, 10 kg of titanium dioxide, 6.5 kg of quartz powder and 1 kg of polymethylphenylsiloxane are added sequentially. The mixture is continued to be mixed at 300 r / min for 50 min, and then extruded, pulverized and passed through a 180-mesh sieve to obtain the coating.

[0092] Experimental Example 1

[0093] The powder coatings obtained in the above examples and comparative examples were subjected to the following tests after electrostatic spraying, with a coating thickness of 70 μm.

[0094] (1) Coating hardness: The coating hardness was tested according to the pencil test method specified in GB / T6739-2006.

[0095] (2) Impact resistance of coating: The test shall be conducted in accordance with the method for determining the impact resistance of coatings as specified in GB / T1732-2020.

[0096] (3) Abrasion resistance: S-33 type sandpaper was used as the friction material. New sandpaper was changed every 100 tests. The test load was 500g, and the coating wear was measured after 200 revolutions.

[0097] (5) Salt spray resistance: The test shall be conducted in accordance with the test method for neutral salt spray resistance of paints and varnishes specified in GB / T1771-2007.

[0098] (6) Humidity test: The test shall be conducted in accordance with the test method for damp heat resistance of paint film specified in GB / T1740-2007.

[0099] (7) Accelerated aging test: The test item is QUV-B test, and the test conditions are 4h of UV light at 50℃ and 4h of water vapor circulation test at 40℃.

[0100] The test results are shown in Tables 1 and 2 below.

[0101] Table 1

[0102] Group Hardness (2H) Impact resistance (kg / cm) Wear amount (mg) Example 1 No scratches 81 85.1 Example 2 No scratches 86 83.0 Example 3 No scratches 82 83.7 Example 4 No scratches 87 80.4 Comparative Example 1 No scratches 70 94.2 Comparative Example 2 No scratches 73 91.6 Comparative Example 3 No scratches 75 90.5 Comparative Example 4 No scratches 74 92.8 Comparative Example 5 No scratches 75 93.0 Comparative Example 6 No scratches 60 99.8 Comparative Example 7 No scratches 65 97.0 Comparative Example 8 No scratches 63 101.7

[0103] As can be seen from the results in Table 1, the powder coating obtained by the present invention forms a smooth and even film. The 2H hardness test shows no scratches, the wear amount is 80-86mg, and it has good wear resistance and high impact strength.

[0104] The wear of the coating obtained in Example 4 was lower than that in Example 2, indicating that the wear resistance of the coating can be further improved by mixing polytetrafluoroethylene wax powder and calcined kaolin and then adding it to the resin.

[0105] The results of Comparative Examples 1 to 5 show that the epoxy resin in Comparative Example 1 was not modified, and the resulting coating had a significantly lower impact strength and a higher wear rate than that in Example 2. The impact resistance and wear resistance of the coatings obtained in Comparative Examples 2 to 5 were also not as good as those in Example 2. It is evident that the modification of epoxy resin helps to improve the strength and wear resistance of the coating.

[0106] The results of Comparative Examples 6 and 7 show that the simultaneous presence of polytetrafluoroethylene wax micropowder and calcined kaolin in powder coatings helps to improve the strength and wear resistance of powder coatings.

[0107] Table 2

[0108] Group Salt spray resistance Humidity test Gloss retention rate (%) after 1000 hours of accelerated aging Example 1 ＞1000h ＞2000h 78.6 Example 2 ＞1000h ＞2200h 81.4 Example 3 ＞1000h ＞2200h 80.3 Example 4 ＞1000h ＞2400h 84.0 Comparative Example 1 ＞800h ＞1500h 68.1 Comparative Example 2 ＞1000h ＞1800h 69.7 Comparative Example 3 ＞1000h ＞2000h 71.4 Comparative Example 4 ＞1000h ＞1800h 70.7 Comparative Example 5 ＞800h ＞1800h 70.1 Comparative Example 6 ＞1000h ＞2000h 70.8 Comparative Example 7 ＞1000h ＞2000h 72.2 Comparative Example 8 ＞600h ＞1400h 67.5

[0109] As can be seen from the results in Table 2, the powder coating obtained by the present invention can still maintain a gloss retention rate of more than 78% after 1000h of accelerated aging (the gloss retention rate in this test refers to the ratio of the gloss of the coating after aging to the gloss before aging). The coating film did not show cracking, blistering or peeling after 1000h of salt spray resistance test and 2000h of humidity test. It can be seen that the powder coating obtained by the present invention has excellent weather resistance and effectively extends its service life.

[0110] The results of humidity test and aging resistance test of the coating obtained in Example 4 are better than those in Example 2. It can be seen that the weather resistance of powder coating can be improved to a certain extent by mixing polytetrafluoroethylene wax powder with calcined kaolin and then adding it to the resin.

[0111] The results of salt spray resistance test, humidity test and accelerated aging test of the powder coating obtained in Comparative Example 1 show that the modification treatment of epoxy resin helps to improve the weather resistance of the powder coating.

[0112] The accelerated aging test results from Comparative Examples 2 to 5 show that the amount of modifier used during epoxy resin modification treatment affects the aging resistance of the coating and its service life.

[0113] The accelerated aging test results of Comparative Examples 6 and 7 show that polytetrafluoroethylene wax micropowder and calcined kaolin have a certain synergistic effect, which helps to improve the aging resistance of powder coatings.

[0114] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A high-wear-resistant powder coating, characterized in that, It contains the following raw materials: modified epoxy resin, modified carboxyl-terminated saturated polyester resin, polytetrafluoroethylene wax powder, calcined kaolin, titanium dioxide, quartz powder, and additives. The modified epoxy resin is obtained by first reacting bisphenol A epoxy resin with phytic acid, then adding cinnamic acid and heptanoic acid, and finally neutralizing with amine. In the preparation process of the modified epoxy resin, the amount of phytic acid used is 8-12% of the weight of the bisphenol A epoxy resin; the amount of cinnamic acid used is 10-18% of the weight of the bisphenol A epoxy resin; and the amount of heptanoic acid used is 20-30% of the weight of the bisphenol A epoxy resin.

2. The high abrasion-resistant powder coating according to claim 1, characterized in that, The amount of phytic acid used is 10% of the weight of bisphenol A epoxy resin; the amount of cinnamic acid used is 15% of the weight of bisphenol A epoxy resin; and the amount of heptanoic acid used is 26% of the weight of bisphenol A epoxy resin.

3. The high abrasion-resistant powder coating according to claim 1, characterized in that, The calcined kaolin has an average particle size of 1-2 μm; the polytetrafluoroethylene wax powder has an average particle size of 2-5 μm.

4. The high abrasion-resistant powder coating according to claim 1, characterized in that, The modified carboxyl-terminated saturated polyester resin is prepared by the following method: diatomaceous earth is dispersed in concentrated sulfuric acid, stirred, filtered, and the filter residue is dried and calcined to obtain refined diatomaceous earth powder; bamboo fiber is added to an alkaline solution for activation treatment, washed with water until neutral, and dried to obtain activated bamboo fiber powder; then the activated bamboo fiber powder is added to the carboxyl-terminated saturated polyester resin, a coupling agent is added, the temperature is raised to 60-80℃, and the refined diatomaceous earth powder is added to react, thus obtaining the modified carboxyl-terminated saturated polyester resin.

5. The high abrasion-resistant powder coating according to any one of claims 1-4, characterized in that, By weight, it contains the following raw materials: 25-35 parts modified epoxy resin, 28-32 parts modified carboxyl-terminated saturated polyester resin, 5-8 parts polytetrafluoroethylene wax powder, 16-20 parts calcined kaolin, 5-6 parts titanium dioxide, 6-8 parts quartz powder, and 1-4 parts additives.

6. The high abrasion-resistant powder coating according to claim 5, characterized in that, By weight, it contains the following raw materials: 32 parts modified epoxy resin, 30 parts modified carboxyl-terminated saturated polyester resin, 7.5 parts polytetrafluoroethylene wax powder, 16.6 parts calcined kaolin, 5.2 parts titanium dioxide, 7 parts quartz powder, and 1.7 parts additives.

7. The method for preparing the high abrasion-resistant powder coating according to any one of claims 1-6, characterized in that, Includes the following steps: Modified epoxy resin and modified carboxyl-terminated saturated polyester resin are mixed to obtain a mixed resin. Under stirring, polytetrafluoroethylene wax powder, calcined kaolin, titanium dioxide, quartz powder and additives are added to the mixed resin, mixed, extruded, crushed and sieved to obtain the high wear-resistant powder coating.

8. The preparation method according to claim 7, characterized in that, The polytetrafluoroethylene wax powder and calcined kaolin are first mixed and then added to the mixed resin. The mixing process is as follows: At room temperature, polytetrafluoroethylene wax micro powder is added to 5-8 times its weight of isopropanol and dispersed evenly. Then, calcined kaolin is added while stirring. After being dispersed evenly, the temperature is lowered to 5-10℃ and kept at that temperature for 20-50 minutes. Then, the temperature is raised to 60-70℃ and kept at that temperature for 60-100 minutes, while stirring is maintained during the holding process. Finally, the powder is dried, pulverized, and then added to the mixed resin.

9. The use of the high wear-resistant powder coating according to any one of claims 1-6 in the preparation of wear-resistant materials.

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