A high-adhesion, corrosion-resistant powder coating and its preparation method

Abstract

This invention discloses a highly adhesive and corrosion-resistant powder coating and its preparation method, belonging to the field of coating technology. The powder coating is composed of modified epoxy resin, composite modified filler, curing agent, leveling agent, dispersant, benzoin, and sodium fluoride, among other raw materials. By modifying the epoxy resin, the interaction between amino groups and grafted phosphate ester-based nano-silica is introduced, along with the introduction of BYK-163 to improve compatibility. In the composite modified filler, nano-silica A is grafted with phosphate ester groups, enabling it to form chemical bonds with metals and rapidly form a passivation film; nano-silica B is grafted with fluorine-containing groups, imparting low surface energy and chemical stability to the coating, achieving long-term protection. Sodium fluoride disrupts the metal lattice at high temperatures, forming anchor points and enhancing adhesion. This invention solves the problems of insufficient adhesion and corrosion resistance in traditional powder coatings, making it suitable for metal protection in various complex environments and possessing broad application prospects.

Description

Technical Field

[0001] This invention belongs to the field of coating technology and relates to a highly adhesive and corrosion-resistant powder coating and its preparation method. Background Technology

[0002] In today's industrial production and daily life, metal products are widely used in various fields, such as construction, automobile manufacturing, machining, and electronic equipment. However, metals are susceptible to corrosion in the natural environment, which not only affects their appearance but also reduces their mechanical properties and service life, and can even cause safety hazards. Therefore, it is crucial to apply protective coatings to metal surfaces, and powder coatings, due to their environmental friendliness, high efficiency, and excellent coating performance, have become one of the important choices for metal protection.

[0003] Currently, traditional powder coatings have certain limitations in terms of adhesion and corrosion resistance. Regarding adhesion, conventional powder coatings rely primarily on physical adsorption and simple mechanical bonding to metal surfaces. When subjected to external impacts, vibrations, or temperature changes, the coating is prone to peeling off, failing to meet the requirements of applications with high adhesion demands, such as large outdoor steel structures and marine engineering equipment. In terms of corrosion resistance, ordinary powder coatings struggle to withstand complex and harsh corrosive environments. For example, in high-humidity, high-salinity marine environments, moisture and salt easily penetrate the coating, reacting electrochemically with the metal and causing corrosion and rust. In chemical production environments, coatings may also be subject to erosion by various chemicals, further accelerating coating damage and metal corrosion. Therefore, developing a powder coating with high adhesion and excellent corrosion resistance is of significant practical importance and market demand. Summary of the Invention

[0004] The purpose of this invention is to provide a type of highly adhesive and corrosion-resistant powder coating and its preparation method, which helps to solve the problem that traditional powder coatings in the prior art have limitations in terms of adhesion and corrosion resistance, making it difficult to meet the metal protection requirements in harsh environments.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] In a first aspect, the present invention proposes a highly adhesive and corrosion-resistant powder coating, employing the following technical solution:

[0007] A highly adhesive and corrosion-resistant powder coating, the powder coating comprising the following raw materials in parts by weight:

[0008]

[0009] Preferably, the composite modified filler includes modified nano silica A and modified nano silica B, wherein the modified nano silica A is grafted with phosphate ester groups, the modified nano silica B is grafted with fluorine-containing groups, and the mass ratio of the modified nano silica A to the modified nano silica B is (2.5-3.5):1.

[0010] The method for preparing the composite modified filler is to put the modified nano silica A and the modified nano silica B into a high-speed mixer at a mass ratio and stir at a speed of 800-1200 rpm for 15-25 minutes to obtain the composite modified filler.

[0011] Preferably, the method for preparing the modified nano-silica A includes:

[0012] S1. Surface pretreatment: Nano silica A is added to ethanol and ultrasonically dispersed for 20-30 minutes. Then, γ-glycidoxypropyltrimethoxysilane is added and stirred at 70-80℃ for 2-3 hours to complete the surface pretreatment of nano silica A. The mass ratio of nano silica A to ethanol is 1:(10-15), and the mass ratio of nano silica A to γ-glycidoxypropyltrimethoxysilane is 1:(0.05-0.1).

[0013] S2, Grafting Phosphate Groups: Dibutyl phosphate and triethylamine are added to pretreated nano-silica A, and the mixture is reacted at 100-120℃ and a stirring speed of 300-500 rpm for 4-6 hours to complete the grafting on the surface of nano-silica A; wherein the mass ratio of nano-silica A to dibutyl phosphate is 1:(0.2-0.3), and the mass ratio of nano-silica A to triethylamine is 1:(0.01-0.02);

[0014] S3. Post-treatment: After the grafting reaction is completed, the product is washed with deionized water 3-5 times, and then vacuum dried at 80-90℃ to constant weight to obtain modified nano-silica A.

[0015] Preferably, the method for preparing the modified nano-silica B includes:

[0016] X1. Surface pretreatment: Nano silica B is added to toluene and stirred for 30-40 minutes. Then γ-aminopropyltriethoxysilane is added and stirred at 70-80℃ for 2-3 hours to complete the surface pretreatment of nano silica B. The mass ratio of nano silica B to toluene is 1:(12-18), and the mass ratio of nano silica B to γ-aminopropyltriethoxysilane is 1:(0.06-0.12).

[0017] X2. Grafting fluorine-containing groups: Perfluorooctyltriethoxysilane and dibutyltin dilaurate are added to pretreated nano-silica B, and the reaction is carried out at 80-90℃ with a stirring speed controlled at 200-400 rpm for 5-7 hours to complete the grafting on the surface of nano-silica B; wherein, the mass ratio of nano-silica B to perfluorooctyltriethoxysilane is 1:(0.25-0.35), and the mass ratio of nano-silica B to dibutyltin dilaurate is 1:(0.01-0.03);

[0018] X3. Post-treatment reaction: After the grafting reaction is completed, the product is washed with anhydrous ethanol 4-6 times, and then vacuum dried at 75-85℃ to constant weight to obtain modified nano-silica B.

[0019] Furthermore, the particle size of the nano-silica A and the nano-silica B is 30-60 nm.

[0020] Further, the modified epoxy resin is prepared as follows: Bisphenol A type epoxy resin and aminosilane coupling agent are mixed at a mass ratio of 10:(1-2), and 0.2%-0.5% of dibutyltin dilaurate by mass of bisphenol A type epoxy resin is added. The mixture is reacted at 120-140℃ for 3-5 hours. After the reaction is completed, the product is subjected to vacuum distillation at 80-100℃ for 1-2 hours, and then cooled to room temperature to obtain the modified epoxy resin.

[0021] Preferably, the curing agent includes dicyandiamide, the leveling agent is an acrylate leveling agent, and the dispersant is BYK-163.

[0022] Secondly, the present invention provides a method for preparing a highly adhesive and corrosion-resistant powder coating, employing the following technical solution:

[0023] A method for preparing a highly adhesive and corrosion-resistant powder coating, characterized in that the preparation method includes the following steps:

[0024] Y1. Mix the modified epoxy resin, composite modified filler, curing agent, leveling agent, dispersant, benzoin, and sodium fluoride evenly to obtain a preliminary mixture.

[0025] Y2. The preliminary mixture is fed into an extruder and extruded under controlled temperature. After pressing, cooling, crushing, sieving, and packaging, the finished powder coating is obtained.

[0026] The beneficial effects of this invention are:

[0027] (1) In this invention, sodium fluoride and composite modified filler are introduced into the powder coating. The synergistic effect of sodium fluoride and composite modified filler is utilized to destroy the lattice of the metal substrate and form depressions when the metal substrate is baked at high temperature. This provides a large number of anchor points between the coating and the metal substrate, which greatly increases the mechanical interlocking effect between the coating and the metal. At the same time, the phosphate ester groups grafted by modified nano silica A react quickly with the metal surface to generate a passivation film, which provides immediate adhesion and passivation protection. This not only significantly improves the coating adhesion, but also avoids excessive corrosion of the metal substrate by sodium fluoride. The synergistic effect of sodium fluoride and modified nano silica A effectively solves the problem of insufficient adhesion of traditional powder coatings and easy coating peeling when subjected to external impact, vibration or temperature change. This meets the application scenarios with high requirements for coating adhesion, such as large outdoor steel structures and marine engineering equipment.

[0028] (2) Modified nano-silica A (phosphate ester group) preferentially forms stable metal-oxygen-phosphorus chemical bonds with the metal surface, providing immediate adhesion and passivation protection; modified nano-silica B (fluorine-containing group) forms a dense physical barrier through its low surface energy characteristics, blocking the penetration of moisture, salt spray, and chemical media. The two are combined in a specific ratio to achieve a gradient synergy between chemical bonding and physical shielding, balancing short-term rapid protection with long-term corrosion resistance. In high-humidity, high-salinity marine environments or chemical production environments, it can effectively protect metals from corrosion, overcoming the shortcomings of powder coatings in resisting complex and harsh corrosive environments.

[0029] (3) The epoxy resin is directionally modified by aminosilane coupling agent to introduce amino functional groups, enhance the hydrogen bond interaction between the resin and the phosphate ester filler, and at the same time utilize the synergistic dispersion effect of dispersant (BYK-163) to make the high proportion of inorganic filler uniformly dispersed in organic resin, avoid phase separation, ensure the synergistic effect of each component of the coating, and improve the overall performance of the coating. Detailed Implementation

[0030] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0031] In all embodiments and comparative examples of this invention, the bisphenol A epoxy resin was purchased from Huntsman Corporation; γ-glycidyl etheroxypropyltrimethoxysilane was purchased from Suzhou Qihang Biotechnology Co., Ltd.; dibutyl phosphate was purchased from Jinan Yongyue Chemical Co., Ltd.; perfluorooctyltriethoxysilane was purchased from Shandong Yuanjin New Materials Co., Ltd.; γ-aminopropyltriethoxysilane was purchased from Hangzhou Jessica Chemical Co., Ltd.; dibutyltin dilaurate was purchased from Jinan Jingyu Chemical Co., Ltd.; dicyandiamide was purchased from Zhengzhou Huixi Chemical Products Co., Ltd.; acrylate was purchased from Nanjing Milan New Materials Co., Ltd.; BYK-163 was purchased from Jining Fangyu Chemical Co., Ltd.; sodium fluoride was purchased from Jinan Jiayang Chemical Co., Ltd.; aminosilane coupling agent was purchased from Qufu Yishun Chemical Co., Ltd.; and EFKA-3777 was purchased from Guangzhou Haoliangda International Trade Co., Ltd.

[0032] Example 1

[0033] A highly adhesive and corrosion-resistant powder coating, comprising the following raw materials in parts by weight:

[0034]

[0035]

[0036] The curing agent is dicyandiamide, the leveling agent is EFKA-3777, and the dispersant is BYK-163.

[0037] The composite modified filler includes modified nano silica A and modified nano silica B. Modified nano silica A is grafted with phosphate ester groups, and modified nano silica B is grafted with fluorine-containing groups. The mass ratio of modified nano silica A to modified nano silica B is 2.5:1.

[0038] The preparation method of the modified nano-silica A includes:

[0039] S1. Surface pretreatment: Nano-silica A is added to ethanol and ultrasonically dispersed for 20 minutes. Then, γ-glycidoxypropyltrimethoxysilane is added, and the mixture is stirred and reacted at 70°C for 2 hours to complete the surface pretreatment of nano-silica A. The mass ratio of nano-silica A to ethanol is 1:10, the mass ratio of nano-silica A to γ-glycidoxypropyltrimethoxysilane is 1:0.05, and the particle size of nano-silica A is 30 nm.

[0040] S2, Grafting Phosphate Groups: Dibutyl phosphate and triethylamine are added to pretreated nano-silica A, and the mixture is reacted at 100°C and a stirring speed of 500 rpm for 4 hours to complete the grafting on the surface of nano-silica A; wherein the mass ratio of nano-silica A to dibutyl phosphate is 1:0.2, and the mass ratio of nano-silica A to triethylamine is 1:0.01;

[0041] S3. Post-treatment: After the grafting reaction is completed, the product is washed three times with deionized water and then vacuum dried at 80°C to constant weight to obtain modified nano-silica A.

[0042] The preparation method of the modified nano-silica B includes:

[0043] S1. Surface pretreatment: Nano silica B is added to toluene and stirred for 30 minutes. Then γ-aminopropyltriethoxysilane is added and stirred at 70°C for 3 hours to complete the surface pretreatment of nano silica B. The mass ratio of nano silica B to toluene is 1:12, the mass ratio of nano silica B to γ-aminopropyltriethoxysilane is 1:0.06, and the particle size of nano silica B is 30 nm.

[0044] S2. Grafting fluorine-containing groups: Perfluorooctyltriethoxysilane and dibutyltin dilaurate are added to pretreated nano-silica B and reacted at 80°C with a stirring speed controlled at 400 rpm for 5 hours to complete the grafting on the surface of nano-silica B; wherein, the mass ratio of nano-silica B to perfluorooctyltriethoxysilane is 1:0.25, and the mass ratio of nano-silica B to dibutyltin dilaurate is 1:0.01.

[0045] S3. Post-treatment reaction: After the grafting reaction is completed, the product is washed four times with anhydrous ethanol and then vacuum dried at 75°C to constant weight to obtain modified nano-silica B grafted with fluorine-containing groups.

[0046] The preparation method of the composite modified filler is as follows: Modified nano silica A and modified nano silica B are put into a high-speed mixer at a mass ratio and stirred at a speed of 1200 rpm for 15 minutes to obtain the composite modified filler.

[0047] The modified epoxy resin is prepared as follows: Bisphenol A type epoxy resin and an aminosilane coupling agent are mixed at a mass ratio of 10:1, and 0.2% (by mass) of dibutyltin dilaurate of the bisphenol A type epoxy resin is added. The mixture is reacted at 120°C for 3 hours. After the reaction, the product is subjected to vacuum distillation at 80°C for 1 hour, and then cooled to room temperature to obtain the modified epoxy resin. The aminosilane coupling agent is γ-aminopropyltriethoxysilane.

[0048] The preparation method of powder coating includes the following steps:

[0049] S1. Mix the modified epoxy resin, composite modified filler, dicyandiamide, Efka EFKA-3777, BYK-163, benzoin, and sodium fluoride evenly to obtain a preliminary mixture.

[0050] S2. The preliminary mixture is fed into an extruder and extruded at a controlled temperature (90℃). After pressing, cooling, crushing, sieving, and packaging, the finished powder coating is obtained.

[0051] Example 2

[0052] A highly adhesive and corrosion-resistant powder coating, comprising the following raw materials in parts by weight:

[0053]

[0054] The composite modified filler includes modified nano silica A and modified nano silica B. Modified nano silica A is grafted with phosphate ester groups, and modified nano silica B is grafted with fluorine-containing groups. The mass ratio of modified nano silica A to modified nano silica B is 3:1.

[0055] The preparation method of the modified nano-silica A includes:

[0056] S1. Surface pretreatment: Nano-silica A is added to ethanol and ultrasonically dispersed for 25 minutes. Then, γ-glycidoxypropyltrimethoxysilane is added, and the mixture is stirred and reacted at 75°C for 2.5 hours to complete the surface pretreatment of nano-silica A. The mass ratio of nano-silica A to ethanol is 1:12.5, the mass ratio of nano-silica A to γ-glycidoxypropyltrimethoxysilane is 1:0.075, and the particle size of nano-silica A is 40 nm.

[0057] S2, Grafting Phosphate Groups: Dibutyl phosphate and triethylamine are added to pretreated nano-silica A, and the mixture is reacted at 110°C and a stirring speed of 400 rpm for 5 hours to complete the grafting on the surface of nano-silica A; wherein the mass ratio of nano-silica A to dibutyl phosphate is 1:0.25, and the mass ratio of nano-silica A to triethylamine is 1:0.015;

[0058] S3. Post-treatment: After the grafting reaction is completed, the product is washed four times with deionized water and then vacuum dried at 85°C to constant weight to obtain modified nano-silica A.

[0059] The preparation method of the modified nano-silica B includes:

[0060] X1. Surface pretreatment: Nano silica B is added to toluene and stirred for 30 minutes. Then, γ-aminopropyltriethoxysilane is added and stirred at 75°C for 2.5 hours to complete the surface pretreatment of nano silica B. The mass ratio of nano silica B to toluene is 1:15, the mass ratio of nano silica B to γ-aminopropyltriethoxysilane is 1:0.09, and the particle size of nano silica B is 40 nm.

[0061] X2. Grafting of fluorine-containing groups: Perfluorooctyltriethoxysilane and dibutyltin dilaurate were added to pretreated nano-silica B and reacted at 85°C with a stirring speed of 300 rpm for 6 hours to complete the grafting on the surface of nano-silica B; wherein the mass ratio of nano-silica B to perfluorooctyltriethoxysilane was 1:0.3, and the mass ratio of nano-silica B to dibutyltin dilaurate was 1:0.02.

[0062] X3. Post-treatment reaction: After the grafting reaction is completed, the product is washed 5 times with anhydrous ethanol and then vacuum dried at 80°C to constant weight to obtain modified nano-silica B grafted with fluorine-containing groups.

[0063] The preparation method of the composite modified filler is as follows: Modified nano silica A and modified nano silica B are put into a high-speed mixer at a mass ratio and stirred at a speed of 1000 rpm for 20 minutes to obtain the composite modified filler.

[0064] The modified epoxy resin is prepared as follows: Bisphenol A type epoxy resin and an aminosilane coupling agent are mixed at a mass ratio of 10:1.5, and 0.35% (by mass) of dibutyltin dilaurate of the bisphenol A type epoxy resin is added. The mixture is reacted at 130°C for 4 hours. After the reaction, the product is subjected to vacuum distillation at 90°C for 1.5 hours, and then cooled to room temperature to obtain the modified epoxy resin. The aminosilane coupling agent is γ-aminopropyltriethoxysilane.

[0065] The preparation method of powder coating includes the following steps:

[0066] Y1. Mix the modified epoxy resin, composite modified filler, dicyandiamide, Efka EFKA-3777, BYK-163, benzoin, and sodium fluoride evenly to obtain a preliminary mixture.

[0067] Y2. The preliminary mixture is fed into an extruder and extruded under controlled temperature (90℃). After pressing, cooling, crushing, sieving, and packaging, the finished powder coating is obtained.

[0068] Example 3

[0069] A highly adhesive and corrosion-resistant powder coating, the powder coating comprising the following raw materials in parts by weight:

[0070]

[0071] The composite modified filler includes modified nano silica A and modified nano silica B. Modified nano silica A is grafted with phosphate ester groups, and modified nano silica B is grafted with fluorine-containing groups. The mass ratio of modified nano silica A to modified nano silica B is 3.5:1.

[0072] The preparation method of the modified nano-silica A includes:

[0073] S1. Surface pretreatment: Nano-silica A is added to ethanol and ultrasonically dispersed for 30 minutes. Then, γ-glycidoxypropyltrimethoxysilane is added, and the mixture is stirred and reacted at 80°C for 3 hours to complete the surface pretreatment of nano-silica A. The mass ratio of nano-silica A to ethanol is 1:15, the mass ratio of nano-silica A to γ-glycidoxypropyltrimethoxysilane is 1:0.1, and the particle size of nano-silica A is 50 nm.

[0074] S2, Grafting Phosphate Groups: Dibutyl phosphate and triethylamine are added to pretreated nano-silica A, and the mixture is reacted at 120°C and a stirring speed of 300 rpm for 6 hours to complete the grafting on the surface of nano-silica A; wherein the mass ratio of nano-silica A to dibutyl phosphate is 1:0.3, and the mass ratio of nano-silica A to triethylamine is 1:0.02;

[0075] S3. Post-treatment: After the grafting reaction is completed, the product is washed 5 times with deionized water and then vacuum dried at 90°C to constant weight to obtain nano-silica A.

[0076] The preparation method of the modified nano-silica B includes:

[0077] X1. Surface pretreatment: Nano silica B is added to toluene and stirred for 40 minutes. Then γ-aminopropyltriethoxysilane is added and stirred at 80°C for 3 hours to complete the surface pretreatment of nano silica B. The mass ratio of nano silica B to toluene is 1:18, the mass ratio of nano silica B to γ-aminopropyltriethoxysilane is 1:0.12, and the particle size of nano silica B is 50 nm.

[0078] X2. Grafting of fluorine-containing groups: Perfluorooctyltriethoxysilane and dibutyltin dilaurate were added to pretreated nano-silica B and reacted at 90°C with a stirring speed of 200 rpm for 7 hours to complete the grafting on the surface of nano-silica B; wherein the mass ratio of nano-silica B to perfluorooctyltriethoxysilane was 1:0.35, and the mass ratio of nano-silica B to dibutyltin dilaurate was 1:0.03.

[0079] X3. Post-treatment reaction: After the grafting reaction was completed, the product was washed 6 times with anhydrous ethanol and then vacuum dried at 85°C to constant weight to obtain modified nano-silica B grafted with fluorine-containing groups.

[0080] The preparation method of the composite modified filler is as follows: Modified nano silica A and modified nano silica B are put into a high-speed mixer at a mass ratio and stirred at a speed of 800 rpm for 25 minutes to obtain the composite modified filler.

[0081] The modified epoxy resin is prepared as follows: Bisphenol A type epoxy resin and aminosilane coupling agent are mixed at a mass ratio of 10:2, and 0.5% of dibutyltin dilaurate by mass of bisphenol A type epoxy resin is added. The mixture is reacted at 140℃ for 5 hours. After the reaction is completed, the product is subjected to vacuum distillation at 100℃ for 2 hours, and then cooled to room temperature to obtain the modified epoxy resin.

[0082] The preparation method of powder coating includes the following steps:

[0083] Y1. Mix the modified epoxy resin, composite modified filler, dicyandiamide, Efka EFKA-3777, BYK-163, benzoin, and sodium fluoride evenly to obtain a preliminary mixture.

[0084] Y2. The preliminary mixture is fed into an extruder and extruded under controlled temperature (90℃). After pressing, cooling, crushing, sieving, and packaging, the finished powder coating is obtained.

[0085] Comparative Example 1

[0086] The difference from Example 2 is that sodium fluoride is not added to the raw materials of the powder coating, and an equal amount of composite modified filler is used instead.

[0087] Comparative Example 2

[0088] The difference from Example 2 is that the composite modified filler is replaced with an equal amount of nano-silica.

[0089] Comparative Example 3

[0090] The difference from Example 2 is that the modified epoxy resin in the raw materials of the powder coating is replaced with an equal amount of bisphenol A type epoxy resin; and BYK-163 is not added.

[0091] Comparative Example 4

[0092] The difference from Example 2 is that the composite modified filler contains only modified nano silica A and does not contain modified nano silica B.

[0093] Comparative Example 5

[0094] The difference from Example 2 is that the composite modified filler contains only modified nano silica B and does not contain modified nano silica A.

[0095] Test Case

[0096] Test sample preparation:

[0097] Step 1: Select a steel plate that meets the requirements of GB / T 9271-2008 Standard Test Plate for Paints and Varnishes as the standard test plate. First, use sandpaper to polish the surface of the steel plate. After polishing, immerse the steel plate in acetone and anhydrous ethanol for ultrasonic cleaning, each cleaning time being 15 minutes. After cleaning, place the steel plate in a drying oven and dry it at 80℃ for 30 minutes for later use.

[0098] Step 2: Under the same spraying pressure of 0.4 MPa, the powder coatings prepared in Examples 1-3 and Comparative Examples 1-5 were sprayed onto standard test panels preheated in an oven at 180°C for 15 minutes using high-pressure electrostatic spraying. During the spraying process, the distance between the spray gun and the test panel was maintained at 20 cm, and the spray gun was moved at a uniform speed to ensure uniform coating coverage. The coating thickness was approximately 100 μm.

[0099] Step 3: After spraying, quickly place the coated test panel into the curing oven. Set the curing temperature to 200℃ and the curing time to 15 minutes. After curing, remove the test panel and allow it to cool naturally to room temperature to obtain the test sample.

[0100] The test samples were tested using the following test methods:

[0101] (1) Adhesion test: According to GB / T 9286-1998 standard, the cross-cut test is adopted. 100 small squares are cut on the metal test piece coated with powder coating with a sharp blade. Then, special tape is used to stick the test piece and quickly tear it off. The coating peeling off inside the squares is observed to evaluate the adhesion. The adhesion level is divided into 0-5, with 0 being the best and 5 being the worst.

[0102] (2) Corrosion resistance test: According to GB / T 1771-2007, the sample coated with powder coating was placed in a salt spray test chamber at a temperature of 35℃ and a salt solution concentration of 5%, and sprayed continuously. The time when corrosion (such as rust, blistering, etc.) appeared on the sample was recorded.

[0103] (3) Surface roughness test: The surface roughness of the coating on the test sample was measured using a white light interferometer. Nine different locations were selected on each sample for measurement: the upper left corner, upper center, upper right corner, left center, center, right center, lower left corner, lower center, and lower right corner. After the measurement was completed, the average value of the measurements at these nine locations was taken to obtain the average roughness (Ra), with the unit being μm.

[0104] (4) Impact Resistance Test: The impact resistance of the coating was tested using an impact testing machine according to GB / T 1732-1993. During the test, a weight of a specified mass was dropped freely from different heights onto the powder-coated sample. The impact energy (unit: kg·cm) was used as a quantitative indicator to evaluate the coating's impact resistance. The impact energy was calculated by multiplying the weight's mass by the drop height. The impact resistance data represents the maximum impact energy the coating can withstand without damage (such as cracking or peeling). The higher the value, the better the coating's impact resistance.

[0105] (5) Chemical resistance test: According to GB / T 9274-1988, the coated sample was immersed in 5% sulfuric acid and 5% sodium hydroxide solution, and the appearance change of the coating was recorded after 24 hours of immersion.

[0106] The results of the five test methods are shown in Table 1.

[0107] Table 1

[0108]

[0109] The adhesion of Examples 1-3 was all grade 0, indicating that the coating had extremely strong adhesion to the metal substrate and could effectively resist external impacts and vibrations. The adhesion of Comparative Examples 1-5 was poor, especially Comparative Example 1 (without sodium fluoride) and Comparative Example 2 (without composite modified filler), where the adhesion decreased significantly, indicating that sodium fluoride and composite modified filler play an important role in improving adhesion.

[0110] The corrosion resistance of Examples 1-3 was significantly better than that of Comparative Examples 1-5, indicating that the synergistic effect of sodium fluoride and composite modified filler can effectively improve the corrosion resistance of the coating. Comparative Example 1 (without sodium fluoride) and Comparative Example 2 (without composite modified filler) showed poor corrosion resistance, indicating that sodium fluoride and composite modified filler play an important role in improving corrosion resistance.

[0111] The low surface roughness of Examples 1-3 indicates a smooth coating surface, which is beneficial for improving the corrosion resistance and aesthetics of the coating. The high surface roughness of Comparative Examples 1-5, especially Comparative Example 3 (without modified epoxy resin and BYK-163), indicates that the directional modification of the epoxy resin by the aminosilane coupling agent introduces amino functional groups, enhancing the hydrogen bonding interaction between the resin and the phosphate ester filler. Simultaneously, the synergistic dispersion effect of the dispersant (BYK-163) ensures that the high proportion of inorganic filler is uniformly dispersed in the organic resin, preventing phase separation and guaranteeing the synergistic effect of all components in the coating, thus improving the overall performance of the coating.

[0112] Examples 1-3 exhibited good impact resistance, indicating that the coating possesses good mechanical properties. Comparative Examples 1-5 showed poor impact resistance, demonstrating that the composite modified filler, sodium fluoride, modified epoxy resin, and BYK-163 play a crucial role in improving impact resistance.

[0113] Examples 1-3 exhibited good chemical resistance, indicating that the coatings effectively resist the erosion of chemical media. Comparative Examples 1-5 showed poor chemical resistance, demonstrating that the composite modified filler, sodium fluoride, modified epoxy resin, and BYK-163 play important roles in improving chemical resistance.

[0114] The high-adhesion, corrosion-resistant powder coating provided by this invention significantly improves the coating's adhesion, corrosion resistance, surface smoothness, impact resistance, and chemical resistance by introducing the synergistic effect of sodium fluoride and composite modified fillers, as well as the introduction of modified epoxy resin and BYK-163 to uniformly disperse inorganic fillers in organic resin and prevent phase separation. Test results in Examples 1-3 show that this powder coating outperforms comparative examples 1-5 in terms of adhesion, corrosion resistance, surface roughness, impact resistance, and chemical resistance. Especially in high-humidity, high-salinity marine environments or chemical production environments, it effectively protects metals from corrosion, meeting the high performance requirements of applications such as large outdoor steel structures and marine engineering equipment. Therefore, this invention has significant practical implications and market demand.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A highly adhesive and corrosion-resistant powder coating, characterized in that: The powder coating comprises the following raw materials in parts by weight: 50-60 parts by weight of modified epoxy resin 20-30 parts by weight of composite modified filler 5-10 parts by weight of curing agent Leveling agent 0.5-1.5 parts by weight Dispersant 0.5-1.5 parts by weight 1-3 parts by weight of benzoin 3-8 parts by weight of sodium fluoride; The composite modified filler includes modified nano silica A and modified nano silica B, wherein the modified nano silica A is grafted with phosphate ester groups, and the modified nano silica B is grafted with fluorine-containing groups, and the mass ratio of the modified nano silica A to the modified nano silica B is (2.5-3.5):

1. The modified epoxy resin is prepared as follows: Bisphenol A type epoxy resin and aminosilane coupling agent are mixed at a mass ratio of 10:(1-2), and 0.2%-0.5% of dibutyltin dilaurate by mass of bisphenol A type epoxy resin is added. The mixture is reacted at 120-140℃ for 3-5 hours. After the reaction is completed, the product is subjected to vacuum distillation at 80-100℃ for 1-2 hours, and then cooled to room temperature to obtain the modified epoxy resin.

2. The high-adhesion, corrosion-resistant powder coating according to claim 1, characterized in that: The method for preparing the composite modified filler is to put the modified nano silica A and the modified nano silica B into a high-speed mixer at a mass ratio and stir at a speed of 800-1200 rpm for 15-25 minutes to obtain the composite modified filler.

3. The high-adhesion, corrosion-resistant powder coating according to claim 2, characterized in that: The preparation method of the modified nano-silica A includes: S1. Surface pretreatment: Nano silica A is added to ethanol and ultrasonically dispersed for 20-30 minutes. Then, γ-glycidoxypropyltrimethoxysilane is added, and the mixture is stirred and reacted at 70-80℃ for 2-3 hours to complete the surface pretreatment of nano silica A. The mass ratio of nano silica A to ethanol is 1:(10-15), and the mass ratio of nano silica A to γ-glycidoxypropyltrimethoxysilane is 1:(0.05-0.1). S2. Grafting phosphate groups: Dibutyl phosphate and triethylamine are added to pretreated nano-silica A, and the mixture is reacted at 100-120℃ and a stirring speed of 300-500 rpm for 4-6 hours to complete the grafting on the surface of nano-silica A; wherein the mass ratio of nano-silica A to dibutyl phosphate is 1:(0.2-0.3), and the mass ratio of nano-silica A to triethylamine is 1:(0.01-0.02). S3. Post-treatment: After the grafting reaction is completed, the product is washed with deionized water 3-5 times, and then vacuum dried at 80-90℃ to constant weight to obtain modified nano-silica A.

4. The high-adhesion, corrosion-resistant powder coating according to claim 3, characterized in that: The preparation method of the modified nano-silica B includes: X1. Surface pretreatment: Nano silica B is added to toluene and stirred for 30-40 minutes. Then γ-aminopropyltriethoxysilane is added and stirred at 70-80℃ for 2-3 hours to complete the surface pretreatment of nano silica B. The mass ratio of nano silica B to toluene is 1:(12-18), and the mass ratio of nano silica B to γ-aminopropyltriethoxysilane is 1:(0.06-0.12). X2. Grafting fluorine-containing groups: Perfluorooctyltriethoxysilane and dibutyltin dilaurate are added to pretreated nano-silica B, and the reaction is carried out at 80-90℃ with a stirring speed controlled at 200-400 rpm for 5-7 hours to complete the grafting on the surface of nano-silica; wherein, the mass ratio of nano-silica B to perfluorooctyltriethoxysilane is 1:(0.25-0.35), and the mass ratio of nano-silica B to dibutyltin dilaurate is 1:(0.01-0.03); X3. Post-treatment reaction: After the grafting reaction is completed, the product is washed with anhydrous ethanol 4-6 times, and then vacuum dried at 75-85℃ to constant weight to obtain modified nano-silica B.

5. The high-adhesion, corrosion-resistant powder coating according to claim 4, characterized in that: The particle size of the nano-silica A and the nano-silica B is 30-60 nm.

6. The high-adhesion, corrosion-resistant powder coating according to claim 1, characterized in that: The curing agent includes dicyandiamide, the leveling agent is an acrylate leveling agent, and the dispersant is BYK-163.

7. The method for preparing the highly adhesive and corrosion-resistant powder coating according to any one of claims 1-6, characterized in that: The preparation method includes the following steps: Y1. Mix the modified epoxy resin, composite modified filler, curing agent, leveling agent, benzoin, dispersant, and sodium fluoride evenly to obtain a preliminary mixture. Y2. The preliminary mixture is fed into an extruder and extruded under controlled temperature. After pressing, cooling, crushing, sieving, and packaging, the finished powder coating is obtained.

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