High-adhesiveness corrosion-resistant powder coating and preparation method thereof

Abstract

The invention discloses a high-adhesiveness corrosion-resistant powder coating and a preparation method thereof, and belongs to the technical field of coatings. The powder coating is prepared from the following raw materials: modified epoxy resin, composite modified filler, a curing agent, a flatting agent, a dispersing agent, benzoin, sodium fluoride and the like. The epoxy resin is modified, amino is introduced to enhance the interaction with the grafted phosphate nano-silica, and BYK-163 is introduced, so that the compatibility is improved. In the composite modified filler, nano silicon dioxide A is grafted with a phosphate group, and can form a chemical bond with metal and quickly form a passive film; the nano silicon dioxide B is grafted with a fluorine-containing group, so that the coating is endowed with low surface energy and chemical stability, and long-acting protection is realized. Sodium fluoride destroys metal lattices at high temperature to form anchor points, and adhesive force is improved. The problem that a traditional powder coating is insufficient in adhesive force and corrosion resistance is solved, and the powder coating is suitable for metal protection in various complex environments and has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings and relates to a high-adhesion, corrosion-resistant powder coating and a preparation method thereof. Background Art

[0002] In today's industrial production and daily life, metal products are widely used in various fields, such as construction, automobile manufacturing, mechanical processing, electronic equipment, etc. 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 even causes safety hazards. Therefore, it is very important to treat the metal surface with a protective coating, and powder coating has become one of the important choices for metal protection due to its environmental protection, high efficiency, and excellent coating performance.

[0003] At present, traditional powder coatings have certain limitations in terms of adhesion and corrosion resistance. In terms of adhesion, the bonding force between conventional powder coatings and metal surfaces mainly relies on physical adsorption and simple mechanical bite. When subjected to external impact, vibration or temperature changes, the coating is easy to fall off, and cannot meet some application scenarios with high requirements for coating adhesion, such as large outdoor steel structures, marine engineering equipment, etc. In terms of corrosion resistance, ordinary powder coatings are difficult to withstand complex and harsh corrosion environments. For example, in a marine environment with high humidity and high salinity, moisture and salt can easily penetrate into the coating and react electrochemically with the metal, causing metal corrosion and rust; in a chemical production environment, the coating may also be corroded by various chemicals, further accelerating the damage of the coating and the corrosion of the metal. Therefore, the development of a powder coating with high adhesion and excellent corrosion resistance has important practical significance and market demand. Summary of the invention

[0004] The purpose of the present invention is to provide a high-adhesion and corrosion-resistant powder coating and a preparation method thereof, which is conducive to solving the problem that traditional powder coatings in the prior art have limitations in adhesion and corrosion resistance and are difficult to meet the needs of metal protection in harsh environments.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] In the first aspect, the present invention proposes a high-adhesion and corrosion-resistant powder coating, which adopts the following technical solution:

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

[0008]

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

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

[0011] Preferably, the preparation method of the modified nano-silicon dioxide A comprises:

[0012] S1. Surface pretreatment: Add nano-silicon dioxide A to ethanol, use ultrasonic dispersion for 20-30 minutes, then add γ-glycidyloxypropyltrimethoxysilane, and stir and react at 70-80° C. for 2-3 hours, thereby completing the surface pretreatment of nano-silicon dioxide A; wherein the mass ratio of the nano-silicon dioxide A to the ethanol is 1:(10-15), and the mass ratio of the nano-silicon dioxide A to the γ-glycidyloxypropyltrimethoxysilane is 1:(0.05-0.1);

[0013] S2, grafting phosphate groups: adding dibutyl phosphate and triethylamine to the pretreated nano-silicon dioxide A, reacting at 100-120° C. and stirring at 300-500 rpm for 4-6 hours, thereby completing the grafting of the surface of the nano-silicon dioxide A; wherein the mass ratio of the nano-silicon dioxide A to dibutyl phosphate is 1:(0.2-0.3), and the mass ratio of the nano-silicon dioxide 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 for 3-5 times, and then vacuum dried at 80-90° C. to constant weight to obtain modified nano-silica A.

[0015] Preferably, the preparation method of the modified nano-silicon dioxide B comprises:

[0016] X1. Surface pretreatment: Add nano-silica B to toluene, stir for 30-40 minutes, then add γ-aminopropyltriethoxysilane, stir and react at 70-80° C. for 2-3 hours, thereby completing the surface pretreatment of nano-silica B; wherein the mass ratio of the nano-silica B to toluene is 1:(12-18), and the mass ratio of the nano-silica B to γ-aminopropyltriethoxysilane is 1:(0.06-0.12);

[0017] X2. Grafting fluorine-containing groups: adding perfluorooctyltriethoxysilane and dibutyltin dilaurate to the pretreated nano-silica B, reacting at 80-90° C. and controlling the stirring speed at 200-400 rpm for 5-7 hours, thereby completing the grafting of the surface of the nano-silica B; wherein the mass ratio of the nano-silica B to perfluorooctyltriethoxysilane is 1:(0.25-0.35), and the mass ratio of the 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 for 4-6 times, and then vacuum dried at 75-85°C to constant weight to obtain modified nano-silica B.

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

[0020] Furthermore, the preparation method of the modified epoxy resin is as follows: bisphenol A epoxy resin and aminosilane coupling agent are mixed according to a mass ratio of 10:(1-2), and 0.2%-0.5% of dibutyltin dilaurate by mass of the bisphenol A epoxy resin is added, and the mixture is reacted at 120-140° C. for 3-5 hours; after the reaction is completed, the product is subjected to reduced pressure distillation at 80-100° C. 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 acrylic leveling agent, and the dispersant is BYK-163.

[0022] In a second aspect, the present invention provides a method for preparing a high-adhesion, corrosion-resistant powder coating, which adopts the following technical scheme:

[0023] A method for preparing a high-adhesion, corrosion-resistant powder coating, characterized in that the preparation method comprises the following steps:

[0024] Y1. Evenly mix the modified epoxy resin, the composite modified filler, the curing agent, the leveling agent, the dispersant, the benzoin and the sodium fluoride to obtain a preliminary mixed material;

[0025] Y2. The preliminary mixed material is put into the extruder for temperature-controlled extrusion, and the powder coating product is obtained through tableting, cooling, crushing, screening and packaging.

[0026] Beneficial effects of the present invention:

[0027] (1) The present invention introduces the synergistic effect of sodium fluoride and the composite modified filler into the powder coating, and utilizes the characteristics of sodium fluoride that destroys the metal substrate lattice and forms depressions when baked at high temperature, thereby providing a large number of anchor points for the coating and the metal substrate, greatly increasing the mechanical bite between the coating and the metal; at the same time, the phosphate groups grafted by the modified nano-silicon dioxide A react quickly with the metal surface to form a passivation film, providing instant adhesion and passivation protection, which not only significantly improves the adhesion of the coating, but also avoids excessive corrosion of the metal substrate by sodium fluoride. The synergistic effect of sodium fluoride and modified nano-silicon dioxide A effectively solves the problem of insufficient adhesion of traditional powder coatings and easy detachment of the coating when subjected to external impact, vibration or temperature change, and 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 group) preferentially forms a stable metal-oxygen-phosphorus chemical bond 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 compounded in a specific ratio to achieve a gradient synergy of chemical bonding and physical shielding, taking into account both short-term rapid protection and long-term corrosion resistance. In high-humidity, high-salinity marine environments or chemical production environments, it can effectively protect metals from corrosion, overcoming the defect that powder coatings are difficult to resist complex and harsh corrosion environments.

[0029] (3) The epoxy resin is modified by aminosilane coupling agent to introduce amino functional groups, thereby enhancing the hydrogen bond interaction between the resin and the phosphate-based filler. At the same time, the synergistic dispersion effect of the dispersant (BYK-163) is utilized to evenly disperse a high proportion of inorganic fillers in the organic resin to avoid phase separation, ensure the synergistic effect of the various components of the coating, and improve the overall performance of the coating. DETAILED DESCRIPTION

[0030] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0031] The bisphenol A epoxy resin in all the embodiments and comparative examples of the present invention was purchased from Huntsman Corporation; γ-glycidyloxypropyltrimethoxysilane 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 high-adhesion, corrosion-resistant powder coating, the powder coating comprising the following raw materials in parts by weight:

[0034]

[0035]

[0036] Wherein, 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. The modified nano-silica A is grafted with a phosphate group, and the modified nano-silica B is grafted with a fluorine-containing group. The mass ratio of the modified nano-silica A to the modified nano-silica B is 2.5:1.

[0038] The preparation method of the modified nano-silicon dioxide A comprises:

[0039] S1. Surface pretreatment: Add nano-silica A to ethanol, use ultrasonic dispersion for 20 minutes, then add γ-glycidyloxypropyltrimethoxysilane, and stir and react at 70°C for 2 hours to complete the surface pretreatment of nano-silica A; wherein the mass ratio of nano-silica A to ethanol is 1:10, the mass ratio of nano-silica A to γ-glycidyloxypropyltrimethoxysilane is 1:0.05, and the particle size of nano-silica A is 30 nm;

[0040] S2, grafting phosphate groups: adding dibutyl phosphate and triethylamine to the pretreated nano-silica A, reacting at 100° C. and stirring at 500 rpm for 4 hours, thereby completing the grafting of the surface of the nano-silica A; wherein the mass ratio of the nano-silica A to dibutyl phosphate is 1:0.2, and the mass ratio of the 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 a constant weight to obtain modified nano-silica A.

[0042] The preparation method of the modified nano silicon dioxide B comprises:

[0043] S1. Surface pretreatment: Add nano-silica B to toluene, stir for 30 minutes, then add γ-aminopropyltriethoxysilane, stir and react at 70°C for 3 hours, thereby completing the surface pretreatment of nano-silica B; wherein 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: adding perfluorooctyltriethoxysilane and dibutyltin dilaurate to the pretreated nano-silica B, reacting at 80° C. and controlling the stirring speed at 400 rpm for 5 hours, thereby completing the grafting of the surface of the nano-silica B; wherein the mass ratio of the nano-silica B to the perfluorooctyltriethoxysilane is 1:0.25, and the mass ratio of the nano-silica B to the dibutyltin dilaurate is 1:0.01;

[0045] S3. Post-treatment reaction: After the grafting reaction is completed, the product is washed with anhydrous ethanol for 4 times, 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: adding modified nano silicon dioxide A and modified nano silicon dioxide B into a high-speed mixer according to a mass ratio, stirring at a speed of 1200 rpm for 15 minutes, and obtaining the composite modified filler.

[0047] The preparation method of the modified epoxy resin is as follows: bisphenol A epoxy resin and aminosilane coupling agent are mixed in a mass ratio of 10:1, and 0.2% of dibutyltin dilaurate by mass of the bisphenol A epoxy resin is added, and the mixture is reacted at 120° C. for 3 hours; after the reaction is completed, the product is subjected to reduced pressure 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 comprises the following steps:

[0049] S1, uniformly mixing the modified epoxy resin, the composite modified filler, dicyandiamide, EFKA-3777, BYK-163, benzoin and sodium fluoride to obtain a preliminary mixed material;

[0050] S2. The preliminary mixed material is put into an extruder and extruded at a controlled temperature (90° C.), and the powder coating product is obtained after tableting, cooling, crushing, screening and packaging.

[0051] Example 2

[0052] A high-adhesion, corrosion-resistant powder coating, the 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. The modified nano-silica A is grafted with a phosphate group, and the modified nano-silica B is grafted with a fluorine-containing group. The mass ratio of the modified nano-silica A to the modified nano-silica B is 3:1.

[0055] The preparation method of the modified nano-silicon dioxide A comprises:

[0056] S1. Surface pretreatment: Add nano-silica A to ethanol, disperse by ultrasound for 25 minutes, then add γ-glycidyloxypropyltrimethoxysilane, and stir and react at 75°C for 2.5 hours to complete the surface pretreatment of nano-silica A; wherein the mass ratio of nano-silica A to ethanol is 1:12.5, the mass ratio of nano-silica A to γ-glycidyloxypropyltrimethoxysilane is 1:0.075, and the particle size of nano-silica A is 40 nm;

[0057] S2, grafting phosphate groups: adding dibutyl phosphate and triethylamine to the pretreated nano-silica A, reacting at 110° C. and stirring at 400 rpm for 5 hours, thereby completing the grafting of the surface of the nano-silica A; wherein the mass ratio of the nano-silica A to dibutyl phosphate is 1:0.25, and the mass ratio of the nano-silica A to triethylamine is 1:0.015;

[0058] S3. Post-treatment: After the grafting reaction is completed, the product is washed with deionized water for 4 times, and then vacuum dried at 85° C. to a constant weight to obtain modified nano-silica A.

[0059] The preparation method of the modified nano silicon dioxide B comprises:

[0060] X1. Surface pretreatment: Add nano-silica B to toluene, stir for 30 minutes, then add γ-aminopropyltriethoxysilane, stir and react at 75°C for 2.5 hours, thereby completing the surface pretreatment of nano-silica B; wherein 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 fluorine-containing groups: adding perfluorooctyltriethoxysilane and dibutyltin dilaurate to the pretreated nano-silica B, reacting at 85°C and controlling the stirring speed at 300 rpm for 6 hours, thereby completing the grafting of the surface of the nano-silica B; wherein the mass ratio of the nano-silica B to the perfluorooctyltriethoxysilane is 1:0.3, and the mass ratio of the nano-silica B to the dibutyltin dilaurate is 1:0.02;

[0062] X3. Post-treatment reaction: After the grafting reaction is completed, the product is washed with anhydrous ethanol for 5 times 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: adding modified nano silicon dioxide A and modified nano silicon dioxide B into a high-speed mixer according to a mass ratio, stirring at a speed of 1000 rpm for 20 minutes, and obtaining the composite modified filler.

[0064] The preparation method of the modified epoxy resin is as follows: bisphenol A epoxy resin and aminosilane coupling agent are mixed in a mass ratio of 10:1.5, and 0.35% of dibutyltin dilaurate by mass of the bisphenol A epoxy resin is added, and the mixture is reacted at 130° C. for 4 hours; after the reaction is completed, the product is subjected to reduced pressure 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 comprises the following steps:

[0066] Y1. Evenly mix the modified epoxy resin, the composite modified filler, dicyandiamide, EFKA-3777, BYK-163, benzoin and sodium fluoride to obtain a preliminary mixed material;

[0067] Y2. The preliminary mixed material is put into an extruder and extruded at a controlled temperature (90°C). After tableting, cooling, crushing, screening and packaging, the finished powder coating product is obtained.

[0068] Example 3

[0069] A high-adhesion, corrosion-resistant 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. The modified nano-silica A is grafted with a phosphate group, and the modified nano-silica B is grafted with a fluorine-containing group. The mass ratio of the modified nano-silica A to the modified nano-silica B is 3.5:1.

[0072] The preparation method of the modified nano-silicon dioxide A comprises:

[0073] S1. Surface pretreatment: Add nano-silica A to ethanol, use ultrasonic dispersion for 30 minutes, then add γ-glycidyloxypropyltrimethoxysilane, and stir and react at 80°C for 3 hours to complete the surface pretreatment of nano-silica A; wherein the mass ratio of nano-silica A to ethanol is 1:15, the mass ratio of nano-silica A to γ-glycidyloxypropyltrimethoxysilane is 1:0.1, and the particle size of nano-silica A is 50 nm;

[0074] S2, grafting phosphate groups: adding dibutyl phosphate and triethylamine to the pretreated nano-silica A, reacting at 120° C. and stirring at 300 rpm for 6 hours, thereby completing the grafting of the surface of the nano-silica A; wherein the mass ratio of the nano-silica A to dibutyl phosphate is 1:0.3, and the mass ratio of the nano-silica A to triethylamine is 1:0.02;

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

[0076] The preparation method of the modified nano silicon dioxide B comprises:

[0077] X1. Surface pretreatment: Add nano-silica B to toluene, stir for 40 minutes, then add γ-aminopropyltriethoxysilane, stir and react at 80°C for 3 hours, thereby completing the surface pretreatment of nano-silica B; wherein 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 fluorine-containing groups: adding perfluorooctyltriethoxysilane and dibutyltin dilaurate to the pretreated nano-silica B, reacting at 90°C and controlling the stirring speed at 200 rpm for 7 hours, thereby completing the grafting of the surface of the nano-silica B; wherein the mass ratio of the nano-silica B to the perfluorooctyltriethoxysilane is 1:0.35, and the mass ratio of the nano-silica B to the dibutyltin dilaurate is 1:0.03;

[0079] X3. Post-treatment reaction: After the grafting reaction is completed, the product is washed with anhydrous ethanol for 6 times 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: adding modified nano silicon dioxide A and modified nano silicon dioxide B into a high-speed mixer according to a mass ratio, stirring at a speed of 800 rpm for 25 minutes, and obtaining the composite modified filler.

[0081] The preparation method of the modified epoxy resin is as follows: bisphenol A epoxy resin and aminosilane coupling agent are mixed in a mass ratio of 10:2, and 0.5% of dibutyltin dilaurate by mass of the bisphenol A epoxy resin is added, and the mixture is reacted at 140° C. for 5 hours; after the reaction is completed, the product is subjected to reduced pressure distillation at 100° C. for 2 hours, and then cooled to room temperature to obtain the modified epoxy resin.

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

[0083] Y1. Evenly mix the modified epoxy resin, the composite modified filler, dicyandiamide, EFKA-3777, BYK-163, benzoin and sodium fluoride to obtain a preliminary mixed material;

[0084] Y2. The preliminary mixed material is put into an extruder and extruded at a controlled temperature (90°C). After tableting, cooling, crushing, screening and packaging, the finished powder coating product 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 by an equal amount of nano-silicon dioxide.

[0089] Comparative Example 3

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

[0091] Comparative Example 4

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

[0093] Comparative Example 5

[0094] The difference from Example 2 is that the composite modified filler only contains modified nano-silicon dioxide B, and does not contain modified nano-silicon dioxide 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 for testing. First, use sandpaper to polish the surface of the steel plate. After polishing, put the steel plate into acetone and anhydrous ethanol for ultrasonic cleaning in turn. Each cleaning time is 15 minutes. After cleaning, place the steel plate in a drying oven and dry it at 80°C for 30 minutes for use.

[0098] Step 2: Under the same spraying pressure setting of 0.4 MPa, the powder coating products prepared in Examples 1-3 and Comparative Examples 1-5 were sprayed on standard test plates preheated in an oven at 180°C for 15 minutes by high-voltage electrostatic spraying. During the spraying process, the distance between the spray gun and the test plate was kept at 20 cm, and the spray gun was moved at a constant speed to ensure uniform coverage of the coating. The thickness of the sprayed coating was about 100 μm.

[0099] Step 3: After spraying, quickly place the coated test board into a curing oven, set the curing temperature to 200°C, and the curing time to 15 minutes. After curing, take out the test board and cool it naturally to room temperature to obtain a test sample.

[0100] The test sample is tested using the following test method:

[0101] (1) Adhesion test: According to GB / T 9286-1998, the cross-hatch method is used. A sharp blade is used to scratch 100 small squares on a metal test piece coated with powder coating. The test piece is then taped with special adhesive tape and quickly torn off. The peeling of the coating 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 is placed in a salt spray test chamber at a temperature of 35°C and a salt solution concentration of 5%. The spray is continuously applied and the time when corrosion (such as rust, blistering, etc.) occurs on the sample is recorded.

[0103] (3) Surface roughness test: Use a white light interferometer to measure the surface roughness of the test sample coating. Select 9 different positions on each sample for measurement, namely the upper left corner, upper middle, upper right corner, left middle, center, right middle, lower left corner, lower middle, and lower right corner of the sample. After the measurement is completed, take the average value of the measured values ​​of these 9 positions to obtain the average roughness (Ra) in μm.

[0104] (4) Impact resistance test: According to GB / T 1732-1993, the impact resistance of the coating is tested using an impact tester. During the test, a heavy hammer of specified mass is allowed to fall freely from different heights to impact the sample coated with powder coating, and the impact energy (unit: kg·cm) is used as a quantitative indicator to evaluate the impact resistance of the coating. The impact energy is calculated by multiplying the mass of the heavy hammer by the drop height. The impact resistance data represents the maximum impact energy value that the coating can withstand without being damaged (such as cracking, falling off, etc.). The larger the value, the better the impact resistance of the coating.

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

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

[0107] Table 1

[0108]

[0109] The adhesion of Examples 1-3 is all level 0, indicating that the bonding force between the coating and the metal substrate is extremely strong and can effectively resist external impact and vibration. The adhesion of Comparative Examples 1-5 is poor, especially Comparative Example 1 (without adding sodium fluoride) and Comparative Example 2 (without adding composite modified filler), the adhesion is significantly reduced, indicating that sodium fluoride and composite modified filler play an important role in improving adhesion.

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

[0111] The surface roughness of Examples 1-3 is relatively low, indicating that the coating surface is smooth, which is beneficial to improving the corrosion resistance and aesthetics of the coating. The surface roughness of Comparative Examples 1-5 is relatively high, especially Comparative Example 3 (without adding modified epoxy resin and BYK-163) is the highest, indicating that the aminosilane coupling agent is used to modify the epoxy resin in a directional manner, introduce amino functional groups, enhance the hydrogen bond interaction between the resin and the phosphate-based filler, and utilize the synergistic dispersion effect of the dispersant (BYK-163) to make a high proportion of inorganic fillers uniformly dispersed in the organic resin, avoid phase separation, ensure the synergistic effect of the various components of the coating, and help improve the comprehensive performance of the coating.

[0112] The impact resistance of Examples 1-3 is good, indicating that the coating has good mechanical properties. The impact resistance of Comparative Examples 1-5 is poor, indicating that the composite modified filler, sodium fluoride, modified epoxy resin and BYK-163 play an important role in improving the impact resistance.

[0113] The chemical resistance of Examples 1-3 is good, indicating that the coating can effectively resist the erosion of chemical media. The chemical resistance of Comparative Examples 1-5 is poor, indicating that the composite modified filler, sodium fluoride, modified epoxy resin and BYK-163 play an important role in improving the chemical resistance.

[0114] The high-adhesion corrosion-resistant powder coating provided by the present invention introduces the synergistic effect of sodium fluoride and the composite modified filler, and introduces the modified epoxy resin and BYK-163 to make the inorganic filler uniformly dispersed in the organic resin to avoid phase separation, thereby significantly improving the adhesion, corrosion resistance, surface smoothness, impact resistance and chemical resistance of the coating. The test results of Examples 1-3 show that the powder coating is superior to Comparative Examples 1-5 in terms of adhesion, corrosion resistance, surface roughness, impact resistance and chemical resistance, especially in a marine environment with high humidity and high salinity or a chemical production environment, and can effectively protect the metal from corrosion, meeting the application scenarios with high requirements for coating performance such as outdoor large-scale steel structures and marine engineering equipment. Therefore, the present invention has important practical significance and market demand.

[0115] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A high-adhesion, corrosion-resistant powder coating, characterized in that: The powder coating comprises the following raw materials in parts by weight:

2. The high-adhesion, corrosion-resistant powder coating according to claim 1, characterized in that: The composite modified filler comprises modified nano-silicon dioxide A and modified nano-silicon dioxide B, wherein the modified nano-silicon dioxide A is grafted with a phosphate group, and the modified nano-silicon dioxide B is grafted with a fluorine-containing group, and the mass ratio of the modified nano-silicon dioxide A to the modified nano-silicon dioxide B is (2.5-3.5):1; The preparation method of the composite modified filler is to put the modified nano silicon dioxide A and the modified nano silicon dioxide B into a high-speed mixer according to the mass ratio, and stir them 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-silicon dioxide A comprises: S1. Surface pretreatment: Add nano-silica A to ethanol, use ultrasonic dispersion for 20-30 minutes, then add γ-glycidyloxypropyltrimethoxysilane, and stir and react at 70-80° C. for 2-3 hours to complete the surface pretreatment of nano-silica A; wherein the mass ratio of the nano-silica A to the ethanol is 1:(10-15), and the mass ratio of the nano-silica A to the γ-glycidyloxypropyltrimethoxysilane is 1:(0.05-0.1); S2, grafting phosphate groups: adding dibutyl phosphate and triethylamine to the pretreated nano-silicon dioxide A, reacting at 100-120° C. and stirring at 300-500 rpm for 4-6 hours, thereby completing the grafting of the surface of the nano-silicon dioxide A; wherein the mass ratio of the nano-silicon dioxide A to dibutyl phosphate is 1:(0.2-0.3), and the mass ratio of the nano-silicon dioxide 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 for 3-5 times, and then vacuum dried at 80-90° C. 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 silicon dioxide B comprises: X1. Surface pretreatment: Add nano-silica B to toluene, stir for 30-40 minutes, then add γ-aminopropyltriethoxysilane, stir and react at 70-80° C. for 2-3 hours, thereby completing the surface pretreatment of nano-silica B; wherein the mass ratio of the nano-silica B to toluene is 1:(12-18), and the mass ratio of the nano-silica B to γ-aminopropyltriethoxysilane is 1:(0.06-0.12); X2. Grafting fluorine-containing groups: adding perfluorooctyl triethoxysilane and dibutyltin dilaurate to the pretreated nano-silica B, reacting at 80-90° C. and controlling the stirring speed at 200-400 rpm for 5-7 hours, thereby completing the grafting of the nano-silica surface; wherein the mass ratio of the nano-silica B to perfluorooctyl triethoxysilane is 1:(0.25-0.35), and the mass ratio of the 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 for 4-6 times, and then vacuum dried at 75-85°C 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-silicon dioxide A and the nano-silicon dioxide B is 30-60 nm.

6. The high-adhesion, corrosion-resistant powder coating according to claim 1, characterized in that: The preparation method of the modified epoxy resin is as follows: bisphenol A epoxy resin and aminosilane coupling agent are mixed according to a mass ratio of 10:(1-2), and 0.2%-0.5% of dibutyltin dilaurate by mass of the bisphenol A epoxy resin is added, and the mixture is reacted at 120-140° C. for 3-5 hours; after the reaction is completed, the product is subjected to reduced pressure distillation at 80-100° C. for 1-2 hours, and then cooled to room temperature to obtain the modified epoxy resin.

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

8. The method for preparing a high-adhesion, corrosion-resistant powder coating according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: Y1. Evenly mix the modified epoxy resin, the composite modified filler, the curing agent, the leveling agent, the benzoin, the dispersant and the sodium fluoride to obtain a preliminary mixed material; Y2. The preliminary mixed material is put into the extruder for temperature-controlled extrusion, and the powder coating product is obtained through tableting, cooling, crushing, screening and packaging.

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