Phenolic resin-based heavy-duty anti-corrosion anti-scale antibacterial coating and preparation method thereof

Abstract

The invention provides a phenolic resin-based heavy-duty anti-corrosion and anti-scaling antibacterial coating and a preparation method thereof, and relates to the technical field of multifunctional coatings, the phenolic resin-based heavy-duty anti-corrosion and anti-scaling antibacterial coating comprises a layer A and a layer B. The layer A comprises an agent A. The agent A comprises the following raw materials in parts by mass: 95-115 parts of phenolic resin powder, 2-5 parts of polydopamine coated zinc powder, 1-3 parts of nano anti-corrosion filler and 1-2 parts of graphene nanosheets, and the layer B comprises an agent B. The agent A comprises the following raw materials in parts by mass: 1-3 parts of nano anti-corrosion filler and 1-2 parts of graphene nanosheets. The agent B is prepared from the following raw materials in parts by mass: 90-110 parts of phenolic resin powder, 5-10 parts of polydimethylsiloxane, 2-4 parts of a bacteriostatic agent, 3-4 parts of nano silicon dioxide grafted cetyltrimethylammonium bromide and 1-3 parts of mica powder; and the layer A is covered with the layer B. The preparation method has the beneficial effect that the synchronous breakthrough of the carbon steel protective coating in the core performances of corrosion prevention, scale prevention, bacteriostasis and the like is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of multifunctional coating, and particularly relates to a heavy-duty anticorrosive and antifouling antibacterial coating based on phenolic resin and a preparation method thereof. BACKGROUND

[0002] Multifunctional protective coating technology has important application value in the fields of marine engineering, petrochemical industry and energy equipment, especially plays a key role in the long-term protection of carbon steel structures. This kind of coating needs to simultaneously solve the problems of metal substrate corrosion, inorganic scale deposition and microbial fouling, and its performance is directly related to the safe operation period and maintenance cost of industrial facilities. With the increasing requirements of extreme service environment on material protection, developing an integrated coating system with efficient corrosion resistance, persistent scale resistance and broad-spectrum antibacterial function has become an urgent need for the development of the technology in this field.

[0003] The current mainstream protective coating mostly uses a single functional material system. For example, although the zinc-rich epoxy coating has good corrosion resistance, it lacks antibacterial and antifouling ability. The added antifouling coating often causes the deterioration of corrosion resistance due to poor dispersion of fillers. The more prominent contradiction is that the traditional technology cannot realize multifunctional synergy in harsh environments. There is a performance antagonism between corrosion-resistant components and antibacterial and antifouling components, such as that the corrosion inhibitor accelerates the reproduction of microorganisms and the antifouling agent weakens the adhesion of the coating. At the same time, high temperature and humidity environment easily causes the delamination and peeling of the coating, and the common attachment of inorganic scale and biofilm further aggravates the protection failure. The existing technology has always been unable to break through the functional balance bottleneck of corrosion resistance, antifouling and antibacterial, and cannot meet the long-term and stable protection requirements under complex working conditions.

[0004] How to solve the above technical problems is the subject faced by the present application. SUMMARY

[0005] In order to solve the problems of the prior art, the present application provides a heavy-duty anticorrosive and antifouling antibacterial coating based on phenolic resin and a preparation method thereof, which can realize the simultaneous breakthrough of the core performances such as corrosion resistance, antifouling and antibacterial of the carbon steel protective coating.

[0006] The technical scheme adopted by the present application to solve the technical problems is that the present application provides a heavy-duty anticorrosive and antifouling antibacterial coating based on phenolic resin, which comprises an A layer and a B layer. The A layer comprises an A agent, and the A agent comprises the following raw materials in parts by mass: 95-115 parts of phenolic resin powder, 2-5 parts of polydopamine coated zinc powder, 1-3 parts of nanometer anticorrosive filler and 1-2 parts of graphene nanosheet. The B layer comprises a B agent, and the B agent comprises the following raw materials in parts by mass: 90-110 parts of phenolic resin powder, 5-10 parts of polydimethylsiloxane, 2-4 parts of antibacterial agent, 3-4 parts of nanometer silica grafted hexadecyl trimethyl ammonium bromide and 1-3 parts of mica powder. The B layer is covered on the A layer.

[0007] The polydopamine-coated zinc powder coating layer has a thickness of 10-50 nm, and the zinc powder has a particle size of 1-5 μm.

[0008] The nano-corrosion-preventing filler is benzotriazole-modified nano-silicon dioxide, the modification grafting rate is 18-28%, and the silicon dioxide has a particle size of 20-100 nm.

[0009] The bacteriostatic agent is silver-doped zinc oxide powder, the silver doping amount is 0.5-1.5 wt%, and the particle size is 50-200 nm.

[0010] The thickness ratio of the A layer to the B layer is (1.25-1.6):1.

[0011] A preparation method of a phenolic resin-based heavy-duty corrosion-preventing and scale-preventing bacteriostatic coating, comprising the following steps: S1, 95-115 parts of phenolic resin powder, 2-5 parts of polydopamine-coated zinc powder, 1-3 parts of benzotriazole-modified nano-silicon dioxide, 1-2 parts of graphene nanosheet, and 90-110 parts of phenolic resin powder, 5-10 parts of polydimethylsiloxane, 2-4 parts of silver-doped zinc oxide powder, 3-4 parts of nano-silicon dioxide grafted hexadecyltrimethylammonium bromide, and 1-3 parts of mica powder are respectively crushed to 20-80 μm by using a mechanical crushing device; S2, the pretreated substrate surface after S1 is cleaned and dried, the spray gun is 15-25 cm away from the substrate, A agent is first uniformly sprayed on the substrate to a thickness of 50-80 μm, and then B agent is sprayed to a thickness of 30-60 μm under the same spraying process parameters; S3, the sprayed substrate is placed in an oven, heated to 110-120℃ at a rate of 5-8℃ / min, and kept for 15-25 min to make the coating layer fully melt; S4, the coating is slowly cooled to room temperature to form a dense, uniform multifunctional coating.

[0012] The spraying in S2 uses electrostatic spraying at 40-60 kV.

[0013] The polydopamine-coated zinc powder is prepared by the following steps: Under stirring conditions, dopamine hydrochloride is dissolved in 10 mM Tris buffer with a pH of 8.0-9.0 to prepare a 2 mg / mL solution, poured into a clean container, and then zinc powder is added under stirring conditions to a concentration of 1 mg / mL. Stirring is carried out under constant temperature conditions of 30-60℃ for 10-15 hours. After the reaction is completed, the composite particles are obtained by suction filtration, washed with deionized water three times, and dried to obtain polydopamine-coated zinc powder.

[0014] The benzotriazole-modified nano-silica is prepared through the following steps: Under constant temperature conditions of 25℃, 1 g of hydrophilic nano-silica was first dispersed in 200 mL of anhydrous ethanol and ultrasonicated at 300 W for 30 min to obtain a uniform suspension. Subsequently, 40 mL of ethanol solution containing 0.2 g of benzotriazole (BTA) was added dropwise to the suspension over 10 min with continuous mechanical stirring at 300 rpm, while maintaining the pH of the system between 6 and 7. After the addition was complete, the reaction was continued with constant temperature stirring for 12 hours. During this process, benzotriazole molecules were firmly adsorbed onto the silica surface mainly through hydrogen bonding. After the reaction was completed, the product was separated by centrifugation at 8000 rpm for 10 minutes and washed three times with fresh anhydrous ethanol to remove physically adsorbed impurities. Finally, the obtained solid was dried in a vacuum drying oven at 50℃ for 6 h to obtain benzotriazole-silica composite particles.

[0015] The nano-silica grafted with hexadecyltrimethylammonium bromide is prepared by the following steps: First, nano-silica was vacuum dried at 100℃ for 2 h to activate the surface hydroxyl groups. Then, it was ultrasonically dispersed in anhydrous ethanol, and 3 wt% KH-550γ-aminopropyltriethoxysilane was added. The mixture was stirred and refluxed at 70℃ for 6 h to hydrolyze and condense KH-550 onto the SiO2 surface, forming amino-functionalized SiO2-NH2. Then, 0.5 g of SiO2-NH2 was dispersed in 30 mL of anhydrous DMF, and 0.3 g of hexadecyltrimethylammonium bromide was added. The mixture was stirred at 80℃ for 10-15 h to carry out a quaternization reaction, so that CTAB was covalently grafted onto the SiO2 surface. The reaction product was centrifuged, washed, and dried to obtain CTAB-modified SiO2-CTAB.

[0016] The beneficial effects of this invention are as follows: Through the functional layering design of agent A and agent B and the synergistic effect of key components, this invention achieves simultaneous breakthroughs in the core performance of carbon steel protective coatings in terms of corrosion prevention, scale prevention, and antibacterial properties. The coating exhibits excellent mechanical properties and environmental durability, including excellent adhesion, impact strength, and hardness stability. It maintains structural integrity even after long-term exposure to harsh environments. Compared with traditional epoxy coatings, this coating significantly extends the protective life of the substrate in corrosive media, effectively reduces the corrosion tendency and rate of the metal substrate, and exhibits more durable protective performance.

[0017] In Agent A, polydopamine-coated zinc powder provides active protection through a controlled release mechanism, while benzotriazole-modified nano-silica forms a dense passivation film at the metal interface, and graphene nanosheets provide physical barrier function. The synergistic effect of these three components significantly enhances the coating's cathodic protection, corrosion inhibitor targeting, and media shielding capabilities, resulting in a more stable protective system in corrosive environments. This synergistic mechanism greatly improves the coating's impermeability and interfacial stability, effectively inhibiting the occurrence and development of localized corrosion. In Agent B, nano-silica grafted with hexadecyltrimethylammonium bromide achieves long-lasting antibacterial properties through molecular structure design, while silver-doped zinc oxide enhances the microbial inhibition effect through multiple mechanisms. The synergistic effect of these two components significantly reduces the adhesion and reproduction of microorganisms on the coating surface. Simultaneously, the low surface energy of polydimethylsiloxane and the synergistic effect of the hydrophobic segments of the grafted molecules endow the coating with excellent surface anti-adhesion properties, effectively hindering the deposition and growth of inorganic scale. This coupling of anti-scaling and antibacterial functions allows the coating to maintain long-term cleanliness in complex environments where biofouling and scaling coexist.

[0018] The interpenetrating network structure formed by the curing of AB agent enables the coating to maintain stable performance under a wide range of acid and alkaline environments and high temperature conditions, providing a more reliable full-cycle protection solution for industrial equipment and demonstrating outstanding engineering practical value. Attached Figure Description

[0019] Fig. 1 This is a test graph showing the anti-scaling rate (%) of the coating of the present invention against calcium carbonate.

[0020] Fig. 2 This is a test graph showing the anti-scaling rate (%) of the coating of the present invention against magnesium carbonate.

[0021] Fig. 3 This is a test graph showing the anti-scaling rate (%) of the coating of the present invention against barium sulfate.

[0022] Fig. 4 This is a test graph showing the anti-scaling rate (%) of the coating of the present invention against strontium sulfate. Detailed Implementation

[0023] To clearly illustrate the technical features of this solution, the following detailed implementation method will be used to explain the solution.

[0024] Example 1 This embodiment is a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating, including layer A and layer B. Layer A includes agent A, which includes the following raw materials in parts by weight: 100 parts phenolic resin powder, 3 parts polydopamine-coated zinc powder, 2 parts benzotriazole-modified nano silica, and 1.5 parts graphene nanosheets. The B layer includes agent B, which comprises the following raw materials in parts by weight: 100 parts phenolic resin powder, 8 parts polydimethylsiloxane, 3 parts silver-doped zinc oxide powder, 3 parts nano-silica grafted hexadecyltrimethylammonium bromide, and 1 part mica powder. Layer B covers layer A.

[0025] Preferably, the polydopamine-coated zinc powder coating layer has a thickness of 25 nm and the zinc powder particle size is 2.5 μm.

[0026] Preferably, the benzotriazole-modified nano-silica has a grafting rate of 22% and a silica particle size of 65 nm.

[0027] Preferably, the silver-doped zinc oxide powder has a silver doping amount of 1.1 wt% and a particle size of 120 nm.

[0028] Preferably, the polydopamine-coated zinc powder is prepared by the following steps: Under stirring conditions, dopamine hydrochloride was dissolved in 10 mM Tris buffer at pH 8.5 to prepare a 2 mg / mL solution, which was then poured into a clean container. Zinc powder was then added under stirring conditions to a concentration of 1 mg / mL. The mixture was stirred at a constant temperature of 45°C for 12 hours. After the reaction was completed, the composite particles were obtained by filtration, washed three times with deionized water, and dried to obtain polydopamine-coated zinc powder.

[0029] Preferably, the benzotriazole-modified nano-silica is prepared by the following steps: Under constant temperature conditions of 25℃, 1 g of hydrophilic nano-silica was first dispersed in 200 mL of anhydrous ethanol and ultrasonicated at 300 W for 30 min to obtain a uniform suspension. Subsequently, 40 mL of ethanol solution containing 0.2 g of benzotriazole (BTA) was added dropwise to the suspension over 10 min with continuous mechanical stirring at 300 rpm, while maintaining the pH of the system between 6 and 7. After the addition was complete, the reaction was continued with constant temperature stirring for 12 hours. During this process, benzotriazole molecules were firmly adsorbed onto the silica surface mainly through hydrogen bonding. After the reaction was completed, the product was separated by centrifugation at 8000 rpm for 10 minutes and washed three times with fresh anhydrous ethanol to remove physically adsorbed impurities. Finally, the obtained solid was dried in a vacuum drying oven at 50℃ for 6 h to obtain benzotriazole-silica composite particles.

[0030] Preferably, the nano-silica grafted with hexadecyltrimethylammonium bromide is prepared by the following steps: First, nano-silica was vacuum dried at 100℃ for 2 h to activate the surface hydroxyl groups. Then, it was ultrasonically dispersed in anhydrous ethanol, and 3 wt% KH-550γ-aminopropyltriethoxysilane was added. The mixture was stirred and refluxed at 70℃ for 6 h to hydrolyze and condense KH-550 onto the SiO2 surface, forming amino-functionalized SiO2-NH2. Then, 0.5 g of SiO2-NH2 was dispersed in 30 mL of anhydrous DMF, and 0.3 g of hexadecyltrimethylammonium bromide was added. The mixture was stirred at 80℃ for 12 h to carry out a quaternization reaction, so that CTAB was covalently grafted onto the SiO2 surface. The reaction product was centrifuged, washed, and dried to obtain CTAB-modified SiO2-CTAB.

[0031] A method for preparing a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating includes the following steps: S1. Use a ball mill to pulverize component A and component B to 50±10 μm respectively; S2. Clean and dry the surface of the substrate after S1 pretreatment. Use 50kV electrostatic spraying with the spray gun 15-25cm away from the substrate. First, spray agent A evenly on the substrate to a thickness of 60μm. Then, under the same spraying process parameters, spray agent B to a thickness of 40μm. S3. Place the sprayed substrate in an oven and heat it to 115℃ at a rate of 5-8℃ / min. Hold the temperature for 20 minutes to allow the coating layer to fully melt. S4. Slowly cool the coating to room temperature, and finally cure it to form a dense, uniform, multifunctional coating.

[0032] The performance of Example 1 was tested, and the test showed that it had no red rust after 7200 hours of salt spray test, a bacteriostatic rate of >90%, a water contact angle of 132.7°, and scale inhibition rates of 76.4% (calcium carbonate), 78.5% (magnesium carbonate), 74.1% (barium sulfate) and 75.7% (strontium sulfate), respectively, demonstrating excellent overall performance.

[0033] Example 2 This embodiment is a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating, including layer A and layer B. Layer A includes agent A, which includes the following raw materials in parts by weight: 95 parts phenolic resin powder, 5 parts polydopamine-coated zinc powder, 3 parts benzotriazole-modified nano-silica, and 2 parts graphene nanosheets. The B layer includes agent B, which comprises the following raw materials in parts by weight: 110 parts phenolic resin powder, 10 parts polydimethylsiloxane, 4 parts silver-doped zinc oxide powder, 4 parts nano-silica grafted hexadecyltrimethylammonium bromide, and 2 parts mica powder. Layer B covers layer A.

[0034] Preferably, the polydopamine-coated zinc powder coating layer has a thickness of 25 nm and the zinc powder particle size is 2.5 μm.

[0035] Preferably, the benzotriazole-modified nano-silica has a grafting rate of 22% and a silica particle size of 65 nm.

[0036] Preferably, the silver-doped zinc oxide powder has a silver doping amount of 1.1 wt% and a particle size of 120 nm.

[0037] Preferably, the polydopamine-coated zinc powder is prepared by the following steps: Under stirring conditions, dopamine hydrochloride was dissolved in 10 mM Tris buffer at pH 8.5 to prepare a 2 mg / mL solution, which was then poured into a clean container. Zinc powder was then added under stirring conditions to a concentration of 1 mg / mL. The mixture was stirred at a constant temperature of 45°C for 12 hours. After the reaction was completed, the composite particles were obtained by filtration, washed three times with deionized water, and dried to obtain polydopamine-coated zinc powder.

[0038] Preferably, the benzotriazole-modified nano-silica is prepared by the following steps: Under constant temperature conditions of 25℃, 1 g of hydrophilic nano-silica was first dispersed in 200 mL of anhydrous ethanol and ultrasonicated at 300 W for 30 min to obtain a uniform suspension. Subsequently, 40 mL of ethanol solution containing 0.2 g of benzotriazole (BTA) was added dropwise to the suspension over 10 min with continuous mechanical stirring at 300 rpm, while maintaining the pH of the system between 6 and 7. After the addition was complete, the reaction was continued with constant temperature stirring for 12 hours. During this process, benzotriazole molecules were firmly adsorbed onto the silica surface mainly through hydrogen bonding. After the reaction was completed, the product was separated by centrifugation at 8000 rpm for 10 minutes and washed three times with fresh anhydrous ethanol to remove physically adsorbed impurities. Finally, the obtained solid was dried in a vacuum drying oven at 50℃ for 6 h to obtain benzotriazole-silica composite particles.

[0039] Preferably, the nano-silica grafted with hexadecyltrimethylammonium bromide is prepared by the following steps: First, nano-silica was vacuum dried at 100℃ for 2 h to activate the surface hydroxyl groups. Then, it was ultrasonically dispersed in anhydrous ethanol, and 3 wt% KH-550γ-aminopropyltriethoxysilane was added. The mixture was stirred and refluxed at 70℃ for 6 h to hydrolyze and condense KH-550 onto the SiO2 surface, forming amino-functionalized SiO2-NH2. Then, 0.5 g of SiO2-NH2 was dispersed in 30 mL of anhydrous DMF, and 0.3 g of hexadecyltrimethylammonium bromide was added. The mixture was stirred at 80℃ for 12 h to carry out a quaternization reaction, so that CTAB was covalently grafted onto the SiO2 surface. The reaction product was centrifuged, washed, and dried to obtain CTAB-modified SiO2-CTAB.

[0040] A method for preparing a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating includes the following steps: S1. Pulverize component A and component B to 30±5μm using a ball mill at 350 rpm; S2. Clean and dry the substrate surface after S1 pretreatment. Use 45 kV electrostatic spraying with the spray gun 15-25cm away from the substrate. First, spray agent A evenly on the substrate to a thickness of 50μm. Then, under the same spraying process parameters, spray agent B to a thickness of 60μm. S3. Place the sprayed substrate in an oven and heat it to 120°C at a rate of 5-8°C / min. Hold the temperature for 25 minutes to allow the coating layer to fully melt. S4. Slowly cool the coating to room temperature, and finally cure it to form a dense, uniform, multifunctional coating.

[0041] The performance of Example 2 was tested, and its antibacterial rate was >90%, salt spray durability was 7200 hours, hydrophobic angle was 133.4°, and scale inhibition rates reached 77.1% (calcium carbonate), 79.3% (magnesium carbonate), 75.3% (barium sulfate) and 76.6% (strontium sulfate), respectively.

[0042] Example 3 This embodiment is a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating, including layer A and layer B. Layer A includes agent A, which includes the following raw materials in parts by weight: 115 parts phenolic resin powder, 2 parts polydopamine-coated zinc powder, 1 part benzotriazole-modified nano silica, and 1 part graphene nanosheets. The B layer includes agent B, which comprises the following raw materials in parts by weight: 90 parts phenolic resin powder, 5 parts polydimethylsiloxane, 2 parts silver-doped zinc oxide powder, 3 parts nano-silica grafted hexadecyltrimethylammonium bromide, and 3 parts mica powder. Layer B covers layer A.

[0043] Preferably, the polydopamine-coated zinc powder coating layer has a thickness of 25 nm and the zinc powder particle size is 2.5 μm.

[0044] Preferably, the benzotriazole-modified nano-silica has a grafting rate of 22% and a silica particle size of 65 nm.

[0045] Preferably, the silver-doped zinc oxide powder has a silver doping amount of 1.1 wt% and a particle size of 120 nm.

[0046] Preferably, the polydopamine-coated zinc powder is prepared by the following steps: Under stirring conditions, dopamine hydrochloride was dissolved in 10 mM Tris buffer at pH 8.5 to prepare a 2 mg / mL solution, which was then poured into a clean container. Zinc powder was then added under stirring conditions to a concentration of 1 mg / mL. The mixture was stirred at a constant temperature of 45°C for 12 hours. After the reaction was completed, the composite particles were obtained by filtration, washed three times with deionized water, and dried to obtain polydopamine-coated zinc powder.

[0047] Preferably, the benzotriazole-modified nano-silica is prepared by the following steps: Under constant temperature conditions of 25℃, 1 g of hydrophilic nano-silica was first dispersed in 200 mL of anhydrous ethanol and ultrasonicated at 300 W for 30 min to obtain a uniform suspension. Subsequently, 40 mL of ethanol solution containing 0.2 g of benzotriazole (BTA) was added dropwise to the suspension over 10 min with continuous mechanical stirring at 300 rpm, while maintaining the pH of the system between 6 and 7. After the addition was complete, the reaction was continued with constant temperature stirring for 12 hours. During this process, benzotriazole molecules were firmly adsorbed onto the silica surface mainly through hydrogen bonding. After the reaction was completed, the product was separated by centrifugation at 8000 rpm for 10 minutes and washed three times with fresh anhydrous ethanol to remove physically adsorbed impurities. Finally, the obtained solid was dried in a vacuum drying oven at 50℃ for 6 h to obtain benzotriazole-silica composite particles.

[0048] Preferably, the nano-silica grafted with hexadecyltrimethylammonium bromide is prepared by the following steps: First, nano-silica was vacuum dried at 100℃ for 2 h to activate the surface hydroxyl groups. Then, it was ultrasonically dispersed in anhydrous ethanol, and 3 wt% KH-550γ-aminopropyltriethoxysilane was added. The mixture was stirred and refluxed at 70℃ for 6 h to hydrolyze and condense KH-550 onto the SiO2 surface, forming amino-functionalized SiO2-NH2. Then, 0.5 g of SiO2-NH2 was dispersed in 30 mL of anhydrous DMF, and 0.3 g of hexadecyltrimethylammonium bromide was added. The mixture was stirred at 80℃ for 12 h to carry out a quaternization reaction, so that CTAB was covalently grafted onto the SiO2 surface. The reaction product was centrifuged, washed, and dried to obtain CTAB-modified SiO2-CTAB.

[0049] A method for preparing a phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating includes the following steps: S1. Pulverize component A and component B to 70±10μm using a ball mill at 450 rpm; S2. Clean and dry the surface of the substrate after S1 pretreatment. Use 60 kV electrostatic spraying with the spray gun 15-25cm away from the substrate. First, spray agent A evenly on the substrate to a thickness of 80μm. Then, under the same spraying process parameters, spray agent B to a thickness of 30μm. S3. Place the sprayed substrate in an oven and heat it to 110℃ at a rate of 5-8℃ / min. Hold the temperature for 15 minutes to allow the coating layer to fully melt. S4. Slowly cool the coating to room temperature, and finally cure it to form a dense, uniform, multifunctional coating.

[0050] The performance of Example 3 was tested, and the test results showed that it could withstand salt spray for 7200 hours, had an antibacterial rate of >90%, a hydrophobic angle of 129.6°, and scale inhibition rates of 75.6% (calcium carbonate), 77.9% (magnesium carbonate), 73.0% (barium sulfate) and 74.5% (strontium sulfate), respectively.

[0051] Comparative Example Traditional epoxy coatings, which are mainly composed of epoxy resin, rust after 2100 hours of salt spray testing, with an antibacterial rate of less than 30% and scaling inhibition rates of 50.5% (calcium carbonate), 53.1% (magnesium carbonate), 45.9% (barium sulfate), and 48.2% (strontium sulfate), respectively. Their performance is significantly lower than that of the embodiments of the present invention, highlighting the technical advantages of the present invention in component synergy and process optimization.

[0052] Performance testing: See Table 1 for the basic performance tests of the coating of this patent.

[0053] Impact resistance test: First, place the coating samples of the examples and comparative examples with the paint film facing upwards on the hemispherical die of the impact tester. After fixing, raise a 1 kg weight to the specified height, and then release the weight to allow it to fall freely, impacting the test plate on the die and forming a dent. Immediately after the impact, remove the test plate and use a 4x magnifying glass to check whether the coating in the dented area shows any damage such as cracks, wrinkles, or peeling. By repeatedly testing at different heights or changing the weight, the maximum impact energy that the coating can withstand is finally determined. The results are expressed in kilogram-centimeter (kg·cm). The higher the value, the better the impact resistance of the coating.

[0054] Adhesion testing: First, using a multi-blade cutting tool with specified spacing, cut two sets of mutually perpendicular parallel lines on the coating surface of the example and comparative examples with stable pressure and uniform speed, forming a regular grid array. Then, gently sweep the grid area along the diagonal direction with a soft brush to remove loose coating debris. Next, firmly adhere the special pressure-sensitive tape to the grid and press it firmly to ensure full contact with the coating. Finally, holding one end of the tape, smoothly and quickly peel it off at an angle as close to 180° as possible within 1 to 2 seconds. Immediately compare the grid area with the tape with the standard grade chart to determine the adhesion grade. "ISO grade 0" means that the cut edge is completely smooth and no grid has fallen off, indicating the best adhesion.

[0055] Vickers hardness test of coating: First, select a flat and representative area of ​​the coating in the example and comparative examples. Select an appropriate test force according to the estimated hardness. Place the sample firmly on the Vickers hardness tester platform, and align the 136° diamond square pyramid indenter vertically with the test point. Apply the selected test force smoothly and hold it for the specified time before removing it. Then, use the microscope equipped with the hardness tester to measure the precise length of the two diagonals of the indentation, take the average value, and read the Vickers hardness value by the equipment.

[0056] Salt, acid and alkali resistance tests of the coating: First, prepare corrosive media such as 5% NaCl solution, hydrochloric acid solution with pH=1, and sodium hydroxide solution with pH=13 and inject them into appropriate containers respectively. Then, vertically immerse ≥2 / 3 of the area of ​​the coating test plate in the solution and maintain a constant temperature. Observe and record the coating status regularly. After the specified time, take out the test plate, rinse it with deionized water and immediately check whether there are any damage phenomena such as blistering, discoloration, loss of gloss, wrinkling, or peeling on the coating surface. This is used to evaluate the chemical corrosion resistance of the examples and comparative examples.

[0057] Coating temperature resistance test: Place the coating test plate in a constant temperature drying oven that has been heated to 120℃, keeping the test plate at a certain distance from the oven wall to ensure uniform heating. After heating, remove the test plate and cool it to room temperature at ambient temperature. Then immediately check the coating surface for defects such as discoloration, cracking, and blistering to evaluate the heat resistance stability of the coating.

[0058] Salt spray resistance test of coating: First, prepare the example and comparative sample, clean the surface with solvent and mark it, and protect the edges. Then, prepare a 5% sodium chloride solution and adjust its pH value to the neutral range. Then, place the sample in the salt spray chamber at an angle of 15-30° to ensure that the salt spray can settle freely. Set the test chamber temperature to 35°C and adjust the spray system to stabilize the salt spray settling rate between 1.0~2.0 mL / 80cm2 / h. Then, start continuous spraying and time it. After the test reaches the specified time, take out the sample, gently rinse the surface with running water below 40°C to remove residual salt solution, and immediately dry it with low-temperature warm air. Finally, check and rate the corrosion phenomenon on the sample surface, such as blistering and rusting, according to relevant standards.

[0059] Testing of the water contact angle of the coating: First, place the coating samples of the examples and comparative examples horizontally on the sample stage, ensuring that the test surface is clean, flat and free of contamination. Then, use an automatic droplet system to deposit a 4 μL drop of ultrapure water on the sample surface. Quickly capture the side image of the droplet using an optical contact angle measuring instrument equipped with a high-resolution camera, and use the instrument to read its static contact angle value. Repeat the measurement at different positions on the sample surface at least 5 times, and the final result is given in the form of an average value.

[0060] In terms of mechanical properties, the three embodiments of this patent have flexibility (impact resistance) of 31.5 kg·cm, 31.7 kg·cm and 32.4 kg·cm respectively, which are slightly better than the comparative epoxy coating, and have excellent resistance to mechanical impact. In the examples, the adhesion of the coatings using the cross-cut adhesion test all reached the highest ISO 0 standard, the same as the epoxy coating level, and the coating bonded extremely firmly to the substrate; The Vickers hardness of the three embodiments reached 28.8 Hv, 29.4 Hv and 30.8 Hv respectively, which were higher than those of the comparative epoxy coating, showing moderate surface hardness. In environmental resistance tests, the coatings in the examples remained intact after 7200 hours of salt spray, salt solution, acid and alkali (pH=1 and 13) immersion and high temperature of 120°C, demonstrating superior chemical stability and environmental durability, far superior to epoxy coatings. In particular, the fact that the coating showed no change after 7,200 hours of neutral salt spray testing fully demonstrates its long-term protective capability in extreme environments such as marine engineering and petrochemical equipment. The coatings in the three embodiments exhibit strong hydrophobic properties, with water contact angles reaching 132.7°, 133.4°, and 129.6°, respectively. Compared with conventional epoxy resin coatings, they represent a leap from weak hydrophilicity to highly hydrophobicity. This property significantly reduces surface energy, greatly weakens the adsorption and adhesion of scale particles, grains, and microorganisms on the surface, and effectively prevents scale formation.

[0061] Table 1. Test results of basic coating properties

[0062] The corrosion resistance of the coatings in the examples and comparative examples was tested using an electrochemical workstation. The corrosive medium was a 3.5% (w / w) sodium chloride solution. Bare metal samples and coated samples with the same exposed surface area were placed in NaCl solution. The sample was used as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet as the counter electrode. All three were connected to the electrochemical workstation. The samples were stabilized at the open circuit potential for at least 30 minutes. When the potential fluctuation was less than ±2 mV / min, the test was initiated. The corrosion potential, corrosion current density, corrosion rate, and electrochemical impedance spectroscopy (EIS) data of the coatings were obtained through Tafel polarization curves and electrochemical impedance spectroscopy. The polarization curves were measured at a scan rate of 0.5 mV / s within a potential range of ±250 mV relative to the open circuit potential. The EIS test was performed with an AC amplitude of 20 mV within a frequency range of 10,000 Hz to 0.01 Hz.

[0063] As shown in Table 2, the anti-corrosion performance of the coating in this patent embodiment is significantly improved compared with the conventional epoxy coating in the comparative example. Electrochemical test results (using the average values ​​of the embodiments for comparison with the comparative example) show that the corrosion potential of the carbon steel specimen coated with this coating shifted positively from -0.587 V of the epoxy coating to -0.532 V, -0.508 V, and -0.537 V in the embodiments; simultaneously, the corrosion current density decreased significantly from 3.53 × 10⁻¹¹ A·cm⁻² to 4.93 × 10⁻¹² A·cm⁻², 4.53 × 10⁻¹² A·cm⁻², and 5.14 × 10⁻¹² A·cm⁻² in the embodiments, demonstrating excellent kinetic corrosion inhibition; the calculated corrosion rate decreased from 0.0074 mm / a to 0.0023 mm / a, 0.0019 mm / a, and 0.0025 mm / a in the embodiments, fully verifying the coating's superior performance in long-term protection; the charge transfer resistance decreased from 1326... The increase in Ω·cm2 to 3.4E08Ω·cm2, 3.9E08Ω·cm2, and 2.9E08Ω·cm2 in the examples demonstrates that the protective performance of the coating has been significantly enhanced, and its ability to suppress electrochemical corrosion reactions has been improved by several orders of magnitude.

[0064] Table 2 Test results of electrochemical parameters of coating

[0065] The scale inhibition performance of the coatings in the examples and comparative examples against calcium carbonate, magnesium carbonate, barium sulfate, and strontium sulfate was evaluated using the mass difference method. Uncoated (blank control) and coated standard specimens were immersed in a 3.5 wt% sodium chloride solution for a total experimental period of 150 days. Samples were taken every 30 days to test the scale inhibition performance of the four sparingly soluble salts. The specific test procedures for each scale type are shown below.

[0066] Examples and comparative examples of anti-scaling performance tests of coatings for calcium carbonate and magnesium carbonate: Taking CaCO3 as an example, a supersaturated calcium carbonate solution consisting of 0.02 mol / L CaCl2 and 0.04 mol / L NaHCO3 is first prepared. Uncoated blank test pieces and coated test pieces are simultaneously immersed in the solution, and the reaction system is placed in a constant temperature water bath at 60℃ and stirred continuously at 300 rpm for 12 hours. After the reaction is completed, all test pieces are taken out, gently rinsed with deionized water and dried. The mass of scale deposited on the surface of each test piece is weighed using a precision electronic balance, and the scale prevention rate is calculated according to the following formula.

[0067] Examples and comparative methods for testing the anti-scaling performance of coatings against barium sulfate and strontium sulfate: Taking BaSO4 as an example, firstly, 0.01 mol / L barium ion solutions and sulfate ion solutions were prepared using highly soluble barium chloride and sodium sulfate, respectively. 300 mL of each solution was placed in two separate beakers and stirred continuously at 300 rpm. The sample was immersed in the barium ion solution and allowed to stand for 5 minutes to allow the barium ions to reach adsorption equilibrium on the sample surface. Then, the sample was removed and transferred to the sulfate ion solution, and allowed to stand for another 5 minutes to ensure sufficient sulfate adsorption and induce crystallization. This completes one test cycle. The above process was repeated for a total of 10 cycles. Finally, the sample was removed, dried to constant weight, and weighed. The scale buildup per unit area was calculated based on the mass difference before and after the test, and the scale inhibition rate of the coating was calculated using the following formula.

[0068] E = (1 - (A1 - A0) / (B1 - B0)) × 100% In the formula, E is the scale inhibition rate, A0 and A1 represent the mass of the coated test piece before and after the test, respectively, and B0 and B1 represent the mass of the uncoated test piece before and after the corresponding test.

[0069] See Figs. 1 to 4 The coating material developed in this patent has excellent anti-scaling properties. It was evaluated against four common scales: calcium carbonate, magnesium carbonate, barium sulfate, and strontium sulfate. A comparative experiment was conducted with the traditional epoxy coating in Comparative Example 1. The test was carried out in a 3.5 wt% sodium chloride solution and continuously immersed for 150 days.

[0070] The results show that the coating of the present invention achieves scale prevention rates of 70.3-76.3%, 72.4-78.6%, 66.5-74.2%, and 69.8-75.7% for the four types of scale, respectively, which are significantly better than the corresponding scale prevention rates (43.2-50.7%, 45.5-53.4%, 38.1-45.6%, and 40.9-48.6%) of the traditional epoxy coating in Comparative Example 1. Therefore, the coating of the present invention exhibits a significant advantage in long-term scale resistance and possesses higher engineering application value.

[0071] Various samples (blank samples, examples, and comparative examples) with a surface area of ​​22.43 cm² were immersed in actual oilfield reinjection water for a 30-day field simulation experiment. The main water quality parameters of the reinjection water were: salinity 9500 mg / L, oil content 26 mg / L, suspended solids concentration 9.5 mg / L, and initial total bacterial count approximately 1×10⁴ CFU / mL. Samples were removed on days 10, 20, and 30 of immersion for surface bacterial count determination. The test procedure was as follows: the sample surface was gently rinsed with distilled water to remove loose adhering substances; then, in a sterile environment, the operator, wearing sterile gloves, rubbed the biofilm and attached bacteria on the sample surface into a conical flask containing 50 mL of sterile distilled water to ensure sufficient bacterial transfer. 5 mL of eluent was taken and serially diluted using the sterile dilution method, with gradients set from 10⁻¹ to 10⁻⁵. 0.5 mL of bacterial solution from each gradient was taken and spread onto solid culture plates. The culture medium consisted of: 5 g / L peptone, 3.0 g / L beef extract, 10 g / L sodium chloride, and 15 g / L agar. The pH was adjusted to 7.0-7.2, and the medium was autoclaved at 121°C for 20 minutes. The spread plates were then inverted and incubated at 40°C for 14 days. After incubation, the plates were counted, and the total bacterial count on the sample surface was calculated according to the dilution factor. The results were expressed as CFU / cm².

[0072] As shown in Table 3, compared with the conventional pure epoxy resin coating in the comparative example, the coating of the present invention exhibits extremely significant antibacterial adhesion performance. Due to the lack of antibacterial activity, the surface of the conventional coating has a very high bacterial adhesion level, usually reaching 106-108 CFU / cm2, which easily forms a biofilm. However, the modified coating achieves a highly efficient and continuous antibacterial effect through multiple synergistic mechanisms of CTAB destroying cell membranes, zinc oxide generating reactive oxygen species, and silver ions attacking enzymes and DNA. The surface bacterial adhesion level can be reduced to 103-104 CFU / cm2 (3 examples), and the anti-biofilm performance is excellent. This design significantly improves the coating's ability to prevent biofouling in harsh environments such as oilfield produced water.

[0073] Table 3 Results of antibacterial experiment

[0074] The technical features of this invention not described can be implemented by or using existing technology, and will not be repeated here. Of course, the above description is not a limitation of this invention, and this invention is not limited to the examples above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of this invention should also be within the protection scope of this invention.

Claims

1. A phenol formaldehyde resin based heavy-duty anti-corrosion, anti-fouling and anti-bacterial coating characterized in that, The A layer and the B layer are included, the A layer includes an A agent, the A agent includes the following mass parts of raw materials: 95-115 parts of phenolic resin powder, 2-5 parts of polydopamine coated zinc powder, 1-3 parts of nanometer anticorrosive filler, 1-2 parts of graphene nanosheet; The B layer includes a B agent, the B agent includes the following mass parts of raw materials: 90-110 parts of phenolic resin powder, 5-10 parts of polydimethylsiloxane, 2-4 parts of bacteriostatic agent, 3-4 parts of nanometer silicon dioxide grafted hexadecyl trimethyl ammonium bromide, 1-3 parts of mica powder; The B layer is covered on the A layer.

2. The phenol-formaldehyde resin based heavy-duty anti-corrosion, anti-fouling and bacteria-inhibiting coating according to claim 1, characterized in that, The polydopamine coated zinc powder coating layer has a thickness of 10-50 nm, and the zinc powder has a particle size of 1-5 μm.

3. The phenol-formaldehyde resin based heavy-duty anti-corrosion, anti-fouling and bacteria-inhibiting coating according to claim 1, characterized in that, The nanometer anticorrosive filler is benzotriazole modified nanometer silicon dioxide, the modification grafting rate is 18-28%, and the particle size of the silicon dioxide is 20-100 nm.

4. The phenol formaldehyde resin based heavy duty anti-corrosive, anti-fouling and anti-bacterial coating as claimed in claim 1 and the process for preparation thereof, wherein, The bacteriostatic agent is silver doped zinc oxide powder, the silver doping amount is 0.5-1.5 wt%, and the particle size is 50-200 nm.

5. The phenol formaldehyde resin based heavy duty anti-corrosive, anti-fouling and anti-bacterial coating as claimed in claim 1, wherein, The thickness ratio of the A layer to the B layer is (1.25-1.6):

1. ​ 6. A method for preparing a phenolic resin based heavy-duty anti-corrosive, anti-fouling and anti-bacterial coating as claimed in any one of claims 1 to 6, characterized in that, The following steps are included: S1, 95-115 parts of phenolic resin powder, 2-5 parts of polydopamine coated zinc powder, 1-3 parts of benzotriazole modified nanometer silicon dioxide, 1-2 parts of graphene nanosheet of the A agent component and 90-110 parts of phenolic resin powder, 5-10 parts of polydimethylsiloxane, 2-4 parts of silver doped zinc oxide powder, 3-4 parts of nanometer silicon dioxide grafted hexadecyl trimethyl ammonium bromide, 1-3 parts of mica powder of the B agent component are respectively crushed to 20-80 μm; S2, the pretreated substrate in S1 is uniformly sprayed with the A agent to a thickness of 50-80 μm, and then the B agent is sprayed to a thickness of 30-60 μm; S3, the sprayed substrate is heated to 110-120℃ at a rate of 5-8℃ / min, and is kept for 15-25 min; S4, cooling to room temperature.

7. The method for preparing the phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating according to claim 6, characterized in that, The spraying in S2 adopts electrostatic spraying of 40-60 kV.

8. The method for preparing the phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating according to claim 6, characterized in that, The polydopamine coated zinc powder is prepared by the following steps: Dopamine hydrochloride is dissolved in Tris buffer solution with pH 8.0-9.0, zinc powder is added, and reaction is carried out at 30-60℃ for 10-15 hours.

9. The method for preparing the phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating according to claim 6, characterized in that, The benzotriazole modified nanometer silicon dioxide is prepared by the following steps: Nanometer silicon dioxide and benzotriazole are compounded by hydrogen bond in ethanol solution.

10. The method for preparing the phenolic resin-based heavy-duty anti-corrosion, anti-scaling, and antibacterial coating according to claim 6, characterized in that, The nanometer silicon dioxide grafted hexadecyl trimethyl ammonium bromide is prepared by the following steps: After the nanometer silicon dioxide is aminated by amino silane coupling agent, hexadecyl trimethyl ammonium bromide is reacted at 80℃ for 10-15 hours.

Images