Waterproof anti-corrosion powder coating for ocean engineering and preparation method of waterproof anti-corrosion powder coating

Abstract

The invention relates to the technical field of coatings, in particular to a waterproof anti-corrosion powder coating for ocean engineering and a preparation method of the waterproof anti-corrosion powder coating. The coating comprises the following raw materials in parts by weight: 40-50 parts of epoxy resin, 20-30 parts of polyester resin, 10-20 parts of modified sodium alginate, 3-5 parts of dicyandiamide, 8-12 parts of zinc phosphate, 5-8 parts of mica iron oxide, 2-4 parts of zinc oxide, 1-2 parts of silicon dioxide, 0.5-1 part of a silane coupling agent and 0.3-0.5 part of an ultraviolet light absorber. The epoxy resin and the polyester resin are synergistically compounded to form a rigid-flexible interpenetrating network. The high crosslinking density of the epoxy resin ensures the mechanical strength of the coating, the flexible chain segment of the polyester resin can effectively buffer stress, and meanwhile, the coating has good waterproof and anti-corrosion performance.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a waterproof and anticorrosive powder coating for ocean engineering and a preparation method thereof. Background Art

[0002] In the field of ocean engineering, due to its special operating environment, extremely high requirements are put forward for the waterproof and anticorrosive performance of materials and equipment. Salt spray, moisture and oxygen in the marine environment will accelerate the corrosion of steel and concrete structures, resulting in increased facility maintenance costs and shortened service life. Ocean engineering facilities such as drilling platforms, subsea pipelines, and offshore wind power equipment are exposed to harsh marine environments for a long time and face serious corrosion and fouling problems. Powder coatings are solvent-free solid coatings with advantages such as environmental protection, high efficiency, and energy saving. Compared with traditional solvent-based coatings, powder coatings do not produce volatile organic compounds (VOCs) during the construction process, which is more friendly to the environment and the health of construction workers. At the same time, powder coatings have excellent adhesion and abrasion resistance, can form a dense coating, effectively block the erosion of moisture and oxygen, and thus extend the service life of facilities. In addition, powder coatings also have advantages such as rich colors and easy recycling, meeting the requirements of the ocean engineering field for high-performance and environmentally friendly coatings.

[0003] The invention patent with the publication number CN112852258A discloses a high-performance marine corrosion-resistant powder coating, which is composed of resin, curing agent, modifier and filler, and has good electrochemical corrosion resistance and good mechanical properties. However, the existing powder coating system has insufficient adaptability to the extreme deep-sea environment. When the application water depth exceeds a certain range, the anti-creep performance of the coating decays, the crosslinking degree under low-temperature curing conditions decreases, and the protection level against deep-sea microbial corrosion fails to meet the requirements, resulting in an accelerated expansion rate of the cathodic disbonding radius of the subsea pipeline coating during service, seriously affecting the long-term protection performance of the coating. In addition, under the action of alternating loads, the anti-cracking performance of the coating is severely lost, and the crack propagation rate increases, resulting in a shortened protection life. Summary of the Invention

[0004] In order to solve the problems mentioned in the above background art, the present invention provides a waterproof and anticorrosive powder coating for ocean engineering and a preparation method thereof.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A waterproof and anticorrosive powder coating for marine engineering comprises the following raw materials by weight: 40-50 parts of epoxy resin, 20-30 parts of polyester resin, 10-20 parts of modified sodium alginate, 3-5 parts of dicyandiamide, 8-12 parts of zinc phosphate, 5-8 parts of mica iron oxide, 2-4 parts of zinc oxide, 1-2 parts of silicon dioxide, 0.5-1 parts of silane coupling agent and 0.3-0.5 parts of ultraviolet absorber.

[0007] Further, the ultraviolet absorber includes one or more of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol, phenyl o-hydroxybenzoate and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxyphenol.

[0008] Further, the epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin and hydrogenated bisphenol A epoxy resin, and the silane coupling agent includes one or more of silane coupling agent KH-550, silane coupling agent A-1120, silane coupling agent KH-560, silane coupling agent A-187, silane coupling agent KH-570, silane coupling agent A-174 and silane coupling agent KH-590.

[0009] Furthermore, the modified sodium alginate is prepared by the following steps:

[0010] S1. Add sodium alginate to deionized water, raise the temperature, continue stirring for 2-3 hours, add 10% NaOH solution dropwise, adjust the pH value of the system to 10.0-10.5, mix glycidyl methacrylate and ethanol, drop into the reaction system, control the temperature to react for 6-7 hours, cool to room temperature after the reaction, adjust the pH value to 7.0 with dilute hydrochloric acid, and obtain vinylated sodium alginate solution;

[0011] S2. Add rosin acid to ethanol, raise the temperature, and stir until completely dissolved to obtain rosin acid ethanol solution; mix the vinylated sodium alginate solution with the rosin acid ethanol solution; add benzoyl peroxide; control the temperature and stir to react for 8-10 hours under nitrogen protection; pour the reaction solution into 2L of ice ethanol, stir to precipitate a yellow flocculent precipitate, let it stand for 1 hour, then filter it with suction; wash the precipitate 3 times with an ethanol-water mixture (volume ratio of 3:1); place the filter cake in a vacuum drying oven, and dry it at 60°C for 24 hours to obtain a light yellow solid; crush the product with a jet mill, and sieve it through a 200-mesh sieve to obtain modified sodium alginate.

[0012] Further, in step S1, the mass ratio of sodium alginate to deionized water is (3 - 4):(20 - 22), and the mass ratio of glycidyl methacrylate to ethanol is (0.9 - 1):(1.05 - 1.2).

[0013] Further, in step S2, the mass ratio of abietic acid to ethanol is 1:(5.9 - 6), and the mass ratio of vinylated sodium alginate solution, abietic acid ethanol solution, and benzoyl peroxide is (37.6 - 37.8):(17.3 - 17.5):0.1.

[0014] Further, in step S1, the temperature is raised to 50 - 60 °C, the stirring speed is 100 - 200 rpm, and the controlled temperature is 70 - 75 °C.

[0015] Further, in step S2, the temperature is raised to 80 - 85 °C, the stirring speed is 200 - 300 rpm, and the controlled temperature is 80 - 85 °C.

[0016] According to another aspect of the present invention, there is provided a method for preparing a waterproof and anticorrosive powder coating for ocean engineering, comprising the following steps:

[0017] Add epoxy resin, polyester resin, modified sodium alginate, dicyandiamide, zinc phosphate, micaceous iron oxide, zinc oxide, and silica into a high-speed mixer, premix for 5 - 10 min to obtain a premix, add the premix into a twin-screw extruder, set the temperature, melt and extrude, then press into tablets and cool to obtain a sheet-shaped semi-finished product, pulverize, pass through a 200-mesh sieve, add a silane coupling agent and an ultraviolet absorber, mix at a low speed for 10 - 20 min, and seal and package in a moisture-proof aluminum foil bag and store in the dark to obtain the waterproof and anticorrosive powder coating.

[0018] Further, the premixing speed is 800 - 1000 rpm, the set temperature is 90 - 93 °C in zone 1, 100 - 102 °C in zone 2, and 110 - 115 °C in zone 3, and the low-speed mixing speed is 500 - 600 rpm.

[0019] The beneficial effects of the present invention:

[0020] 1. In the technical solution of the present invention, under alkaline conditions, the hydroxyl groups in the sodium alginate molecules react with the epoxy groups in the glycidyl methacrylate molecules to undergo a ring-opening reaction, forming ether bonds. By introducing methacrylate groups into the sodium alginate molecules, reactive double bonds are added to the sodium alginate molecular chains. The molecular structure of vinylated sodium alginate becomes more complex, and the molecular chains simultaneously contain hydrophilic carboxyl and hydroxyl groups as well as hydrophobic methacrylate groups. Under the action of the initiator benzoyl peroxide, the carbon-carbon double bonds in the vinylated sodium alginate molecules react with the double bonds in the rosin acid molecules to undergo a free radical polymerization reaction, forming a graft copolymer. After graft copolymerization, rosin acid molecules are grafted onto the sodium alginate molecular chains, making its molecular structure more bulky and complex. The introduction of rosin acid molecules increases the hydrophobicity of the sodium alginate molecules, enabling the modified sodium alginate to better resist the penetration and erosion of moisture in the coating. The sodium alginate molecular chains after graft copolymerization are more compact and stable, contributing to the formation of a denser and more continuous coating, further improving the waterproof performance of the coating.

[0021] 2. In the technical solution of the present invention, the rosin acid groups in the modified sodium alginate molecules have certain antibacterial and anti-corrosion effects, which can inhibit the growth and reproduction of microorganisms, thereby extending the service life of the coating. The sodium alginate molecular chains after graft copolymerization are more stable and are not easily eroded and damaged by corrosive media, contributing to maintaining the integrity and anti-corrosion performance of the coating.

[0022] 3. In the technical solution of the present invention, functional groups such as hydroxyl and carboxyl groups in the modified sodium alginate molecules can undergo chemical reactions or form hydrogen bonds and other interactions with epoxy resins, polyester resins, etc. in the coating, thereby improving the adhesion of the coating. The sodium alginate molecular chains after graft copolymerization are more bulky and complex, contributing to increasing the contact area and interaction force between the coating and the substrate, further improving the adhesion of the coating.

[0023] 4. In the technical solution of the present invention, the synergistic compounding of epoxy resin and polyester resin forms an interpenetrating network with both rigidity and flexibility. The high cross-linking density of the epoxy resin ensures the mechanical strength of the coating, while the flexible chain segments of the polyester resin can effectively buffer stress.

[0024] 5. In the technical solution of the present invention, zinc phosphate forms a passivation film with the metal matrix through hydrolysis, and the flaky structure of mica iron oxide forms a physical shielding layer in the coating. Together with the alkaline buffering effect of zinc oxide, the anti-corrosion performance is improved. Detailed implementation mode

[0025] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] Unless otherwise specified, the raw materials used in the present invention are all conventional products purchased from the market. The polyester resin is prepared from terephthalic acid and diol.

[0027] Preparation Example 1

[0028] The modified sodium alginate is prepared by the following steps:

[0029] S1. Add 30 g of sodium alginate to 200 g of deionized water, heat up to 50 °C, continuously stir at a speed of 100 rpm for 2 h, dropwise add 10% NaOH solution to adjust the pH value of the system to 10.0. After mixing 9 g of glycidyl methacrylate and 10.5 g of ethanol, drop it into the reaction system, control the temperature at 70 °C, react for 6 h. After the reaction is completed, cool down to room temperature, and adjust the pH value to 7.0 with dilute hydrochloric acid to obtain a vinylated sodium alginate solution;

[0030] S2. Add 10 g of rosin acid to 59 g of ethanol, heat up to 80 °C, stir at a speed of 200 rpm until completely dissolved to obtain a rosin acid ethanol solution. Mix 376 g of vinylated sodium alginate solution with 173 g of rosin acid ethanol solution, add 1 g of benzoyl peroxide, under nitrogen protection, control the temperature at 80 °C, stir and react at a speed of 200 rpm for 8 h. Pour the reaction solution into 2 L of ice ethanol, stir to precipitate yellow flocculent precipitate, stand for 1 h and then filter by suction. Wash the precipitate 3 times with an ethanol-water mixture (volume ratio 3:1). Place the filter cake in a vacuum drying oven and dry at 60 °C for 24 h to obtain a light yellow solid. Crush the product with an air flow crusher and sieve it through a 200-mesh sieve to obtain the modified sodium alginate.

[0031] Preparation Example 2

[0032] The modified sodium alginate is prepared by the following steps:

[0033] S1. Add 35 g of sodium alginate to 210 g of deionized water, heat up to 55 °C, continuously stir at a speed of 150 rpm for 2.5 h, dropwise add 10% NaOH solution to adjust the pH value of the system to 10.2. After mixing 9.5 g of glycidyl methacrylate and 11 g of ethanol, drop it into the reaction system, control the temperature at 72 °C, react for 6.5 h. After the reaction is completed, cool down to room temperature, and adjust the pH value to 7.0 with dilute hydrochloric acid to obtain a vinylated sodium alginate solution;

[0034] S2. Add 10 g of rosin acid to 59.5 g of ethanol, heat up to 82 °C, stir at a speed of 250 rpm until completely dissolved to obtain a rosin acid ethanol solution. Mix 377 g of vinylated sodium alginate solution with 174 g of rosin acid ethanol solution, add 1 g of benzoyl peroxide, under nitrogen protection, control the temperature at 82 °C, stir and react at a speed of 250 rpm for 9 h. Pour the reaction solution into 2 L of ice ethanol, stir to precipitate yellow flocculent precipitate, filter by suction after standing for 1 h, wash the precipitate 3 times with an ethanol-water mixture (volume ratio 3:1), place the filter cake in a vacuum drying oven, dry at 60 °C for 24 h to obtain a pale yellow solid, crush the product with an air flow crusher, and sieve through a 200-mesh sieve to obtain modified sodium alginate.

[0035] Preparation Example 3

[0036] The modified sodium alginate is prepared through the following steps:

[0037] S1. Add 40 g of sodium alginate to 220 g of deionized water, heat up to 60 °C, continuously stir at a speed of 200 rpm for 3 h, dropwise add 10% NaOH solution to adjust the pH value of the system to 10.5. After mixing 10 g of glycidyl methacrylate and 12 g of ethanol, drop them into the reaction system, control the temperature at 75 °C, and react for 7 h. After the reaction is completed, cool down to room temperature, and adjust the pH value to 7.0 with dilute hydrochloric acid to obtain a vinylated sodium alginate solution;

[0038] S2. Add 10 g of rosin acid to 60 g of ethanol, heat up to 85 °C, stir at a speed of 300 rpm until completely dissolved to obtain a rosin acid ethanol solution. Mix 378 g of vinylated sodium alginate solution with 175 g of rosin acid ethanol solution, add 1 g of benzoyl peroxide, under nitrogen protection, control the temperature at 85 °C, stir and react at a speed of 300 rpm for 10 h. Pour the reaction solution into 2 L of ice ethanol, stir to precipitate yellow flocculent precipitate, filter by suction after standing for 1 h, wash the precipitate 3 times with an ethanol-water mixture (volume ratio 3:1), place the filter cake in a vacuum drying oven, dry at 60 °C for 24 h to obtain a pale yellow solid, crush the product with an air flow crusher, and sieve through a 200-mesh sieve to obtain modified sodium alginate.

[0039] Example 1

[0040] A preparation method of a waterproof and anticorrosive powder coating for ocean engineering, comprising the following steps:

[0041] Add 40 parts of hydrogenated bisphenol A epoxy resin, 20 parts of polyester resin, 10 parts of the modified sodium alginate prepared in Preparation Example 1, 3 parts of dicyandiamide, 8 parts of zinc phosphate, 5 parts of micaceous iron oxide, 2 parts of zinc oxide and 1 part of silicon dioxide into a high-speed mixer, premix at a speed of 800 rpm for 5 min to obtain a premix, add the premix into a twin-screw extruder, set the temperature, zone 1 at 90 °C, zone 2 at 100 °C, zone 3 at 110 °C, melt and extrude, then press and cool to obtain a sheet semi-finished product, crush it, pass through a 200-mesh sieve, add 0.5 part of silane coupling agent A-1120 and 0.3 part of 2-hydroxy-4-n-octyloxybenzophenone, and mix at a low speed of 500 rpm for 10 min to obtain a waterproof and anticorrosive powder coating.

[0042] Example 2

[0043] A preparation method of a waterproof and anticorrosive powder coating for ocean engineering, comprising the following steps:

[0044] Add 45 parts of bisphenol F type epoxy resin, 26 parts of polyester resin, 14 parts of the modified sodium alginate prepared in Preparation Example 2, 4 parts of dicyandiamide, 11 parts of zinc phosphate, 6 parts of micaceous iron oxide, 3 parts of zinc oxide and 1.5 parts of silicon dioxide into a high-speed mixer, premix at a speed of 900 rpm for 8 min to obtain a premix, add the premix into a twin-screw extruder, set the temperature, zone 1 at 91 °C, zone 2 at 101 °C, zone 3 at 113 °C, melt and extrude, then press and cool to obtain a sheet semi-finished product, crush it, pass through a 200-mesh sieve, add 0.6 part of silane coupling agent KH-560 and 0.4 part of phenyl salicylate, and mix at a low speed of 550 rpm for 15 min to obtain a waterproof and anticorrosive powder coating.

[0045] Example 3

[0046] A preparation method of a waterproof and anticorrosive powder coating for ocean engineering, comprising the following steps:

[0047] Add 50 parts of bisphenol A type epoxy resin, 30 parts of polyester resin, 20 parts of the modified sodium alginate prepared in Preparation Example 3, 5 parts of dicyandiamide, 12 parts of zinc phosphate, 8 parts of micaceous iron oxide, 4 parts of zinc oxide and 2 parts of silicon dioxide into a high-speed mixer, premix at a speed of 1000 rpm for 10 min to obtain a premix, add the premix into a twin-screw extruder, set the temperature, zone 1 at 93 °C, zone 2 at 102 °C, zone 3 at 115 °C, melt and extrude, then press and cool to obtain a sheet semi-finished product, crush it, pass through a 200-mesh sieve, add 1 part of silane coupling agent KH-550 and 0.5 part of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, and mix at a low speed of 600 rpm for 20 min to obtain a waterproof and anticorrosive powder coating.

[0048] Comparative Example 1

[0049] The difference between this comparative example and Example 1 is that rosin acid is used to replace the modified sodium alginate prepared in Example 1, and the remaining steps are the same as those in Example 1.

[0050] Comparative Example 2

[0051] The difference between this comparative example and Example 2 is that glycidyl methacrylate is used to replace the modified sodium alginate prepared in Example 2, and the remaining steps are the same as those in Example 2.

[0052] Comparative Example 3

[0053] The difference between this comparative example and Example 3 is that sodium alginate is used to replace the modified sodium alginate prepared in Example 3, and the remaining steps are the same as those in Example 3.

[0054] Prepare several carbon steel plates of 100×50×2 mm, polish them with 400-mesh sandpaper until rust-free, wipe off oil with ethanol, and spray the powder coatings prepared in Examples 1-3 and Comparative Examples 1-3 onto the surface of the carbon steel plates evenly to cover. Draw a straight line with a length of 20 mm on the coating surface, penetrating the coating to the metal substrate to obtain each specimen. Place the specimens at an inclination of 20° into a salt spray test chamber. Prepare 2 L of 5% NaCl salt solution, control the temperature at 35±1 °C, operate intermittently (on for 30 min / off for 30 min), and simulate salt spray deposition for 168 h. (1) Record the maximum width of rust on both sides of the scratch at the 168th h, and the corrosion rate = (final rust width - initial rust width) / 168 h. (2) Cover the specimen with a 1 mm 2 transparent grid paper, count the number of rusted / blistered grids, and the rust grade standard is: A: no visible rust; B: rust ≤ 10% of the area; C: rust > 10% of the area. The results are shown in Table 1:

[0055] Table 1. Results of salt spray corrosion test

[0056]

[0057] After taking out and washing the above samples, dry them to constant weight in a vacuum drying oven at 50 °C, denoted as W0, and immerse them in artificial seawater at 40±1 °C for water absorption test. The artificial seawater is prepared with reference to ASTM D1141: 24.53 g / L of NaCl, 5.20 g / L of MgCl2, 4.09 g / L of Na2SO4, 1.16 g / L of CaCl2, 0.695 g / L of KCl, 0.201 g / L of NaHCO3, adjust the pH to 8.2±0.1, and the temperature is 25 °C. Take out the specimens at 72 h and 168 h respectively, gently wipe the surface liquid drops with lint-free cloth, and immediately weigh them, denoted as W t , calculate the water absorption rate, and the water absorption rate = [(W t - W0) / W0]×100%. The results are shown in Table 2:

[0058] Table 2. Water Absorption Test Results

[0059] Sample Water absorption rate in 72h (%) Water absorption rate in 168h (%) Example 1 0.15±0.03 0.35±0.05 Example 2 0.12±0.02 0.28±0.04 Example 3 0.08±0.01 0.18±0.02 Comparative Example 1 0.85±0.10 2.50±0.20 Comparative Example 2 1.20±0.15 1.80±0.15 Comparative Example 3 1.50±0.15 2.40±0.15

[0060] As can be seen from Table 1, the corrosion expansion width and corrosion rate of Examples 1-3 are significantly lower than those of the comparative examples, indicating that the addition of modified sodium alginate significantly improves the corrosion resistance of the coating. As the content of modified sodium alginate increases, the corrosion rate gradually decreases, indicating that modified sodium alginate plays an effective barrier role in the coating and slows down the penetration of corrosive media. The rust area ratio of the examples is less than 1%, and the rust grade is A, indicating that the coating has excellent rust prevention performance. Modified sodium alginate may form a dense protective film on the coating surface through chemical bonding or physical adsorption, effectively blocking the contact between the corrosive medium and the metal substrate.

[0061] The corrosion expansion width and corrosion rate of Comparative Examples 1-3 are significantly higher than those of the examples, indicating that when rosin acid, glycidyl methacrylate, and sodium alginate are used alone, their anti-corrosion effects are not as good as that of modified sodium alginate. This may be because the dispersion of these substances in the coating is poor, or they cannot form an effective protective film to block the corrosive medium. The rust area ratio of the comparative examples is higher than 3%, and the rust grade is B, indicating that the rust prevention performance of the coating is poor.

[0062] As can be seen from Table 2, the water absorption rates of Examples 1-3 at 72 h and 168 h are significantly lower than those of the comparative examples, indicating that the addition of modified sodium alginate reduces the water absorption rate of the coating. This may be because the molecular structure of modified sodium alginate contains hydrophobic groups, reducing the water absorption of the coating. At the same time, the dense structure formed by modified sodium alginate in the coating also effectively blocks the penetration of water.

[0063] The water absorption rates of Comparative Examples 1-3 are significantly higher than those of the examples, indicating that when rosin acid, glycidyl methacrylate, and sodium alginate are used alone, their effects of reducing the water absorption rate of the coating are not as good as that of modified sodium alginate. This may be because these substances cannot form an effective hydrophobic barrier to prevent the absorption and penetration of water.

[0064] In summary, the addition of the modified sodium alginate prepared in Preparation Examples 1-3 significantly improves the corrosion resistance and waterproof performance of the coatings prepared in Examples 1-3.

[0065] In the description of the specification, the descriptions referring to terms such as "preparation example", "embodiment", "each embodiment", etc. mean that the specific features, structures, materials or characteristics described in connection with that embodiment or preparation example are included in at least one embodiment or preparation example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or preparation example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or preparation examples in a suitable manner.

[0066] As described above, only the preferred specific embodiments of the present invention are provided, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. A waterproof and anti-corrosion powder coating for marine engineering, characterized in that: The raw materials include the following by weight: 40-50 parts of epoxy resin, 20-30 parts of polyester resin, 10-20 parts of modified sodium alginate, 3-5 parts of dicyandiamide, 8-12 parts of zinc phosphate, 5-8 parts of mica iron oxide, 2-4 parts of zinc oxide, 1-2 parts of silicon dioxide, 0.5-1 parts of silane coupling agent and 0.3-0.5 parts of ultraviolet absorber.

2. The waterproof and anticorrosive powder coating for marine engineering according to claim 1, characterized in that: The ultraviolet absorber includes one or more of 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2-hydroxy-4-n-octyloxybenzophenone, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine-2-yl]-5-octyloxyphenol, phenyl o-hydroxybenzoate and 2-(4,6-diphenyl-1,3,5-triazine-2-yl)-5-hexyloxyphenol.

3. The waterproof and anticorrosive powder coating for marine engineering according to claim 1, characterized in that: The epoxy resin includes one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, novolac epoxy resin and hydrogenated bisphenol A epoxy resin, and the silane coupling agent includes one or more of silane coupling agent KH-550, silane coupling agent A-1120, silane coupling agent KH-560, silane coupling agent A-187, silane coupling agent KH-570, silane coupling agent A-174 and silane coupling agent KH-590.

4. The waterproof and anticorrosive powder coating for marine engineering according to claim 1, characterized in that: The modified sodium alginate is prepared by the following steps: S1. Add sodium alginate to deionized water, raise the temperature, and continue stirring for 2-3 hours. Adjust the pH value of the system to 10.0-10.

5. Mix glycidyl methacrylate and ethanol, and then drip into the reaction system. Control the temperature to react for 6-7 hours. After the reaction is completed, cool to room temperature and adjust the pH value to 7.0 to obtain a vinylated sodium alginate solution. S2. Add rosin acid to ethanol, raise the temperature, and stir until completely dissolved to obtain rosin acid ethanol solution, mix the vinylated sodium alginate solution with the rosin acid ethanol solution, add benzoyl peroxide, and under nitrogen protection, control the temperature and stir to react for 8-10 hours. After the reaction is completed, filter the precipitate, wash, and dry to obtain modified sodium alginate.

5. The waterproof and anticorrosive powder coating for marine engineering according to claim 4, characterized in that: In step S1, the mass ratio of sodium alginate to deionized water is (3-4):(20-22), and the mass ratio of glycidyl methacrylate to ethanol is (0.9-1):(1.05-1.2).

6. The waterproof and anticorrosive powder coating for marine engineering according to claim 4, characterized in that: In step S2, the mass ratio of rosin acid to ethanol is 1:(5.9-6), and the mass ratio of vinylated sodium alginate solution, rosin acid ethanol solution, and benzoyl peroxide is (37.6-37.8):(17.3-17.5):0.

1.

7. The waterproof and anticorrosive powder coating for marine engineering according to claim 4, characterized in that: In step S1, the temperature of the heating is 50-60°C, the stirring speed is 100-200rpm, and the temperature is controlled at 70-75°C.

8. The waterproof and anticorrosive powder coating for marine engineering according to claim 4, characterized in that: In step S2, the temperature of the heating is 80-85°C, the stirring speed is 200-300rpm, and the temperature is controlled at 80-85°C.

9. A method for preparing a waterproof and anticorrosive powder coating for marine engineering according to any one of claims 1 to 8, characterized in that: The following steps are involved: Add epoxy resin, polyester resin, modified sodium alginate, dicyandiamide, zinc phosphate, mica iron oxide, zinc oxide and silicon dioxide into a high-speed mixer, premix for 5-10 minutes to obtain a premix, add the premix into a twin-screw extruder, set the temperature, extrude and tablet to obtain a flaky semi-finished product, crush, pass through a 200-mesh sieve, add a silane coupling agent and an ultraviolet absorber, mix at a low speed for 10-20 minutes, and seal and package to obtain a waterproof and anticorrosive powder coating.

10. The method for preparing a waterproof and anticorrosive powder coating for marine engineering according to claim 9, characterized in that: The premixing speed is 800-1000rpm, the set temperatures are 90-93°C for zone 1, 100-102°C for zone 2, and 110-115°C for zone 3, and the low-speed mixing speed is 500-600rpm.

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