Super-soft anti-corrosion solvent-free polyester coating and preparation method thereof

Abstract

The invention relates to the technical field of coatings, and discloses a super-soft anticorrosive solvent-free polyester coating and a preparation method thereof. The solvent-free polyester coating comprises a component A and a component B, wherein the component A comprises modified polyester polyol, polycarbonate diol, modified organic silicon, a catalyst, an auxiliary agent and an inorganic filler; the component B is polymethylene polyphenyl isocyanate; the solvent-free polyester coating prepared by the invention has the advantages of ultrahigh solid content, accurate regulation and control of coating thickness, high reaction film-forming speed, primer and topcoat integration, ultrahigh flexibility, and favorable adhesive force and corrosion resistance to a base material.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and particularly relates to a super-flexible anti-corrosion solvent-free polyester coating and a preparation method thereof. Background Art

[0002] The protection of metal corrosion has important protective significance and economic value in aspects such as national defense and military industry, aerospace, petroleum, chemical industry, and civil construction. The corrosion of metal materials in the atmospheric environment is the most common existence in nature, especially in some environments with high temperature, high humidity, and high salinity / alkalinity. The usual protection measure is to apply a coating on the surface of the object to be protected or decorated, and a continuous film that can form a firm attachment with the coated object can be formed. At present, higher requirements have been put forward for the anti-corrosion systems and materials of traditional thermal insulation and oil pipelines in China, requiring ultra-high solid content, construction not affected by environmental temperature, good acid, alkali, and salt resistance, excellent flexibility, significant high-temperature resistance, good flexibility, impact resistance, and chemical corrosion resistance, so that the solvent-free anti-corrosion materials develop in the direction of high efficiency, easy application, and green preparation process.

[0003] However, the existing two-component solvent-free ultra-high solid content has a very limited anti-corrosion effect on the outer wall of external metal pipelines in high-temperature and high-salinity areas. The main reason is its poor flexibility, easy cracking, and poor adhesion on smooth galvanized surfaces, residual paint surfaces, etc. Therefore, HK Company has developed an anti-corrosion coating with a high solid content, good flexibility, excellent corrosion resistance, and excellent adhesion. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a super-flexible anti-corrosion solvent-free polyester coating and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A super-flexible anti-corrosion solvent-free polyester coating, comprising component A and component B, and the mass ratio of component A to component B is 100:35 - 45; Component A comprises raw materials with the following mass percentages: 30.0wt% - 40.0wt% modified polyester polyol, 8.0wt% - 15.0wt% polycarbonate diol, 5.0wt% - 10.0wt% modified silicone, 0.5wt% - 1.5wt% catalyst, 5.0wt% - 10.0wt% auxiliary agent, 35.0wt% - 50.0wt% inorganic filler; Component B is polymethylene polyphenyl isocyanate; Further, the isocyanate group content in the polymethylene polyphenyl isocyanate is 32% - 36%; Further, the auxiliaries include 1.0wt%-2.5wt% dispersant, 0.7wt%-2.0wt% defoamer, 1.5wt%-3.0wt% water remover, 0.3wt%-0.5wt% light stabilizer and 1.5wt%-2.0wt% didecyl phthalate; Further, the inorganic fillers include 15wt%-20wt% aluminosilicate, 7wt%-12wt% potassium feldspar, 5wt%-10wt% quartz powder, 2wt%-6wt% barium sulfate and 2-5wt% modified zinc phosphate; The modified silicone is prepared by the following steps: Step A1: Stir dopamine hydrochloride and dibutyltin dilaurate evenly in ethanol. Slowly drop allyl isothiocyanate under stirring conditions and react at 45-55°C for 3-5h. Filter under reduced pressure, wash and dry to obtain dopamine derivative; Further, in step A1, the molar ratio of dopamine hydrochloride, dibutyltin dilaurate and allyl isothiocyanate is 0.05-0.15:0.0003-0.001:0.05-0.15; Step A2: Mix 1-hydroxyethyl-2-methylimidazole evenly in tetrahydrofuran. Add triethylamine and stir for 10 min under nitrogen conditions. Then slowly add allylphosphine dichloride in an ice-water bath and react at room temperature for 2h and at 40°C for 6h in sequence. Filter, rotary evaporate, wash and dry to obtain the phosphate-imidazole product; Further, in step A2, the molar ratio of 1-hydroxyethyl-2-methylimidazole, allylphosphine dichloride and triethylamine is 0.01-0.03:0.006-0.018:0.015-0.045; Step A3: Mix the phosphate-imidazole product, γ-mercaptopropyltrimethoxysilane and benzoin dimethyl ether evenly and stir. Irradiate under ultraviolet light for 25-45 min. Add n-hexane for precipitation, filter and dry to obtain the functionalized siloxane; Further, in step A3, the dosage ratio of the phosphate-imidazole product, γ-mercaptopropyltrimethoxysilane, benzoin dimethyl ether and n-hexane is 0.18-0.54mol:0.185-0.555mol:0.007-0.021g:300mL; Step A4: Mix dimethyldimethoxysilane, functionalized siloxane, tetramethyldihydrodisiloxane, and trifluoromethanesulfonic acid, and stir and react at 25 °C under nitrogen for 24 h. Add anhydrous sodium bicarbonate and stir for 1 h, then add anhydrous sodium sulfate and stir for 1 h. Filter, rotary evaporate, and vacuum dry to collect the terminal hydrogen-functionalized organosilicon. Then add an isopropyl alcohol solution of chloroplatinic acid at 0.2 - 0.4 mg / mL thereto, stir and heat to 80 °C, and then add the dopamine derivative and react for 3 - 5 h. Stop introducing nitrogen and perform vacuum distillation to obtain the modified organosilicon; Further, in step A4, the molar ratio of dimethyldimethoxysilane, functionalized siloxane, and tetramethyldihydrodisiloxane is 0.02 - 0.04:0.003 - 0.006:0.01 - 0.015; Further, the trifluoromethanesulfonic acid in step A4 accounts for 0.3 wt% - 0.5 wt% of the total amount of the reactants; Further, the anhydrous sodium bicarbonate in step A4 accounts for 20 wt% - 40 wt% of the total amount of the reactants; Further, the anhydrous sodium sulfate in step A4 accounts for 30 wt% - 50 wt% of the total amount of the reactants; Further, in step A4, the molar ratio of the dopamine derivative to tetramethyldihydrodisiloxane is 2:1; Further, the isopropyl alcohol solution of chloroplatinic acid in step A4 accounts for 2 wt% - 3 wt% of the total amount of the terminal hydrogen-functionalized organosilicon and the dopamine derivative.

[0006] A preparation method of a super-flexible anti-corrosion solvent-free polyester coating comprises the following steps: Step S1: Weigh the raw materials by mass percentage. Stir the modified polyester polyol and the polycarbonate diol evenly at 40 - 60 °C, add the modified organosilicon, catalyst, dispersant, defoamer, water remover, light stabilizer, and didecyl phthalate, and stir for 15 - 25 min. Then add the aluminosilicate, potassium feldspar, quartz powder, barium sulfate, and modified zinc phosphate and stir evenly to obtain Component A; Step S2: Weigh Component A and the polymethylene polyphenyl isocyanate of Component B according to a mass ratio of 100:35 - 45, and mix Component A and Component B to obtain the super-flexible anti-corrosion solvent-free polyester coating.

[0007] The beneficial effects of the present invention: The solvent-free polyester coating prepared by the present invention has an ultra-high solid content, the coating thickness can be accurately controlled, the reaction film-forming speed is fast, the top and bottom are integrated, and it has super flexibility and good adhesion to the substrate.

[0008] The coating film of the solvent-free polyester coating prepared by the present invention has excellent chemical stability and can effectively prevent the penetration of corrosion media such as water vapor, acids, and alkalis.

[0009] In the solvent-free polyester coating prepared by the present invention, modified silicone containing phosphate groups, thiourea groups, catechol structures and imidazole structures is also introduced. Their synergistic effects improve the flexibility, adhesion and corrosion resistance of the coating after film formation. Among them, the phosphate groups and thiourea groups can form stable compounds through chemical bonding with the surface of the metal pipeline, improving the adhesion and corrosion resistance of the coating to the metal surface. The catechol structure forms strong coordination bonds or hydrogen bonds with the metal surface through the ortho-phenolic hydroxyl groups, and at the same time its polyphenol structure can produce multiple adsorption effects, further enhancing the interfacial adhesion. The nitrogen atoms in the imidazole ring can catalyze the reaction of isocyanate and hydroxyl groups in the coating, promoting complete curing and forming a denser coating. At the same time, imidazole itself has a corrosion inhibition effect and can adsorb on the metal surface to inhibit corrosion. In addition, the main chain -Si-O-Si- segment of the modified silicone has high flexibility, which can reduce the glass transition temperature (Tg) of the coating, endowing the coating with better elasticity to adapt to the deformation of the metal pipeline caused by temperature or stress. Specific Embodiments

[0010] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all 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.

[0011] The sources of some raw materials used in the following examples are as follows: Modified polyester polyol resin: Waxfu (Shanghai) New Materials Co., Ltd. is used. The hydroxyl value of the resin is 260 - 290 mgKOH / g, the functionality is 3.6, and the water content is <0.1%.

[0012] Polycarbonate diol: Shanghai Shuyu Chemical Co., Ltd. is used, with the product number SYH1000, the hydroxyl value is 102 - 118 mgKOH / g, and the water content is <0.1%.

[0013] Dispersant: A polyester-based dispersant produced by BYK Chemie GmbH, product named DISPERBYK-163.

[0014] Defoamer: A non-silicon defoamer produced by BYK Chemie GmbH, product named BYK-A501.

[0015] Water scavenger: A molecular sieve water scavenger produced by Chengsong International Trade (Shanghai) Co., Ltd., product named SYLOSIVE A3.

[0016] Light stabilizer: Light stabilizer HS-508 is selected.

[0017] Example 1: The modified silicone is prepared by the following steps: Step A1: Stir 0.05 mol of dopamine hydrochloride and 0.0003 mol of dibutyltin dilaurate evenly in ethanol. Slowly add 0.05 mol of allyl isothiocyanate dropwise under stirring conditions and react at 45 °C for 3 h. Then, perform suction filtration, washing, and drying to obtain the dopamine derivative. Step A2: Mix 0.01 mol of 1 - hydroxyethyl - 2 - methylimidazole evenly in tetrahydrofuran. Add 0.015 mol of triethylamine and stir for 10 min under nitrogen conditions. Then, slowly add 0.006 mol of allylphosphine dichloride in an ice - water bath and react at room temperature for 2 h and at 40 °C for 6 h in sequence. Perform suction filtration, rotary evaporation, washing, and drying to obtain the phosphate - imidazole product. Step A3: Mix 0.18 mol of the phosphate - imidazole product, 0.185 mol of γ - mercaptopropyltrimethoxysilane, and 0.007 g of benzoin dimethyl ether evenly and stir. Irradiate under ultraviolet light for 25 min, add 300 mL of n - hexane for precipitation, filter, and dry to obtain the functionalized siloxane. Step A4: After mixing 0.02 mol of dimethyldimethoxysilane, 0.003 mol of the functionalized siloxane, 0.01 mol of tetramethyldihydrodisiloxane, and trifluoromethanesulfonic acid (accounting for 0.3 wt% of the total amount of reactants), stir and react at 25 °C under nitrogen for 24 h. Add anhydrous sodium bicarbonate (accounting for 20 wt% of the total amount of reactants) and stir for 1 h, then add anhydrous sodium sulfate (30 wt%) and stir for 1 h. Filter, perform rotary evaporation, and vacuum dry to collect the end - hydrogen functionalized organosilicon. Then, add 0.2 mg / mL of chloroplatinic acid isopropanol solution (accounting for 3 wt% of the total amount of the end - hydrogen functionalized organosilicon and the dopamine derivative) and stir and heat to 80 °C. Then, add the dopamine derivative (the molar ratio of the dopamine derivative to tetramethyldihydrodisiloxane is 2:1) and react for 3 h. Stop introducing nitrogen and perform vacuum distillation to obtain the modified organosilicon.

[0018] Example 2: The modified organosilicon is prepared by the following steps: Step A1: Stir 0.1 mol of dopamine hydrochloride and 0.0006 mol of dibutyltin dilaurate evenly in ethanol. Slowly add 0.1 mol of allyl isothiocyanate dropwise under stirring conditions and react at 50 °C for 4 h. Then, perform suction filtration, washing, and drying to obtain the dopamine derivative. Step A2: Mix 0.02 mol of 1 - hydroxyethyl - 2 - methylimidazole evenly in tetrahydrofuran. Add 0.03 mol of triethylamine and stir for 10 min under nitrogen conditions. Then, slowly add 0.0012 mol of allylphosphine dichloride in an ice - water bath and react at room temperature for 2 h and at 40 °C for 6 h in sequence. Perform suction filtration, rotary evaporation, washing, and drying to obtain the phosphate - imidazole product. Step A3: Mix 0.36 mol of the phosphate-imidazole product, 0.37 mol of γ-mercaptopropyltrimethoxysilane, and 0.014 g of benzoin dimethyl ether uniformly, stir for 35 min under ultraviolet light irradiation, add 300 mL of n-hexane for precipitation, filter and dry to obtain the functionalized siloxane; Step A4: Mix 0.03 mol of dimethyldimethoxysilane, 0.0045 mol of the functionalized siloxane, 0.012 mol of tetramethyldihydrodisiloxane, and trifluoromethanesulfonic acid (0.4 wt% of the total amount of reactants), then stir and react at 25 °C under nitrogen for 24 h. Add anhydrous sodium bicarbonate (30 wt% of the total amount of reactants) and stir for 1 h, then add anhydrous sodium sulfate (40 wt%) and stir for 1 h. Filter, rotary evaporate, and vacuum dry to collect the end-hydrogen functionalized organosilicon. Then add 0.3 mg / mL of chloroplatinic acid isopropanol solution (2.5 wt% of the total amount of the end-hydrogen functionalized organosilicon and the dopamine derivative), stir and heat to 80 °C, and then add the dopamine derivative (the molar ratio of the dopamine derivative to tetramethyldihydrodisiloxane is 2:1) and react for 4 h. Stop passing nitrogen and perform vacuum distillation to obtain the modified organosilicon.

[0019] Example 3: The modified organosilicon is prepared by the following steps: Step A1: Mix 0.15 mol of dopamine hydrochloride and 0.001 mol of dibutyltin dilaurate uniformly in ethanol, slowly dropwise add 0.15 mol of allyl isothiocyanate under stirring conditions, and react at 55 °C for 5 h. Perform vacuum filtration, washing, and drying to obtain the dopamine derivative; Step A2: Mix 0.03 mol of 1-hydroxyethyl-2-methylimidazole uniformly in tetrahydrofuran, add 0.045 mol of triethylamine and stir for 10 min under nitrogen conditions, then slowly add 0.018 mol of allylphosphine dichloride in an ice-water bath, and react at room temperature for 2 h and at 40 °C for 6 h in sequence. Perform suction filtration, rotary evaporation, washing, and drying to obtain the phosphate-imidazole product; Step A3: Mix 0.54 mol of the phosphate-imidazole product, 0.555 mol of γ-mercaptopropyltrimethoxysilane, and 0.021 g of benzoin dimethyl ether uniformly, stir for 45 min under ultraviolet light irradiation, add 300 mL of n-hexane for precipitation, filter and dry to obtain the functionalized siloxane; Step A4: Mix 0.04 mol of dimethyldimethoxysilane, 0.006 mol of functionalized siloxane, 0.015 mol of tetramethyldihydrodisiloxane and trifluoromethanesulfonic acid (0.5 wt% of the total amount of reactants), and stir and react at 25 °C under nitrogen for 24 h. Add anhydrous sodium bicarbonate (40 wt% of the total amount of reactants) and stir for 1 h, then add anhydrous sodium sulfate (50 wt%) and stir for 1 h. Filter, rotary evaporate, and vacuum dry to collect the end-hydrogen functionalized organosilicon. Then add 0.4 mg / mL of isopropyl alcohol solution of chloroplatinic acid (2 wt% of the total amount of end-hydrogen functionalized organosilicon and dopamine derivative), stir and heat to 80 °C, and then add the dopamine derivative (the molar ratio of dopamine derivative to tetramethyldihydrodisiloxane is 2:1) and react for 5 h. Stop passing nitrogen and distill under reduced pressure to obtain the modified organosilicon.

[0020] Example 4: A preparation method of a super-soft anti-corrosion solvent-free polyester coating comprises the following steps: Component A: 30.0 wt% of modified polyester polyol, 10.0 wt% of polycarbonate diol, 5.0 wt% of the modified organosilicon prepared in Example 1, 0.5 wt% of catalyst, 9.0 wt% of additives, 45.5 wt% of inorganic fillers; wherein, the additives: 2.0 wt% of dispersant, 2.0 wt% of defoamer, 2.5 wt% of water remover, 0.5 wt% of light stabilizer and 2.0 wt% of didecyl phthalate; the inorganic fillers: 19.0 wt% of aluminosilicate, 10.0 wt% of potassium feldspar, 9.0 wt% of quartz powder, 4.5 wt% of barium sulfate and 3.0 wt% of modified zinc phosphate; Step S1: Weigh the raw materials according to the mass percentage, stir the modified polyester polyol and polycarbonate diol evenly at 40 °C, add the modified organosilicon prepared in Example 1, catalyst, dispersant, defoamer, water remover, light stabilizer and didecyl phthalate and stir for 15 min, then add aluminosilicate, potassium feldspar, quartz powder, barium sulfate and modified zinc phosphate and mix and stir evenly to obtain Component A; Step S2: Weigh Component A and polymethylene polyphenyl isocyanate of Component B according to the mass ratio of 100:35, and mix Component A and Component B to obtain the super-soft anti-corrosion solvent-free polyester coating.

[0021] Example 5: A preparation method of a super-soft anti-corrosion solvent-free polyester coating comprises the following steps: Component A: 32.5 wt% modified polyester polyol, 12.0 wt% polycarbonate diol, 7.5 wt% modified silicone prepared in Example 2, 1.0 wt% catalyst, 7.0 wt% additives, 40.0 wt% inorganic filler; among them, additives: 1.5 wt% dispersant, 1.1 wt% defoamer, 2.5 wt% water remover, 0.4 wt% light stabilizer and 1.5 wt% dioctyl phthalate; inorganic filler: 17.0 wt% aluminosilicate, 12.0 wt% potassium feldspar, 6.5 wt% quartz powder, 2.0 wt% barium sulfate and 2.5 wt% modified zinc phosphate; Step S1: Weigh the raw materials by mass percentage. Stir the modified polyester polyol and polycarbonate diol evenly at 50 °C, add the modified silicone, catalyst, dispersant, defoamer, water remover, light stabilizer and dioctyl phthalate prepared in Example 2 and stir for 20 min, then add aluminosilicate, potassium feldspar, quartz powder, barium sulfate and modified zinc phosphate and mix and stir evenly to obtain Component A; Step S2: Weigh Component A and polymethylene polyphenyl isocyanate of Component B according to the mass ratio of 100:40, and mix Component A and Component B to obtain the super-soft anti-corrosion solvent-free polyester coating.

[0022] Example 6: A preparation method of a super-soft anti-corrosion solvent-free polyester coating includes the following steps: 40.0 wt% modified polyester polyol, 8.0 wt% polycarbonate diol, 9.0 wt% modified silicone prepared in Example 3, 1.5 wt% catalyst, 5.0 wt% additives, 36.5 wt% inorganic filler; among them, additives: 1.0 wt% dispersant, 0.7 wt% defoamer, 1.5 wt% water remover, 0.3 wt% light stabilizer and 1.5 wt% dioctyl phthalate; inorganic filler: a mixture of 15.5 wt% aluminosilicate, 7.0 wt% potassium feldspar, 5.0 wt% quartz powder, 6.0 wt% barium sulfate and 3.0 wt% modified zinc phosphate; Step S1: Weigh the raw materials by mass percentage. Stir the modified polyester polyol and polycarbonate diol evenly at 60 °C, add the modified silicone, catalyst, dispersant, defoamer, water remover, light stabilizer and dioctyl phthalate prepared in Example 3 and stir for 25 min, then add aluminosilicate, potassium feldspar, quartz powder, barium sulfate and modified zinc phosphate and mix and stir evenly to obtain Component A; Step S2: Weigh Component A and polymethylene polyphenyl isocyanate of Component B according to the mass ratio of 100:45, and mix Component A and Component B to obtain the super-soft anti-corrosion solvent-free polyester coating.

[0023] Comparative Example 1: This comparative example is a solvent-free polyester coating, which is different from Example 6 in that a commercially available silicone is used instead of the modified silicone prepared in Example 3, and the rest are the same.

[0024] Comparative Example 2: This comparative example is a solvent-free polyester coating, which is different from Example 6 in that polycarbonate diol is used instead of the modified silicone prepared in Example 3, and the rest are the same.

[0025] The solvent-free polyester coatings prepared in Examples 4 - 6 and Comparative Examples 1 - 2 were subjected to performance tests: Adhesion test: Referring to the SY / T 6854-2012 standard, after the solvent-free polyester coating was applied to the surface of the steel pipe after cleaning and formed a film, the adhesion test was carried out at 20°C ± 2°C, and the standard was ≥15 MPa; Corrosion resistance test: Referring to the GB / T 1763 standard, the steel pipe coated with the coating was subjected to corrosion resistance tests in 10wt% sulfuric acid solution, 10wt% sodium hydroxide solution and 3wt% sodium chloride solution, and whether there were bubbles or peeling on the surface of the coating was observed; Flexibility test: Referring to the SY / T 6854-2012 standard, the steel pipe coated with the coating was bent at -20°C ± 3°C by 1.5°, and whether there were cracks or leakage points on the surface of the coating of the steel pipe was observed; The test results are shown in Table 1: Table 1: Performance test results As can be seen from Table 1, the solvent-free polyester coating prepared by the present invention has excellent adhesion, flexibility and corrosion resistance when applied to the surface of metal pipes.

[0026] The above content is only an example and explanation of the concept of the present invention. Those skilled in the art of this technology can make various modifications, supplements or use similar methods to replace the specific embodiments described, as long as they do not deviate from the scope defined by the concept of the invention, they should all belong to the protection scope of the present invention.

Claims

1. A super soft anti-corrosion solvent-free polyester coating, characterized in that: Comprising component A and component B, wherein the mass ratio of component A to component B is 100:35-45; The component A comprises the following raw materials in percentage by weight: 30.0wt%-40.0wt% of modified polyester polyol, 8.0wt%-15.0wt% of polycarbonate diol, 5.0wt%-10.0wt% of modified silicone, 0.5wt%-1.5wt% of catalyst, 5.0wt%-10.0wt% of auxiliary agent, and 35.0wt%-50.0wt% of inorganic filler; The component B is polymethylene polyphenyl isocyanate; The modified organosilicon is obtained by the reaction of terminal hydrogen functionalized organosilicon and dopamine derivatives, the terminal hydrogen functionalized organosilicon is obtained by the reaction of dimethyldimethoxysilane, functionalized siloxane and tetramethyldihydrodisiloxane, the functionalized siloxane is obtained by the reaction of phosphate-imidazole product and γ-mercaptopropyltrimethoxysilane, the phosphate-imidazole product is obtained by the reaction of 1-hydroxyethyl-2-methylimidazole and allylphosphine dichloride, and the dopamine derivative is obtained by the reaction of dopamine hydrochloride and allyl isothiocyanate.

2. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 1, characterized in that: The modified silicone is prepared by the following steps: Step A1, dopamine hydrochloride and dibutyltin dilaurate are uniformly stirred in ethanol, allyl isothiocyanate is slowly added dropwise under stirring, and the mixture is reacted at 45-55° C. for 3-5 hours, filtered under reduced pressure, washed, and dried to obtain a dopamine derivative; Step A2, 1-hydroxyethyl-2-methylimidazole was mixed evenly in tetrahydrofuran, triethylamine was added and stirred for 10 min under nitrogen, and allylphosphine dichloride was slowly added in an ice-water bath, and the mixture was reacted at room temperature for 2 h and at 40° C. for 6 h, and then filtered, rotary evaporated, washed and dried to obtain a phosphate-imidazole product; Step A3, mixing the phosphate-imidazole product, γ-mercaptopropyltrimethoxysilane and benzoin dimethyl ether, irradiating under ultraviolet light for 25-45 minutes, adding n-hexane for precipitation, filtering and drying to obtain functionalized siloxane; Step A4, after mixing dimethyldimethoxysilane, functionalized siloxane, tetramethyldihydrodisiloxane and trifluoromethanesulfonic acid, stir and react under nitrogen at 25°C for 24 hours, add anhydrous sodium bicarbonate and stir for 1 hour, add anhydrous sodium sulfate and stir for 1 hour, filter, rotary evaporate, and vacuum dry to collect the terminal hydrogen functionalized organosilicon, add 0.2-0.4 mg / mL chloroplatinic acid isopropanol solution thereto, stir and heat to 80°C, add dopamine derivative and react for 3-5 hours, stop passing nitrogen, and distill under reduced pressure to obtain modified organosilicon.

3. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 2, characterized in that: In step A1, the molar ratio of dopamine hydrochloride, dibutyltin dilaurate and allyl isothiocyanate is 0.05-0.15:0.0003-0.001:0.05-0.

15.

4. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 2, characterized in that: In step A2, the molar ratio of 1-hydroxyethyl-2-methylimidazole, allylphosphine dichloride and triethylamine is 0.01-0.03:0.006-0.018:0.015-0.

045.

5. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 2, characterized in that: In step A3, the usage ratio of the phosphate-imidazole product, γ-mercaptopropyltrimethoxysilane, benzoin dimethyl ether and n-hexane is 0.18-0.54 mol: 0.185-0.555 mol: 0.007-0.021 g: 300 mL.

6. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 2, characterized in that: In step A4, the molar ratio of dimethyldimethoxysilane, functionalized siloxane and tetramethyldihydrogendisiloxane is 0.02-0.04:0.003-0.006:0.01-0.015, the trifluoromethanesulfonic acid, anhydrous sodium bicarbonate and anhydrous sodium sulfate account for 0.3wt%-0.5wt%, 20wt%-40wt% and 30wt%-50wt% of the total amount of the reactants, respectively, the molar ratio of the dopamine derivative and tetramethyldihydrogendisiloxane is 2:1, and the chloroplatinic acid isopropanol solution accounts for 2wt%-3wt% of the total amount of the hydrogen-functionalized silicone and the dopamine derivative.

7. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 1, characterized in that: The isocyanate content of the polymethylene polyphenyl isocyanate is 32%-36%.

8. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 1, characterized in that: The auxiliary agent includes 1.0wt%-2.5wt% of a dispersant, 0.7wt%-2.0wt% of a defoamer, 1.5wt%-3.0wt% of a water remover, 0.3wt%-0.5wt% of a light stabilizer and 1.5wt%-2.0wt% of didecyl phthalate.

9. The ultra-soft anti-corrosion solvent-free polyester coating according to claim 1, characterized in that: The inorganic filler comprises 15wt%-20wt% of aluminosilicate, 7wt%-12wt% of potassium feldspar, 5wt%-10wt% of quartz powder, 2wt%-6wt% of barium sulfate and 2-5wt% of modified zinc phosphate.

10. A method for preparing the ultra-soft anti-corrosion solvent-free polyester coating according to any one of claims 1 to 9, characterized in that: The following steps are involved: Step S1, weighing the raw materials according to mass percentage, stirring the modified polyester polyol and polycarbonate diol at 40-60° C., adding modified silicone, catalyst, dispersant, defoamer, dewatering agent, light stabilizer and didecyl phthalate and stirring for 15-25 minutes, then adding aluminosilicate, potassium feldspar, quartz powder, barium sulfate and modified zinc phosphate and mixing and stirring evenly to obtain component A; Step S2, weighing component A and component B of polymethylene polyphenyl isocyanate at a mass ratio of 100:35-45, mixing component A and component B to obtain an ultra-soft anti-corrosion solvent-free polyester coating.

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