Composite anticorrosive and fireproof dual functional steel structure coating and preparation method thereof

Abstract

This invention discloses a composite anti-corrosion and fireproof dual-function steel structure coating and its preparation method, relating to the field of fireproof coating technology. The composite anti-corrosion and fireproof dual-function steel structure coating comprises the following raw materials in parts by weight: 35-40 parts of silicon-modified epoxy resin, 4-6 parts of nano-reinforcing material, 0.8-1.2 parts of dispersant, 8-10 parts of phosphorus-nitrogen-carbon flame retardant, 3-5 parts of corrosion resistant agent, 1-2 parts of silane coupling agent, 0.5-1.0 parts of rheology modifier, 12-15 parts of polyamide curing agent, and 20-30 parts of xylene. The composite anti-corrosion and fireproof dual-function steel structure coating prepared by this invention exhibits excellent impact resistance, flame retardancy, salt resistance, and adhesion.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, specifically to a composite anti-corrosion and fire-retardant dual-function steel structure coating and its preparation method. Background Technology

[0002] Steel structures, as a crucial material in modern construction, possess advantages such as high strength, stable performance, good toughness, convenient processing, and ease of mass production, making them particularly suitable for constructing large-span, super-high, or super-heavy buildings. However, in practical applications, steel structures are susceptible to corrosion due to environmental factors, such as vehicle exhaust in urban atmospheres, industrial fumes, salt spray erosion in coastal areas, and the hot and humid climate of southern regions. These corrosive media can cause oxidation of the steel surface, reduce strength, and thus shorten the structural lifespan. Furthermore, steel structures are relatively vulnerable under fire conditions. Their high thermal conductivity leads to rapid temperature rise during a fire, and their strength decreases sharply with increasing temperature, potentially causing structural collapse. Therefore, the application of fire-retardant coatings is crucial, primarily aiming to provide sufficient escape time during a fire by delaying the temperature rise of the steel through heat insulation or expansion mechanisms. Currently, fire-retardant coatings for steel structures are mainly classified into organic, inorganic, and semi-inorganic types. Among them, organic types are based on polymers or resins, but their overall fire-retardant performance needs further optimization. In existing technologies, anti-corrosion coatings and fire-retardant coatings are often used independently, resulting in the need for multiple layers in the coating system. For example, applying an anti-corrosion layer first and then covering it with a fire-retardant layer not only increases the complexity and cost of construction but may also affect the overall protective effect due to poor interlayer compatibility. For instance, traditional thick-film fire-retardant coatings for steel structures mainly use inorganic mineral insulation materials, but their anti-corrosion performance is limited. While phosphorus-nitrogen intumescent fire-retardant coatings have a certain fire-retardant effect, they are insufficient in terms of outdoor weather resistance and anti-corrosion. In addition, existing dual-function coatings still need improvement in adhesion and durability to meet the comprehensive requirements of modern buildings for performance, aesthetics, and environmental protection.

[0003] Chinese invention patent CN111826047A discloses a fireproof and anti-corrosion coating for steel structures and its preparation method. The fireproof and anti-corrosion coating is made by mixing acrylic resin, water-based polyester resin, ammonium polyphosphate, melamine, pentaerythritol, expanded perlite, decabromodiphenyl ethane, silicate stannate, zinc phosphate, aluminum tripolyphosphate, nano zinc oxide, mica iron oxide, heavy calcium carbonate, organobentonite, fumed silica and additives. The coating prepared by this invention has excellent fire resistance, good gloss, and does not peel or crack after long-term application. However, its anti-corrosion performance needs to be improved. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a composite anti-corrosion and fireproof dual-function steel structure coating and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A composite anti-corrosion and fireproof dual-function steel structure coating comprises the following raw materials in parts by weight: 35-40 parts of silicone-modified epoxy resin, 4-6 parts of nano-reinforcing material, 0.8-1.2 parts of dispersant, 8-10 parts of phosphorus-nitrogen-carbon flame retardant, 3-5 parts of corrosion resistant agent, 1-2 parts of silane coupling agent, 0.5-1.0 parts of rheology modifier, 12-15 parts of polyamide curing agent, and 20-30 parts of xylene; The structural formula of the corrosion resistant agent is as follows: ; The structural formula of the dispersant is as follows: .

[0006] The nano-reinforcing material is composed of 2-4 parts by weight of graphene oxide and 2-3 parts by weight of nano zinc oxide.

[0007] The phosphorus-nitrogen-carbon flame retardant is composed of ammonium polyphosphate, melamine, and pentaerythritol in a mass ratio of 5:3:2.

[0008] The silane coupling agent is γ-aminopropyltriethoxysilane; the rheology modifier is fumed silica.

[0009] The corrosion resistant agent is prepared by the following method: S1: N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide reacts with 3-(2-perfluorohexylethoxy)-1,2-epoxypropane to generate intermediate 1. S2: Intermediate 1 reacts with 3-(3-(3-chloropropoxy)propoxy)propionic acid to generate intermediate 2. S3: Intermediate 2 reacts with (2-mercaptoethyl)phosphonic acid to generate a corrosion resistant agent.

[0010] The dispersant is prepared by the following method: 1,1,3,3,5,5,7,7,9,9,11,11,13,13-Tetradecyl heptasiloxane reacts with tetraethylene glycol monoallyl ether to form a dispersant.

[0011] In step S1, the molar ratio of N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide to 3-(2-perfluorohexylethoxy)-1,2-epoxypropane is 1:2.05.

[0012] In step S2, the molar ratio of intermediate 1 to 3-(3-(3-chloropropoxy)propoxy)propionic acid is 1:2.03; in step S3, the molar ratio of intermediate 2 to (2-mercaptoethyl)phosphonic acid is 1:2.08.

[0013] The molar ratio of 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecyl heptasiloxane to tetraethylene glycol monoallyl ether is 1:(2.02-2.05).

[0014] A method for preparing a composite anti-corrosion and fireproof dual-function steel structure coating includes the following steps: (1) Weigh out the following by weight: 35-40 parts of silicone-modified epoxy resin, 4-6 parts of nano-reinforcing material, 0.8-1.2 parts of dispersant, 8-10 parts of phosphorus-nitrogen-carbon flame retardant, 3-5 parts of corrosion resistant agent, 1-2 parts of silane coupling agent, 0.5-1.0 parts of rheology modifier, 12-15 parts of polyamide curing agent, and 20-30 parts of xylene; (2) Add the nano-reinforcing material to the silicon-modified epoxy resin, stir and mix well, then add the dispersant, stir and ultrasonically disperse; add phosphorus-nitrogen-carbon flame retardant, corrosion resistant agent, silane coupling agent and rheology modifier in sequence, stir and mix well, then add polyamide curing agent and xylene, stir and mix well, and let stand to mature to obtain the product.

[0015] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include: The composite anti-corrosion and fireproof dual-function steel structure coating prepared by this invention has excellent impact resistance, flame retardancy, salt resistance and adhesion. Attached Figure Description

[0016] Figure 1 The 1H NMR spectrum of the dispersant prepared in Example 1; Figure 2 Here is a high-resolution mass spectrum of the dispersant prepared in Example 1; Figure 3 The 1H NMR spectrum of the corrosion resistant agent prepared in Example 4; Figure 4 The image shows a high-resolution mass spectrum of the corrosion resistant agent prepared in Example 4. Detailed Implementation

[0017] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0018] Example 1: Preparation of Dispersant Under nitrogen protection, 200 mL of anhydrous toluene, 10 mg of platinum catalyst, and 0.1 mol of 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecyl heptasiloxane were added to a reaction flask. The mixture was stirred and heated to 70 °C. Then, 200 mL of anhydrous toluene solution containing 0.202 mol of tetraethylene glycol monoallyl ether was slowly added dropwise over 1 hour. After the addition was complete, the reaction was allowed to proceed for 8 hours. The mixture was then rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a gradient elution of ethyl acetate / petroleum ether volume ratio of 1:4 → 1:1). The solution was then rotary evaporated at 50 °C to constant weight and dried under vacuum at 60 °C for 10 hours to obtain the dispersant. The reaction equation is shown below. Its hydrogen NMR spectrum is as follows Figure 1 As shown, its 1H NMR spectrum data are as follows: 1 ¹H NMR (400 MHz, Chloroform-d) δ 3.75–3.59 (m, 32H), 3.34 (t, J = 6.8 Hz, 4H), 3.19 (t, J = 6.3 Hz, 2H), 1.51 (tt, J = 8.9, 6.8 Hz, 4H), 0.78 (t, J = 8.9 Hz, 4H), 0.10–0.02 (s, 42H); its high-resolution mass spectrum is shown below. Figure 2 As shown, HRMS (m / z): 973.4459 [M+H] + .

[0019] Example 2: Preparation of dispersant: Under nitrogen protection, 200 ml of anhydrous toluene, 10 mg of platinum catalyst, and 0.1 mol of 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecyl heptasiloxane were added to the reaction flask. The mixture was stirred and heated to 75 °C. Then, 200 ml of anhydrous toluene solution containing 0.203 mol of tetraethylene glycol monoallyl ether was slowly added dropwise over 1 hour. After the addition was complete, the reaction was allowed to proceed for 7.5 hours. The mixture was then rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a volume ratio of ethyl acetate to petroleum ether of 1:4 → 1:1 gradient elution). The solution was then rotary evaporated at 50 °C to constant weight and dried under vacuum at 60 °C for 10 hours to obtain the dispersant.

[0020] Example 3: Preparation of dispersant: Under nitrogen protection, 200 ml of anhydrous toluene, 10 mg of platinum catalyst, and 0.1 mol of 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecyl heptasiloxane were added to a reaction flask. The mixture was stirred and heated to 80 °C. Then, 200 ml of anhydrous toluene solution containing 0.205 mol of tetraethylene glycol monoallyl ether was slowly added dropwise over 1 hour. After the addition was complete, the reaction was allowed to proceed for 7 hours. The mixture was then rotary evaporated at 70 °C to constant weight. The solution was purified by silica gel column chromatography (using a mixed solution of ethyl acetate and petroleum ether as eluent, with a volume ratio of ethyl acetate to petroleum ether of 1:4 → 1:1 gradient elution). The solution was then rotary evaporated at 50 °C to constant weight and dried under vacuum at 60 °C for 10 hours to obtain the dispersant.

[0021] Example 4: Preparation of corrosion resistance agent: S1: Under ice bath conditions, 200 mL of anhydrous tetrahydrofuran and 0.1 mol N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide were added to a reaction flask and stirred until well mixed. Then, 1.0 g of boron trifluoride diethyl ether was added, followed by dropwise addition of 600 mL of anhydrous tetrahydrofuran solution containing 0.205 mol 3-(2-perfluorohexylethoxy)-1,2-epoxypropane over 1 hour. After the addition was complete, the temperature was raised to 40 °C and the reaction was allowed to proceed for 8 hours. The mixture was then cooled to 0 °C, and saturated sodium carbonate solution was slowly added until the pH of the reaction solution reached 7. The mixture was then rotary evaporated at 55 °C to constant weight. 400 mL of dichloromethane was added and stirred to dissolve the residue. The solution was washed once with 150 mL of saturated sodium chloride solution, dried with 40 g of anhydrous sodium sulfate, filtered, and rotary evaporated at 35 °C to constant weight to obtain intermediate 1. The reaction equation is shown below: Its 1H NMR spectrum data is as follows: 1 H NMR (400 MHz, Chloroform-d) δ 8.40 (t, J =6.1 Hz, 2H), 7.91 - 7.77 (m, 3H), 7.20 (t, J = 3.5 Hz, 8H), 4.62 - 4.44 (m,8H), 3.91 - 3.40 (m, 14H), 3.30 (d, J = 6.7 Hz, 2H), 2.76 - 2.58 (m, 4H); HRMS(m / z): 1246.2473[M+H] + .

[0022] S2: Under nitrogen protection, 800 ml of anhydrous tetrahydrofuran and 0.203 mol of 3-(3-(3-chloropropoxy)propoxy)propionic acid were stirred and mixed. 0.21 mol of dicyclohexylcarbodiimide and 0.05 mol of 4-dimethylaminopyridine were added, and the mixture was stirred for 15 min. 0.1 mol of intermediate 1 was added, and the mixture was reacted at 25 °C for 10 h. The mixture was filtered, and the solution was rotary evaporated at 40 °C to constant weight. Purification was performed by silica gel column chromatography (using an ethyl acetate / methanol mixture as eluent, with a gradient elution ratio of 10:1 to 5:1, v / v). The solution was rotary evaporated at 50 °C to constant weight to obtain intermediate 2. The reaction equation is shown below: Its 1H NMR data are as follows: 1 H NMR (400 MHz, Chloroform-d) δ 8.41 (t, J = 6.0Hz, 2H), 7.90 - 7.76 (m, 3H), 7.19 (t, J = 3.7 Hz, 8H), 4.93 (p, J = 5.5 Hz,2H), 4.63 - 4.45 (m, 8H), 3.97 - 3.44 (m, 32H), 2.70 - 2.49 (m, 8H), 2.02(tt, J = 5.1, 3.9 Hz, 4H), 1.83 (p, J = 6.7 Hz, 4H); HRMS (m / z): 1658.3894[M+H] + .

[0023] S3: Under nitrogen protection, 1000 mL of anhydrous N,N-dimethylformamide, 0.1 mol of intermediate 2, and 0.208 mol of (2-mercaptoethyl)phosphonic acid were stirred and mixed. 0.21 mol of triethylamine was added, and the mixture was heated to 35 °C and reacted for 12 h. After filtration, the mixture was rotary evaporated at 70 °C to constant weight. 300 mL of dichloromethane was added and stirred to dissolve the solution. The solution was washed successively with 200 mL of 0.5 M hydrochloric acid solution and 200 mL of saturated brine. The organic phase was separated, dried with 40 g of anhydrous sodium sulfate, filtered, and the filtrate was rotary evaporated at 40 °C to constant weight. 400 mL of acetone was added for recrystallization. The solution was filtered and dried under vacuum at 60 °C for 10 h to obtain the corrosion-resistant agent. The reaction equation is shown below: Its hydrogen NMR spectrum is as follows Figure 3 As shown, its 1H NMR spectrum data are as follows: 1¹H NMR (400 MHz, Chloroform-d) δ 9.31 (s, 4H), 8.39 (t, J = 6.2 Hz, 2H), 7.91 - 7.75 (m, 3H), 7.21 (t, J = 3.6 Hz, 8H), 4.95 (p, J = 5.6 Hz, 2H), 4.60 - 4.48 (m, 8H), 3.99 - 3.47 (m, 28H), 2.88 (t, J = 7.1 Hz, 4H), 2.69 - 2.45 (m, 12H), 2.16 (t, J = 7.2 Hz, 4H), 1.90 - 1.68 (m, 8H); its high-resolution mass spectrum is shown below. Figure 4 As shown, HRMS (m / z): 1870.4076 [M+H] + .

[0024] Example 5: Preparation of a composite anti-corrosion and fireproof dual-function steel structure coating: (1) Add 20g of graphene oxide to 200ml of anhydrous ethanol, disperse it by ultrasonication at 20kHz for 60min, then mix it with 20g of nano zinc oxide, stir for 20min, and evaporate it by rotary evaporation at 60℃ to constant weight to obtain nano-reinforced material. (2) Weigh out: 350g of silicon-modified epoxy resin, 40g of nano-reinforcing material, 8g of dispersant (prepared in Example 1), 80g of phosphorus-nitrogen-carbon flame retardant (40g of ammonium polyphosphate, 24g of melamine and 16g of pentaerythritol), 30g of corrosion resistant agent (prepared in Example 4), 10g of silane coupling agent (γ-aminopropyltriethoxysilane), 5g of rheology modifier (fumed silica), 120g of polyamide curing agent, and 200g of xylene; (3) Add the nano-reinforcing material to the silicon-modified epoxy resin, stir at 1500 rpm for 40 min, then add the dispersant, stir at 1200 rpm for 5 min, and ultrasonically disperse at 20 kHz for 5 min. Repeat the stirring and ultrasonication 4 times. Add the phosphorus-nitrogen-carbon flame retardant, corrosion resistant agent, silane coupling agent and rheology modifier in sequence, stir at 300 rpm for 20 min, then add the polyamide curing agent and xylene, stir at 500 rpm for 10 min, and let it stand at room temperature for 20 min to obtain the composite anti-corrosion and fireproof dual-function steel structure coating.

[0025] Example 6: Preparation of a composite anti-corrosion and fireproof dual-function steel structure coating: (1) Add 30g of graphene oxide to 300ml of anhydrous ethanol, disperse it by ultrasonication at 20kHz for 60min, then mix it with 25g of nano zinc oxide, stir for 20min, and evaporate it by rotary evaporation at 60℃ to constant weight to obtain nano-reinforced material. (2) Weigh out: 380g of silicon-modified epoxy resin, 50g of nano-reinforcing material, 10g of dispersant (prepared in Example 2), 90g of phosphorus-nitrogen-carbon flame retardant (45g of ammonium polyphosphate, 27g of melamine and 18g of pentaerythritol), 40g of corrosion resistant agent (prepared in Example 4), 15g of silane coupling agent (γ-aminopropyltriethoxysilane), 8g of rheology modifier (fumed silica), 140g of polyamide curing agent, and 250g of xylene; (3) Add the nano-reinforcing material to the silicon-modified epoxy resin, stir at 1500 rpm for 40 min, then add the dispersant, stir at 1200 rpm for 5 min, and ultrasonically disperse at 20 kHz for 5 min. Repeat the stirring and ultrasonication 4 times. Add the phosphorus-nitrogen-carbon flame retardant, corrosion resistant agent, silane coupling agent and rheology modifier in sequence, stir at 400 rpm for 18 min, then add the polyamide curing agent and xylene, stir at 500 rpm for 10 min, and let it stand at room temperature for 20 min to obtain the composite anti-corrosion and fireproof dual-function steel structure coating.

[0026] Example 7: Preparation of a composite anti-corrosion and fireproof dual-function steel structure coating: (1) Add 40g of graphene oxide to 400ml of anhydrous ethanol, disperse it by ultrasonication at 20kHz for 60min, then mix it with 30g of nano zinc oxide, stir for 20min, and evaporate it by rotary evaporation at 60℃ to constant weight to obtain nano-reinforced material. (2) Weigh out: 400g of silicon-modified epoxy resin, 60g of nano-reinforcing material, 12g of dispersant (prepared in Example 3), 100g of phosphorus-nitrogen-carbon flame retardant (50g of ammonium polyphosphate, 30g of melamine and 20g of pentaerythritol), 50g of corrosion resistant agent (prepared in Example 4), 20g of silane coupling agent (γ-aminopropyltriethoxysilane), 10g of rheology modifier (fumed silica), 150g of polyamide curing agent, and 300g of xylene; (3) Add the nano-reinforcing material to the silicon-modified epoxy resin, stir at 1500 rpm for 40 min, then add the dispersant, stir at 1200 rpm for 5 min, and ultrasonically disperse at 20 kHz for 5 min. Repeat the stirring and ultrasonication 4 times. Add the phosphorus-nitrogen-carbon flame retardant, corrosion resistant agent, silane coupling agent and rheology modifier in sequence, stir at 500 rpm for 15 min, then add the polyamide curing agent and xylene, stir at 500 rpm for 10 min, and let it stand at room temperature for 20 min to obtain the composite anti-corrosion and fireproof dual-function steel structure coating.

[0027] Comparative Example 1 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 2, except that 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecylmethylheptasiloxane is replaced with an equimolar amount of 1,1,3,3,5,5,7,7,9,9-decamethylpentasiloxane.

[0028] Comparative Example 2 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 2, except that 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecylheptasiloxane is replaced with an equimolar amount of tris(trimethylsilyl)silane, and the amount of tetraethylene glycol monoallyl ether is 0.103 mol.

[0029] Comparative Example 3 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 2, except that tetraethylene glycol monoallyl ether is replaced with an equimolar amount of diethylene glycol monoallyl ether.

[0030] Comparative Example 4 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the dispersant is replaced with an equal weight of a dispersant prepared by the following method: The preparation method of the dispersant is basically the same as that in Example 2, except that tetraethylene glycol monoallyl ether is replaced with an equimolar amount of undecenol.

[0031] Comparative Example 5 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the corrosion resistant agent is replaced with an equal weight of corrosion resistant agent prepared by the following method: The preparation method of the corrosion resistant agent is basically the same as that in Example 4, except that the feed ratio of 3-(2-perfluorohexylethoxy)-1,2-epoxypropane in step S1 is replaced with 0.105 mol.

[0032] Comparative Example 6 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the corrosion resistant agent is replaced with an equal weight of corrosion resistant agent prepared by the following method: The preparation method of the corrosion resistant agent is basically the same as that in Example 4, except that 3-(2-perfluorohexylethoxy)-1,2-epoxypropane in step S2 is replaced with an equimolar amount of 3-(perfluorohexyl)epoxypropane.

[0033] Comparative Example 7 The composite anti-corrosion and fireproof dual-function steel structure coating is basically the same as that in Example 6, except that the corrosion resistant agent is replaced with an equal weight of corrosion resistant agent prepared by the following method: The preparation method of the corrosion resistant agent is basically the same as that in Example 4, except that 3-(3-(3-chloropropoxy)propoxy)propionic acid in step S2 is replaced with an equimolar amount of 9-chlorononanoic acid.

[0034] The silicone-modified epoxy resin used in the embodiments and comparative examples of this application is EPSI-3201, manufactured by Complex High-Tech Materials (Shanghai) Co., Ltd.; the fumed silica is AEROSIL 200; the ammonium polyphosphate is XS-APPII-040, manufactured by Zhejiang Xusen Flame Retardant Co., Ltd.; the nano zinc oxide has a particle size uniformly distributed between 20-40 nm; the graphene oxide is GTO-802S, manufactured by Suzhou Gaotong New Materials Technology Co., Ltd.; the polyamide curing agent is EPIKURE 3274; and the CAS number of N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide is 3094734-14-9.

[0035] The platinum catalysts used in Examples 1-3 of this application were prepared by the following method: Weigh 0.205 g of chloroplatinic acid and add it to 9.88 g of isopropanol. Stir at room temperature for 2 h to fully dissolve the chloroplatinic acid in the isopropanol. The solution turns orange-yellow, and the platinum catalyst is obtained.

[0036] The performance of the composite anti-corrosion and fireproof dual-function steel structure coatings prepared in Examples 5-7 and Comparative Examples 1-7 was tested, and the test results are shown in Table 1.

[0037] Sample preparation: Select a steel plate of 8.0cm×8.0cm×0.1cm, sand it with sandpaper, wipe it with alcohol until there are no obvious impurities on the surface, and then apply the prepared coating evenly on the steel plate in alternating directions until the coating thickness on the steel plate reaches 1.0mm. After the coating is completely dry at room temperature, the performance test is carried out.

[0038] Impact resistance test: Referring to GB / T 1732-2020 "Test Method for Impact Resistance of Coating Film", a paint film impactor was used to conduct a forward impact test on the composite anti-corrosion and fireproof dual-function steel structure coatings prepared in the examples and comparative examples. The cured sample was placed flat on the base of the impactor, and a 1kg hammer was dropped freely from a height of 30cm to impact the coating. After the test, the sample was removed, and the impact point was observed with a magnifying glass for cracks, wrinkles, and peeling. If no cracks, wrinkles, or peeling were observed, the test was repeated at higher positions (each time the height increased by 5cm or multiples of 5cm) until cracks, wrinkles, and peeling were observed. If cracks, wrinkles, and peeling were observed, the test was repeated at lower positions (each time decreasing by 1cm) until no cracks, wrinkles, or peeling were observed. The result is expressed as the maximum height (cm) at which no cracks, wrinkles, or peeling were observed in three tests.

[0039] Flame retardancy test: The flame retardancy performance of the composite anti-corrosion and fire-retardant dual-function steel structure coatings prepared in the examples and comparative examples was tested according to the UL 94 flame retardancy test method and standard. The sample was vertically fixed on the fixture, with its longitudinal axis perpendicular. A Bunsen burner (producing a 20mm high blue flame) was used, with the center of the flame aligned with the lower center point of the sample, and ignited for 10 seconds. The flame was removed, and the flaming burning time (t1) of the sample was recorded. After the afterflame of the sample was extinguished, the same sample was immediately ignited again for 10 seconds. The flame was removed again, and the flaming burning time (t2) and the afterglow burning time (t3) were recorded for the second time. Throughout the process, it was observed whether any burning droplets igniting cotton were produced, and whether the flame burned to the clamping end of the fixture. The rating was determined according to the judgment indicators in the UL 94 standard.

[0040] Salt resistance test: The prepared sample was soaked in 2.5wt% NaCl solution for 1000h and observed for peeling, wrinkling, blistering and softening. After 900h, it was observed every 10h.

[0041] Adhesion Test: Referring to GB / T 9286-2021 "Cross-cut Test for Paint and Varnish Films", the adhesion of samples prepared using the anti-corrosion and fire-retardant dual-function steel structure coatings obtained in the examples and comparative examples was tested. A 5×5 grid pattern (6 horizontal lines, 6 vertical lines, 3mm spacing, penetrating to the substrate) was cut into the paint film using a single-edged cross-cutting tool. Debris was brushed away, and special pressure-sensitive adhesive tape was applied and quickly peeled off. The degree of paint film peeling off the grid areas was observed. Adhesion was graded from best to worst as 0-5, with 0 representing the best and 5 representing the worst.

[0042] Table 1 Performance Test Data of Composite Anti-corrosion and Fireproof Dual-function Steel Structure Coating Note: If the salt resistance test data is 1000, it means that the coating did not show any peeling, wrinkling, blistering, or softening at 1000h; if the data is in the form of AAA / BBB, it means that the coating did not show any peeling, wrinkling, blistering, or softening at AAAh, but blistering was observed at BBBh.

[0043] As can be seen from Table 1, the composite anti-corrosion and fireproof dual-function steel structure coatings prepared in Examples 5-7 of this application have good impact resistance, flame retardancy, salt resistance and adhesion.

[0044] The dispersant prepared in this application has a linear molecular structure with a hydrophobic backbone of siloxane and hydrophilic side chains of polyether. In the composite anti-corrosion and fireproof steel structure coating system, the siloxane backbone has low surface energy and excellent flexibility, which can significantly improve the coating's wetting and spreading ability on the metal substrate. Under external force, it disperses stress through chain segment slippage, thereby improving impact resistance. Meanwhile, the ether oxygen atoms in the polyether side chains have strong polarity and can form hydrogen bonds or dipole-dipole interactions with the hydroxylated oxide layer on the steel substrate surface and polar groups (such as hydroxyl groups) in the epoxy resin, enhancing interfacial adhesion. At the same time, the spatial flexibility of the siloxane backbone and the stability of silicon-carbon bonds enable the dispersant to form an interfacial transition layer with both toughness and stability during the coating curing process, achieving a synergistic effect of stress buffering and interfacial energy matching. Through a comprehensive mechanism of "flexible chain segment buffering + polar group anchoring + low surface energy wetting," the coating's adhesion and impact resistance are simultaneously improved.

[0045] In Comparative Example 1, the shortening of the compliant segments (Si-O-Si) in the molecular chain weakens its ability to absorb and disperse impact energy. At the same time, the reduction in molecular volume weakens its entanglement with the epoxy resin matrix, resulting in a decrease in coating flexibility and adhesion, thereby reducing the impact resistance of the coating.

[0046] The side chain introduced in Comparative Example 4 is a single long-chain alkyl structure, which reduces the polarity of the system and makes it difficult to form hydrogen bonds with the polar sites on the substrate surface and the hydroxyl groups in the epoxy resin, thus weakening the interfacial anchoring ability. At the same time, the lack of flexibility and spatial configuration of polyether chains reduces the orientation and spreading ability of molecules at the interface, resulting in a poorer stress buffering effect and a significant reduction in coating adhesion and impact resistance.

[0047] The corrosion resistant agent prepared in this application is a multifunctional compound with pyridine-2,6-dicarboxamide as the core, incorporating perfluoroalkyl segments and phosphonic acid groups. First, the phosphonic acid groups at the molecule's ends can chemically chelate with iron ions on the steel structure surface, forming stable PO-Fe coordination bonds. This not only firmly anchors the corrosion resistant agent to the metal substrate surface but also constructs a dense passivation film at the interface. The thioether bond, as a sulfur-containing coordination group that readily binds to iron ions, further synergistically anchors the agent. The chemical adsorption of the phosphonic acid groups provides a stable interfacial foundation for the remaining functional segments of the molecule, allowing the perfluoroalkyl segments to be densely enriched on the coating surface. This fully utilizes the extremely low surface energy characteristics to construct a durable and dense hydrophobic and oleophobic barrier, effectively blocking the penetration of corrosive media. Simultaneously, the pyridine ring in the molecular framework contains a highly electronegative nitrogen atom, which can complex metal ions (such as Fe...). 2+ / Fe 3+ The amide bond generates stable complex precipitates, blocking ion migration channels and further delaying the electrochemical corrosion process. The strong polarity and hydrogen bonding of the amide bond significantly enhance the adhesion between the molecule and the metal surface, as well as the coating's cohesiveness. It also synergistically complexes metal ions with the nitrogen atoms of the pyridine ring, further delaying corrosion. Regarding impact resistance, the ethoxy and propoxy flexible segments in the molecular structure play a crucial stress buffering role. When the coating is subjected to external impact, these segments can effectively absorb and disperse impact energy through adjustments in the molecular chain conformation, preventing the formation of microcracks due to brittle cracking of the coating, thus ensuring the integrity of the anti-corrosion barrier. In summary, this corrosion inhibitor achieves a synergistic improvement in both corrosion resistance and impact resistance through the physical shielding of the fluorocarbon chain, the chemical anchoring of the phosphonic acid group, the ionic complexation of the pyridine ring, and the mechanical buffering of the flexible segments.

[0048] In Comparative Example 6, 3-(2-perfluorohexylethoxy)-1,2-epoxypropane was replaced with an equimolar amount of 3-(perfluorohexyl)epoxypropane, resulting in the loss of ether oxygen bonds in the side chain. This reduced the flexibility of the perfluorinated chain and weakened its ability to form a dense superhydrophobic barrier through directional migration, thus decreasing its corrosion resistance.

[0049] In Comparative Example 7, after replacing 3-(3-(3-chloropropoxy)propoxy)propionic acid with an equimolar amount of 9-chlorononanoic acid, the propoxy flexible segment was missing from the molecular structure. The internal toughening and stress buffering effect of the flexible segment was reduced, resulting in a decrease in the impact resistance of the coating.

[0050] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A composite anti-corrosion and fireproof dual-function steel structure coating, characterized in that, The raw materials include the following parts by weight: 35-40 parts of silicone-modified epoxy resin, 4-6 parts of nano-reinforcing material, 0.8-1.2 parts of dispersant, 8-10 parts of phosphorus-nitrogen-carbon flame retardant, 3-5 parts of corrosion resistant agent, 1-2 parts of silane coupling agent, 0.5-1.0 parts of rheology modifier, 12-15 parts of polyamide curing agent, and 20-30 parts of xylene; The structural formula of the corrosion resistant agent is as follows: ； The structural formula of the dispersant is as follows: 。 2. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 1, characterized in that, The nano-reinforcing material is composed of 2-4 parts by weight of graphene oxide and 2-3 parts by weight of nano zinc oxide.

3. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 1, characterized in that, The phosphorus-nitrogen-carbon flame retardant is composed of ammonium polyphosphate, melamine, and pentaerythritol in a mass ratio of 5:3:

2.

4. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 1, characterized in that, The silane coupling agent is γ-aminopropyltriethoxysilane; the rheology modifier is fumed silica.

5. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 1, characterized in that, The corrosion resistant agent is prepared by the following method: S1: N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide reacts with 3-(2-perfluorohexylethoxy)-1,2-epoxypropane to generate intermediate 1. S2: Intermediate 1 reacts with 3-(3-(3-chloropropoxy)propoxy)propionic acid to generate intermediate 2. S3: Intermediate 2 reacts with (2-mercaptoethyl)phosphonic acid to generate a corrosion resistant agent.

6. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 1, characterized in that, The dispersant is prepared by the following method: 1,1,3,3,5,5,7,7,9,9,11,11,13,13-Tetradecyl heptasiloxane reacts with tetraethylene glycol monoallyl ether to form a dispersant.

7. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 5, characterized in that, In step S1, the molar ratio of N2,N6-bis(4-(hydroxymethyl)benzyl)pyridine-2,6-dicarboxamide to 3-(2-perfluorohexylethoxy)-1,2-epoxypropane is 1:2.

05.

8. The composite anti-corrosion and fireproof dual-function steel structure coating according to claim 5, characterized in that, In step S2, the molar ratio of intermediate 1 to 3-(3-(3-chloropropoxy)propoxy)propionic acid is 1:2.03; in step S3, the molar ratio of intermediate 2 to (2-mercaptoethyl)phosphonic acid is 1:2.

08.

9. A composite anti-corrosion and fireproof dual-function steel structure coating according to claim 6, characterized in that, The molar ratio of 1,1,3,3,5,5,7,7,9,9,11,11,13,13-tetradecyl heptasiloxane to tetraethylene glycol monoallyl ether is 1:(2.02-2.05).

10. A method for preparing a composite anti-corrosion and fireproof dual-function steel structure coating as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 35-40 parts of silicone-modified epoxy resin, 4-6 parts of nano-reinforcing material, 0.8-1.2 parts of dispersant, 8-10 parts of phosphorus-nitrogen-carbon flame retardant, 3-5 parts of corrosion resistant agent, 1-2 parts of silane coupling agent, 0.5-1.0 parts of rheology modifier, 12-15 parts of polyamide curing agent, and 20-30 parts of xylene; (2) Add the nano-reinforcing material to the silicon-modified epoxy resin, stir and mix well, then add the dispersant, stir and ultrasonically disperse; add phosphorus-nitrogen-carbon flame retardant, corrosion resistant agent, silane coupling agent and rheology modifier in sequence, stir and mix well, then add polyamide curing agent and xylene, stir and mix well, and let stand to mature to obtain the product.

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