A fire-retardant corrosion-resistant coating and a method for preparing the same

Abstract

The application discloses a kind of fire-retardant corrosion-resistant coating and preparation method thereof, it is related to fluorocarbon resin powder coating technical field.The fire-retardant corrosion-resistant coating includes the following weight parts of raw materials: fluorocarbon resin 15-25 parts, epoxy resin 40-50 parts, curing agent 3-5 parts, reinforcing agent 5-7 parts, corrosion inhibitor 4-6 parts, filler 6-8 parts, leveling agent 1-2 parts, benzoin 0.5-1 part.The application is generated by the reaction of hexachlorocyclotriphosphazene and p-hydroxybenzaldehyde intermediate 1, intermediate 1 is generated by the reaction of p-aminobenzoic acid and intermediate 2, and intermediate 2 is generated by the reaction of 2-heptyl oxirane and reinforcing agent.The fire-retardant corrosion-resistant coating prepared by the application has excellent mechanical properties, corrosion resistance, aging resistance and fire-retardant performance.

Description

Technical Field

[0001] This invention relates to the field of fluorocarbon resin powder coating technology, specifically to a flame-retardant and corrosion-resistant coating and its preparation method. Background Technology

[0002] With the continuous development of industrial equipment, construction facilities, transportation, and other fields, the service life of metals and composite materials in complex environments is constantly being extended, placing higher demands on their surface protective coatings. Protective coatings not only need to possess good adhesion and mechanical properties, but also must simultaneously meet multiple performance requirements such as flame retardancy, corrosion resistance, and aging resistance to ensure the safety and reliability of materials in various complex environments. Existing flame-retardant and corrosion-resistant coatings typically achieve their respective functions by introducing reinforcing agents and corrosion inhibitors into the resin system. However, traditional reinforcing agents are mostly inorganic fillers or structurally simple phosphorus-based and nitrogen-based compounds, which, while improving flame retardancy, often weaken the mechanical properties and density of the coating. Furthermore, some reinforcing agents have poor compatibility with the resin matrix, easily migrating or precipitating, limiting their application in high-performance protective coatings. Regarding corrosion resistance, existing technologies mostly rely on inorganic corrosion inhibitors or simple organic corrosion inhibitors to form a physical shielding layer. Their protective effect is mainly concentrated on short-term protection, with limited resistance to long-term acid and alkali corrosion, salt spray erosion, and environmental aging. Meanwhile, traditional corrosion inhibitors, while improving corrosion resistance, often fail to simultaneously address the coating's aging resistance and mechanical properties, making it difficult to meet the comprehensive protection requirements under complex service conditions. Therefore, it is necessary to develop a novel flame-retardant and corrosion-resistant coating. Through the rational design of the molecular structure of functional additives, a synergistic improvement in efficient flame retardancy, stable corrosion inhibition, and aging resistance can be achieved within the coating system, thereby enhancing the coating's comprehensive protective capabilities in complex environments.

[0003] Chinese invention patent CN120041039A discloses a flame-retardant and corrosion-resistant coating and its preparation method. In preparing the flame-retardant and corrosion-resistant coating, hexaarylbiimidazole and epichlorohydrin are reacted to obtain epoxidized hexaarylbiimidazole; pre-modified mica sheets and 3-aminopropyltriethoxysilane are reacted to obtain modified mica sheets; allylamine and 4'-[4-(bromomethyl)phenyl]-2,2':6',2"-terpyridine are reacted to obtain allyl terpyridine; epoxy resin and allyl terpyridine are reacted to obtain modified epoxy resin; the modified epoxy resin, epoxidized hexaarylbiimidazole, modified mica sheets, isoflurane diamine, and acetone are mixed uniformly to obtain the flame-retardant and corrosion-resistant coating. The flame-retardant and corrosion-resistant coating prepared by this invention has excellent corrosion resistance, flame retardancy, and self-healing properties, but its mechanical properties and aging resistance are still insufficient. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a flame-retardant and corrosion-resistant coating and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A flame-retardant and corrosion-resistant coating comprises the following raw materials in parts by weight:

[0007] Fluorocarbon resin 15-25 parts, epoxy resin 40-50 parts, curing agent 3-5 parts, reinforcing agent 5-7 parts, corrosion inhibitor 4-6 parts, filler 6-8 parts, leveling agent 1-2 parts, benzoin 0.5-1 parts;

[0008] The reinforcing agent is prepared by the following method:

[0009] S1: Hexachlorocyclotriphosphazene reacts with p-hydroxybenzaldehyde to generate intermediate 1; the reaction equation is shown below.

[0010]

[0011] S2: Intermediate 1 reacts with p-aminobenzoic acid to generate intermediate 2; the reaction equation is shown below.

[0012]

[0013] S3: Intermediate 2 reacts with 2-heptylethylene oxide to generate a reinforcing agent; the reaction equation is shown below.

[0014]

[0015] The corrosion inhibitor is prepared by the following method:

[0016] N1: 1,3-Dibromo-2-(bromomethyl)propane reacts with 5-(dimethylamino)valerate to form intermediate A; the reaction equation is shown below:

[0017]

[0018] N2: Intermediate A reacts with oleoyl hydroxyethyl imidazoline to generate intermediate B; the reaction equation is shown below.

[0019]

[0020] N3: Intermediate B reacts with 1H-benzotriazole-1-methanethiol to form a corrosion inhibitor; the reaction equation is shown below.

[0021]

[0022] In step S1, the molar ratio of hexachlorocyclotriphosphazene to p-hydroxybenzaldehyde is 1:(6.1-6.2).

[0023] In step S2, the molar ratio of intermediate 1 to p-aminobenzoic acid is 1:(6.05-6.1).

[0024] In step S3, the molar ratio of intermediate 2 to 2-heptylethylene oxide is 1:(6.03-6.05).

[0025] In step N1, the molar ratio of 1,3-dibromo-2-(bromomethyl)propane to 5-(dimethylamino)valerate is 1:3.1.

[0026] In step N2, the molar ratio of intermediate A to oil-based hydroxyethyl imidazoline is 1:3.05.

[0027] In step N3, the molar ratio of intermediate B to 1H-benzotriazole-1-methylthiol is 1:3.02.

[0028] The curing agent is dimethylimidazole; the filler is nano-titanium dioxide.

[0029] The leveling agent is BYK-307.

[0030] A method for preparing a flame-retardant and corrosion-resistant coating includes the following steps:

[0031] (1) Weigh out the following by weight: 15-25 parts of fluorocarbon resin, 40-50 parts of epoxy resin, 3-5 parts of curing agent, 5-7 parts of reinforcing agent, 4-6 parts of corrosion inhibitor, 6-8 parts of filler, 1-2 parts of leveling agent, and 0.5-1 parts of benzoin.

[0032] (2) Fluorocarbon resin, epoxy resin, curing agent, reinforcing agent, corrosion inhibitor, filler, leveling agent and benzoin are added to a mixer and mixed. The mixture is then fed into a twin-screw extruder to melt and extrude the material. After being pressed into tablets, crushed and sieved, a flame-retardant and corrosion-resistant coating is obtained.

[0033] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0034] The flame-retardant and corrosion-resistant coating prepared by this invention has excellent mechanical properties, corrosion resistance, aging resistance, and flame-retardant properties. The added reinforcing agent contains cyclotriphosphazene, aromatic Schiff base, long-chain alkyl, and hydroxyl structures, which improve the flame-retardant and mechanical properties of the coating through multiple mechanisms such as phosphorus-nitrogen synergy, rigid-flexible structural balance, and reactive interface bonding. The added corrosion inhibitor improves the corrosion resistance and aging resistance of the coating through the combined action of quaternary ammonium salt, imidazoline, benzotriazole, and long-chain alkyl structures. Attached Figure Description

[0035] Figure 1 The image shows the proton NMR spectrum of the enhancer prepared in Example 1.

[0036] Figure 2 The image shows the proton NMR spectrum of the corrosion inhibitor prepared in Example 4. Detailed Implementation

[0037] The following description, in conjunction with specific embodiments, provides further details, but the present invention is not limited to these embodiments.

[0038] Example 1: Preparation of the reinforcing agent:

[0039] S1: Mix 900 ml of tetrahydrofuran, 0.1 mol of hexachlorocyclotriphosphazene, 0.61 mol of p-hydroxybenzaldehyde, and 0.61 mol of anhydrous potassium carbonate. Heat to reflux and react for 35 h. Cool to room temperature, filter, and distill under reduced pressure at 40 °C for 1 h. Purify the crude product by silica gel column chromatography (V... 石油醚 :V 乙酸乙酯 The mixture was distilled at 50°C under reduced pressure for 1 hour (r=1:1) to obtain intermediate 1; its 1H NMR data are as follows: 1 HNMR (400 MHz, DMSO- d 6) δ 9.93 (t, J = 1.0 Hz, 6H), 7.97-7.89 (m, 12H), 7.31-7.24 (m, 12H); HRMS (m / z):862.1034[M+H] + ;

[0040] S2: Under nitrogen protection, 1200 ml of anhydrous ethanol, 36 ml of glacial acetic acid, 0.1 mol of intermediate 1, 0.605 mol of p-aminobenzoic acid, and 0.6 mol of anhydrous magnesium sulfate were stirred and mixed thoroughly. The mixture was heated to 70 °C and reacted for 6 h. After cooling to room temperature, the mixture was filtered and washed successively with deionized water (3 × 50 ml) and anhydrous methanol (3 × 50 ml). The mixture was then dried under vacuum at 60 °C for 12 h to obtain intermediate 2. Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 12.17 (s, 6H), 8.62 (dt, J = 9.4, 1.0Hz, 6H), 7.96-7.88 (m, 12H), 7.79-7.71 (m, 12H), 7.41-7.34 (m, 12H), 7.32-7.24 (m, 12H); HRMS (m / z):1576.3265[M+H] + ;

[0041] S3: Under nitrogen protection, 1500 ml of dimethyl sulfoxide, 0.1 mol of intermediate 2, 0.603 mol of 2-heptylethylene oxide, and 0.061 mol of tetraethylammonium bromide were stirred and mixed. The mixture was heated to 110 °C and reacted for 3 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 80 °C for 2 h. 800 ml of cold anhydrous n-hexane was slowly added and stirred to precipitate the solid. The solid was filtered, and the filter cake was washed with cold anhydrous n-hexane (3 × 80 ml). The solid was recrystallized with 300 ml of anhydrous ethanol, filtered, and dried under vacuum at 60 °C for 8 h to obtain the reinforcing agent. Its proton NMR spectrum is shown below. Figure 1 As shown, the proton NMR data are as follows: 1 H NMR (400 MHz, DMSO- d 6) δ 8.62 (dt, J = 9.4, 1.0 Hz,6H), 8.01-7.93 (m, 12H), 7.79-7.71 (m, 12H), 7.50-7.42 (m, 12H), 7.32-7.24(m, 12H), 4.79 (d, J HRMS (m / z):2430.1437[M+H] + .

[0042] Example 2: Preparation of the reinforcing agent:

[0043] S1: 900 ml of tetrahydrofuran, 0.1 mol of hexachlorocyclotriphosphazene, 0.615 mol of p-hydroxybenzaldehyde, and 0.615 mol of anhydrous potassium carbonate were stirred and mixed thoroughly. The mixture was heated to reflux and reacted for 36 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 40 °C for 1 h. The crude product was purified by silica gel column chromatography (V... 石油醚 :V 乙酸乙酯 =1:1), distilled under reduced pressure at 50℃ for 1 h to obtain intermediate 1;

[0044] S2: Under nitrogen protection, 1200 ml of anhydrous ethanol, 36 ml of glacial acetic acid, 0.1 mol of intermediate 1, 0.608 mol of p-aminobenzoic acid, and 0.6 mol of anhydrous magnesium sulfate were stirred and mixed evenly. The mixture was heated to 70 °C and reacted for 6 h. After cooling to room temperature, the mixture was filtered and washed successively with deionized water (3 × 50 ml) and anhydrous methanol (3 × 50 ml). The mixture was then dried under vacuum at 60 °C for 12 h to obtain intermediate 2.

[0045] S3: Under nitrogen protection, 1500 ml of dimethyl sulfoxide, 0.1 mol of intermediate 2, 0.604 mol of 2-heptyl ethylene oxide, and 0.061 mol of tetraethylammonium bromide were stirred and mixed. The mixture was heated to 115 °C and reacted for 2.5 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 80 °C for 2 h. 800 ml of cold anhydrous n-hexane was slowly added and stirred to precipitate the solid. The solid was filtered, and the filter cake was washed with cold anhydrous n-hexane (3 × 80 ml). The solid was recrystallized with 300 ml of anhydrous ethanol, filtered, and dried under vacuum at 60 °C for 8 h to obtain the reinforcing agent.

[0046] Example 3: Preparation of the reinforcing agent:

[0047] S1: 900 ml of tetrahydrofuran, 0.1 mol of hexachlorocyclotriphosphazene, 0.62 mol of p-hydroxybenzaldehyde, and 0.62 mol of anhydrous potassium carbonate were stirred and mixed thoroughly. The mixture was heated to reflux and reacted for 37 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 40 °C for 1 h. The crude product was purified by silica gel column chromatography (V... 石油醚 :V 乙酸乙酯 =1:1), distilled under reduced pressure at 50℃ for 1 h to obtain intermediate 1;

[0048] S2: Under nitrogen protection, 1200 ml of anhydrous ethanol, 36 ml of glacial acetic acid, 0.1 mol of intermediate 1, 0.61 mol of p-aminobenzoic acid, and 0.6 mol of anhydrous magnesium sulfate were stirred and mixed evenly. The mixture was heated to 75 °C and reacted for 5 h. After cooling to room temperature, the mixture was filtered and washed successively with deionized water (3 × 50 ml) and anhydrous methanol (3 × 50 ml). The mixture was then dried under vacuum at 60 °C for 12 h to obtain intermediate 2.

[0049] S3: Under nitrogen protection, 1500 ml of dimethyl sulfoxide, 0.1 mol of intermediate 2, 0.605 mol of 2-heptyl ethylene oxide, and 0.061 mol of tetraethylammonium bromide were stirred and mixed. The mixture was heated to 120 °C and reacted for 2 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 80 °C for 2 h. 800 ml of cold anhydrous n-hexane was slowly added and stirred to precipitate the solid. The solid was filtered, and the filter cake was washed with cold anhydrous n-hexane (3 × 80 ml). The solid was recrystallized with 300 ml of anhydrous ethanol, filtered, and dried under vacuum at 60 °C for 8 h to obtain the reinforcing agent.

[0050] Example 4: Preparation of corrosion inhibitor:

[0051] N1: Mix 350 ml of anhydrous acetonitrile, 0.1 mol of 1,3-dibromo-2-(bromomethyl)propane, and 0.31 mol of 5-(dimethylamino)valerate. Heat to reflux and react for 24 h. Cool to room temperature and distill under reduced pressure at 50 °C for 2 h. Distill using a mixture of 200 ml of ethyl acetate and anhydrous ethanol (V... 乙酸乙酯 :V 无水乙醇Recrystallization of (8:2) and vacuum drying at 60℃ for 12 h yielded intermediate A; its 1H NMR data are as follows. 1 H NMR (400 MHz, Chloroform- d ) δ 11.49 (s, 3H), 3.50 (s, 1H), 3.43-3.26 (m, 12H), 3.20 (s, 18H), 2.30 (s, 6H), 1.83-1.64 (m, 12H); HRMS (m / z): 163.4602[M-3Br] 3+ ;

[0052] Under nitrogen protection, 1200 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate A, 0.31 mol of dicyclohexylcarbodiimide, and 0.06 mol of 4-dimethylaminopyridine were stirred and mixed. Then, 0.305 mol of oleoylhydroxyethylimidazoline was added, and the mixture was reacted at 25 °C for 18 h. After filtration, the mixture was concentrated under reduced pressure at 40 °C for 2 h. The crude product was purified by silica gel column chromatography (V... 二氯甲烷 :V 甲醇 The ratio of crude oil to distillate was 10:1. The intermediate B was obtained by vacuum distillation at 40℃ for 1 hour. Its 1H NMR data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 5.35 (s, 6H), 4.20 (s, 6H), 3.68-3.61 (m, 18H), 3.50 (s, 1H), 3.43-3.25 (m, 12H), 3.20 (s,18H), 2.43 (s, 6H), 2.31 (s, 6H), 2.02 (s, 12H), 1.83-1.65 (m, 12H), 1.56 (s,6H), 1.37 (s, 6H), 1.34-1.26 (m, 54H), 0.90 (s, 9H); HRMS (m / z):495.7812[M-3Br] 3+ ;

[0053] N3: Under nitrogen protection, 1000 ml of anhydrous tetrahydrofuran, 0.1 mol of intermediate B, 0.302 mol of 1H-benzotriazole-1-methanethiol, and 1.5 g of 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated for 20 min at 100 W under 365 nm UV light at room temperature, followed by vacuum distillation at 40 °C for 2 h. 500 ml of cold anhydrous n-hexane was added and stirred to precipitate the precipitate. The precipitate was filtered, washed with a mixture of 80 ml of cold anhydrous n-hexane and 20 ml of cold ethyl acetate, and dried under vacuum at 50 °C for 12 h to obtain the corrosion inhibitor. Its 1H NMR spectrum is shown below. Figure 2As shown, the proton NMR data are as follows: 1 H NMR (400 MHz, Chloroform- d ) δ 7.94(d, J = 1.5 Hz, 3H), 7.63 (d, J = 1.6 Hz, 3H), 7.46 (d, J = 13.7 Hz, 6H), 5.04 (d, J = 1.5 Hz, 6H), 4.20 (s, 6H), 3.70-3.61 (m, 18H), 3.50 (s, 1H), 3.43-3.25 (m, 12H), 3.20 (s, 18H), 3.06 (s, 3H), 2.43 (d, J = 1.8 Hz, 6H), 2.31 (s, 6H), 1.83-1.66 (m, 12H), 1.58-1.46 (m, 18H), 1.38-1.26 (m, 66H),0.90 (s, 9H); HRMS (m / z):661.1504[M-3Br] 3+ .

[0054] Example 5: Preparation of flame-retardant and corrosion-resistant coatings:

[0055] (1) Weigh the following by weight: 150g fluorocarbon resin, 400g epoxy resin, 100g curing agent (dimethylimidazole), 80g reinforcing agent (prepared in Example 1), 50g corrosion inhibitor (prepared in Example 4), 100g filler (nano titanium dioxide), 10g leveling agent (GS-1853), and 5g benzoin;

[0056] (2) Add fluorocarbon resin, epoxy resin, curing agent, reinforcing agent, corrosion inhibitor, filler, leveling agent and benzoin to a mixer and mix at 800 rpm for 30 min. Then put it into a twin-screw extruder (feeding section temperature: 80℃, compression section temperature: 100℃, melting section temperature: 110℃, metering section temperature: 100℃, die head temperature: 90℃, screw speed 300 rpm) to melt and extrude the material. Use a tablet press with a tap water cooling system to press the material into tablets. Put it into a pulverizer and pulverize at 2000 rpm for 20 min. Pass it through a 200 mesh sieve to obtain a flame-retardant and corrosion-resistant coating.

[0057] Example 6: Preparation of flame-retardant and corrosion-resistant coatings:

[0058] (1) Weigh the following by weight: 200g fluorocarbon resin, 450g epoxy resin, 150g curing agent (dimethylimidazole), 100g reinforcing agent (prepared in Example 2), 75g corrosion inhibitor (prepared in Example 4), 125g filler (nano titanium dioxide), 15g leveling agent (GS-1853), and 8g benzoin;

[0059] (2) Add fluorocarbon resin, epoxy resin, curing agent, reinforcing agent, corrosion inhibitor, filler, leveling agent and benzoin to a mixer and mix at 800 rpm for 30 min. Then put it into a twin-screw extruder (feeding section temperature: 85℃, compression section temperature: 105℃, melting section temperature: 115℃, metering section temperature: 105℃, die head temperature: 95℃, screw speed 350 rpm) to melt and extrude the material. Use a tablet press with a tap water cooling system to press the material into tablets. Put it into a pulverizer and pulverize at 2000 rpm for 20 min. Pass it through a 200 mesh sieve to obtain a flame-retardant and corrosion-resistant coating.

[0060] Example 7 Preparation of flame-retardant and corrosion-resistant coatings:

[0061] (1) Weigh the following by weight: 250g fluorocarbon resin, 500g epoxy resin, 200g curing agent (dimethylimidazole), 120g reinforcing agent (prepared in Example 3), 100g corrosion inhibitor (prepared in Example 4), 150g filler (nano titanium dioxide), 20g leveling agent (GS-1853), and 10g benzoin;

[0062] (2) Add fluorocarbon resin, epoxy resin, curing agent, reinforcing agent, corrosion inhibitor, filler, leveling agent and benzoin to a mixer and mix at 800 rpm for 30 min. Then put it into a twin-screw extruder (feeding section temperature: 90℃, compression section temperature: 110℃, melting section temperature: 120℃, metering section temperature: 110℃, die head temperature: 100℃, screw speed 400 rpm) to melt and extrude the material. Use a tablet press with a tap water cooling system to press the material into tablets. Put it into a pulverizer and pulverize at 2000 rpm for 20 min. Pass it through a 200 mesh sieve to obtain a flame-retardant and corrosion-resistant coating.

[0063] Comparative Example 1

[0064] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the reinforcing agent is replaced with an equal weight of the reinforcing agent prepared by the following method:

[0065] The preparation method of the reinforcing agent is basically the same as that in Example 2, except that the p-hydroxybenzaldehyde in step S1 is replaced with an equimolar amount of 3-hydroxypropanal.

[0066] Comparative Example 2

[0067] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the reinforcing agent is replaced with an equal weight of the reinforcing agent prepared by the following method:

[0068] The preparation method of the reinforcing agent is basically the same as that in Example 2, except that 2-heptylethylene oxide in step S2 is replaced with an equimolar amount of 1,2-epoxypentane.

[0069] Comparative Example 3

[0070] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the reinforcing agent is replaced with an equal weight of the reinforcing agent prepared by the following method:

[0071] S1: 900 ml of tetrahydrofuran, 0.1 mol of hexachlorocyclotriphosphazene, 0.615 mol of p-hydroxybenzaldehyde, and 0.615 mol of anhydrous potassium carbonate were stirred and mixed thoroughly. The mixture was heated to reflux and reacted for 36 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 40 °C for 1 h. The crude product was purified by silica gel column chromatography (V... 石油醚 :V 乙酸乙酯 =1:1), distilled under reduced pressure at 50℃ for 1 h to obtain intermediate 1;

[0072] S2: Under nitrogen protection, 900 ml of tetrahydrofuran, 0.1 mol of intermediate 1, 0.608 mol of 4-mercaptobenzoic acid, and 0.001 mol of zirconium tetrachloride were stirred and mixed thoroughly. The mixture was heated to 25 °C and reacted for 3 h. After filtration, the mixture was distilled under reduced pressure at 40 °C for 1 h. The crude product was purified by silica gel column chromatography (V... 二氯甲烷 :V 甲醇 =15:1), distilled under reduced pressure at 50℃ for 1 h to obtain the intermediate;

[0073] S3: Under nitrogen protection, 1500 ml of dimethyl sulfoxide, 0.1 mol of intermediate, 0.604 mol of 2-heptyl ethylene oxide, and 0.061 mol of tetraethylammonium bromide were stirred and mixed. The mixture was heated to 115 °C and reacted for 2.5 h. After cooling to room temperature, the mixture was filtered and distilled under reduced pressure at 80 °C for 2 h. 800 ml of cold anhydrous n-hexane was slowly added and stirred to precipitate the solid. The solid was filtered, and the filter cake was washed with cold anhydrous n-hexane (3 × 80 ml). The solid was recrystallized with 300 ml of anhydrous ethanol, filtered, and dried under vacuum at 60 °C for 8 h to obtain the reinforcing agent.

[0074] Comparative Example 4

[0075] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the corrosion inhibitor is replaced with an equal weight of corrosion inhibitor prepared by the following method:

[0076] The preparation method of the corrosion inhibitor is basically the same as that in Example 4, except that 1,3-dibromo-2-(bromomethyl)propane in step N1 is replaced with 0.15 mol of 1,3-dibromopropane; the amount of oleoyl hydroxyethyl imidazoline in step N2 is replaced with 0.205 mol; and the amount of 1H-benzotriazole-1-methanethiol in step N3 is replaced with 0.202 mol.

[0077] Comparative Example 5

[0078] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the corrosion inhibitor is replaced with an equal weight of corrosion inhibitor prepared by the following method:

[0079] The preparation method of the corrosion inhibitor is basically the same as that in Example 4, except that the oil-based hydroxyethyl imidazoline in step N2 is replaced with an equimolar amount of 9-octadecene-1-ol.

[0080] Comparative Example 6

[0081] The raw material composition and preparation method of the flame-retardant and corrosion-resistant coating are basically the same as those in Example 6, except that the corrosion inhibitor is replaced with an equal weight of corrosion inhibitor prepared by the following method:

[0082] The preparation method of the corrosion inhibitor is basically the same as that in Example 4, except that 1H-benzotriazole-1-methanethiol in step N3 is replaced with an equimolar amount of benzyl mercaptan.

[0083] The fluorocarbon resin used in the embodiments and comparative examples of this application is model HLR-P, produced by Shandong Huafu Chemical Co., Ltd.; the epoxy resin is bisphenol A type epoxy resin E-44, produced by Shandong Deyuan Epoxy Technology Co., Ltd.; the nano titanium dioxide is anatase type nano titanium dioxide, model SS-TA05, produced by Hangzhou Jikang New Materials Co., Ltd.; and the CAS number of 1H-benzotriazole-1-methanethiol is 5745-53-9.

[0084] The flame-retardant and corrosion-resistant coatings prepared in Examples 5-7 and Comparative Examples 1-6 were tested, and the test results are shown in Table 1.

[0085] Sample Preparation: Samples were prepared according to HG / T 2006-2006 standard. Carbon steel plates (150mm×70mm×0.5mm and 125mm×13mm×0.4mm in size) were used as the substrate. The coating thickness was 0.06mm. The prepared samples were placed in a forced-air drying oven and dried at 180℃ for 15 minutes, then cooled to 23℃ and placed at 50% relative humidity for 24 hours to obtain the samples. The 150mm×70mm×0.5mm samples were tested for anti-aging properties, impact resistance, acid resistance, and alkali resistance. The 125mm×13mm×0.4mm samples were tested for flame retardancy.

[0086] Anti-aging performance test: The samples were placed in a QUV accelerated aging test chamber for aging tests, with an ultraviolet wavelength of 340nm and an irradiance of 0.76W / m. 2 The impact resistance of the samples before and after aging was tested at a temperature of 60℃, a relative humidity of 80%, and an aging time of 1200h.

[0087] Impact resistance was tested using the following method: Referring to GB / T 1732-2020 standard, a paint film impactor was used to test the impact resistance of the specimen. The specimen was placed flat on the base of the impactor, and a 1kg hammer was dropped freely from a height of 50cm. The height was increased by 5cm each time, and the specimen was impacted. When cracks appeared on the specimen, the height was decreased by 1cm each time, and the impact was repeated until no cracks appeared. The maximum height at which no cracks appeared was recorded.

[0088] Corrosion resistance test: The acid resistance (immersion time 240h) and alkali resistance (immersion time 500h) of the sample were tested according to the HG / T 2006-2006 standard.

[0089] Flame retardant performance test: Fix the sample on a support with the coating tilted downwards at a 45° angle to the ground. Prepare a fuel cup made of brass, with an outer diameter of 24 mm, a wall thickness of 1 mm, a height of 17 mm, and a volume of 6 ml. Use a dropper to inject 5 ml of anhydrous ethanol into the fuel cup. The closest vertical distance from the rim of the fuel cup to the surface of the sample is 25 mm. Ignite until the flame self-extinguishes. Repeat the test for 5 samples per group. Remove the burned sample and saw it into 4 pieces along the line of maximum flame propagation length and width. Measure the length and width of the charred (obviously blackened) substrate under the coating at the longitudinal and transverse cuts, and then measure the maximum char depth. Calculate the char volume. Finally, take the average of the char volumes of the 5 samples to obtain the final char volume. The calculation formula is as follows:

[0090]

[0091] Where: V—carbonization volume, cm3 ; —Carbonization length, cm; —Carburization width, cm; —Carbonization depth, cm; n—Number of samples.

[0092] Table 1 Performance Test Data

[0093]

[0094] As can be seen from Table 1, the flame-retardant and corrosion-resistant coatings prepared in Examples 5-7 of this application have excellent mechanical properties, corrosion resistance, aging resistance and flame retardant properties.

[0095] The reinforcing agents added to the coating components prepared in Examples 5-7 of this application contain cyclotriphosphazene, aromatic Schiff bases, long-chain alkyl groups, and hydroxyl structures. The cyclotriphosphazene structure serves as the flame-retardant core, decomposing upon heating to release PO· / PO2· free radicals that quench flame-active groups (gas-phase flame retardancy) and catalyze the dehydration of the resin matrix to form a dense phosphate ester protective layer (condensed-phase flame retardancy). The conjugated benzene rings and C=N bonds in the aromatic Schiff base structure enhance molecular rigidity through π-π stacking, promoting graphitization of the char layer and capturing combustion free radicals, synergistically improving flame retardant performance and mechanical strength. The long-chain alkyl segments improve compatibility with fluorocarbon resins by reducing molecular polarity, while providing flexibility to alleviate the brittleness caused by the rigid structure. The hydroxyl groups can react with the epoxy groups of the epoxy resin, achieving interfacial anchoring between the reinforcing agent molecules and the resin network, reducing phase separation and enhancing interfacial bonding. The reinforcing agent molecules improve the flame retardant performance of the coatings through multiple mechanisms, including phosphorus-nitrogen synergistic flame retardancy, rigid-flexible structural balance, and reactive interfacial bonding, while effectively enhancing its mechanical properties. The reinforcing agent molecule used in Comparative Example 3 lacks a Schiff base structure, making it difficult to achieve a synergistic flame-retardant effect with the cyclotriphosphazene structure, resulting in a decrease in the flame-retardant performance of the coating.

[0096] The corrosion inhibitors added to the coating components prepared in Examples 5-7 of this application contain quaternary ammonium salts, imidazoline, benzotriazole, and long-chain alkyl structures. The quaternary ammonium salt structure can be adsorbed onto the metal surface through strong electrostatic interactions. The nitrogen atom in the imidazoline heterocycle further forms stable coordination bonds with metal ions, constructing a chemical protective film to inhibit the cathodic hydrogen evolution reaction. The benzotriazole unit passivates the metal surface through nitrogen atom coordination, synergistically blocking anodic dissolution. Simultaneously, its conjugated structure can absorb ultraviolet light and quench free radicals, preventing photo-oxidative breakage of resin segments. The long-chain alkyl segments provide a hydrophobic layer to reduce water and oxygen permeability and improve compatibility with the resin through molecular flexibility, preventing protective failure caused by phase separation. Through multiple synergistic mechanisms of physical adsorption, chemical coordination, metal passivation, and ultraviolet shielding, the corrosion inhibitor molecules not only significantly improve the corrosion resistance of the coating but also delay coating chalking and cracking caused by ultraviolet aging, achieving long-term, high-efficiency protection. The corrosion inhibitor used in Comparative Example 6 lacks a benzotriazole structure, which weakens its coordination with metal ions and reduces its ability to absorb ultraviolet light, resulting in a decrease in the corrosion resistance and aging resistance of the prepared coating.

[0097] 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 flame-retardant and corrosion-resistant coating, characterized in that, The ingredients include the following parts by weight: Fluorocarbon resin 15-25 parts, epoxy resin 40-50 parts, curing agent 3-5 parts, reinforcing agent 5-7 parts, corrosion inhibitor 4-6 parts, filler 6-8 parts, leveling agent 1-2 parts, benzoin 0.5-1 parts; The reinforcing agent is prepared by the following method: S1: Tetrahydrofuran, hexachlorocyclotriphosphazene, p-hydroxybenzaldehyde and anhydrous potassium carbonate were stirred and mixed, heated to reflux, reacted, cooled to room temperature, filtered, and distilled under reduced pressure. The crude product was purified by silica gel column chromatography and distilled under reduced pressure to obtain intermediate 1. S2: Under nitrogen protection, anhydrous ethanol, glacial acetic acid, intermediate 1, p-aminobenzoic acid and anhydrous magnesium sulfate were stirred and mixed, heated to react, cooled to room temperature, filtered, washed with deionized water and anhydrous methanol in sequence, and dried under vacuum to obtain intermediate 2. S3: Under nitrogen protection, dimethyl sulfoxide, intermediate 2, 2-heptyl ethylene oxide, and tetraethylammonium bromide were stirred and mixed, heated to react, cooled to room temperature, filtered, and distilled under reduced pressure. Cold anhydrous n-hexane was slowly added and stirred to precipitate. The precipitate was filtered, washed with cold anhydrous n-hexane, recrystallized with anhydrous ethanol, filtered, and dried under vacuum to obtain the reinforcing agent. The corrosion inhibitor is prepared by the following method: N1: Anhydrous acetonitrile, 1,3-dibromo-2-(bromomethyl)propane, and 5-(dimethylamino)valerate were stirred and mixed, heated to reflux, reacted, cooled to room temperature, distilled under reduced pressure, recrystallized with a mixed solution of ethyl acetate and anhydrous ethanol, and dried under vacuum to obtain intermediate A. Under nitrogen protection, anhydrous tetrahydrofuran, intermediate A, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine were stirred and mixed. Oil-based hydroxyethyl imidazoline was added, the reaction was carried out, filtered, concentrated under reduced pressure, and the crude product was purified by silica gel column chromatography and distilled under reduced pressure to obtain intermediate B. N3: Under nitrogen protection, anhydrous tetrahydrofuran, intermediate B, 1H-benzotriazole-1-methanethiol, and 2,2-dimethoxy-2-phenylacetophenone were stirred and mixed. The mixture was then irradiated under ultraviolet light at room temperature, followed by vacuum distillation. Cold anhydrous n-hexane was added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with a mixed solution of cold anhydrous n-hexane and cold ethyl acetate. The mixture was then dried under vacuum to obtain the corrosion inhibitor.

2. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step S1, the molar ratio of hexachlorocyclotriphosphazene to p-hydroxybenzaldehyde is 1:(6.1-6.2).

3. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step S2, the molar ratio of intermediate 1 to p-aminobenzoic acid is 1:(6.05-6.1).

4. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step S3, the molar ratio of intermediate 2 to 2-heptylethylene oxide is 1:(6.03-6.05).

5. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step N1, the molar ratio of 1,3-dibromo-2-(bromomethyl)propane to 5-(dimethylamino)valerate is 1:3.

1.

6. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step N2, the molar ratio of intermediate A to oil-based hydroxyethyl imidazoline is 1:3.

05.

7. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, In step N3, the molar ratio of intermediate B to 1H-benzotriazole-1-methylthiol is 1:3.

02.

8. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, The curing agent is dimethylimidazole; the filler is nano-titanium dioxide.

9. The flame-retardant and corrosion-resistant coating according to claim 1, characterized in that, The leveling agent is BYK-307.

10. A method for preparing a flame-retardant and corrosion-resistant coating according to any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 15-25 parts of fluorocarbon resin, 40-50 parts of epoxy resin, 3-5 parts of curing agent, 5-7 parts of reinforcing agent, 4-6 parts of corrosion inhibitor, 6-8 parts of filler, 1-2 parts of leveling agent, and 0.5-1 parts of benzoin. (2) Fluorocarbon resin, epoxy resin, curing agent, reinforcing agent, corrosion inhibitor, filler, leveling agent and benzoin are added to a mixer and mixed. The mixture is then fed into a twin-screw extruder to melt and extrude the material. After being pressed into tablets, crushed and sieved, a flame-retardant and corrosion-resistant coating is obtained.

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