A corrosion-resistant crosslinked polyketone coating and its preparation method

Abstract

This invention relates to a corrosion-resistant crosslinked polyketone coating and its preparation method, belonging to the field of organic coatings. The invention provides a method for preparing a corrosion-resistant crosslinked polyketone coating, comprising: firstly, reacting furan-functionalized polyketone with N,N'-(4,4'-methylenediphenyl)bismaleimide as raw materials to obtain a crosslinked polyketone resin solution with a viscosity of 50-200 mPa·s; then, forming a coating from the obtained crosslinked polyketone resin solution; finally, subjecting the obtained coating to sequential hot pressing and cold pressing treatments to obtain the corrosion-resistant crosslinked polyketone coating; wherein, the hot pressing temperature is 110-130℃. The crosslinked polyketone coating prepared by this invention exhibits excellent corrosion resistance; after continuous immersion in 3.5 wt% NaCl solution for 60 days, the impedance modulus at 0.01 Hz is 5.31 × 10⁻⁶. 11 Ω·cm 2 .

Description

Technical Field

[0001] This invention relates to a corrosion-resistant crosslinked polyketone coating and its preparation method, belonging to the field of organic coatings. Background Technology

[0002] Aliphatic polyketones (PK) are novel, environmentally friendly materials with excellent properties, synthesized by alternating copolymerization of α-olefins and carbon monoxide under palladium catalysis. They possess superior barrier and wear resistance. Currently, they are mainly processed into fibers and structural materials through extrusion molding, injection molding, and other methods.

[0003] Chinese patents (CN111205624B and CN111205625B) respectively disclose an aliphatic polyketone fully coated sucker rod and its preparation method, and an aliphatic polyketone liner tube and its preparation method. The above technical solutions use aliphatic polyketone resin with a number average molecular weight of 70,000-110,000 as the matrix, and obtain a polyketone layer coated on the surface of the sucker rod or inside a steel tube by extrusion molding. US Patent (US 5698663) discloses a polyketone resin composite powder coating. A ternary copolymer aliphatic polyketone resin, a binary copolymer aliphatic polyketone resin, and a phenolic resin are melt-blended and then pulverized at low temperature to obtain a powder, which is then prepared by electrostatic spraying, fluidized bed coating, or flame spraying to form a coating with good corrosion resistance. Although the coating prepared using the above technical solutions exhibits excellent wear resistance and corrosion resistance, its processing temperature is relatively high (220-270℃). Moreover, the above technical solutions mainly use low molecular weight polyketones. If the number-average molecular weight of aliphatic polyketones exceeds 110,000, special processing equipment is required, which results in higher costs.

[0004] Aliphatic polyketone resin-based composites and their molding and processing have received widespread attention. However, there are currently no reports on the direct use of intrinsic cross-linked polyketone resins as corrosion-resistant coatings through simple spraying. Summary of the Invention

[0005] This invention aims to provide a method for preparing a corrosion-resistant cross-linked polyketone coating. The intrinsically cross-linked polyketone coating obtained by this method exhibits excellent corrosion resistance without the need for additional inorganic fillers. After continuous immersion in a 3.5 wt% NaCl solution for 60 days, its impedance modulus at 0.01 Hz is 5.31 × 10⁻⁶. 11 Ω·cm 2 This demonstrates excellent corrosion resistance.

[0006] The technical solution of this invention:

[0007] The first technical problem to be solved by the present invention is to provide a method for preparing a corrosion-resistant crosslinked polyketone coating. The preparation method is as follows: firstly, a crosslinked polyketone resin solution with a viscosity of 50-200 mPa·s is prepared by reacting furan-functionalized polyketone with N,N'-(4,4'-methylenediphenyl)bismaleimide as raw materials; then, the obtained crosslinked polyketone resin solution is made into a coating; finally, the obtained coating is subjected to hot pressing and cold pressing treatments in sequence to obtain the corrosion-resistant crosslinked polyketone coating; wherein, the hot pressing temperature in the hot pressing treatment is 110-130℃.

[0008] Furthermore, in the above-mentioned method for preparing the corrosion-resistant crosslinked polyketone coating, the method for preparing the crosslinked polyketone resin (PKFM) solution is as follows: furan-functionalized polyketone and N,N'-(4,4'-methylenediphenyl)bismaleimide are reacted at 45-55°C for 18-36 h to obtain a crosslinked polyketone resin solution with a viscosity of 50-200 mPa·s; wherein, the reaction mass ratio of furan-functionalized polyketone to N,N'-(4,4'-methylenediphenyl)bismaleimide is 1:(0.8-2.5); preferably 1:1.6.

[0009] Furthermore, the preparation method of the cross-linked polyketone resin solution is as follows: first, furan-functionalized polyketone is dissolved in chloroform and added to a reaction apparatus equipped with a stirrer, condenser, and thermometer. Under inert gas protection, N,N'-(4,4'-methylenediphenyl)bismaleimide is added, and the reaction is carried out in a water bath at 45-55°C for 18-36 hours to obtain the cross-linked polyketone resin solution. The reaction equation is shown below:

[0010]

[0011] Furthermore, the viscosity of the cross-linked polyketone resin solution at room temperature is 80 mPa·s.

[0012] Furthermore, in the above-mentioned method for preparing corrosion-resistant cross-linked polyketone coating, the obtained cross-linked polyketone resin solution is coated by spraying or coating.

[0013] Furthermore, in the above-mentioned method for preparing the corrosion-resistant crosslinked polyketone coating, the method for preparing the corrosion-resistant crosslinked polyketone coating by obtaining the crosslinked polyketone resin solution is as follows: spray the crosslinked polyketone resin solution onto the surface of a clean metal substrate, spray at least 5 times, each spray lasting 5 to 30 seconds; then dry the sample, and then hot-press it at 110 to 130°C and 2 to 10 MPa for 10 to 20 minutes, and cold-press it at 30 to 50°C for 5 to 20 minutes to obtain the corrosion-resistant crosslinked polyketone coating.

[0014] Furthermore, the specific spraying process is as follows: fix the metal substrate, spray the above-mentioned cross-linked polyketone resin solution onto the surface of the substrate through a spray gun, with a nozzle diameter of 1mm, a spraying air pressure of 1.0MPa, a spraying distance of 10-40cm, spraying 5-10 times, and each spraying lasting 10-20 seconds.

[0015] In this invention, the furan-functionalized polyketone is a furan-modified polyketone, which can be prepared by the following method: first, aliphatic polyketone and furfurylamine are stirred evenly in a solvent, and then reacted at 30-40°C for 10-15 hours under nitrogen or inert gas protection; finally, the furan-functionalized polyketone is obtained by purification treatment; wherein, the molar ratio of the aliphatic polyketone to furfurylamine, calculated as 1,4-dicarbonyl, is 1:(1-8), preferably 1:5.

[0016] Furthermore, the solvent is selected from at least one of dichloromethane, hexafluoroisopropanol, trifluoroacetic acid, or m-cresol; preferably a mixed solvent of dichloromethane and hexafluoroisopropanol (preferably in a mass ratio of 6:4).

[0017] Furthermore, a catalyst can be added to the above reaction, which can be selected from bismuth nitrate pentahydrate or triethylamine.

[0018] Furthermore, the molar ratio of the aliphatic polyketide to bismuth nitrate pentahydrate is 80 to 50:1 (preferably 60:1).

[0019] Furthermore, in the preparation method of furan-functionalized polyketide, the purification process is as follows: after the reaction is completed, the reaction solution is added dropwise to anhydrous ethanol at a volume several times that of the reaction solvent, resulting in a pale yellow flocculent precipitate. The precipitate is then washed by alternating soaking and filtration with anhydrous ethanol and deionized water 3-5 times to remove unreacted impurities, and dried to obtain furan-functionalized polyketide.

[0020] Furthermore, the aliphatic polyketide is a linear alternating copolymer synthesized from carbon monoxide, ethylene, and propylene, with a number average molecular weight of 10,000-100,000, and is commercially available.

[0021] The second technical problem to be solved by the present invention is to provide a corrosion-resistant crosslinked polyketone coating, wherein the coating is prepared by the above-described preparation method.

[0022] The beneficial effects of this invention are:

[0023] (1) The cross-linked polyketone coating prepared in this invention has excellent corrosion resistance. After continuous immersion in 3.5wt% NaCl solution for 60 days, the impedance modulus at 0.01Hz is 5.31×10⁻⁶. 11 Ω·cm 2 .

[0024] (2) The process provided by this invention, which involves multiple spraying combined with hot pressing on the surface of Q235 steel, gradually forms a complete and dense cross-linked polyketone coating as the number of spraying times increases. This significantly reduces the impact of micropores formed by solvent evaporation during the spraying process on the deterioration of coating performance, and significantly improves the uniformity, interfacial adhesion, and corrosion resistance of the coating. This process is low in cost, simple to operate, and conducive to large-scale production and widespread application.

[0025] (3) Existing organic coatings often improve the barrier properties and corrosion resistance of the coating by adding two-dimensional lamellar fillers to the organic resin. However, the dispersion of the fillers in the matrix greatly affects the performance of the composite coating, leading to unstable coating performance. Based on this, the present invention can improve the corrosion resistance of the coating by relying on its own cross-linking network without adding fillers.

[0026] (4) Direct synthesis of novel polymers involves the design and optimization of molecular structures, which is a complex and time-consuming process. This invention modifies commercial polyketone resins in a simple and quick manner. Moreover, the aliphatic polyketones selected in this invention have excellent mechanical properties, heat resistance, corrosion resistance and barrier properties, and are environmentally friendly. This invention further broadens the application fields of polyketone resins. Attached image description:

[0027] Figure 1 The 1H NMR spectrum of the furan-functionalized polyketide prepared in Example 1 of this invention (…) 1 The NMR spectrum (H-NMR) results confirm the successful preparation of furan-functionalized polyketide.

[0028] Figure 2 The infrared (FTIR) spectra of furan-functionalized polyketone PKF5 and cross-linked polyketone resin (PKF5M5) prepared in step 1) of Example 1 of this invention are shown. The infrared results prove that the cross-linked polyketone resin was successfully prepared.

[0029] Figure 3 This is a digital photograph of the appearance of the cross-cut polyketide coating prepared in Example 1 of the present invention during a cross-cut test.

[0030] Figure 4 Electrochemical impedance spectroscopy (EIS) of the cross-linked polyketone coatings prepared according to Examples 1, 2, 3 and 5 of the present invention after immersion in 3.5 wt% NaCl solution for 60 days.

[0031] Figure 5 Nyquist plots of the cross-linked polyketone coatings prepared in Examples 1, 2, 3 and 5 of this invention after immersion in 3.5 wt% NaCl solution for 60 days. Detailed Implementation

[0032] This invention provides a method for preparing a corrosion-resistant crosslinked polyketone coating. The method comprises: first, reacting furan-functionalized polyketone with N,N'-(4,4'-methylenediphenyl)bismaleimide as raw materials to obtain a crosslinked polyketone resin solution with a viscosity of 50–200 mPa·s; then, forming a coating from the obtained crosslinked polyketone resin solution by spraying or coating; finally, subjecting the obtained coating to hot pressing and cold pressing treatments sequentially to obtain the corrosion-resistant crosslinked polyketone coating; wherein the hot pressing temperature is 110–130°C; the reaction process of this invention is as follows:

[0033]

[0034] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0035] Example 1

[0036] (1) Preparation of furan-functionalized polyketides

[0037] 4.01 g of dried polyketone resin (purchased from Hyosung, South Korea, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained.

[0038] Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, and alternating soaking and washing with anhydrous ethanol and deionized water three times to remove unreacted impurities, the product was dried in an oven at 60°C to obtain a pale yellow solid product, furan-functionalized polyketide (PKF5). Its 1H NMR spectrum and infrared spectrum are shown below. Figure 1 and Figure 2 As shown in the figure, the peak at position g (2.6 ppm-2.8 ppm) in the 1H NMR spectrum represents the hydrogen atoms of the methylene group on the aliphatic polyketide backbone. The hydrogen atoms on the pyrrole ring of the furan-functionalized polyketide backbone exhibit a broad chemical shift peak at position d (5.8 ppm), while the hydrogen atoms on the methylene bridge connected to the pyrrole ring exhibit a chemical shift peak at position a (4.8 ppm). Simultaneously, the hydrogen atoms of the furan groups on the polymer backbone exhibit chemical shift peaks at 7.2 ppm, 6.2 ppm, and 5.9 ppm. By comparing the intensities of the chemical shift peaks at positions a and g in the reaction product, the reaction yield of the furan-functionalized polyketide in PKF5 was calculated to be 33.3%.

[0039] Figure 2 In the middle, the PK curve is at 1688cm. -1 Corresponding to the carbonyl peak on the polyketide backbone, the PKF5 curve is 3109 cm⁻¹. -1 and 1588cm -1 The peak corresponds to the pyrrole ring present in the main chain, at 1420 cm⁻¹. -1 The peak at 731 cm⁻¹ belongs to the stretching vibration peak of CN in the pyrrole ring. -1 The corresponding out-of-plane vibration peak of CH in the furan ring is 10¹⁰ cm⁻¹. -1 The elution peaks belong to the stretching vibration peaks of the CN side groups. These results indicate the presence of pyrrole rings and furan rings in furan-functionalized polyketide resins, further confirming the successful preparation of furan-functionalized polyketides.

[0040] (2) Preparation of cross-linked polyketide resin

[0041] Weigh 4.00 g of the furan-functionalized polyketide (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 6.39 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown crosslinked polyketide resin solution (PKF5M5). After evaporating the solvent from the PKF5M5 solution, the infrared spectrum is as follows. Figure 2 As shown.

[0042] For PKF5M5, 1701cm -1 The elution peak corresponds to the carbonyl peak on the polyketide backbone, at 1184 cm⁻¹. -1 The newly appearing peak indicates the presence of the COC structure in the Diels-Alder addition product, proving that the furan-functionalized polyketide and bismaleimide underwent a Diels-Alder reaction, demonstrating the successful preparation of the crosslinked polyketide resin. Furthermore, the characteristic absorption peak of the furan ring can still be detected in the crosslinked polymer, indicating the reversibility of the Diels-Alder reaction; the reactants and products in the system always exist in dynamic equilibrium.

[0043] (3) Preparation of cross-linked polyketone organic coating

[0044] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M5).

[0045] Example 2

[0046] (1) Preparation of furan-functionalized polyketides

[0047] 4.00 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.61 g dichloromethane and 38.42 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. Over 20 minutes, 10.39 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF3).

[0048] (2) Preparation of cross-linked polyketide resin

[0049] Weigh 4.01 g of the furan-functionalized polyketone (PKF3) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 6.39 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown crosslinked polyketone resin solution (PKF3M5).

[0050] (3) Preparation of cross-linked polyketone organic coating

[0051] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF3M5).

[0052] Example 3

[0053] (1) Preparation of furan-functionalized polyketides

[0054] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.36 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0055] (2) Preparation of cross-linked polyketide resin

[0056] Weigh 4.00 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 3.22 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown crosslinked polyketone resin solution (PKF5M2.5).

[0057] (3) Preparation of cross-linked polyketone organic coating

[0058] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M2.5).

[0059] Example 4

[0060] (1) Preparation of furan-functionalized polyketides

[0061] 4.00 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.40 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.34 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0062] (2) Preparation of cross-linked polyketide resin

[0063] Weigh 4.01 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 9.88 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a crosslinked polyketone resin solution (PKF5M7.5).

[0064] (3) Preparation of cross-linked polyketone organic coating

[0065] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M7.5).

[0066] Example 5

[0067] (1) Preparation of furan-functionalized polyketides

[0068] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.40 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0069] (2) Preparation of cross-linked polyketide resin

[0070] Weigh 4.01 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 6.40 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown crosslinked polyketone resin solution (PKF5M5).

[0071] (3) Preparation of cross-linked polyketone organic coating

[0072] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 110℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M5-110).

[0073] Comparative Example 1

[0074] (1) Preparation of polyketide solution

[0075] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was added to a 250 mL three-necked flask and dissolved in a mixed solvent of 57.60 g dichloromethane and 38.40 g hexafluoroisopropanol. The mixture was stirred at room temperature to prepare a polyketone solution.

[0076] (2) Preparation of polyketone organic coating

[0077] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The polyketone solution prepared in step (1) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 5 minutes, followed by cold pressing at 50℃ for 10 minutes to obtain a cross-linked polyketone coating. The above spraying process was repeated three times, but due to the low viscosity of the solution, a coating suitable for testing could not be obtained.

[0078] Comparative Example 2

[0079] (1) Preparation of furan-functionalized polyketides

[0080] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0081] (2) Preparation of furan-functionalized polyketone organic coating

[0082] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. 4g of the furan-functionalized polyketone (PKF5) prepared in step (1) was dissolved in 500g of chloroform solution and sprayed onto the treated Q235 sample surface using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the spraying was repeated 5 times, each time for 10 seconds. The sample was placed in a 50℃ vacuum drying oven for 3 hours, then hot-pressed at 130℃ and 4MPa for 5 minutes, followed by cold-pressing at 50℃ for 10 minutes. This spraying process was repeated three times to obtain the furan-functionalized polyketone coating (PKF5).

[0083] Comparative Example 3

[0084] (1) Preparation of furan-functionalized polyketides

[0085] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0086] (2) Preparation of cross-linked polyketide resin

[0087] Weigh 4.00 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 6.39 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown cross-linked polyketone resin solution (PKF5M5).

[0088] (3) Preparation of cross-linked polyketone organic coating

[0089] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 90℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M5-90).

[0090] Comparative Example 4

[0091] (1) Preparation of furan-functionalized polyketides

[0092] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0093] (2) Preparation of cross-linked polyketide resin

[0094] Weigh 4.01 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 6.39 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown crosslinked polyketone resin solution (PKF5M5).

[0095] (3) Preparation of cross-linked polyketone organic coating

[0096] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 150℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M5-150).

[0097] Comparative Example 5

[0098] (1) Preparation of furan-functionalized polyketides

[0099] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.40 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0100] (2) Preparation of cross-linked polyketide resin

[0101] Weigh 4.01 g of the furan-functionalized polyketone (PKF5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Add the above solution to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, add 2.56 g of N,N'-(4,4'-methylenediphenyl)bismaleimide and react in a water bath at 50 °C for 24 h to obtain a dark brown cross-linked polyketone resin solution (PKF5M2).

[0102] (3) Preparation of cross-linked polyketone organic coating

[0103] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5M2).

[0104] Comparative Example 6

[0105] (1) Preparation of furan-functionalized polyketides

[0106] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0107] (2) Preparation of cross-linked polyketide resin

[0108] 4.02 g of the furan-functionalized polyketone (PKF5) prepared in step (1) was dissolved in 500 g of chloroform solution. The solution was added to a three-necked flask equipped with a stirrer, condenser, and thermometer. Under inert gas protection, 6.39 g of N,N'-(4,4'-methylenediphenyl)bismaleimide was added, and the mixture was reacted in a water bath at 50 °C for 12 h to obtain a dark brown cross-linked polyketone resin gel (PKF5M5-gel). Due to the formation of the gel, the viscosity was too high, making it impossible to continue with subsequent spraying or coating processes to prepare a coating.

[0109] Comparative Example 7

[0110] (1) Preparation of furan-functionalized polyketides

[0111] 4.01 g of dried polyketone resin (Hyosung, M630, melt flow index MFI of 6 g / 10 min (240℃ / 2.16 kg), Mn = 100,000 g / mol, Mw = 320,000, d = 3.2) was dissolved in a mixed solvent of 57.60 g dichloromethane and 38.41 g hexafluoroisopropanol and stirred at room temperature until homogeneous. 0.289 g of bismuth nitrate pentahydrate powder was then added as a catalyst and uniformly dispersed in the polyketone solution. 17.32 g of 2-furanylamine (furfurylamine) solution was added dropwise to the above solution over 20 minutes. The reaction was carried out under vigorous stirring in a 35℃ water bath for 12 hours at 500 rpm. After the reaction was complete, a light brown solution A was obtained. Solution A was flocculated and precipitated in excess anhydrous ethanol to obtain a flocculated product. After filtration, the product was washed three times with alternating soaking in anhydrous ethanol and deionized water to remove unreacted impurities. The product was then dried in an oven at 60°C to obtain a pale yellow solid product, which was furan-functionalized polyketide (PKF5).

[0112] (2) Preparation of cross-linked polyketide resin

[0113] Weigh 4.00 g of the furan-functionalized polyketide (PKF-5) prepared in step (1) and dissolve it in 500 g of chloroform solution. Under inert gas protection, add 4.80 g of N,N'-m-phenylenebismaleimide and react in a water bath at 50 °C for 24 h to obtain a cross-linked polyketide resin solution (PKF5P5).

[0114] (3) Preparation of cross-linked polyketone organic coating

[0115] The Q235 sample (100mm×30mm×3mm) was sanded to remove rust using existing substrate treatment methods, then degreased with acetone, ultrasonically cleaned with anhydrous ethanol for 5 minutes, and dried for later use. The cross-linked polyketone resin solution prepared in step (2) was sprayed onto the surface of the treated Q235 sample using a spray gun. The nozzle diameter was 1mm, the spraying pressure was 1.0MPa, the spraying distance was 20cm, and the sample was sprayed 5 times, each time for 10 seconds. The sample was placed in a vacuum drying oven at 50℃ for 3 hours, and then hot-pressed at 130℃ and 4MPa for 15 minutes, followed by cold pressing at 50℃ for 10 minutes. The above spraying process was repeated three times to obtain the cross-linked polyketone coating (PKF5P5).

[0116] Performance testing:

[0117] A series of coating performance tests were conducted on the cross-linked polyketone coatings prepared in the examples and comparative examples. The thickness of the coatings was measured using a Mikro Test F6 magnetic thickness gauge from EPK GmbH, Germany. To ensure accuracy, three points were taken from each sample, and the average value was calculated. The resistance of the coatings to detach from the substrate was evaluated according to GB / T 9286-2021 "Cross-cut Test for Paints and Varnishes," with higher grades indicating poorer resistance. Table 1 shows the thickness and cross-cut test grading results for different examples and comparative examples.

[0118] Table 1. Performance of coatings prepared in different examples and comparative examples

[0119]

[0120] Furthermore, for the coating samples with good adhesion, electrochemical impedance spectroscopy (EIS) tests were performed on the cross-linked polyketide coatings prepared in Examples 1, 2, 3, and 5 above after immersion in 3.5 wt% NaCl solution for different times using a CHI660E electrochemical workstation from Shanghai Chenhua Instruments Co., Ltd. Test conditions: A typical three-electrode system was used, where the sample, platinum electrode, and saturated calomel electrode (SCE) were used as the working electrode, auxiliary electrode, and reference electrode, respectively. The test area was a base area of ​​1 cm². 2 The test was conducted using a 3.5 wt% NaCl solution in a circular electrolyte, with a frequency range of 10. -2 -10 5 The test signal was a 10mV sine wave, and after the system stabilized, its electrochemical impedance spectroscopy (EIS) was measured. The impedance data were analyzed using ZsimDemo software. Figure 4 and Figure 5 Electrochemical impedance spectroscopy (EIS) and Nyquist plots of the crosslinked polyketone coatings prepared according to Examples 1, 2, 3, and 5 of the present invention were obtained after immersion in a 3.5 wt% NaCl solution for 60 days. As shown in the figures, the coatings prepared in the examples maintained a high impedance modulus after immersion in a 3.5 wt% NaCl solution for 60 days, indicating that the crosslinked coatings in the examples provide good corrosion resistance.

Claims

1. A method for producing a corrosion resistant crosslinked polyketone coating, characterized by, The preparation method is as follows: first, the furan-functionalized polyketone is dissolved in chloroform, and then is added into a reaction device provided with a stirrer, a condenser and a thermometer under the protection of inert gas, N,N'- (4, 4'-methylene diphenyl) bismaleimide is added, and the reaction is carried out in a water bath at 45-55 ℃ for 18-36 h to obtain a cross-linked polyketone resin solution with a viscosity of 50-200 mpa·s; the cross-linked polyketone resin solution is sprayed on the surface of a clean metal substrate for at least 5 times, each time for 5-30 s; then the sample is dried, and the corrosion-resistant cross-linked polyketone coating is prepared by hot pressing at 110-130 ℃ and 2-10 MPa for 10-20 min and cold pressing at 30-50 ℃ for 5-20 min; the reaction mass ratio of the furan-functionalized polyketone and N,N'- (4, 4'-methylene diphenyl) bismaleimide is 1: (0.8-2.5) ; the furan-functionalized polyketone is prepared by the following method: first, the aliphatic polyketone and furfurylamine are uniformly stirred in a solvent, and then the reaction is carried out at 30-40 ℃ for 10-15 h under the protection of nitrogen or inert gas; finally, the furan-functionalized polyketone is obtained by purification treatment; wherein, the aliphatic polyketone is calculated based on 1, 4-dicarbonyl: the reaction molar ratio of polyketone and furfurylamine is 1: (1-8).

2. The method for preparing a corrosion-resistant crosslinked polyketone coating according to claim 1, characterized in that, The solvent is selected from at least one of dichloromethane, hexafluoroisopropyl alcohol, trifluoroacetic acid or m-cresol.

3. The method of claim 2, wherein the method further comprises the step of: The solvent is a mixed solvent of dichloromethane and hexafluoroisopropyl alcohol. ​ 4. The method of claim 1 to 3, wherein the method is characterized in that, A catalyst is also added in the preparation process of the furan-functionalized polyketone, and the catalyst is bismuth nitrate pentahydrate or triethylamine.

5. The method of claim 4, wherein the method further comprises the step of: The reaction molar ratio of the aliphatic polyketone and the catalyst is 80-50:

1. ​ 6. A process for the production of a corrosion resistant crosslinked polyketone coating according to any one of claims 1 to 3, characterized in that, The aliphatic polyketone is a linear alternating copolymer synthesized from carbon monoxide, ethylene and propylene, and has a number average molecular weight of 10,000-100,000.

7. A corrosion resistant crosslinked polyketone coating, characterized in that, The polyketone coating is prepared by the preparation method of any one of claims 1-6.

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