Multi-chemical-medium-resistant cross-linked network coating and preparation method thereof

Abstract

The invention belongs to the technical field of protective coatings, and particularly discloses a multi-chemical-medium-resistant cross-linked network coating and a preparation method thereof.The preparation method comprises the steps that trifunctional epoxy resin and a phenolic aldehyde amine curing agent are weighed according to the weight part and evenly stirred, a perfluoropolyether side chain modifier is added according to the weight part, and stirring continues to be conducted and evenly mixed; the surface of a substrate is coated with the coating in a spraying, dip-coating or blade-coating mode, and the thickness of the coating is controlled to be 50-60 microns; and putting the coated substrate into a drying oven, and curing to obtain the cross-linked network coating. According to the cross-linked network coating disclosed by the invention, the polyfunctional group resin and the phenolic aldehyde amine curing agent are matched, and a basic cross-linked system is constructed by utilizing the structural characteristics of the polyfunctional group resin and matching the phenolic aldehyde amine curing agent; meanwhile, a perfluoropolyether side chain with the fluorine content of 8-10% is introduced, and the surface and internal microstructures of the coating are changed by means of the characteristics of the perfluoropolyether side chain; through the combination, the cross-linking density of the coating is greater than 3000mol / m, and a compact cross-linked coating capable of synchronously resisting acid, alkali, detergent and diesel oil is formed.

Description

Technical Field

[0001] This invention belongs to the field of protective coating technology, specifically relating to a cross-linked network coating resistant to multiple chemical media and its preparation method. Background Technology

[0002] In many industrial fields, such as industrial protection and protection of everyday cleaning equipment, equipment is exposed to harsh environments for extended periods, facing severe corrosion problems. Coatings are required to resist the erosion of chemical media such as acids, alkalis, detergents, and diesel fuel. From a corrosion perspective, traditional anti-corrosion coatings, such as ordinary paint coatings, have limited protective capabilities in extreme environments such as high temperature, high humidity, strong acids and alkalis, and high salinity. With prolonged contact with corrosive chemicals, traditional anti-corrosion measures are difficult to maintain their effectiveness in the long term.

[0003] The molecular structure of epoxy resin is characterized by the presence of reactive epoxy groups in its molecular chain. These reactive epoxy groups allow it to undergo cross-linking reactions with various types of curing agents, forming insoluble polymers with a three-dimensional network structure. Cured epoxy resin exhibits excellent physical and chemical properties. It demonstrates superior adhesion strength to both metallic and non-metallic surfaces, good dielectric properties, low shrinkage, good dimensional stability, high hardness, and good flexibility. It is also stable to alkalis and most solvents. Therefore, it is widely used in national defense and various sectors of the national economy for casting, impregnation, lamination, adhesives, coatings, and other applications.

[0004] However, in existing technologies, ordinary epoxy resin coatings use conventional bifunctional epoxy resins and general-purpose curing agents (such as aliphatic amine curing agents), resulting in simple cross-linking structures. When faced with complex chemical media, they are easily penetrated and corroded. Some coatings that attempt to introduce fluorine-containing groups have unreasonable fluorine side chain structure designs (such as short fluorocarbon chains and improper grafting methods). The fluorine element cannot effectively play its role in reducing surface energy and preventing media penetration. Moreover, the cross-linking density is less than 2500 mol / m³, resulting in poor coating density. Under the long-term action of acids, alkalis, detergents, diesel, etc., the coating is prone to swelling, cracking, and peeling, failing to provide continuous and effective protection to the substrate and affecting the service life and performance stability of the protected object.

[0005] Therefore, there is an urgent need to develop dense cross-linked coatings resistant to chemical media to overcome the shortcomings of existing technologies in providing poor protection against various chemical media. Summary of the Invention

[0006] The purpose of this invention is to solve the problem that existing coatings have insufficient protective performance against chemical media such as acids, alkalis, detergents, and diesel fuel. The invention provides a dense cross-linked coating that is resistant to multiple chemical media. By using specific resins, curing agents, and introducing fluorinated side chains, the coating performance is optimized to form a dense cross-linked coating with high cross-linking density that can simultaneously resist acids, alkalis, detergents, and diesel fuel.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A cross-linked network coating resistant to multiple chemical media, the coating comprising the following raw materials in parts by weight: 100 parts of multifunctional resin, 28-35 parts of phenolic amine curing agent, and 10-12 parts of perfluoropolyether side chain modifier.

[0008] The working principle of this invention is as follows: A basic crosslinking system is constructed using a multifunctional resin and a phenolic amine curing agent. The multifunctional resin has more reactive sites than conventional difunctional epoxy resins, enabling it to form a more complex and stable crosslinking network with the phenolic amine curing agent. Simultaneously, a perfluoropolyether side chain with a fluorine content of 8-10% is introduced. Due to its extremely low surface energy, this effectively reduces the affinity of the coating surface for chemical media such as acids, alkalis, detergents, and diesel fuel, thus reducing the adhesion and penetration of these media on the coating surface. Furthermore, its synergistic effect with the basic crosslinking system further enhances the chemical stability of the coating. Through specific material selection and process control, a high crosslinking density of >3000 mol / m³ is achieved, greatly improving the coating's density and making it difficult for chemical media to penetrate the coating's interior, fundamentally enhancing the coating's resistance to chemical corrosion.

[0009] Preferably, the multifunctional resin includes any one of trifunctional epoxy resin, neopentyl glycol diglycidyl ether acrylate, polyepoxy acrylate, and diglycidyl ether diacrylate.

[0010] Preferably, the phenolic amine curing agent is a β-naphthol-based trifunctional resin / diethylenetriamine (DEA) composite material.

[0011] Preferably, the perfluoropolyether side chain modifier is prepared by the following method: (1) The perfluoroether precursor is reacted in the presence of a catalyst to obtain a long-chain perfluoropolyether monomer. The polymerization reaction is terminated by adding a terminator. The residual monomer and catalyst are removed by extraction and recrystallization to obtain the end-capped perfluoropolyether. (2) The synthesized perfluoropolyether is mixed with acrylic acid in an organic solvent, and an accelerator is added to crosslink the reaction at 50-80℃ for 3-6 hours. After the reaction is completed, the unreacted acrylic acid is removed by neutralization and extraction, and then the perfluoropolyether side chain modifier is obtained by purification.

[0012] Preferably, the terminator in step (1) is any one of hydrofluoric acid and fluorinating agent; the acrylic acid in step (2) includes any one of acrylic acid and ethyl acrylate; and the promoter is any one of acid catalyst and free radical initiator.

[0013] Another object of the present invention is to provide a method for preparing a cross-linked network coating resistant to multiple chemical media, comprising the following steps: (1) Weigh the trifunctional epoxy resin and phenolic amine curing agent according to the weight parts, pour them into the mixing tank under the environment of temperature 25-30℃ and humidity 35-42%, stir evenly at a rate of 200-300r / min for 15-20min, add the perfluoropolyether side chain modifier according to the weight parts, continue stirring for 10-15min, and mix evenly. (2) Apply the above-mentioned uniformly mixed coating to the substrate surface by spraying, dipping or scraping, and control the coating thickness to be 50-60μm; (3) Place the coated substrate in an oven and pre-cur it at 70-80℃ for 30-40 min. Then, raise the temperature to 120-130℃ at a rate of 2-3℃ / min and keep it at the temperature for 1.5-2.5 h to obtain the cross-linked network coating.

[0014] Preferably, the substrate in step (2) is any one of stainless steel, aluminum alloy, or polypropylene (PP) board.

[0015] Preferably, the spraying method in step (2) includes uniformly spraying the evenly mixed coating onto the substrate surface through a spray gun, setting the spray gun pressure to 0.4 MPa, and maintaining a spraying distance of 15 cm.

[0016] Preferably, the dip coating method in step (2) includes slowly immersing the substrate in the mixed coating, holding it for 30 seconds, and then lifting it at a uniform speed of 5 cm / min.

[0017] Preferably, the coating method in step (2) includes uniformly coating the mixed coating onto the substrate surface using a scraper.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. The cross-linked network coating of this invention uses a combination of multifunctional resin and phenolic amine curing agent. Utilizing the structural characteristics of the multifunctional resin and the phenolic amine curing agent, a basic cross-linking system is constructed. Simultaneously, perfluoropolyether side chains with a fluorine content of 8-10% are introduced. By leveraging the properties of the perfluoropolyether side chains, the surface and internal microstructure of the coating are altered. Through the above combination, the cross-linking density of the coating reaches >3000 mol / m³, forming a dense cross-linked coating that can simultaneously resist acids, alkalis, detergents, and diesel fuel.

[0019] 2. The coating of this invention uses a multifunctional resin as the coating substrate, which has more reactive sites than conventional difunctional epoxy resins. It can form a more complex and stable cross-linking network with phenolic amine curing agents, providing a basic support for the high protective performance of the coating. The coating prepared by the invention can be immersed in acid, alkali, detergent and diesel environments for 72 hours and its adhesion reaches level 1. Moreover, the internal structure is dense and there are no pores, cracks or erosion marks caused by corrosion.

[0020] 3. Through specific material selection and process control, this invention achieves a high cross-linking density in the coating, making the coating structure more compact and preventing chemical media from penetrating and damaging the coating. It achieves simultaneous resistance to acids, alkalis, detergents, and diesel fuel, significantly improving the coating's tolerance to complex chemical environments. It effectively avoids problems such as swelling, cracking, and peeling of the coating, ensuring the long-term protective stability of the substrate when in contact with these chemical media.

[0021] 4. The coating of this invention can be applied to product fields with strict protection requirements, such as aerospace component coatings, marine equipment coatings, waterproof and anti-corrosion coatings for electronic equipment, stain-resistant coatings for building exterior walls, chemical pipeline coatings, protective coatings for food processing equipment, and protective coatings for industrial equipment. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a SEM image of the coating in Embodiment 2 of the present invention; Figure 2 This is a SEM image of the coating in Example 2 of the present invention after an acid resistance test; Figure 3 This is a SEM image of the coating in Example 2 of the present invention after an alkali resistance test; Figure 4 This is a SEM image of the coating of Comparative Example 5 after acid resistance testing. Figure 5 This is a SEM image of the coating of Comparative Example 5 of the present invention after alkali resistance testing; Figure 6 This is a SEM image of the coating of Comparative Example 6 of the present invention after acid resistance testing; Figure 7 This is a SEM image of the coating of Comparative Example 6 of the present invention after alkali resistance testing. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. In the absence of conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

[0025] A cross-linked network coating resistant to multiple chemical media, the coating comprising the following raw materials in parts by weight: 100 parts of multifunctional resin, 28-35 parts of phenolic amine curing agent, and 10-12 parts of perfluoropolyether side chain modifier.

[0026] It should be noted that the multifunctional resin includes any one of trifunctional epoxy resin, neopentyl glycol diglycidyl ether acrylate, polyepoxy acrylate, and diglycidyl ether diacrylate. In order to achieve the optimal results of the present invention, the most commonly used resin in the embodiments of the present invention is trifunctional epoxy resin.

[0027] It should be noted that the phenolic amine curing agent can be any phenolic amine curing agent currently available on the market, such as BASF EC331, Huntsman 500 series, Chenguang Chemical CC-200, etc. In order to reflect the optimal results of the present invention, the embodiments of the present invention use β-naphthol-based trifunctional resin / diethylenetriamine composite material as phenolic amine curing agent.

[0028] It should be noted that the perfluoropolyether side chain modifier is prepared by the following method: (1) Perfluoroether diol was reacted in the presence of a catalyst to obtain a long-chain perfluoropolyether monomer. The polymerization reaction was terminated by adding hydrofluoric acid. The residual monomer and catalyst were removed by extraction and recrystallization to obtain a capped perfluoropolyether. (2) The synthesized perfluoropolyether and acrylic acid were mixed in an organic solvent at a mass ratio of 1:6.5. An acid catalyst was added and the crosslinking reaction was carried out at 50°C for 6 hours. After the reaction was completed, the unreacted acrylic acid was removed by neutralization and extraction. Then, the perfluoropolyether side chain modifier 1# with a fluorine content of 8% was obtained by purification and impurity removal.

[0029] It should be noted that the perfluoropolyether side chain modifier is prepared by the following method: (1) Perfluoroether diol was reacted in the presence of a catalyst to obtain a long-chain perfluoropolyether monomer. The polymerization reaction was terminated by adding hydrofluoric acid. The residual monomer and catalyst were removed by extraction and recrystallization to obtain a capped perfluoropolyether. (2) The synthesized perfluoropolyether and ethyl acrylate were mixed in an organic solvent at a mass ratio of 1:5.67. A free radical initiator was added and the crosslinking reaction was carried out at 60°C for 4 hours. After the reaction was completed, the unreacted ethyl acrylate was removed by neutralization and extraction. Then, the perfluoropolyether side chain modifier 2# with a fluorine content of 9% was obtained by purification and impurity removal.

[0030] It should be noted that the perfluoropolyether side chain modifier is prepared by the following method: (1) Perfluoroether diol is reacted in the presence of a catalyst to obtain a long-chain perfluoropolyether monomer. The polymerization reaction is terminated by adding a fluorinating agent. The residual monomer and catalyst are removed by extraction and recrystallization to obtain a capped perfluoropolyether. (2) The synthesized perfluoropolyether and ethyl acrylate were mixed in an organic solvent at a mass ratio of 1:5. A free radical initiator was added and the crosslinking reaction was carried out at 80°C for 3 hours. After the reaction was completed, the unreacted ethyl acrylate was removed by neutralization and extraction. Then, the perfluoropolyether side chain modifier 3# with a fluorine content of 10% was obtained by purification and impurity removal.

[0031] It should be noted that, in addition to being prepared using the method of this invention, the perfluoropolyether side chain modifier of this invention can also be prepared using common perfluoropolyether side chain modifiers available on the market, such as Solvay THV 220G and DuPont Zonyl FS-3000. Example

[0032] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts trifunctional epoxy resin, 35 parts phenolic amine curing agent, and 10 parts perfluoropolyether side chain modifier #1. Its preparation includes the following steps: (1) Weigh 100 parts of trifunctional epoxy resin and 35 parts of phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 25℃ and a humidity of 40%, stir evenly at a speed of 200r / min for 15min, add 10 parts of perfluoropolyether side chain modifier 1# according to the weight, continue stirring for 10min, and mix evenly. (2) Using a spraying process, the uniformly mixed coating is sprayed evenly onto the surface of a 304 stainless steel substrate through a spray gun. The spray gun pressure is set to 0.4 MPa and the spraying distance is maintained at 15 cm to form a wet film with a thickness of 50 μm. (3) Place the coated substrate in an oven and pre-cur it at 70°C for 40 min. Then, raise the temperature to 120°C at a rate of 2°C / min and keep it at the temperature for 2 h to obtain the cross-linked network coating. Example

[0033] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts trifunctional epoxy resin, 28 parts phenolic amine curing agent, and 12 parts perfluoropolyether side chain modifier #2. Its preparation includes the following steps: (1) Weigh 100 parts of trifunctional epoxy resin and 28 parts of phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 30℃ and a humidity of 35%, stir evenly at a speed of 300r / min for 20min, add 12 parts of perfluoropolyether side chain modifier 2# according to the weight, continue stirring for 12min, and mix evenly. (2) Using the dip coating process, the aluminum alloy substrate is slowly immersed in the mixed coating for 30 seconds, and then pulled up at a constant speed of 5 cm / min to form a 60 μm wet film on the substrate surface. (3) Place the coated substrate in an oven and pre-cur it at 80°C for 30 min. Then, raise the temperature to 130°C at a rate of 3°C / min and keep it at the temperature for 1.5 h to obtain the cross-linked network coating. Example

[0034] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts trifunctional epoxy resin, 33 parts phenolic amine curing agent, and 10 parts perfluoropolyether side chain modifier #3. Its preparation includes the following steps: (1) Weigh 100 parts of trifunctional epoxy resin and 33 parts of phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 28℃ and a humidity of 42%, stir evenly at a speed of 250r / min for 18min, add 11 parts of perfluoropolyether side chain modifier 3# according to the weight, continue stirring for 15min, and mix evenly. (2) The coating process is adopted. The mixed coating is evenly coated on the surface of the PP board using a scraper, and the wet film thickness of the coating is controlled to be 55μm. (3) Place the coated substrate in an oven and pre-cur it at 70°C for 40 min. Then, raise the temperature to 125°C at a rate of 2.5°C / min and keep it at the temperature for 2.5 h to obtain the cross-linked network coating. Example

[0035] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts of epoxy acrylate, 28 parts of phenolic amine curing agent, and 12 parts of perfluoropolyether side chain modifier #3. Its preparation includes the following steps: (1) Weigh 100 parts of polyepoxy acrylate and 28 parts of phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 30℃ and a humidity of 35%, stir evenly at a speed of 300r / min for 20min, add 12 parts of perfluoropolyether side chain modifier 3# according to the weight, continue stirring for 12min, and mix evenly. (2) Using a spraying process, the uniformly mixed coating is sprayed evenly onto the surface of a 304 stainless steel substrate through a spray gun. The spray gun pressure is set to 0.4 MPa and the spraying distance is maintained at 15 cm to form a wet film with a thickness of 50 μm. (3) Place the coated substrate in an oven and pre-cur it at 70-80℃ for 30-40 min. Then, raise the temperature to 120-130℃ at a rate of 2-3℃ / min and keep it at the temperature for 1.5-2.5 h to obtain the cross-linked network coating. Example

[0036] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts diglycidyl ether diacrylate, 28 parts phenolic amine curing agent, and 12 parts perfluoropolyether side chain modifier (Solvay THV 220G). Its preparation includes the following steps: (1) Weigh 100 parts of diglycidyl ether diacrylate and phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 30℃ and a humidity of 35%, stir evenly at a speed of 300r / min for 20min, add perfluoropolyether side chain modifier according to the weight, continue stirring for 12min, and mix evenly. (2) Slowly immerse the aluminum alloy substrate into the mixed coating for 30 seconds, and then lift it at a constant speed of 5 cm / min to form a 60 μm wet film on the substrate surface. (3) Place the coated substrate in an oven and pre-cur it at 70-80℃ for 30-40 min. Then, raise the temperature to 120-130℃ at a rate of 2-3℃ / min and keep it at the temperature for 1.5-2.5 h to obtain the cross-linked network coating. Example

[0037] A cross-linked network coating resistant to multiple chemical media comprises the following raw materials in parts by weight: 100 parts neopentyl glycol diglycidyl ether acrylate, 28 parts phenolic amine curing agent, and 12 parts perfluoropolyether side chain modifier (DuPont Zonyl FS-3000). Its preparation includes the following steps: (1) Weigh 100 parts of neopentyl glycol diglycidyl ether acrylate and phenolic amine curing agent according to the weight, pour them into a mixing tank at a temperature of 30℃ and a humidity of 35%, stir evenly at a speed of 300r / min for 20min, add perfluoropolyether side chain modifier according to the weight, continue stirring for 12min, and mix evenly. (2) The coating process is adopted. The mixed coating is evenly coated on the surface of the PP board using a scraper, and the wet film thickness of the coating is controlled to be 55μm. (3) Place the coated substrate in an oven and pre-cur it at 70-80℃ for 30-40 min. Then, raise the temperature to 120-130℃ at a rate of 2-3℃ / min and keep it at the temperature for 1.5-2.5 h to obtain the cross-linked network coating.

[0038] Comparative Example 1 Compared with Example 2, the trifunctional epoxy resin was replaced with a difunctional epoxy resin, while the rest of the formulation and steps were exactly the same as in Example 2.

[0039] Comparative Example 2 Compared with Example 2, the phenolic amine curing agent was replaced with aliphatic amine curing agent, while the rest of the formulation and steps were exactly the same as in Example 2.

[0040] Comparative Example 3 Compared with Example 2, the trifunctional epoxy resin was replaced with a difunctional epoxy resin, and the phenolic amine curing agent was replaced with an aliphatic amine curing agent. The rest of the formulation and steps were exactly the same as in Example 2.

[0041] Comparative Example 4 Compared to Example 2, the perfluoropolyether side chain modifier was replaced with polysiloxane acrylate, while the rest of the formulation and steps were exactly the same as in Example 2.

[0042] Comparative Example 5 Compared with Example 2, the trifunctional epoxy resin was replaced with a difunctional epoxy resin, the phenolic amine curing agent was replaced with a fatty amine curing agent, and the perfluoropolyether side chain modifier was replaced with polysiloxane acrylate. The rest of the formulation and steps were exactly the same as in Example 2.

[0043] Comparative Example 6 A coating comprising the following raw materials in parts by weight: 100 parts trifunctional epoxy resin and 30 parts phenolic amine curing agent, the preparation of which includes the following steps: (1) Weigh 100 parts of trifunctional epoxy resin and 28 parts of phenolic amine curing agent according to the weight ratio, pour them into a mixing tank at a temperature of 30℃ and a humidity of 35%, and stir evenly at a speed of 300r / min for 20min until they are evenly mixed. (2) Using the dip coating process, the aluminum alloy substrate is slowly immersed in the mixed coating for 30 seconds, and then pulled up at a constant speed of 5 cm / min to form a 60 μm wet film on the substrate surface. (3) Place the coated substrate in an oven and pre-cur it at 80°C for 30 min. Then, raise the temperature to 130°C at a rate of 3°C / min and keep it at the temperature for 1.5 h to obtain the cross-linked network coating.

[0044] Test case The coatings prepared above were subjected to crosslinking density tests and tests for acid resistance, alkali resistance, detergent resistance, and diesel fuel resistance. The specific test methods are as follows: Crosslinking density test: The crosslinking density of the coating is tested using DMA. The specific test steps are as follows: 1. Sample preparation Prepare the sample to be tested into a thin sheet or small strip suitable for DMA testing, ensuring that its surface is smooth and free of obvious defects; dry the sample to remove moisture and solvent residue; correctly install the sample in the fixture of the DMA testing instrument, ensuring that the sample is stretched or compressed evenly for accurate measurement.

[0045] Temperature scan Heating rate: 2–3 °C / min (avoid thermal hysteresis).

[0046] Temperature range: Start with Tg − 50 °C (or room temperature), sweep up to Tg + 80-120 °C or higher, but must be 40 °C or more below the decomposition temperature.

[0047] Atmosphere: Nitrogen (recommended 20–50 mL / min) to inhibit oxidation.

[0048] 3. Data Collection Temperature scan data: Within a specified temperature range, DMA will record parameters such as storage modulus (E': representing the elastic part of the material, reflecting the energy stored in the material during deformation), loss modulus (E'': representing the viscous part of the material, reflecting the energy dissipated in the material during deformation), and loss factor (tan δ: the ratio of storage modulus to loss modulus) of the sample at different temperatures.

[0049] 4. Test ends During the temperature scan, DMA will automatically record and analyze the data at each temperature point and provide temperature dependence curves for the energy storage modulus (E'), loss modulus (E''), and loss factor (tan δ).

[0050] Based on the data, the glass transition temperature (Tg) is obtained, and then the crosslinking density or the elastic and viscous properties of the material are estimated.

[0051] Calculation formula: v = E' / (RT) E' is the storage modulus (Pa), R is the gas constant (8.314 J / mol·K), and T is the temperature (K).

[0052] Acid resistance test: The cured coating sample is immersed in a 10% sulfuric acid solution at room temperature for 72 hours. The coating surface is observed with the naked eye to check for swelling, discoloration, peeling, etc. At the same time, the microstructure of the coating surface is observed by scanning electron microscopy to determine whether there are pores or cracks caused by acid erosion. If there are no pores or cracks, it indicates strong acid resistance.

[0053] Alkali resistance test: The cured coating sample is immersed in a 15% sodium hydroxide solution at room temperature for 72 hours. The coating surface is observed with the naked eye to check for swelling, discoloration, peeling, etc. At the same time, the microstructure of the coating surface is observed by scanning electron microscopy to determine whether there are pores or cracks caused by alkali erosion. If there are no pores or cracks, it indicates strong alkali resistance.

[0054] Detergent resistance test: The cured coating sample is immersed in a common industrial detergent with a mass fraction of 5% (Alconox detergent is used in this test) for 72 hours at 40°C. The coating surface is then visually inspected for detergent residue or damage. If there is no residue, it indicates strong detergent resistance.

[0055] Diesel fuel resistance test: Immerse the coating sample in diesel fuel and leave it at room temperature for 72 hours. Observe with the naked eye whether there is swelling or softening on the coating surface. At the same time, test the coating adhesion according to the standards ISO 4624:2016 / GB / T 5210-2006 / ASTM D4541-22. The higher the grade, the better the stability of the coating in the diesel fuel environment.

[0056] Specific test results are shown in Table 1 and... Figure 1-7 As shown. From Figure 1-3 As can be seen, after a 72-hour acid-base test, the coating prepared in this embodiment of the invention did not show swelling, discoloration, or peeling on the surface, and no pores or cracks appeared inside the coating. Figure 4-7 The acid and alkali tests of the coatings prepared in Comparative Examples 5 and 6 are shown in the figures. As can be seen from the figures, different degrees of voids and cracks appeared inside the coatings, and obvious swelling, discoloration and peeling were also observed on the surface of the coatings. The experimental results of Comparative Examples 6 and 3 show that the crosslinking system constructed by using traditional bifunctional resin and aliphatic amine curing agent has a simple structure and is easily penetrated and corroded by complex chemical media. The experimental results of Comparative Examples 4 and 5 show that even if traditional fluorine-containing groups are introduced into the coating, due to the unreasonable design of the fluorine-containing side chain structure, the fluorine element is difficult to effectively play the role of reducing surface energy and preventing media penetration. Moreover, the crosslinking density is less than 2000 mol / m³, the coating has poor density, and under the long-term action of acids, alkalis, detergents, diesel, etc., the coating is prone to swelling, cracking and peeling, and cannot continuously and effectively protect the substrate, affecting the service life and performance stability of the protected objects (such as industrial equipment, cleaning tools, etc.).

[0057] As shown in Table 1, the crosslinking density of the coatings prepared by this invention all reached over 3000 mol / m³, significantly higher than that of Comparative Examples 1-6. Data from Comparative Examples 1, 2, and 4 indicate that this invention uses a trifunctional epoxy resin and a phenolic amine curing agent to construct the basic crosslinking system. This system possesses more reactive sites than conventional difunctional epoxy resins, enabling it to form a more complex and stable crosslinking network with the phenolic amine curing agent. Simultaneously, a perfluoropolyether side chain with a fluorine content of 8-10% is introduced. The properties of the perfluoropolyether side chain are utilized to optimize the coating performance. Through the above combination, the crosslinking density of the coating reaches >3000 mol / m³, forming a dense crosslinked coating that can simultaneously resist acids, alkalis, detergents, and diesel fuel, demonstrating significant advantages compared to traditional resin-curing agent combinations.

[0058] Table 1 Performance test results of different coatings

[0059] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A cross-linked network coating resistant to multiple chemical media, characterized in that, The coating comprises the following raw materials in parts by weight: 100 parts of multifunctional resin, 28-35 parts of phenolic amine curing agent, and 10-12 parts of perfluoropolyether side chain modifier.

2. The multi-chemical-resistant cross-linked network coating according to claim 1, characterized in that, The multifunctional resin includes any one of trifunctional epoxy resin, neopentyl glycol diglycidyl ether acrylate, polyepoxy acrylate, and diglycidyl ether diacrylate.

3. The multi-chemical-resistant cross-linked network coating according to claim 1, characterized in that, The phenolic amine curing agent is a β-naphthol-based trifunctional resin / diethylenetriamine composite material.

4. The multi-chemical-resistant cross-linked network coating according to claim 1, characterized in that, The perfluoropolyether side-chain modifier has a fluorine content of 8-10% and is prepared by the following method: (1) The perfluoroether precursor is reacted in the presence of a catalyst to obtain a long-chain perfluoropolyether monomer. The polymerization reaction is terminated by adding a terminator. The residual monomer and catalyst are removed by extraction and recrystallization to obtain the end-capped perfluoropolyether. (2) The synthesized perfluoropolyether is mixed with acrylic acid in an organic solvent, and an accelerator is added to crosslink the reaction at 50-80℃ for 3-6 hours. After the reaction is completed, the unreacted acrylic acid is removed by neutralization and extraction, and then the perfluoropolyether side chain modifier is obtained by purification.

5. The multi-chemical-resistant cross-linked network coating according to claim 4, characterized in that, The terminator in step (1) is any one of hydrofluoric acid and fluorinating agent; the acrylic acid in step (2) includes any one of acrylic acid and ethyl acrylate; the accelerator is any one of acid catalyst and free radical initiator.

6. A method for preparing a multi-chemical-resistant cross-linked network coating according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Weigh the trifunctional epoxy resin and phenolic amine curing agent according to the weight parts, pour them into the mixing tank under the environment of temperature 25-30℃ and humidity 35-42%, stir evenly at a rate of 200-300r / min for 15-20min, add the perfluoropolyether side chain modifier according to the weight parts, continue stirring for 10-15min, and mix evenly. (2) Apply the above-mentioned uniformly mixed coating to the substrate surface by spraying, dipping or scraping, and control the coating thickness to be 50-60μm; (3) Place the coated substrate in an oven and pre-cur it at 70-80℃ for 30-40 min. Then, raise the temperature to 120-130℃ at a rate of 2-3℃ / min and keep it at the temperature for 1.5-2.5 h to obtain the cross-linked network coating.

7. The method for preparing a multi-chemical-resistant cross-linked network coating according to claim 6, characterized in that, The substrate in step (2) can be any one of stainless steel, aluminum alloy, or polypropylene (PP) board.

8. The method for preparing a multi-chemical-resistant cross-linked network coating according to claim 6, characterized in that, The spraying method in step (2) includes uniformly spraying the evenly mixed coating onto the substrate surface through a spray gun, setting the spray gun pressure to 0.4 MPa, and maintaining a spraying distance of 15 cm.

9. The method for preparing a multi-chemical-resistant cross-linked network coating according to claim 6, characterized in that, The dip coating method in step (2) includes slowly immersing the substrate into the mixed coating, holding it for 30 seconds, and then pulling it up at a uniform speed of 5 cm / min.

10. The method for preparing a multi-chemical-resistant cross-linked network coating according to claim 6, characterized in that, Step (2) involves using a scraper to uniformly apply a mixed coating onto the substrate surface.

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