A corrosion-resistant modified coating for polymer film and preparation method thereof

Abstract

The invention discloses a corrosion-resistant modified coating for polymer film and a preparation method thereof, and belongs to the technical field of coating materials. 55-65 parts of polyurethane resin, 0.5-2 parts of dispersant, 0.05-0.1 parts of leveling agent, 0.1-0.4 parts of defoamer, 1-3 parts of film-forming aid, 0.4-0.8 parts of thickener, 30-40 parts of diluent, 1-3 parts of auxiliary agent are mechanically mixed to obtain corrosion-resistant modified coating. Montmorillonite can be evenly dispersed in the auxiliary agent, and the auxiliary agent contains a variety of functional groups and can be stably present in the coating, so the auxiliary agent can fully and stably play its role, so that the coating has excellent corrosion resistance, oxidation resistance, hydrophobicity and impact resistance. Under the joint action of the auxiliary agent and other raw materials, the modified coating of the present invention also has excellent weather resistance, wear resistance and chemical resistance and other properties.

Description

Technical Field

[0001] The invention belongs to the technical field of coating materials, and in particular, relates to a corrosion-resistant modified coating for a polymer film and a preparation method thereof. Background Art

[0002] Polymer film is a film made of organic polymers. With the development of petroleum industry and science and technology, the application field of polymer membranes has been continuously expanded, from the initial packaging film to intelligent polymer membranes, polymer functional membranes, etc. Among them, the most widely used is the selective separation membrane, such as ion exchange membrane, microporous filtration membrane, ultrafiltration membrane, liquid membrane, liquid crystal membrane, etc., which has been applied in the fields of nuclear fuel and metal refining, gas separation, seawater desalination, ultrapure water preparation, waste treatment, artificial organ manufacturing, medicine, food, agriculture, chemical industry, etc. These products have brought great convenience to people's lives. With the popularization of polymer film in various fields, coating modified coatings on its surface also has a very important application prospect. Modified coatings can not only give polymer membranes new functions, but also improve their durability, which can further enhance the application value of polymer films.

[0003] Paint is a viscous liquid that is coated on the surface of an object or film to be protected or decorated, and can form a continuous film that is firmly attached to the object. It is usually mainly resin, oil, or emulsion, with fillers and corresponding additives, etc., and is prepared with organic solvents or water. The book "Coating Technology", which is relatively authoritative in the Chinese coating industry, defines it as: "Coating is a material that can be applied to the surface of an object using different construction processes to form a solid film that is firmly adhered, has a certain strength, and is continuous. The film formed in this way is generally called a coating film, also known as a paint film or coating." In the early days, most coatings used vegetable oil as the main raw material, so they were called "paints." Whether it is a traditional coating product made from natural substances or a modern coating product made from synthetic chemical products, they all belong to organic chemical polymer materials, and the coating film formed belongs to the type of polymer compounds. According to the classification of modern chemical products, coatings belong to fine chemical products. Modern coatings are gradually becoming a type of multifunctional engineering material and an important industry in the chemical industry. With the development of modern science and technology, scientific and technological innovation in coatings is also developing. At present, most coatings have poor corrosion resistance and single performance, which is insufficient to meet the needs of modern development. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a corrosion-resistant modified coating for polymer film and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A corrosion-resistant modified coating for polymer film, comprising the following raw materials in parts by weight: 55-65 parts of polyurethane resin, 0.5-2 parts of dispersant, 0.05-0.1 parts of leveling agent, 0.1-0.4 parts of defoamer, 1-3 parts of film-forming aid, 0.4-0.8 parts of thickener, 30-40 parts of diluent, and 1-3 parts of additive;

[0007] Furthermore, the dispersant is one or more of polyacrylate, hydroxyethyl cellulose and polyvinyl alcohol.

[0008] Furthermore, the leveling agent is one of silicone resin and fatty alcohol polyoxyethylene ether.

[0009] Furthermore, the defoaming agent is one or more of polyvinyl alcohol defoaming agent, polydimethylsiloxane and polymethylsiloxane.

[0010] Furthermore, the film-forming aid is one or more of propylene glycol, propylene glycol methyl ether acetate, propylene glycol ethyl ether and propylene glycol butyl ether.

[0011] Furthermore, the thickener is cellulose ether.

[0012] Wherein, the auxiliary agent is prepared by the following steps:

[0013] S1. Add 4-(bromomethyl)-2,6-di-tert-butylphenol, 2-amino-1,3-propanediol, N,N-dimethylformamide and triethylamine to a three-necked flask at room temperature and under nitrogen protection, mix and stir evenly, then slowly add 20% sodium hydroxide solution by mass, control the reaction temperature to 80°C, react for 3 hours, first remove part of the solvent by rotary evaporation, then purify by column chromatography (the eluent is a mixed solvent of chloroform and ether, and the volume ratio of chloroform and ether is 9:1), and remove the eluent by reduced pressure distillation to obtain intermediate 1; the amount ratio of 4-(bromomethyl)-2,6-di-tert-butylphenol, 2-amino-1,3-propanediol, N,N-dimethylformamide, triethylamine and sodium hydroxide is 29g:9g:100mL:14mL:5mL;

[0014] Under alkaline conditions, the -Br of 4-(bromomethyl)-2,6-di-tert-butylphenol and the -NH2 of 2-amino-1,3-propanediol undergo a nucleophilic substitution reaction, and triethylamine removes the hydrogen chloride generated by the reaction. The reaction process is as follows:

[0015]

[0016] S2. At room temperature and under nitrogen protection, (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid and intermediate 1 were added to a three-necked flask, followed by dimethyl sulfoxide, stirred evenly, and then concentrated sulfuric acid was slowly added. The temperature was raised to 110°C and the reaction was carried out for 4 hours. After the reaction was completed, the mixed solution was cooled to room temperature, and sodium bicarbonate solution was slowly added to neutralize it, and then the liquid was separated. The organic layer was distilled under reduced pressure to remove part of the solvent, and then purified by column chromatography (the eluent was a mixed solvent of benzene and ether, and the volume ratio of benzene and ether was 6:4), and finally distilled under reduced pressure to obtain intermediate 2;

[0017] The molar ratio of intermediate 1 and (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid is controlled to be 1.05-1.1:1, and then a hydroxyl group of intermediate 1 and a carboxyl group of (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid undergo an esterification reaction. The reaction process is as follows:

[0018]

[0019] S3, adding n-octadecyltriethoxysilane, intermediate 2, toluene and tetraisopropyl titanate into a three-necked flask, reacting at 90°C for 24 hours, cooling to room temperature after the reaction, washing the reaction product twice with tartaric acid, then washing three times with sodium bicarbonate solution, drying the organic phase with anhydrous magnesium sulfate, filtering and distilling under reduced pressure to obtain intermediate 3;

[0020] The molar ratio of n-octadecyltriethoxysilane to intermediate 2 is controlled to be 1.05-1.1:1, and n-octadecyltriethoxysilane and intermediate 2 will undergo the following chemical reaction under the catalysis of tetraisopropyl titanate. The reaction process is shown below:

[0021]

[0022] S4. Pour the intermediate 3 and nano-montmorillonite into a beaker filled with deionized water, stir at room temperature for 3 hours, then centrifuge and wash with anhydrous ethanol for 3 times, and finally dry at 80° C. to obtain an auxiliary agent.

[0023] After hydrolysis, the silaneoxy groups in intermediate 3 will form a chemical bond - a covalent bond - with the hydroxyl groups on the surface of montmorillonite, which not only achieves a high degree of dispersion of montmorillonite, but also modifies the montmorillonite from oleophobic to hydrophobic.

[0024] The additive of the present invention contains montmorillonite, which is a natural silicate mineral material with a flaky structure, good thermal stability, high aspect ratio and high specific surface area, and can improve the protective performance of the coating by reducing micropores and holes and increasing the crosslinking density in some cases. The montmorillonite with a flaky structure is dispersed in the coating, which can effectively increase the diffusion path, making it difficult for water and corrosive ions to penetrate the coating, thereby enhancing the corrosion resistance of the coating. In addition, due to the presence of its microporous structure, montmorillonite has a strong adsorption capacity, so it can adsorb harmful chemicals in the use process and further improve the corrosion resistance of the coating. The siloxane in the additive is firmly combined with the montmorillonite through chemical bonds, which improves the dispersibility and uniformity of the montmorillonite on the one hand, and ensures that the montmorillonite can fully and stably play its role, thereby improving the corrosion resistance, chemical resistance and weather resistance of the coating; the additive structure also contains functional groups such as amino, ester and hydroxyl groups, and due to similar compatibility, the additive can also be fully dispersed in the coating, so that it can stably play its role; the additive also has a methyl long branch chain (18 carbons), and the hydrophobic long branch chain can provide hydrophobicity for the coating and ensure the hydrophobic effect; in addition, the presence of the long carbon chain also enhances the impact resistance and toughness of the coating; the additive structure also contains hindered phenols and hindered amines, both of which can capture free radicals generated when organic matter decomposes, thereby preventing a series of subsequent free radical chain reactions, thereby avoiding the degradation and yellowing of organic molecules, so that the additive of the present invention can also improve the oxidation resistance of the coating.

[0025] A method for preparing a corrosion-resistant modified coating for a polymer film comprises the following steps:

[0026] The raw materials are mechanically blended according to a proportion to obtain a corrosion-resistant modified coating.

[0027] The beneficial effects of the present invention are as follows: montmorillonite can be uniformly dispersed in the additive, and the additive contains a variety of functional groups and can stably exist in the coating. Therefore, the additive can fully and stably play its role, so that the coating has excellent corrosion resistance, oxidation resistance, hydrophobicity and impact resistance. Under the joint action of the additive and other raw materials, the modified coating of the present invention also has excellent weather resistance, wear resistance and chemical resistance and other properties. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] Preparation of auxiliary agent, the specific steps are as follows:

[0031] S1. Add 29 g of 4-(bromomethyl)-2,6-di-tert-butylphenol, 9 g of 2-amino-1,3-propanediol, 100 mL of N,N-dimethylformamide and 14 mL of triethylamine into a 250 mL three-necked flask at room temperature and under nitrogen protection, mix and stir evenly, then slowly add 5 mL of 20% sodium hydroxide solution by mass, control the reaction temperature to 80°C, react for 3 hours, first remove part of the solvent by rotary evaporation, then purify by column chromatography (the eluent is a mixed solvent of chloroform and ether, and the volume ratio of chloroform and ether is 9:1), and remove the eluent by reduced pressure distillation to obtain a stabilizer;

[0032] S2. At room temperature and under nitrogen protection, add 7.97 g of (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid and 13.6 g of intermediate 1 into a 100 mL three-necked flask, then add 60 mL of dimethyl sulfoxide, stir evenly, then slowly add 2 mL of concentrated sulfuric acid, heat to 110 ° C and react for 4 hours. After the reaction, cool the mixed solution to room temperature, slowly add sodium bicarbonate solution to neutralize, then separate the liquids, take the organic layer and distill under reduced pressure to remove part of the solvent, then purify by column chromatography (the eluent is a mixed solvent of benzene and ether, and the volume ratio of benzene and ether is 6:4), and finally distill under reduced pressure to obtain intermediate 2;

[0033] S3, 9.2 g of n-octadecyltriethoxysilane, 9.8 g of intermediate 2, 60 mL of toluene and 0.01 g of tetraisopropyl titanate were added to a 100 mL three-necked flask, and the mixture was reacted at 90° C. for 24 h. After the reaction was completed, the mixture was cooled to room temperature. The reaction product was washed twice with 5 wt % tartaric acid and then three times with 5 wt % sodium bicarbonate solution. The organic phase was dried over anhydrous magnesium sulfate, filtered and distilled under reduced pressure to obtain intermediate 3;

[0034] S4. Pour 4.2 g of intermediate 3 and 10.4 g of nano-montmorillonite into a beaker filled with 60 mL of deionized water, stir for 3 h at room temperature, then centrifuge and wash with anhydrous ethanol for 3 times, and finally dry at 80° C. to obtain an auxiliary agent.

[0035] Example 2

[0036] The remaining steps remain unchanged, and step S4 of embodiment 1 is removed.

[0037] Example 3

[0038] The specific steps for preparing the modified coating are as follows:

[0039] 55 parts of polyurethane resin, 0.5 parts of polyacrylate, 0.05 parts of silicone resin, 0.1 parts of polyvinyl alcohol defoamer, 1 part of propylene glycol, 0.4 parts of cellulose ether, 30 parts of water, ethanol and isopropanol, and 1 part of the auxiliary agent of Example 1 are added into a mixer for mixing and stirring. After the stirring is completed, the mixture is added into the mixer for stirring to obtain a corrosion-resistant modified coating.

[0040] Example 4

[0041] The specific steps for preparing the modified coating are as follows:

[0042] 56 parts of polyurethane resin, 0.6 parts of hydroxyethyl cellulose, 0.07 parts of fatty alcohol polyoxyethylene ether, 0.2 parts of polydimethylsiloxane, 2 parts of propylene glycol methyl ether acetate, 0.6 parts of cellulose ether, 32 parts of water, ethanol and isopropanol, and 1-3 parts of the additives of Example 1 are added into a blender for mixing and stirring. After the stirring is completed, the mixture is added into the blender for stirring to obtain a corrosion-resistant modified coating.

[0043] Example 5

[0044] The specific steps for preparing the modified coating are as follows:

[0045] 65 parts of polyurethane resin, 2 parts of hydroxyethyl cellulose, 0.1 parts of silicone resin, 0.4 parts of polymethylsiloxane, 3 parts of propylene glycol ethyl ether and propylene glycol butyl ether, 0.8 parts of cellulose ether, 40 parts of water, ethanol and isopropanol, and 3 parts of the additives of Example 1 are added into a mixer for mixing and stirring. After the stirring is completed, the mixture is added into the mixer for stirring to obtain a corrosion-resistant modified coating.

[0046] Comparative Example 1

[0047] The additive of Example 5 is removed to obtain a modified coating.

[0048] Comparative Example 2

[0049] The auxiliary agent in Example 5 is replaced by the auxiliary agent in Example 2 to obtain a modified coating.

[0050] Comparative Example 3

[0051] The auxiliary agent in Example 5 was replaced by montmorillonite to obtain a modified coating.

[0052] Performance Testing

[0053] The modified coatings prepared in Examples 3-5 and Comparative Examples 1-3 were subjected to corrosion resistance tests, and the test results are shown in Table 1 below.

[0054] The modified coatings prepared in Examples 3-5 and Comparative Examples 1-3 were sprayed on polymer films of the same material, respectively, and cured. After curing, the following performance tests were performed: (1) Determination of tensile strength and elongation at break: According to Part 3 of the national standard GB / T 1040.3-2006 "Determination of tensile properties of plastics", the test conditions for films and sheets are: dumbbell-shaped specimens with a length of 150 mm, a narrow parallel width of 10 mm, a tensile speed of 50 mm / min, and a room temperature of 25°C; (2) Determination of tear strength: According to GB / T16578-1996 "Test method for tear resistance of plastic films and sheets: trouser tear method", the tensile speed is 200±20 mm / min; (3) Artificial accelerated light aging test: A fluorescent ultraviolet lamp with a wavelength of 340 nm imported from the United States is used, and the irradiation intensity is 0.68 W / m 2 , blackboard temperature 60℃, condensation temperature 60℃; single cycle process: illumination 3h, condensation 3h, wind blowing 10min; repeat the cycle process continuously, the total experimental time is 168h; after aging, the tensile strength, tear strength and elongation at break are tested, and the test results are shown in Table 2 below.

[0055] Table 1 Corrosion resistance test results of modified coatings of Examples 3-5 and Comparative Examples 1-3

[0056]

[0057]

[0058] Table 2 Performance test of polymer films sprayed with modified coatings of Examples 3-5 and Comparative Examples 1-3

[0059]

[0060] From the data in Table 1 above, it can be seen that the modified coating prepared in the embodiment of the present invention has excellent corrosion resistance. From the data in Example 5 and Comparative Examples 2 and 3, it can be seen that the montmorillonite in the additive plays an important role in improving the corrosion resistance of the modified coating; from the comparison between Example 5 and Comparative Example 1, it can be seen that the additive prepared in the embodiment of the present invention greatly improves the corrosion resistance of the modified coating; from the comparison between the data in the embodiment and the comparative example in Table 2 above, it can be seen that the polymer film sprayed with the modified coating prepared in the embodiment of the present invention has more excellent mechanical properties and anti-aging properties.

[0061] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0062] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A corrosion-resistant modified coating for polymer film, characterized in that: The invention comprises the following raw materials in parts by weight: 55-65 parts of polyurethane resin, 0.5-2 parts of dispersant, 0.05-0.1 parts of leveling agent, 0.1-0.4 parts of defoamer, 1-3 parts of film-forming aid, 0.4-0.8 parts of thickener, 30-40 parts of diluent, and 1-3 parts of auxiliary agent; Wherein, the auxiliary agent is prepared by the following steps: S1. Add 4-(bromomethyl)-2,6-di-tert-butylphenol, 2-amino-1,3-propanediol, N,N-dimethylformamide and triethylamine into a flask, stir and then add sodium hydroxide solution, react at 80°C for 3h, and then perform rotary evaporation, column chromatography and vacuum distillation to obtain intermediate 1; the dosage ratio of 4-(bromomethyl)-2,6-di-tert-butylphenol, 2-amino-1,3-propanediol, N,N-dimethylformamide, triethylamine and sodium hydroxide is 29g:9g:100mL:14mL:5mL; S2, add (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid, intermediate 1 and dimethyl sulfoxide into a flask, add concentrated sulfuric acid after stirring, react at 110°C for 4 hours, first add sodium bicarbonate solution to neutralize, then separate the liquids, perform vacuum distillation, column chromatography, and vacuum distillation to obtain intermediate 2; the molar ratio of intermediate 1 to (2,2,6,6-tetramethyl-piperidin-4-yl)-acetic acid is 1.05-1.1:1; S3, adding n-octadecyltriethoxysilane, intermediate 2, toluene and tetraisopropyl titanate into a flask, reacting at 90°C for 24 hours, washing the product with tartaric acid, then washing with sodium bicarbonate solution, drying, filtering and distilling under reduced pressure to obtain intermediate 3; the molar ratio of n-octadecyltriethoxysilane to intermediate 2 is 1.05-1.1:1; S4. Pour the intermediate 3 and nano-montmorillonite into a beaker filled with deionized water, stir for 3 hours, centrifuge, wash with anhydrous ethanol, and dry to obtain an auxiliary agent.

2. The corrosion-resistant modified coating for polymer film according to claim 1, characterized in that: The dispersant is one or more of polyacrylate, hydroxyethyl cellulose and polyvinyl alcohol.

3. The corrosion-resistant modified coating for polymer film according to claim 1, characterized in that: The leveling agent is one of silicone resin and fatty alcohol polyoxyethylene ether.

4. The corrosion-resistant modified coating for polymer film according to claim 1, characterized in that: The defoaming agent is one or more of polyvinyl alcohol defoaming agent, polydimethylsiloxane and polymethylsiloxane.

5. The corrosion-resistant modified coating for polymer film according to claim 1, characterized in that: The film-forming aid is one or more of propylene glycol, propylene glycol methyl ether acetate, propylene glycol ethyl ether and propylene glycol butyl ether.

6. The corrosion-resistant modified coating for polymer film according to claim 1, characterized in that: The thickener is cellulose ether.

7. The method for preparing a corrosion-resistant modified coating for a polymer film according to claim 1, characterized in that: The following steps are involved: The raw materials are mechanically blended according to a proportion to obtain a corrosion-resistant modified coating.

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