Preparation method of corrosion-resistant protective coating for metal

Abstract

The invention relates to a preparation method of a corrosion-resistant protective coating for metal, and belongs to the technical field of metal corrosion-resistant coatings. The preparation method comprises the following steps: sequentially adding 3, 3-diamino-4, 4-dicarboxyl biphenyl and cerous nitrate into a reaction kettle with a mixed solvent, carrying out ultrasonic treatment and heating reaction, distilling to remove the mixed solvent, and cooling to room temperature to obtain a cerium-containing precursor; the preparation method comprises the following steps: adding epoxy resin and epoxy cyclohexyl-polyhedral oligomeric silsesquioxane into solvent oil, then adding a cerium-containing precursor, carrying out a heating reaction, and carrying out ultrasonic treatment; continuously adding a curing agent, and stirring to obtain the novel corrosion-resistant coating. Coating the cleaned metal hook by using a dip-coating method, and drying at room temperature; the novel corrosion-resistant coating prepared by the preparation method disclosed by the invention is good in humidity and heat resistance and excellent in corrosion resistance.

Description

Technical Field

[0001] The invention relates to the technical field of metal corrosion-resistant coatings, in particular to a method for preparing a corrosion-resistant protective coating for metals. Background Art

[0002] Coating technology is the most common and important method for metal corrosion protection, and it has been widely used in corrosion protection across various industries. Coating protection involves applying a protective coating of various materials to the metal surface. By passivating, shielding, and inhibiting corrosion, the coating prevents the corrosive medium from coming into contact with the metal, thereby reducing the rate of metal corrosion.

[0003] Chinese patent CN102585702A discloses a metal anticorrosion and antirust coating and its application. The coating is composed of the following ingredients by weight: 60-90% asphalt, 5-30% metal protective agent, and 5-35% metal penetrant. The coating is readily available and simple to prepare, requiring only a simple mixing process. Each component in the coating has distinct functions, forming three mutually adherent layers on the metal surface, effectively isolating the metal from the outside world.

[0004] Chinese patent CN104761943B provides a magnesium alloy corrosion-resistant coating, comprising a uniform mixture of zinc powder, aluminum powder, zirconium oxide, yttrium oxide, yttrium nitrate, polyethylene glycol, sodium molybdate, hydroxymethyl cellulose, a silane coupling agent KH-560, diphenyldimethoxysilane, and deionized water in a predetermined proportion. The invention also provides a method for improving the corrosion resistance of a magnesium alloy using the coating, comprising the following steps: 1. pretreating the surface of the magnesium alloy; 2. applying the coating to the magnesium alloy surface; 3. performing a preheating treatment; and 4. performing a curing treatment to form a corrosion-resistant coating on the magnesium alloy surface.

[0005] Chinese patent CN104060273B: discloses a long-lasting corrosion-resistant coating for steel structures, which is composed of the following by mass percentage: 1-4% barium sulfate, 0.1-2% zinc phosphate, 0.5-3% ferrosoferric oxide, 0.1-2% ferric oxide, 0.2-3% alpha-carboxyl iron oxide, 2-6% phosphoric acid, 0.5-2% montmorillonite, 2-8% polyvinyl butyral resin, and 70-80% ethanol.

[0006] The corrosion-resistant coatings prepared by the above patents and prior art have poor moisture and heat resistance, and their corrosion resistance needs to be further improved. Summary of the Invention

[0007] In order to solve the above problems, the present invention provides a method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are as follows: S1: 8-16 parts by weight of 3,3-diamino-4,4-dicarboxybiphenyl CAS: 1799740-97-8 and 27-33 parts of cerium nitrate are sequentially added to a reactor containing 140-150 parts of a mixed solvent, ultrasonically treated for 10-20 minutes, heated for reaction, and then the mixed solvent is distilled off. The mixture is cooled to room temperature to obtain a cerium-containing precursor; S2: Add 12-18 parts of epoxy resin E44 and 0.3-0.7 parts of epoxycyclohexyl-cage polysilsesquioxane CAS No.: 187333-74-0 to 120-130 parts of solvent oil, then add 0.04-0.4 parts of the cerium-containing precursor prepared in S1, and react at 60-75°C for 1-3 hours; ultrasonically treat for 10-20 minutes; continue to add 2-6 parts of curing agent, and stir for 10-20 minutes to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

[0008] The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:1.

[0009] The reaction temperature of S1 is 90-100°C and the reaction time is 40-50h.

[0010] The curing agent is polyamide 650 or polyamide 651.

[0011] The immersion time of the immersion pulling method is 5-10 minutes, the pulling speed is 60-100 mm / min, and the coating number is 1 time.

[0012] The drying time of S3 at room temperature is 18-24 hours.

[0013] Reaction mechanism Complex formation: The carboxyl oxygen of 3,3-diamino-4,4-dicarboxybiphenyl coordinates with the cerium ion of cerium nitrate to form a diaminobiphenyl cerium complex.

[0014] Ring-opening addition: The amino group of the complex nucleophilically attacks the epoxy group of the epoxy resin and epoxycyclohexyl-cage polysilsesquioxane, causing a ring-opening reaction to achieve connection.

[0015] Curing: After the ring opening, the remaining active groups continue to react, and the molecular chains are cross-linked to form a three-dimensional network structure, which cures the coating.

[0016] Technical Effects The present invention provides a method for preparing a corrosion-resistant protective coating for metal. Compared with the prior art, the present invention has the following significant effects: 1. Improved corrosion resistance: Cerium ions form a passivation film and act as a corrosion inhibitor. The dense structure of the coating acts as a shield to block corrosive media.

[0017] 2. Enhanced mechanical properties: Epoxy resin provides strength and adhesion, while cage-shaped polysilsesquioxane increases rigidity and toughness.

[0018] 3. Improved thermal stability: The cerium complex is anti-oxidative, and the silicon-oxygen bond of the cage-shaped polysilsesquioxane makes the coating structure stable at high temperatures.

[0019] 4. Improved chemical stability: Biphenyl and other components make the coating resistant to corrosion by chemical media. DETAILED DESCRIPTION

[0020] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention object, the following is a detailed description in conjunction with examples and comparative examples: 1. Moisture and heat resistance test: refer to GB / T1740 for testing, the test time is 1000h.

[0021] 2. Salt spray test: Refer to GB / T10125-2021 for neutral salt spray test. The corrosive liquid is 50g / L sodium chloride solution with neutral pH value. The test temperature is room temperature.

[0022] Example 1 A method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are: S1: 8 g of 3,3-diamino-4,4-dicarboxybiphenyl CAS: 1799740-97-8 and 27 g of cerium nitrate were sequentially added to a reactor containing 140 g of a mixed solvent. After ultrasonic treatment for 10 min, the mixture was heated for reaction, and the mixed solvent was distilled off. The mixture was cooled to room temperature to obtain a cerium-containing precursor. S2: 12 g of epoxy resin E44 and 0.3 g of epoxycyclohexyl-cage polysilsesquioxane CAS No.: 187333-74-0 were added to 120 g of solvent oil, and then 0.04 g of the cerium-containing precursor prepared in S1 was added, and the mixture was reacted at 60°C for 1 hour; ultrasonic treatment was performed for 10 minutes; 2 g of curing agent was further added, and the mixture was stirred for 10 minutes to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

[0023] The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:1.

[0024] The reaction temperature of S1 is 90°C and the reaction time is 40 hours.

[0025] The curing agent is polyamide 650.

[0026] The immersion time of the immersion pulling method is 5 minutes, the pulling speed is 60 mm / min, and the coating number is 1 time.

[0027] The room temperature drying time of S3 is 18 hours.

[0028] Example 2 A method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are: S1: 10 g of 3,3-diamino-4,4-dicarboxybiphenyl CAS: 1799740-97-8 and 29 g of cerium nitrate were sequentially added to a reactor containing 145 g of a mixed solvent. After ultrasonic treatment for 15 min, the mixture was heated for reaction, and the mixed solvent was distilled off. The mixture was cooled to room temperature to obtain a cerium-containing precursor. S2: 14 g of epoxy resin E44 and 0.4 g of epoxycyclohexyl-cage polysilsesquioxane CAS No.: 187333-74-0 were added to 125 g of solvent oil, and then 0.2 g of the cerium-containing precursor prepared in S1 was added, and the mixture was reacted at 65°C for 1.5 h; ultrasonic treatment was performed for 15 min; 3 g of curing agent was further added, and the mixture was stirred for 15 min to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

[0029] The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:1.

[0030] The reaction temperature of S1 is 95° C. and the reaction time is 44 h.

[0031] The curing agent is polyamide 650.

[0032] The immersion time of the immersion pulling method is 6 minutes, the pulling speed is 70 mm / min, and the coating number is 1 time.

[0033] The room temperature drying time of S3 is 20 hours.

[0034] Example 3 A method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are: S1: 14 g of 3,3-diamino-4,4-dicarboxybiphenyl CAS: 1799740-97-8 and 31 g of cerium nitrate were sequentially added to a reactor containing 145 g of a mixed solvent. After ultrasonic treatment for 15 min, the mixture was heated for reaction, and the mixed solvent was distilled off. The mixture was cooled to room temperature to obtain a cerium-containing precursor. S2: 16 g of epoxy resin E44 and 0.6 g of epoxycyclohexyl-cage polysilsesquioxane CAS No.: 187333-74-0 were added to 125 g of solvent oil, and then 0.3 g of the cerium-containing precursor prepared in S1 was added, and the mixture was reacted at 70°C for 2.5 h; ultrasonic treatment was performed for 15 min; 5 g of curing agent was further added, and the mixture was stirred for 15 min to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

[0035] The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:1.

[0036] The reaction temperature of S1 is 95°C and the reaction time is 48 hours.

[0037] The curing agent is polyamide 651.

[0038] The immersion time of the immersion pulling method is 9 minutes, the pulling speed is 90 mm / min, and the coating number is 1 time.

[0039] The room temperature drying time of S3 is 22h.

[0040] Example 4 A method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are: S1: 16 g of 3,3-diamino-4,4-dicarboxybiphenyl CAS: 1799740-97-8 and 33 g of cerium nitrate were sequentially added to a reactor containing 150 g of a mixed solvent. After ultrasonic treatment for 20 min, the mixture was heated for reaction, and the mixed solvent was distilled off. The mixture was cooled to room temperature to obtain a cerium-containing precursor. S2: 18 g of epoxy resin E44 and 0.7 g of epoxycyclohexyl-cage polysilsesquioxane CAS No.: 187333-74-0 were added to 130 g of solvent oil, and then 0.4 g of the cerium-containing precursor prepared in S1 was added, and the mixture was reacted at 75°C for 3 h; ultrasonic treatment was performed for 20 min; 6 g of curing agent was further added, and the mixture was stirred for 20 min to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

[0041] The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:1.

[0042] The reaction temperature of S1 is 100° C. and the reaction time is 50 h.

[0043] The curing agent is polyamide 651.

[0044] The immersion time of the immersion pulling method is 10 minutes, the pulling speed is 100 mm / min, and the coating number is 1 time.

[0045] The room temperature drying time of S3 is 24 hours.

[0046] Comparative Example 1 The other steps were the same as in Example 1 except that 3,3-diamino-4,4-dicarboxybiphenyl and epoxycyclohexyl-cage polysilsesquioxane were not added.

[0047] Comparative Example 2 The other steps were the same as in Example 1 except that 3,3-diamino-4,4-dicarboxybiphenyl was not added.

[0048] Comparative Example 3 The epoxycyclohexyl-cage polysilsesquioxane was not added, and the other steps were the same as in Example 1.

[0049] The test results of the embodiments and comparative examples are shown in Table 1.

[0050] Table 1 Moisture and heat resistance Salt spray test Example 1 No blistering, no rust No change Example 2 No blistering, no rust No change Example 3 No blistering, no rust No change Example 4 No blistering, no rust No change Comparative Example 1 rust Obvious corrosion Comparative Example 2 foaming Slight pitting Comparative Example 3 foaming Slight pitting Through the data analysis of the above embodiments and comparative examples, the novel corrosion-resistant coating prepared by the present invention has good moisture and heat resistance and excellent corrosion resistance.

[0051] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a corrosion-resistant protective coating for metal, the operating steps of which are: S1: 8-16 parts by weight of 3,3-diamino-4,4-dicarboxybiphenyl and 27-33 parts of cerium nitrate are sequentially added to a reactor containing 140-150 parts of a mixed solvent, ultrasonically treated for 10-20 minutes, heated for reaction, and then the mixed solvent is distilled off and cooled to room temperature to obtain a cerium-containing precursor; S2: Add 12-18 parts of epoxy resin and 0.3-0.7 parts of epoxycyclohexyl-cage polysilsesquioxane to 120-130 parts of solvent oil, then add 0.04-0.4 parts of the cerium-containing precursor prepared in S1, and react at 60-75°C for 1-3 hours; ultrasonically treat for 10-20 minutes; continue to add 2-6 parts of curing agent, and stir for 10-20 minutes to obtain a new corrosion-resistant coating; S3: Coat the cleaned metal hooks using the dip-pull method and dry at room temperature.

2. The method for preparing a corrosion-resistant protective coating for metal according to claim 1, characterized in that: The mixed solvent is N,N-dimethylacetamide, ethanol and deionized water, and the volume ratio thereof is 1:1:

1.

3. The method for preparing a corrosion-resistant protective coating for metal according to claim 1, characterized in that: The reaction temperature of S1 is 90-100°C and the reaction time is 40-50h.

4. The method for preparing a corrosion-resistant protective coating for metal according to claim 1, characterized in that: The curing agent is polyamide 650 or polyamide 651.

5. The method for preparing a corrosion-resistant protective coating for metal according to claim 1, characterized in that: The immersion time of the immersion pulling method is 5-10 minutes, the pulling speed is 60-100 mm / min, and the coating number is 1 time.

6. The method for preparing a corrosion-resistant protective coating for metal according to claim 1, characterized in that: The drying time of S3 at room temperature is 18-24 hours.