Preparation method of efficient weather-resistant metal anticorrosive coating

Abstract

The invention discloses a preparation method of an efficient weather-resistant metal anticorrosive coating, and relates to the technical field of metal protective coatings. According to the method, a resin matrix with excellent weather resistance is selected, a pigment, an auxiliary agent and a weather-resistant auxiliary agent are matched, and a special cross-linking curing process is adopted to prepare the weather-resistant resin. The coating has excellent ultraviolet resistance and temperature resistance, has a high-strength three-dimensional network structure, and can significantly improve the weather resistance and corrosion resistance of the metal substrate. The invention also comprises spraying construction and curing processes, and can be widely applied to anticorrosion protection of various industrial equipment and facilities.

Description

Technical Field

[0001] The present invention relates to the technical field of metal protective coatings, and in particular to a preparation method of an efficient weather-resistant metal anti-corrosion coating. Background Art

[0002] Due to their excellent mechanical properties and processing performance, metal materials are widely used in fields such as construction, bridges, ships, mechanical equipment, etc. However, metal materials are prone to corrosion when exposed to the natural environment for a long time. Especially under harsh conditions such as high temperature, high humidity, strong ultraviolet rays, acid rain, and marine salt spray, oxidation and rusting easily occur on their surfaces, resulting in a decline in mechanical properties, a shortened service life, and even serious economic losses and safety hazards. Therefore, the development of efficient anti-corrosion coating technologies has become an important means to protect metal materials. Currently, the widely used metal anti-corrosion coating technologies on the market mainly include epoxy coatings, polyurethane coatings, and traditional acrylic coatings, etc. For example, patent document CN113831833A discloses a preparation method of a polyurethane metal anti-corrosion coating, and its main raw material formula is as follows: polyol, isocyanate, chain extender, crosslinking agent, acrylic acid, zinc phosphate. In the process of synthesizing polyurethane by the post-chain extension method, hydroxyethyl methacrylate (HEMA) is added. The hydroxyl group in HEMA reacts with the isocyanate in the system. Isooctyl acrylate is added to the salt-formed emulsion to react with HEMA, and the crosslinking density of the system increases; at the same time, diacetone acrylamide (DAAM) is introduced to carry out a crosslinking reaction with the carbon-carbon double bond, the pH value is adjusted to 7-8, and adipic dihydrazide (ADH) is added by using the acylhydrazide reaction. The hydrogen in the amine group of ADH reacts with the ketone carbonyl of DAAM to crosslink it into a dense network, and the obtained polyurethane film has a superhydrophobic surface and anti-corrosion performance.

[0003] Although these coatings have certain anti-corrosion properties, they still have limitations in the following aspects: Insufficient weather resistance: Traditional coatings have poor resistance to ultraviolet rays and are prone to coating cracking, powdering, and peeling due to photoaging, thus losing their protective effect. Limited corrosion resistance: Ordinary anti-corrosion coatings are difficult to maintain stability for a long time in strong acid, strong alkali, or high salt spray environments, and are prone to accelerated corrosion problems. Weak mechanical properties: The adhesion and abrasion resistance of many coatings are insufficient, and they are prone to peeling or damage under external forces, resulting in the direct exposure of the metal substrate to the corrosion environment. Poor environmental adaptability: Some coatings are prone to performance degradation in environments with rapid temperature changes or long-term high humidity, and it is difficult to meet the requirements of special industrial environments. Therefore, the development of an efficient weather-resistant metal anti-corrosion coating with excellent comprehensive performance, simple preparation process and moderate cost, especially a coating technology that can maintain long-term stable performance in extreme environments, is the focus and difficulty of current anti-corrosion coating research. Summary of the Invention

[0004] Based on the above technical problems, the present invention significantly improves the weather resistance, anti-corrosion performance and mechanical strength of the coating by optimizing the ratios of resin matrix, pigment filler and additives, and introducing a special cross-linking and curing process, providing a new solution for the long-term protection of metal materials.

[0005] To achieve the above object, the technical solution adopted by the present invention is as follows: A preparation method of an efficient weather-resistant metal anti-corrosion coating, characterized by comprising the following steps: (1) Material preparation: Weigh 60 - 80 parts of resin matrix, and mix with 5 - 15 parts of pigment, 2 - 5 parts of weather-resistant additive, 0.5 - 1.5 parts of dispersant, 0.3 - 1 part of defoamer, 0.2 - 0.5 part of leveling agent and 10 - 20 parts of solvent; (2) Pre-dispersion: Mix the resin matrix, pigment, weather-resistant additive, dispersant, defoamer and leveling agent evenly in a disperser, with a stirring speed of 1000 - 1500 rpm, a time of 20 - 30 minutes, and the temperature controlled at 25 - 40 °C; (3) Grinding: Add the pre-dispersed material to a grinder, add solvent, and grind to a fineness of 10 - 20 μm, with a grinding time of 40 - 80 minutes; (4) Blending and filtering: Blend the ground material to a coating viscosity of 3000 - 5000 cP, a solid content of 60 - 80%, and a filter screen mesh number of 100 - 200 meshes; (5) Coating and curing: Uniformly coat the coating on the surface of the metal substrate by spraying, brushing or dipping, with a curing temperature of 120 - 180 °C and a curing time of 20 - 60 minutes.

[0006] As a further limitation of the above technical solution, the resin matrix is selected from one or a combination of polyvinylidene fluoride resin (PVDF), ethylene-tetrafluoroethylene copolymer (ETFE), fluorinated ethylene-propylene copolymer (FEVE), and chlorotrifluoroethylene resin (CTFE).

[0007] As a further limitation of the above technical solution, the pigment is selected from titanium dioxide or zinc oxide.

[0008] As a further limitation of the above technical solution, the preparation method of the weather-resistant additive: By mass, add 2.5 - 3.9 parts of epoxycyclohexyl-cage polyhedral oligomeric silsesquioxane (CAS: 187333-74-0), 0.05 - 0.5 parts of cobalt aminosulfonate (CAS: 14017-41-5), and 200 - 230 parts of dichloromethane into reactor 1, and stir and react at 62 - 82 °C for 50 to 100 minutes; Then add 17 - 34 parts of zirconium aminophthalate MOF (UIO-66-BDC-NH2) (CAS: 1260119-00-3) and 1 - 4 parts of triethanolamine, continue to stir and react at 70 - 80 °C for 100 to 150 minutes, and distill off dichloromethane to obtain the weather resistance aid.

[0009] As a further limitation of the above technical solution, the dispersant is selected from one or a combination of several of BYK-110, EFKA 4050, and DISPERBYK-190.

[0010] As a further limitation of the above technical solution, the defoamer is selected from one or a combination of several of BYK-306, TEGO Airex 920, and Defoamer 415.

[0011] As a further limitation of the above technical solution, the leveling agent is selected from one or a combination of several of BYK-377, EFKA-2010, and TEGOGlide 450.

[0012] As a further limitation of the above technical solution, the solvent is selected from one or a combination of several of ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, xylene, and toluene.

[0013] As a further limitation of the above technical solution, the metal substrate can be steel, aluminum alloy, or galvanized metal, and the surface treatment of the substrate adopts sandblasting or pickling, and the surface roughness reaches 5 - 10 μm to ensure the coating adhesion.

[0014] Mechanism and Effect 1. Epoxycyclohexyl-cage polyhedral oligomeric silsesquioxane: The core of this material is inorganic silsesquioxane, and the corners of its skeleton are connected with organic epoxycyclohexyl. This structure endows the material with good thermal stability and antioxidant properties.

[0015] Cobalt aminosulfonate: As a catalyst, cobalt aminosulfonate can promote the ring-opening reaction of epoxy resin and amino group to form stable chemical bonds.

[0016] Zirconium aminophthalate MOF: UIO-66-BDC-NH2 is a metal-organic framework material with a high specific surface area and porous structure, which can enhance the physical barrier effect of the coating.

[0017] 2. Anticorrosion Mechanism The cage structure of silsesquioxane can effectively shield external corrosive media, such as oxygen and moisture, thereby protecting the metal substrate from corrosion.

[0018] The chemical reaction between cobalt sulfamate and cyclohexylene oxide forms stable chemical bonds, which form a strong network structure in the coating and improve the chemical corrosion resistance of the coating.

[0019] The porous structure of zirconium aminophthalate MOF provides an additional physical barrier for the coating, preventing the penetration of corrosive media.

[0020] In summary, the MOF materials containing cobalt complexes and silsesquioxane exhibit excellent technical effects in highly weather-resistant metal anti-corrosion coatings through their unique molecular structures, steric hindrance, and multiple anti-corrosion mechanisms. Specific Embodiments

[0021] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments; it should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention; unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the technical field.

[0022] Example 1: Material Preparation: Weigh 60 g of polyvinylidene fluoride resin (PVDF) as the resin matrix, and add 5 g of titanium dioxide, 2 g of weather resistance additives, 0.5 g of BYK-110 dispersant, 0.3 g of BYK-306 defoamer, 0.2 g of BYK-377 leveling agent, and 10 g of ethylene glycol monoethyl ether acetate solvent.

[0023] Preparation of Weather Resistance Additives: Add 2.5 g of cyclohexylene oxide-caged polyhedral oligomeric silsesquioxane (CAS: 187333-74-0), 0.05 g of cobalt sulfamate (CAS: 14017-41-5), and 200 g of dichloromethane to Reactor 1, and stir and react at 62 °C for 50 minutes; then add 17 g of zirconium aminophthalate MOF (UIO-66-BDC-NH2) (CAS: 1260119-00-3) and 1 g of triethanolamine, and continue to stir and react at 70 °C for 100 minutes, and distill off dichloromethane to obtain the weather resistance additives.

[0024] Pre-dispersion: Mix the resin matrix, pigments, weather resistance additives, dispersant, defoamer, and leveling agent evenly in a disperser, with a stirring speed of 1000 rpm, a time of 20 minutes, and the temperature controlled at 25 °C.

[0025] Grinding: Add the pre-dispersed material into a grinding machine, add a solvent, and grind until the fineness reaches 10 μm, with a grinding time of 40 minutes.

[0026] Formulation and Filtration: Formulate the ground material to a coating viscosity of 3000 cP, a solid content of 60%, and a filter mesh size of 100 mesh.

[0027] Coating and Curing: Uniformly coat the coating on the surface of the steel substrate by spraying (the substrate surface treatment uses sandblasting method, and the surface roughness reaches 5 μm), the curing temperature is 120 °C, and the curing time is 20 minutes.

[0028] Example 2: Material Preparation: Weigh 70 g of ethylene-tetrafluoroethylene copolymer (ETFE) as the resin matrix, and add 10 g of zinc oxide, 3 g of weather resistance aid, 1 g of EFKA 4050 dispersant, 0.6 g of TEGO Airex 920 defoamer, 0.35 g of EFKA-2010 leveling agent, and 15 g of propylene glycol methyl ether acetate solvent.

[0029] Preparation of the weather resistance aid: Add 3.2 g of epoxycyclohexyl-caged polyhedral oligomeric silsesquioxane (CAS: 187333-74-0), 0.3 g of cobalt aminosulfonate (CAS: 14017-41-5), and 215 g of dichloromethane into Reactor 1, and stir and react at 72 °C for 75 minutes; then add 25 g of zirconium aminophthalate MOF (UIO-66-BDC-NH2) (CAS: 1260119-00-3), 2.5 g of triethanolamine, and continue to stir and react at 75 °C for 125 minutes, and distill off dichloromethane to obtain the weather resistance aid.

[0030] Pre-dispersion: Mix the resin matrix, pigment, weather resistance aid, dispersant, defoamer, and leveling agent evenly in a disperser, with a stirring speed of 1250 rpm, a time of 25 minutes, and the temperature controlled at 32 °C.

[0031] Grinding: Add the pre-dispersed material into a grinding machine, add a solvent, and grind until the fineness reaches 15 μm, with a grinding time of 60 minutes.

[0032] Formulation and Filtration: Formulate the ground material to a coating viscosity of 4000 cP, a solid content of 70%, and a filter mesh size of 150 mesh.

[0033] Coating and Curing: Uniformly coat the coating on the surface of the aluminum alloy substrate by brushing (the substrate surface treatment uses pickling method, and the surface roughness reaches 7.5 μm), the curing temperature is 150 °C, and the curing time is 40 minutes.

[0034] Example 3: Material preparation: Weigh 80 g of fluorinated ethylene-propylene copolymer (FEVE) as the resin matrix, and add 15 g of titanium dioxide, 4 g of weather resistance aid, 1.5 g of DISPERBYK-190 dispersant, 1 g of Defoamer 415 defoamer, 0.5 g of TEGOGlide 450 leveling agent, and 20 g of xylene solvent.

[0035] Preparation of weather resistance aid: Add 3.9 g of epoxycyclohexyl-cage-like polyhedral oligomeric silsesquioxane (CAS: 187333-74-0), 0.5 g of cobalt aminosulfonate (CAS: 14017-41-5), and 230 g of dichloromethane into reactor 1, and stir and react at 82 °C for 100 minutes; then add 34 g of zirconium aminophthalate MOF (UIO-66-BDC-NH2) (CAS: 1260119-00-3) and 4 g of triethanolamine, and continue to stir and react at 80 °C for 150 minutes, and distill off dichloromethane to obtain the weather resistance aid.

[0036] Pre-dispersion: Mix the resin matrix, pigment, weather resistance aid, dispersant, defoamer, and leveling agent evenly in a disperser, with a stirring speed of 1500 rpm, a time of 30 minutes, and the temperature controlled at 40 °C.

[0037] Grinding: Add the pre-dispersed material to a grinder, add solvent, and grind to a fineness of 20 μm, with a grinding time of 80 minutes.

[0038] Formulation and filtration: Adjust the viscosity of the ground material to 5000 cP for the coating, with a solid content of 80%, and a filter mesh size of 200 mesh.

[0039] Coating and curing: Use dip coating to evenly coat the coating on the surface of a galvanized metal substrate (the substrate surface treatment uses sandblasting, and the surface roughness reaches 10 μm), with a curing temperature of 180 °C and a curing time of 60 minutes.

[0040] Example 4: Material preparation: Weigh a combination of 65 g of chlorotrifluoroethylene resin (CTFE) and 15 g of polyvinylidene fluoride resin (PVDF) as the resin matrix, and add 8 g of zinc oxide, 5 g of weather resistance aid, a dispersant combination of 1 g of EFKA 4050 and 0.5 g of BYK-110, a defoamer combination of 0.7 g of BYK-306 and 0.3 g of TEGO Airex 920, a leveling agent combination of 0.3 g of EFKA-2010 and 0.2 g of BYK-377, and a solvent combination of 12 g of toluene and 8 g of ethylene glycol monoethyl ether acetate.

[0041] Among them, the preparation of the weather-resistant additive: Add 3 g of epoxycyclohexyl-cage polyhedral oligomeric silsesquioxane (CAS: 187333-74-0), 0.2 g of cobalt aminosulfonate (CAS: 14017-41-5), and 210 g of dichloromethane into reaction kettle 1, and stir and react at 70 °C for 80 minutes; then add 20 g of zirconium aminophthalate MOF (UIO-66-BDC-NH2) (CAS: 1260119-00-3), 3 g of triethanolamine, and continue to stir and react at 75 °C for 130 minutes, and distill off dichloromethane to obtain the weather-resistant additive.

[0042] Pre-dispersion: Mix the resin matrix, pigment, weather-resistant additive, dispersant, defoamer, and leveling agent evenly in a disperser, with a stirring speed of 1300 rpm, a time of 28 minutes, and the temperature controlled at 35 °C.

[0043] Grinding: Add the pre-dispersed material to a grinder, add a solvent, and grind until the fineness reaches 18 μm, with a grinding time of 70 minutes.

[0044] Formulation and filtration: Adjust the ground material to a coating viscosity of 4500 cP, a solid content of 75%, and a filter mesh size of 180 meshes.

[0045] Coating and curing: Spray the coating evenly on the surface of the steel substrate (the substrate surface treatment uses pickling, and the surface roughness reaches 8 μm), the curing temperature is 160 °C, and the curing time is 50 minutes.

[0046] Comparative Example 1: This comparative example provides a highly weather-resistant metal anti-corrosion coating, whose formulation composition and preparation method are basically the same as those of Example 1, except that the weather-resistant additive is not added.

[0047] Comparative Example 2: This comparative example provides a highly weather-resistant metal anti-corrosion coating, whose formulation composition and preparation method are basically the same as those of Example 1, except that epoxycyclohexyl-cage polyhedral oligomeric silsesquioxane is not added during the preparation of the weather-resistant additive.

[0048] Comparative Example 3: This comparative example provides a highly weather-resistant metal anti-corrosion coating, whose formulation composition and preparation method are basically the same as those of Example 1, except that zirconium aminophthalate MOF (UIO-66-BDC-NH2) is not added during the preparation of the weather-resistant additive.

[0049] The test method of the present invention is as follows: 1) Weather resistance test Test equipment: Xenon lamp aging test chamber.

[0050] Test conditions: Temperature: 50 °C; Humidity: 50%; Ultraviolet intensity: 0.75 W / m²; Test time: 2000 hours.

[0051] Evaluation criteria: Observe whether aging phenomena such as chalking, cracking, and blistering occur on the coating surface.

[0052] 2) Corrosion resistance test Test method: Neutral salt spray test (in accordance with the standard of GB / T 10125-2012).

[0053] Test conditions: Concentration of salt solution: 5% NaCl; Temperature: 35 °C; Time: 1000 hours.

[0054] Evaluation criteria: Evaluate the area and grade of blistering, rusting, and peeling on the coating surface.

[0055] 3) Mechanical property test Adhesion test: Conduct a cross-cut test (using a 1 mm grid cutter) in accordance with the standard of GB / T 9286. Observe the peeling of the coating at the grid.

[0056] Impact resistance test: Use an impact testing machine with a falling hammer height of 50 cm. Observe whether cracks or peeling occur on the coating.

[0057] Scratch resistance test: In accordance with the standard of GB / T 9279, use a load scratch tester with a loading force of 2 N. Observe the scratch situation of the coating.

[0058] The test results of the present invention are as follows: Table 1 Test results Weather resistance Salt spray test Adhesion Impact resistance Scratch resistance Example 1 No chalking, no cracking, no bubbles No blistering, no rusting No peeling No cracks, no peeling Scratches are hardly visible and the surface has good restorability Example 2 No chalking, no cracking, no bubbles No blistering, no rusting No peeling No cracks, no peeling Scratches are hardly visible and the surface has good restorability Example 3 No chalking, no cracking, no bubbles No blistering, no rusting No peeling No cracks, no peeling Scratches are hardly visible and the surface has good restorability Example 4 No chalking, no cracking, no bubbles No blistering, no rusting No peeling No cracks, no peeling Scratches are hardly visible and the surface has good restorability Comparative example 1 More chalking and cracking occur More blistering and rusting More peeling Cracks are obvious Scratches are obvious and affect the protective performance Comparative example 2 Slight chalking and cracking occur Slight blistering and rusting Slight peeling Slight cracks Scratches are slight and do not affect the performance Comparative example 3 A small amount of chalking and cracking occur Slight blistering and rusting A small amount of peeling Slight cracks Scratches are slight In summary, the coating preparation method of the present invention realizes excellent weather resistance, corrosion resistance, mechanical strength, and film quality through material selection and process optimization, significantly superior to the comparative example, showing significant technical advantages and practical application value.

[0059] The present invention has been described in detail above in combination with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions of the present invention and their implementation manners, and these all fall within the scope of the present invention. The protection scope of the present invention is subject to the appended claims.

[0060] The content not described in detail in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A method for preparing a highly efficient weather-resistant metal anticorrosion coating, characterized in that: The following steps are involved: (1) Material preparation: weigh 60-80 parts of resin matrix, add 5-15 parts of pigment, 2-5 parts of weathering agent, 0.5-1.5 parts of dispersant, 0.3-1 parts of defoamer, 0.2-0.5 parts of leveling agent and 10-20 parts of solvent; (2) Pre-dispersion: Mix the resin matrix, pigment, weathering agent, dispersant, defoamer and leveling agent in a disperser at a stirring speed of 1000-1500 rpm for 20-30 minutes and control the temperature at 25-40°C; (3) Grinding: Add the pre-dispersed material into the grinder, add solvent, and grind to a fineness of 10-20 μm for 40-80 minutes; (4) Preparation and filtration: Prepare the grinding material to a coating viscosity of 3000-5000 cP, a solid content of 60-80%, and a filter mesh of 100-200 mesh; (5) Coating and curing: Spray, brush or dip the coating evenly on the surface of the metal substrate. The curing temperature is 120-180°C and the curing time is 20-60 minutes. The weathering agent is prepared by reacting epoxy cyclohexyl-cage polysilsesquioxane, aminosulfonic acid cobalt and aminophthalic acid zirconium MOF (UIO-66-BDC-NH2).

2. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The resin matrix is ​​selected from one or a combination of polyvinylidene fluoride resin, ethylene-tetrafluoroethylene copolymer, fluorinated ethylene-propylene copolymer, and trifluorochloroethylene resin.

3. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The pigment is selected from titanium dioxide or zinc oxide.

4. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: Preparation method of the weathering additive: By mass, 2.5-3.9 parts of epoxycyclohexyl-cage polysilsesquioxane, 0.05-0.5 parts of cobalt sulfamate, and 200-230 parts of dichloromethane are added to the reaction kettle 1, and stirred at 62-82° C. for 50 to 100 minutes; Then add 17-34 parts of aminophthalic acid zirconium MOF (UIO-66-BDC-NH2) and 1-4 parts of triethanolamine, continue to stir and react at 70-80°C for 100 to 150 minutes, and distill off dichloromethane to obtain a weathering additive.

5. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The dispersant is selected from one or a combination of BYK-110, EFKA 4050, and DISPERBYK-190.

6. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The defoamer is selected from BYK-306, TEGO Airex 920, Defoamer 415 or a combination thereof.

7. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The leveling agent is selected from BYK-377, EFKA-2010, TEGO Glide 450 or a combination thereof.

8. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The solvent is selected from one or a combination of ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, xylene and toluene.

9. The method for preparing a high-efficiency weather-resistant metal anticorrosion coating according to claim 1, characterized in that: The metal substrate can be steel, aluminum alloy or galvanized metal. The surface of the substrate is treated by sandblasting or pickling, and the surface roughness reaches 5-10 μm to ensure the adhesion of the coating.