Strong-alkali-resistant water-based anticorrosive paint and preparation method thereof

Abstract

The invention discloses a strong-alkali-resistant water-based anticorrosive coating and a preparation method thereof, and belongs to the technical field of coatings. An environment-friendly water-borne epoxy resin matrix and a curing agent coating material are adopted, reduced graphene oxide, mesoporous silica, a dispersing agent, a corrosion inhibitor and a defoaming agent are selected as fillers, and through reasonable formula design, the high-dispersity reduced graphene oxide filler prepared under the action of the dispersing agent has a filling effect on coating pores; and through the corrosion inhibition effect of the corrosion inhibitor loaded on the mesoporous silica, the permeation and corrosion effects of an alkali corrosion medium on a base material are effectively blocked, and the anti-corrosion effect of the coating material in a strong alkali environment is improved. The strong-alkali-resistant water-based anticorrosive paint prepared by the invention has the characteristics of high corrosion resistance, high hardness and high strong-alkali-resistant stability, and has a good application prospect.

Description

Technical Field

[0001] The invention relates to a strong alkali resistant water-based anticorrosive coating and a preparation method thereof, belonging to the technical field of coatings. Background Art

[0002] The corrosion of chemical equipment will not only cause huge economic losses, but also serious corrosion will cause catastrophic accidents such as damage and scrapping of equipment and facilities, leakage of toxic media, fire, explosion, etc. Carbon steel is widely used in chemical equipment due to its excellent mechanical properties and low cost. However, carbon steel is easily corroded and eroded during use. The corrosion process of carbon steel is controlled by the structure and composition of the oxide on the surface of carbon steel. Alkali has significant corrosion damage to carbon steel, and its corrosion damage increases rapidly with the increase of alkali concentration and temperature. In view of the corrosion problem of carbon steel, pickling is often used in industry to treat the oxide layer produced on the surface of carbon steel during processing and the dirt and rust in the structure. Pickling can remove the rust layer and dirt on the surface of carbon steel, but it will also cause corrosion to the metal under the rust layer. The currently developed carbon steel material protection methods mainly include metal essence modification, electrochemical protection, addition of corrosion inhibitors and surface coating. Among them, covering the surface of carbon steel with a coating is an important metal protection measure. The surface coating will directly block the contact between carbon steel and the outside world and thus extend the service life of carbon steel. The protective mechanism of the coating on the metal substrate is to isolate the metal substrate from the corrosive medium by adding an isolation layer between the metal and the corrosive medium, thereby protecting the metal substrate.

[0003] Traditional alkali-resistant coatings are divided into water-based coatings and organic coatings. Water-based coatings are widely used in the protection of metals because of their high environmental friendliness and safety. The solvent of water-based coatings is mainly water. Compared with organic coatings, water-based coatings are more environmentally friendly and cost-effective, and easier to transport and store. However, there are a lot of free spaces and holes in the film-forming process of water-based coatings, which cause defects in the internal structure of the coating, resulting in problems such as reduced surface quality, poor protection ability, and weak mechanical ability of the coating, resulting in limited alkali corrosion resistance. For example, patent CN111154042A discloses a water-based acrylic-epoxy-polyurethane dispersion and alcohol-resistant alkali-resistant coatings, which have good high temperature resistance, alcohol-resistant, fingerprint resistance, flexibility and coating properties, and are stable in a 20% sodium hydroxide alkaline solution at 25°C, but this coating requires a cumbersome synthesis process and has limited storage stability. Patent CN216946825U discloses an acid-base corrosion-resistant composite coating of a substrate, a solvent-free epoxy coating, a vinyl epoxy glass flake coating, and a phenolic epoxy chemical-resistant coating. The coating is immersed in a 15wt% calcium hydroxide alkaline solution for two months without blistering or shedding, but has the problems of complex coating structure and poor alkali resistance. For strong alkaline environment corrosion protection used in the chemical industry, existing anti-corrosion coating materials generally have problems such as poor corrosion resistance, insufficient hardness, and long-term stability. Summary of the invention

[0004] The purpose of the present invention is to propose a strong alkali resistant water-based anti-corrosion coating with the characteristics of high corrosion resistance, high bonding strength, high hardness and high alkali resistance stability, so as to solve the problem that the existing water-based anti-corrosion coating has poor anti-corrosion performance in a strong alkali environment.

[0005] The invention provides a strong alkali resistant water-based anticorrosive coating, comprising component A and component B, wherein component A comprises water-based epoxy resin, reduced graphene oxide, a dispersant and deionized water; and component B comprises a curing agent, mesoporous silica, a corrosion inhibitor, a defoaming agent and deionized water.

[0006] Preferably, the mass ratio of component A to component B is (3-8):1, most preferably 5:1.

[0007] Preferably, the weight ratio of deionized water to water-based epoxy resin in component A is 1:2.

[0008] Preferably, the weight ratio of reduced graphene oxide to deionized water in component A is (0.2-0.3):50.

[0009] Preferably, the dispersant in component A is phenylalanine, polydopamine or polyvinyl pyrrolidone, and the weight ratio of the dispersant to deionized water is (0.4-0.6):50.

[0010] Preferably, the corrosion inhibitor used in the component B is benzotriazole, the weight ratio of the corrosion inhibitor to deionized water is (0.75-1.25):50, and the weight ratio of the mesoporous silica to deionized water is (1.5-2.5):50.

[0011] Preferably, the curing agent in component B is water-based polyurethane, and the weight ratio of the curing agent to deionized water is (15-20):50.

[0012] Preferably, the defoamer in component B is a polydimethylsiloxane defoamer or a polyether defoamer, and the weight ratio of the defoamer to deionized water is (0.1-0.2):50.

[0013] The present invention also provides a method for preparing a strong alkali resistant water-based anticorrosive coating, comprising the following steps: (1) Preparation of component A: reducing graphene oxide and a dispersant are added to deionized water, stirring to obtain a mixed solution, and adding an aqueous epoxy resin to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: adding mesoporous silica and a corrosion inhibitor into deionized water to obtain a mixed solution, stirring the mixed solution under vacuum to obtain a corrosion inhibitor solution in which the corrosion inhibitor is loaded on the mesoporous silica, adding a curing agent and a defoaming agent to the corrosion inhibitor solution, and stirring to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are mixed evenly in proportion to obtain a strong alkali resistant water-based anti-corrosion coating.

[0014] Preferably, in the preparation of component A, the stirring time is 1-2 h, and the water content of the waterborne epoxy resin is 50%; in the preparation of component B, the stirring is carried out for 2-3 h under a vacuum of 0.09-0.1 Mpa, most preferably 0.1 Mpa, and the water content of the curing agent waterborne polyurethane is 45%.

[0015] The strong alkali resistant water-based anti-corrosion coating proposed by the present invention adopts an environmentally friendly water-based epoxy resin matrix and a curing agent coating material, selects reduced graphene oxide, mesoporous silica, a dispersant, a corrosion inhibitor and a defoaming agent as fillers, and through reasonable formula design, utilizes the filling effect of the highly dispersed reduced graphene oxide filler prepared under the action of the dispersant on the pores of the coating, and the corrosion inhibition effect of the corrosion inhibitor loaded on the mesoporous silica, effectively blocks the penetration and corrosion of the alkaline corrosive medium on the substrate, and improves the anti-corrosion effect of the coating material in a strong alkaline environment.

[0016] The strong alkaline water-based anticorrosive coating film prepared by the present invention has the characteristics of few pinholes and microscopic defects, and has high corrosion resistance (|Z|0.01Hz can reach 10 10 ohm.cm 2), strong alkali corrosion resistance (immersed in 32% NaOH solution at 60℃ for 80 days, the corrosion resistance does not decrease significantly), high hardness (pencil hardness test can reach 6H), etc., and it has good application prospects in the field of strong alkali corrosion protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a scanning electron microscope image of the coating cross section of the strong alkaline water-based anti-corrosion coating film of the embodiment.

[0018] Figure 2 This is the electrochemical impedance spectroscopy diagram of the strong alkaline resistant water-based anti-corrosion coating film sample after being immersed in a 3.5% NaCl solution.

[0019] Figure 3 This is the electrochemical impedance spectroscopy diagram of the strong alkaline water-based anti-corrosion coating film sample after being immersed in a 32% NaOH solution at 60°C. Implementation

[0020] The purpose, advantages and features of the present invention will be illustrated and explained by the non-limiting description of the following preferred embodiments. These embodiments are only typical examples of the application of the technical solution of the present invention, and any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention. Example 1

[0021] (1) Preparation of component A: 0.2 g of reduced graphene oxide and 0.4 g of phenylalanine were added to 50 ml of deionized water and stirred for 1 h to obtain a mixed solution. 100 g of water-based epoxy resin (water content 50%) was added to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of water-based polyurethane curing agent (water content 45%) and 0.1 g of polydimethylsiloxane defoaming agent to the above corrosion inhibitor solution, stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 2

[0022] (1) Preparation of component A: Add 0.2 g of reduced graphene oxide and 0.5 g of polydopamine to 50 ml of deionized water and stir for 1 h to obtain a mixed solution. Add 100 g of water-based epoxy resin (water content 50%) to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of water-based polyurethane curing agent (water content 45%) and 0.1 g of polydimethylsiloxane defoaming agent to the above corrosion inhibitor solution, stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 3

[0023] (1) Preparation of component A: Add 0.2 g of reduced graphene oxide and 0.6 g of polyvinyl pyrrolidone to 50 ml of deionized water and stir for 1 h to obtain a mixed solution. Add 100 g of water-based epoxy resin (water content 50%) to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of water-based polyurethane curing agent (water content 45%) and 0.1 g of polydimethylsiloxane defoaming agent to the above corrosion inhibitor solution, stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 4

[0024] (1) Preparation of component A: 0.2 g of reduced graphene oxide and 0.4 g of phenylalanine were added to 50 ml of deionized water and stirred for 1 h to obtain a mixed solution. 100 g of water-based epoxy resin (water content 50%) was added to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of waterborne polyurethane curing agent (water content 45%) and 0.2 g of polyether defoamer to the above corrosion inhibitor solution and stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 5

[0025] (1) Preparation of component A: Add 0.2 g of reduced graphene oxide and 0.5 g of polydopamine to 50 ml of deionized water and stir for 1 h to obtain a mixed solution. Add 100 g of water-based epoxy resin (water content 50%) to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of waterborne polyurethane curing agent (water content 45%) and 0.2 g of polyether defoamer to the above corrosion inhibitor solution and stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 6

[0026] (1) Preparation of component A: 0.2 g of reduced graphene oxide and 0.6 g of polyvinyl pyrrolidone were added to 50 ml of deionized water and stirred for 1 h to obtain a mixed solution. 100 g of water-based epoxy resin (water content 50%) was added to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 1.5 g of mesoporous silica and 0.75 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of waterborne polyurethane curing agent (water content 45%) and 0.2 g of polyether defoamer to the above corrosion inhibitor solution and stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 7

[0027] (1) Preparation of component A: 0.3 g of reduced graphene oxide and 0.6 g of phenylalanine were added to 50 ml of deionized water and stirred for 2 h to obtain a mixed solution. 100 g of water-based epoxy resin (water content 50%) was added to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 2.5 g of mesoporous silica and 1.25 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of water-based polyurethane curing agent (water content 45%) and 0.15 g of polydimethylsiloxane defoaming agent to the above corrosion inhibitor solution, stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating. Example 8

[0028] (1) Preparation of component A: 0.3 g of reduced graphene oxide and 0.6 g of phenylalanine were added to 50 ml of deionized water and stirred for 2 h to obtain a mixed solution. 100 g of water-based epoxy resin (water content 50%) was added to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: Add 2.5 g of mesoporous silica and 1.25 g of benzotriazole to 50 ml of deionized water to obtain a mixed solution. Place the mixed solution in a vacuum oven and stir at 0.1 MPa for 2 h to obtain a corrosion inhibitor solution of benzotriazole loaded on mesoporous silica. Add 15 g of waterborne polyurethane curing agent (water content 45%) and 0.2 g of polyether defoamer to the above corrosion inhibitor solution and stir evenly to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are uniformly mixed in a weight ratio of 5:1 to obtain a strong alkali resistant water-based anti-corrosion coating.

[0029] The coating in the above-mentioned embodiment was applied on a carbon steel sheet to prepare a strong alkaline water-based anti-corrosion coating film sample, and its performance was tested.

[0030] The strong alkaline water-based anticorrosive coating film samples prepared above have the characteristics of few pinholes and few microscopic defects ( Figure 1 ), with high corrosion resistance (AC impedance test |Z| 0.01Hz can reach 10 10 ohm.cm 2 ,like Figure 2 As shown), strong alkali corrosion resistance (32% NaOH solution at 60 ° C for 80 days, the corrosion resistance has no significant decrease, such as Figure 3 As shown in the figure), high hardness (pencil hardness test can reach 6H), etc., it has good application prospects in the field of strong alkali corrosion protection.

Claims

1. A strong alkaline water-based anticorrosive coating, characterized in that The invention comprises component A and component B, wherein component A comprises waterborne epoxy resin, reduced graphene oxide, dispersant and deionized water; and component B comprises curing agent, mesoporous silica, corrosion inhibitor, defoaming agent and deionized water.

2. A strong alkali resistant water-based anticorrosive coating as claimed in claim 1, characterized in that: The mass ratio of component A to component B is (3-8):1, preferably 5:

1.

3. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The weight ratio of deionized water to water-based epoxy resin in the component A is 1:

2.

4. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The weight ratio of reduced graphene oxide to deionized water in component A is (0.2-0.3):

50.

5. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The dispersant in component A is phenylalanine, polydopamine or polyvinyl pyrrolidone, and the weight ratio of the dispersant to deionized water is (0.4-0.6):

50.

6. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The corrosion inhibitor used in the component B is benzotriazole, the weight ratio of the corrosion inhibitor to deionized water is (0.75-1.25):50, and the weight ratio of the mesoporous silica to deionized water is (1.5-2.5):

50.

7. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The curing agent in component B is water-based polyurethane, and the weight ratio of the curing agent to deionized water is (15-20):

50.

8. The strong alkali resistant water-based anticorrosive coating according to claim 1, characterized in that: The defoamer in component B is a polydimethylsiloxane defoamer or a polyether defoamer, and the weight ratio of the defoamer to deionized water is (0.1-0.2):

50.

9. A method for preparing a strong alkali resistant water-based anticorrosive coating according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of component A: reducing graphene oxide and a dispersant are added to deionized water, stirring to obtain a mixed solution, and adding an aqueous epoxy resin to the mixed solution under stirring to obtain a component A solution; (2) Preparation of component B: adding mesoporous silica and a corrosion inhibitor into deionized water to obtain a mixed solution, stirring the mixed solution under vacuum to obtain a corrosion inhibitor solution in which the corrosion inhibitor is loaded on the mesoporous silica, adding a curing agent and a defoaming agent to the corrosion inhibitor solution, and stirring to obtain a component B solution; (3) Preparation of strong alkali resistant water-based anti-corrosion coating: Component A and component B are mixed evenly in proportion to obtain a strong alkali resistant water-based anti-corrosion coating.

10. The method for preparing a strong alkali resistant water-based anticorrosive coating according to claim 9, characterized in that: In the preparation of component A, the stirring time is 1-2 h, and the water content of the water-based epoxy resin is 50%; in the preparation of component B, the stirring is carried out for 2-3 h under a vacuum of 0.09-0.1Mpa, preferably 0.1Mpa, and the water content of the curing agent water-based polyurethane is 45%.

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