A rust conversion hydrophobic weatherable coating, and a preparation method and application thereof

Abstract

The application discloses a rust-converting hydrophobic weather-resistant paint and a preparation method and application thereof, and the rust-converting hydrophobic weather-resistant paint comprises the following components: a fluorinated polyacrylate emulsion grafted and modified by phosphoric acid and phytic acid, an inhibitor, a penetrating agent, an adhesion promoter and a filler. The fluorinated polyacrylate emulsion grafted and modified by phosphoric acid and phytic acid is used as a rust converter and a film former at the same time, chemical reactions and complexation are simultaneously carried out in the rust conversion process, the rust conversion product is integrated with the film forming material, the rust conversion product is completely converted, the internal crosslinking strength of the coating is high, long fluorine side chains are enriched on the surface of the coating, the coating has hydrophobic and weather-resistant properties, and the comprehensive corrosion resistance of the coating is excellent.

Description

Technical Field

[0001] This invention belongs to the field of metal anti-corrosion coating technology, specifically relating to a rust-reducing, hydrophobic, and weather-resistant coating, its preparation method, and its application. Background Technology

[0002] Anti-icing and anti-corrosion issues have long plagued the safe and stable operation of power transmission and transformation equipment. Operating outdoors for extended periods, this equipment suffers from chronic corrosion, leading to a decrease in structural strength and increasing the risk of collapse and breakage under extreme weather conditions such as ice storms. Conventional anti-corrosion and anti-icing solutions typically involve structural reinforcement and the application of organic anti-corrosion coatings to ensure structural safety. Organic anti-corrosion coatings, with their shielding, chemical protection, and electrochemical protection effects, are a viable and effective means of corrosion prevention. However, research indicates that a good coating / metal interface bond is crucial for the coating's effectiveness. Common substrate pretreatment methods, including mechanical and chemical rust removal, ensure a good coating / metal interface bond. However, effective substrate treatment is often limited by equipment, site constraints, and environmental regulations in the field. Therefore, rust-resistant coatings have become a research hotspot. Rust-resistant coatings, also known as low surface tolerance coatings, can directly stabilize, passivate, or transform rust layers, converting reactive rust into stable substances, achieving the dual purpose of rust removal and protection for metal surfaces. Some domestically developed products based on solvent-based epoxy resins have relatively good performance, but their widespread use is hindered by environmental restrictions.

[0003] Developing a water-based, environmentally friendly coating that can be applied with rust-resistant properties, possesses superhydrophobicity, and also exhibits good weather resistance and corrosion resistance is an effective way to solve the problems of corrosion and icing prevention. However, current water-based rust-converting coatings generally have the following problems: 1) The acidic components of water-based rust-converting coatings are added to the coating as rust-converting agents, and the film-forming material is an emulsion. Since the rust-converting substance and the film-forming material are two different substances, it is easy to lead to insufficient bonding force between the rust-converting layer and the substrate, as well as poor cohesive strength of the rust-converting layer, thus affecting the overall protective performance and lifespan of the rust-converting coating; 2) Water-based rust-converting coatings use water-based emulsions as film-forming materials, which have intrinsic hydrophilicity. Water molecules in the air are easily adsorbed on the coating surface, and water molecules can easily penetrate and diffuse inside the coating. Under high temperature and humid climate conditions, the resulting rust-converting coating has poor weather resistance and poor overall corrosion resistance; 3) Conventional water-based coatings do not have superhydrophobic properties, and therefore do not have anti-icing functions. Summary of the Invention

[0004] To address the shortcomings of existing water-based rust-converting coatings, the first objective of this invention is to provide a phosphoric acid and phytic acid grafted modified fluorinated polyacrylate emulsion. This modified emulsion integrates rust-converting components and hydrophobic film-forming substances, thereby forming a rust-converting hydrophobic weather-resistant coating with excellent rust-converting function, high adhesion between the rust-converting film and the coating, high cohesive strength of the coating, and high internal strength and good weather resistance of the rust-converting film.

[0005] The second objective of this invention is to provide a method for preparing rust-reducing, hydrophobic, and weather-resistant coatings that is simple to operate, operates under mild conditions, and has low production costs.

[0006] The third objective of this invention is to provide an application of a rust-reducing, hydrophobic, and weather-resistant coating, which, when applied to the surface of rusted metal for repair, can effectively protect metal equipment and extend its service life.

[0007] To achieve the above technical objectives, the present invention provides a rust-reducing, hydrophobic, and weather-resistant coating, comprising the following components: a fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid, a corrosion inhibitor, a penetrant, a filler, an adhesion promoter, water, and additives.

[0008] The fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid has the structural formula shown in Formula 1:

[0009]

[0010] Wherein: m and n are independently ranged from 200 to 200000, and x and y are independently ranged from 200 to 2000. R1 is an alkyl group, more preferably an alkyl group with less than 4 carbon atoms; R2 is a fluoroalkyl group, more preferably a fluoroalkyl group with less than 4 carbon atoms; when R3 has the structure of formula 2, R4 has the structure of formula 3, and when R3 has the structure of formula 3, R4 has the structure of formula 2. The structural formulas shown in formula 2 and formula 3 are as follows:

[0011]

[0012] Furthermore, the ratio of R2 to (R1+R2+R3+R4) is greater than 40% and less than or equal to 80%, the ratio of R3+R4 to (R1+R2+R3+R4) is 5% to 10%, and the remainder is R1.

[0013] This invention provides a unique conversion agent and film-forming material: a phosphoric acid and phytic acid-modified fluorinated polyacrylate emulsion. The functions of this emulsion are as follows: 1) Due to the simultaneous grafting of phosphoric acid and phytic acid groups, the phosphoric acid and phytic acid-modified fluorinated polyacrylate can directly interact with corrosion products to form a rust conversion layer; 2) Since the fluorinated polyacrylate itself can act as a film-forming substance, the phosphoric acid and phytic acid-modified fluorinated polyacrylate can directly cure into a film during the curing process; 3) Because both the rust conversion component and the film-forming substance component are phosphoric acid and phytic acid-modified fluorinated polyacrylate, the rust conversion product and the film-forming substance are integrated, thus eliminating the problem of poor coating performance caused by poor bonding between the rust conversion product and the film-forming substance. Therefore, this emulsion can endow coatings with characteristics such as good adhesion to the substrate and high cohesive strength, resulting in excellent overall anti-corrosion performance.

[0014] At the same time, this emulsion is also rich in fluorine groups, which gives it better weather resistance and hydrophobicity than ordinary acrylic emulsions or other polyurethane or epoxy resin emulsions, thus helping to improve the anti-corrosion performance of the paint film.

[0015] Importantly, the fluorinated polyacrylate emulsion modified with phosphoric acid and phytic acid also exhibits a synergistic effect. Generally, rust conversion occurs through two processes: a chemical reaction, where a converting agent reacts with the rust products (e.g., phosphoric acid, typically a small-molecule acid), and a complexation reaction, where tannic acid, typically a large-molecule acid, promotes rust conversion through complexation with the rust products. In this invention, the acrylate polymer molecules grafted with phosphoric acid and phytic acid simultaneously possess both chemical reaction and complexation effects. Because phosphoric acid grafted onto polyacrylate still retains two acid radicals capable of chemically reacting with the rust products, and because phytic acid grafted onto polyacrylate possesses the characteristics of a large-molecule acid, it can simultaneously complex with the rust products. The benefits are that the simultaneous chemical reaction and complexation further enhance the wettability and penetration of the rust products, resulting in a more thorough rust conversion and superior adhesion between the rust-converted layer and the substrate. Meanwhile, the polyacrylate modified with phosphoric acid and phytic acid is the film-forming substance, which brings another advantage: the rust conversion products and the film-forming substance are integrated, the internal cross-linking strength of the coating is high, the internal structure of the coating is uniform, and the cohesive strength is high. This avoids the problem of low coating cohesive strength caused by low bonding strength between rust conversion products and film-forming substances.

[0016] In summary, the coating provided by the technical solution of the present invention allows for simultaneous chemical reaction and complexation during the rust conversion process, integrating the rust conversion products with the film-forming substances, resulting in thorough conversion of rust products, high internal cross-linking strength of the coating, and the presence of fluoride ions, which gives the coating hydrophobic and weather-resistant properties, resulting in excellent overall anti-corrosion performance.

[0017] As a preferred embodiment, the rust-converting, hydrophobic, and weather-resistant coating comprises the following components in parts by weight: 100-200 parts of a fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid, 10-60 parts of a corrosion inhibitor, 10-30 parts of a penetrant, 5-20 parts of a filler, 5-10 parts of an adhesion promoter, 5-50 parts of water, and 1-5 parts of additives. In the formulation of this invention, balancing the amounts of the corrosion inhibitor and the fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid can further enhance the overall rust conversion performance of the coating, while balancing the amounts of the adhesion promoter, penetrant, and the fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid can further enhance the internal strength and film-forming properties of the coating.

[0018] As a preferred embodiment, the corrosion inhibitor is hydroxyquinoline and / or mercaptobenzothiazole.

[0019] As a preferred embodiment, the penetrant is sodium dodecyl sulfonate and / or sodium dodecylbenzene sulfonate. All penetrants selected in this invention are anionic surfactants.

[0020] As a preferred embodiment, the adhesion promoter is a silane coupling agent KH560, KH570, or KH590.

[0021] As a preferred embodiment, the additive is an antifoaming agent and / or a wetting and dispersing agent.

[0022] As a preferred embodiment, the defoamer is an aqueous silicone defoamer, such as R920S; and the wetting and dispersing agent is isopropanol.

[0023] As a preferred embodiment, the filler is at least one selected from silicon dioxide, titanium dioxide, mica powder, talc powder, kaolin, montmorillonite, and graphene; more preferably, titanium dioxide or montmorillonite.

[0024] This invention also provides a method for preparing a rust-reducing, hydrophobic, and weather-resistant coating. The method involves mixing a solution containing a fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid, a corrosion inhibitor, a penetrant, a filler, an adhesion promoter, water, and additives. The fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid is obtained by a grafting reaction of phosphoric acid, phytic acid, and fluorinated polyacrylate emulsions. The structure of the fluorinated polyacrylate is shown in Formula 4.

[0025]

[0026] Where p = x + y, x and y are independent and range from 200 to 2000, and q is from 0 to 16.

[0027] This invention involves reacting the epoxy groups in a fluorinated polyacrylate emulsion with the hydroxyl groups in phosphate and phytic acid groups to graft phosphoric acid and phytic acid onto a fluorine-rich emulsion resin, resulting in a rust-converting coating resin that can function as both a conversion agent and a film-forming agent. This invention is simple to operate, operates under mild conditions, has low production costs, and is easily industrialized. The preparation process is as follows:

[0028] (1) Add three monomers: (q=0~16)alkyl (meth)acrylate monomer, fluoroalkyl (meth)acrylate monomer, and (meth)acrylate glycidyl ester to dioxane or butanone solvent. Stir at 500~1000rpm / min. When the temperature rises to 60~80℃, add the initiator azobisisobutyronitrile. Stir at 80℃ for 4~10h to allow the monomers to fully react and polymerize.

[0029] (2) After the monomer polymerization reaction is completed, phosphoric acid and phytic acid are added to the liquid and the grafting reaction continues at 60-100℃ for 2-10 hours to obtain phosphoric acid-phytic acid modified fluorinated poly(meth)acrylate.

[0030] (3) After removing the solvent by rotary evaporation, water is added for emulsification, wherein the amount of deionized water is 20-50% of the remaining mass after rotary evaporation, to obtain a phosphate-phytic acid modified fluorinated poly(meth)acrylate emulsion.

[0031] As a preferred embodiment, the total amount of phosphoric acid and phytic acid and the mass ratio of the fluorinated polyacrylate emulsion are (1-0.6):10.

[0032] As a preferred embodiment, the mass ratio of phosphoric acid to phytic acid is 10:(10-12).

[0033] As a preferred embodiment, the grafting reaction conditions are: a temperature of 60–100°C and a time of 2–10 hours. Within the range selected in this invention, the yield of the modified product can be guaranteed while the generation of by-products can be avoided.

[0034] This invention provides a method for preparing a rust-reducing, hydrophobic, and weather-resistant coating, specifically including the following steps:

[0035] 1) Mix the acidic components (phytic acid and phosphoric acid) with the fluorinated polyacrylate emulsion to obtain a fluorinated polyacrylate emulsion (component A) that is grafted with phytic acid and phosphoric acid.

[0036] 2) Add corrosion inhibitor, penetrant, adhesion promoter and filler to component A to obtain component B.

[0037] 3) Add an appropriate amount of additives and water to component B to obtain component C.

[0038] Finally, this invention also provides an application of a rust-reversing, hydrophobic, and weather-resistant coating for repairing rusted metal surfaces. This rust-reversing, hydrophobic, and weather-resistant coating can be applied to rusted metal surfaces for repair, effectively protecting metal equipment and extending its service life.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1) In general water-based rust conversion agents, the film-forming substance and the rust-converting substance are two separate substances, which usually present bonding problems. In this invention, the conversion agent and the film-forming substance are one substance: a fluorinated polyacrylate emulsion modified with phosphoric acid and phytic acid. It has phosphoric acid and phytic acid groups, and also has functions such as rust conversion and decomposition of rust products, complexation, chemical bonding and physical encapsulation. At the same time, it is also a film-forming substance itself, which makes the rust conversion film and the coating have high adhesion and good weather resistance.

[0041] 2) Phosphoric acid and phytic acid modified fluorinated polyacrylate emulsions have fluorinated groups. The fluorinated side groups provide hydrophobicity to the paint film surface, which has better weather resistance and hydrophobicity than general acrylic emulsions or other polyurethane or epoxy resin emulsions, and helps to improve the anti-corrosion performance of the paint film.

[0042] 3) Fluorinated polyacrylate emulsions modified with phosphoric acid and phytic acid have a synergistic effect. After the acrylic polymer molecules are grafted with phosphoric acid and phytic acid, they can ionize anions, which can increase the wettability and permeability of the conversion products, making the rust layer conversion more thorough and the bonding force between the rust conversion layer and the substrate better.

[0043] 4) The rust-reducing hydrophobic weather-resistant coating provided by this invention is applied to the surface of rusted metal for repair. Through the synergistic effect of fluorinated polyacrylate rust-converting agent modified with phosphoric acid and phytic acid, corrosion inhibitor, penetrant and adhesion promoter, it can effectively protect metal equipment and extend its service life.

[0044] 5) The fluorinated polyacrylate emulsion modified with phosphoric acid and phytic acid in this invention has multiple acid radicals that can directly chemically transform rust products. The fluorinated polyacrylate emulsion modified with phytic acid imparts acidic properties to the polyacrylate macromolecules, allowing it to complex with rust products. The simultaneous chemical reaction and complexation further enhance the wettability and penetration of rust products, resulting in a more thorough rust transformation and superior adhesion between the rust-transformed layer and the substrate. Attached Figure Description

[0045] Figure 1The diagram shows the synthesis principle of fluorinated polyacrylate emulsion modified with phosphoric acid and phytic acid. The value of p in the diagram is equivalent to x+y in Equation 1. (1) is the chemical structural formula of fluorinated polyacrylate, and (2) is the chemical structural formula of fluorinated polyacrylate modified by simultaneous grafting of phosphoric acid and phytic acid. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0047] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0048] In this embodiment, the aqueous fluorinated polyacrylate emulsions were prepared according to the following steps:

[0049] (1) Mix 15g of butyl methacrylate, 35g of hexafluorobutyl methacrylate and 17g of glycidyl methacrylate evenly and dissolve them in 200g of butanone to obtain a monomer mixture.

[0050] (2) Heat the monomer mixture to 80°C, add 3g of initiator azobisisobutyronitrile to initiate the polymerization reaction, and continue the polymerization reaction at a constant temperature for 6 hours with a stirring speed of 800r / min to fully carry out the polymerization reaction and obtain fluorinated poly(meth)acrylate.

[0051] (3) After removing the solvent by rotary evaporation, water is added for emulsification, wherein the amount of deionized water is 50% of the remaining mass after rotary evaporation. Fluorinated poly(meth)acrylate emulsion is obtained.

[0052] Example 1

[0053] Prepare 100 parts of aqueous fluorinated polyacrylate emulsion and 10 parts of phytic acid + phosphoric acid (phytic acid to phosphoric acid mass ratio of 1.2:1). Mix the two together and keep the temperature at 60℃ for 3 hours to obtain a fluorinated polyacrylate emulsion grafted with phytic acid and phosphoric acid, denoted as component A.

[0054] Component A was prepared by adding 25 parts of hydroxyquinoline and mercaptobenzothiazole (functional corrosion inhibitor), 10 parts of sodium dodecyl sulfonate and sodium dodecylbenzene sulfonate (penetrating agent), 5 parts of silane coupling agent KH560 (adhesion promoter), and 8 parts of montmorillonite. The mixture was stirred at 1000 rpm for 10 min to obtain component B.

[0055] Add 1 part of R920S (water-based silicone defoamer) and 1 part of isopropanol (wetting and dispersing agent) to component B, add 5 parts of water, and stir at 200 rpm for 10 minutes to obtain the rust-reducing, hydrophobic, and weather-resistant coating.

[0056] Table 1 shows the adhesion, static water contact angle, and salt spray corrosion data of the rust-reducing hydrophobic weather-resistant coating on rusted metal surfaces.

[0057] Example 2

[0058] Prepare 100 parts of waterborne fluorinated acrylic resin emulsion and 6 parts of phytic acid + phosphoric acid (1:1). Mix the two together and keep the temperature at 80℃ for 2 hours to obtain a fluorinated polyacrylic acid emulsion modified by phytic acid and phosphoric acid grafting, denoted as component A.

[0059] Add 30 parts of hydroxyquinoline (functional corrosion inhibitor), 10 parts of sodium dodecyl sulfonate (penetrating agent), 6 parts of silane coupling agent KH560 (adhesion promoter), and 8 parts of montmorillonite to component A, stir at 1000 rpm for 10 min to obtain component B.

[0060] Add 0.5 parts of R920S (water-based silicone defoamer) and 0.5 parts of isopropanol (wetting and dispersing agent) to component B, add 5 parts of water, and stir at 200 rpm for 10 minutes to obtain the rust-reducing, hydrophobic, and weather-resistant coating.

[0061] Table 1 shows the adhesion, static water contact angle, and salt spray corrosion data of the rust-reducing hydrophobic weather-resistant coating on rusted metal surfaces.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that an equal amount of unmodified fluorinated polyacrylic acid emulsion is used to replace the fluorinated polyacrylic acid grafted with phytic acid and phosphoric acid, while the other steps and conditions are the same, to obtain the rust-converting coating.

[0064] The adhesion of the rust-reducing coating to the rusted metal surface, the static water contact angle, and the salt spray corrosion data are shown in Table 1.

[0065] Comparative Example 2

[0066] Compared with Example 1, the only difference is that an equal amount of phytic acid and phosphate-grafted modified polyacrylic acid emulsion is used to replace the phytic acid and phosphate-grafted modified fluorinated polyacrylic acid emulsion. All other steps and conditions are the same to obtain the rust-converting coating.

[0067] The adhesion of the rust-reducing coating to the rusted metal surface, the static water contact angle, and the salt spray corrosion data are shown in Table 1.

[0068] The adhesion test procedure and evaluation criteria refer to GB / T 31586.1 Evaluation and acceptance criteria for adhesion / cohesion (breaking strength) of protective coating systems for corrosion protection of steel structures - Part 1: Pull-off test;

[0069] The static water contact angle test procedure and evaluation criteria refer to the national standard GB / T 30693-2014, which specifies the measurement of the contact angle between plastic film and water.

[0070] The salt spray corrosion test procedure and evaluation criteria refer to the national standard GB / T 10125-2012 Artificial Atmosphere Corrosion Test - Salt Spray Test.

[0071] Table 1 Preliminary properties (corroded substrate surface)

[0072]

[0073] Note: a. E7040 waterborne epoxy zinc phosphate primer provided by Tushan Company.

[0074] In summary, the components described in this invention can achieve good film-forming and encapsulating effects on both rusted and smooth surfaces, and have superior adhesion.

Claims

1. A rust-reducing, hydrophobic, and weather-resistant coating, characterized in that: The rust-reducing, hydrophobic, and weather-resistant coating is composed of the following components by weight: 100-200 parts of fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid, 10-60 parts of corrosion inhibitor, 10-30 parts of penetrant, 5-20 parts of filler, 5-10 parts of adhesion promoter, 5-50 parts of water, and 1-5 parts of additive. The fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid has the structural formula shown in Formula 1: Formula 1; Wherein: m and n are independently taken from 200 to 200,000, and x and y are independently taken from 200 to 2000; R1 is an alkyl group, R2 is a fluoroalkyl group, when R3 has the structure of formula 2, R4 has the structure of formula 3, and when R3 has the structure of formula 3, R4 has the structure of formula 2. The structural formulas shown in formula 2 and formula 3 are as follows: Formula 2; Formula 3; The fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid is obtained by grafting phosphoric acid, phytic acid, and fluorinated polyacrylate emulsions. The structure of the fluorinated polyacrylate is shown in Formula 4. Equation 4; p = x + y, where x and y are independent and range from 200 to 2000, and q is from 0 to 16.

2. The rust-reducing, hydrophobic, and weather-resistant coating according to claim 1, characterized in that: The penetrant is sodium dodecyl sulfonate and / or sodium dodecylbenzene sulfonate; the corrosion inhibitor is hydroxyquinoline and / or mercaptobenzothiazole.

3. A rust-reducing, hydrophobic, and weather-resistant coating according to claim 1 or 2, characterized in that: The adhesion promoter is a silane coupling agent KH560, KH570 or KH590.

4. The rust-reducing, hydrophobic, and weather-resistant coating according to claim 3, characterized in that: The additives are defoamers and wetting and dispersing agents; the defoamer is an aqueous silicone defoamer; and the wetting and dispersing agent is isopropanol.

5. The rust-reducing, hydrophobic, and weather-resistant coating according to claim 4, characterized in that: The filler is at least one of silicon dioxide, titanium dioxide, mica powder, talc powder, kaolin, montmorillonite and graphene.

6. A method for preparing a rust-reducing, hydrophobic, and weather-resistant coating according to any one of claims 1 to 5, characterized in that: The solution is prepared by mixing a fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid, a corrosion inhibitor, a penetrant, a filler, an adhesion promoter, water, and additives. The fluorinated polyacrylate emulsion grafted with phosphoric acid and phytic acid is obtained by grafting phosphoric acid, phytic acid, and fluorinated polyacrylate emulsions. The structure of the fluorinated polyacrylate is shown in Formula 4. Equation 4; Where p = x + y, x and y are independent and taken from 200 to 2000, and q is 0 to 16.

7. The method for preparing a rust-reducing, hydrophobic, and weather-resistant coating according to claim 6, characterized in that: The total amount of phosphoric acid and phytic acid used is in a mass ratio of (1~0.6):10 to the fluorinated polyacrylate emulsion.

8. The rust-reducing, hydrophobic, and weather-resistant coating according to claim 7, characterized in that: The grafting reaction conditions are: temperature 60~100℃, time 2~10h.

9. The application of the rust-reducing, hydrophobic, and weather-resistant coating according to any one of claims 1 to 5, characterized in that: It is used for the repair of rusty metal surfaces.

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