A coating for preventing oxidation passivation of a steel surface, and a preparation method and application thereof

Abstract

The present application relates to the technical field of paint, and particularly relates to a paint for preventing oxidation passivation of a steel surface and a preparation method and application thereof. The present application discloses a paint for preventing oxidation passivation of a steel surface, which comprises A component and B component; the A component comprises the following raw materials in parts by weight: polyvinyl alcohol 20-25 parts, amphoteric polyurethane 10-15 parts, rust conversion agent 10-12 parts, accelerator 1-2 parts, corrosion inhibitor 3-4 parts, stabilizer 2-3 parts, and solvent A 10-15 parts; the B component comprises the following raw materials in parts by weight: curing agent 2-4 parts and solvent A 10-15 parts; the rust conversion agent is composed of phosphoric acid and tannic acid in a weight ratio of 1:1; the paint can penetrate into the micropores on the surface of the steel, thereby enhancing the protection effect, solving the problem of insufficient adhesion of the traditional paint on the low-surface-treated steel, and solving the problem of poor weather resistance and flexibility.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coatings, and particularly relates to a coating for preventing the passivation of a steel surface and a preparation method and application thereof. BACKGROUND

[0002] With the development of industry, steel materials are increasingly widely used in the fields of construction, bridges, ships, etc. However, the corrosion problem of steel has always been a major challenge that needs to be solved. In order to prolong the service life of steel products and reduce maintenance costs, the research and application of coatings for preventing the passivation of a steel surface (i.e. anticorrosion) are particularly important.

[0003] At present, there are various types of anticorrosion coatings on the market, including but not limited to oil paint, alkyd paint, epoxy resin paint, and polyurethane paint, etc. These coatings form a physical barrier to isolate oxygen and moisture, thereby achieving the purpose of corrosion protection. In recent years, water-based coatings have received more and more attention due to their environmental characteristics. They use water as a solvent, reducing the emission of organic volatile compounds (VOCs), which meets the requirements of modern society for environmental protection.

[0004] However, the existing anticorrosion coatings still face some difficult problems:

[0005] 1. Insufficient adhesion

[0006] Many coatings have poor adhesion on hot-dipped galvanized steel or rusted surfaces, resulting in poor protective effect.

[0007] 2. Poor weather resistance and flexibility

[0008] Some coatings easily age and crack when exposed to natural environments for a long time, losing their protective function.

[0009] 3. Environmental pollution

[0010] Traditional solvent-based coatings contain a large amount of organic solvents, which can pollute the environment and pose a threat to human health during production and use.

[0011] 4. Strict construction conditions

[0012] Some high-performance anticorrosion coatings require strict surface pretreatment, increasing the difficulty and cost of construction.

[0013] Therefore, the present application provides a coating for preventing the passivation of a steel surface and a preparation method and application thereof. SUMMARY

[0014] In order to overcome the deficiencies of the prior art, the present application provides a coating for preventing the passivation of the oxidation of the steel surface, a preparation method and application thereof, the amphoteric polyurethane contains abundant polyhydroxy functional groups, can form a close chemical bond with the metal surface, provide an instant corrosion protection barrier, and due to the presence of a hydrophilic chain extender, can penetrate into the micropores of the steel surface, enhance the protection effect, solve the problems of insufficient adhesion of traditional coatings on low-surface-treated steel, and poor weather resistance and flexibility.

[0015] In a first aspect of the present application, a coating for preventing the passivation of the oxidation of the steel surface is provided, comprising components A and B;

[0016] The component A comprises the following raw materials in parts by weight:

[0017] Polyvinyl alcohol 20-25 parts, amphoteric polyurethane 10-15 parts, rust converter 10-12 parts, accelerator 1-2 parts, corrosion inhibitor 3-4 parts, stabilizer 2-3 parts, solvent A 10-15 parts;

[0018] The component B comprises the following raw materials in parts by weight:

[0019] Curing agent 2-4 parts, solvent A 10-15 parts;

[0020] The rust converter is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0021] The preparation method of the amphoteric polyurethane comprises the following steps: using isophorone diisocyanate, polytetrahydrofuran ether diol, N-methyl diethanolamine and 2,2-dimethylol propionic acid as raw materials, preparing a water-based polyurethane prepolymer by prepolymerization;

[0022] Then introduce D-xylose with multiple hydroxyl groups as a crosslinking modifier, react with the isocyanate groups in the water-based polyurethane prepolymer to graft polymerization, form amphoteric polyurethane.

[0023] In some embodiments, the accelerator is citric acid.

[0024] In some embodiments, the corrosion inhibitor is polyaniline, and the molecular weight of the polyaniline is 5000-15000.

[0025] In some embodiments, the stabilizer is hydroxyl cellulose.

[0026] In some embodiments, the curing agent is any one of 3-methyl-1-aziridine and 1-aziridine ethanol.

[0027] In some embodiments, pigments are further included, and the pigments include any one or both of red iron oxide and titanium white powder.

[0028] In some embodiments, the solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0029] In some embodiments, the polyvinyl alcohol has a molecular weight of 70-100 thousand.

[0030] In a second aspect of the present application, a preparation method of the paint of the first aspect is provided, comprising the following steps:

[0031] (1) Preparation of A component

[0032] According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, the amphoteric polyurethane, the rust converter, the accelerator, the corrosion inhibitor, the stabilizer, and the solvent A are fully mixed at room temperature, and then mixed at 50-60℃ for 2h, and then cooled to room temperature to obtain the A component;

[0033] (2) Preparation of B component

[0034] According to the composition of each raw material of the B component, the materials are taken, and then fully mixed to obtain the B component;

[0035] In use, the A component and the B component are mixed and applied in a weight ratio of 50:2-3.

[0036] In a third aspect of the present application, the paint of the first aspect or prepared by the preparation method of the second aspect is applied to the rust prevention treatment or corrosion prevention treatment of steel products.

[0037] Compared with the prior art, the present application has the following beneficial effects:

[0038] The paint of the present application can not only effectively prevent the oxidation passivation of the steel surface in a short period of time, but also maintain effective protection for a long time due to the long-term existence of chemical bonding.

[0039] The paint of the present application reduces the use of harmful solvents, meets the requirements of modern green chemical industry, and is beneficial to environmental protection and human health. BRIEF DESCRIPTION OF DRAWINGS

[0040] The present application will be further described below in combination with the drawings and examples.

[0041] Figure 1 The process flow chart of the preparation method of the paint for preventing the oxidation passivation of the steel surface according to the present application. DETAILED DESCRIPTION

[0042] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in combination with examples, and the content mentioned in the embodiments is not a limitation of the present application.

[0043] As used herein, the term "and / or", includes any one or all combinations of one or more of the associated listed items. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises", "comprising", "includes" and / or "including", when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0044] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0045] The exemplary applications described herein can suitably lack any one or more of the elements described herein, and such applications should not be deemed outside the scope of the present application. Thus, the terms "comprise", "comprising", "include", "including", and the like should be construed in a non-limiting fashion. Additionally, the term "consisting essentially of to refer to a composition or method comprising the specified ingredients or steps, and nothing additional. The term "consisting essentially of should not be construed to mean that the specified ingredients or steps are absolutely required to practice the application. Furthermore, the term "comprising" as used in this disclosure is intended to mean that other ingredients or steps are optional and do not appear, unless otherwise specified. Accordingly, although specific embodiments and optional features are disclosed herein, such embodiments and features should not be construed as limiting the scope of the present application. It will be apparent to those skilled in the art that various modifications and variations can be made in the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

[0046] A paint for preventing oxidation passivation of steel surface, comprising A component and B component, the A component comprises the following raw materials in parts by weight:

[0047] Polyvinyl alcohol 20-25 parts, amphoteric polyurethane 10-15 parts, rust converter 10-12 parts, accelerator 1-2 parts, corrosion inhibitor 3-4 parts, stabilizer 2-3 parts, solvent A 10-15 parts;

[0048] The B component comprises the following raw materials in parts by weight:

[0049] Curing agent 2-4 parts, solvent A 10-15 parts;

[0050] The rust converter is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0051] The preparation method of the amphoteric polyurethane comprises the following steps: using isophorone diisocyanate (IPDI), polytetramethylene glycol (PTMG), N-methyldiethanolamine (N-MDEA) and 2,2-dimethylol propionic acid (DMPA, a hydrophilic chain extender) as raw materials, and preparing a water-based polyurethane prepolymer by a prepolymerization method;

[0052] Then, D-xylose with multiple hydroxyl groups is introduced as a crosslinking modifier to react with isocyanate groups in the water-based polyurethane prepolymer to graft polymerization, thereby forming the amphoteric polyurethane.

[0053] In the present application, the rust converter is composed of phosphoric acid (concentrated phosphoric acid is used) and tannic acid in a weight ratio of 1:1, and the rust converter converts iron rust into a stable non-toxic filler, realizes rusted painting, and thus prevents the development of corrosion; the amphoteric polyurethane forms a star structure by introducing a multiple hydroxyl structure, improves adhesion and water resistance, and can be adsorbed on the metal surface to form a protective film, preventing oxygen and moisture from contacting the steel substrate; polyvinyl alcohol as part of the film-forming material provides flexibility and strength of the coating film.

[0054] Therefore, the above technical solution, the prepared paint uses the rust converter (such as phosphoric acid and tannic acid) to chemically react with iron rust to generate a stable compound, preventing the iron rust from continuing to expand, and achieving the purpose of rusted painting; the amphoteric polyurethane can form a closely adhered protective layer on the metal surface, physically isolating oxygen and moisture in the external environment, and delaying the corrosion process; the corrosion inhibitor (such as polyaniline) can form a dense film on the metal surface, increase its oxidation and reduction properties, and reduce the possibility of corrosion, in addition, it can also establish multiple connection points with the metal surface to strengthen the adhesion.

[0055] At the same time, the above technical solution uses renewable raw materials instead of traditional fossil resources, reducing environmental pollution; and by modifying and optimizing the formula, the amount of harmful solvents (such as xylene) is reduced, and the environmental performance of the product is improved.

[0056] Specifically, the accelerator is citric acid, which can accelerate the chemical reaction and help the paint to cure faster. The weight of the accelerator is selected to be 1-2 parts, and the amount of the accelerator is too small to have the expected promoting effect, prolonging the construction period; too much accelerator may lead to too fast curing, which is difficult to operate.

[0057] Specifically, the corrosion inhibitor is polyaniline, and the molecular weight of the polyaniline is 5000-15000. The polyaniline hinders electron transfer through electric field effect, shielding effect and passivation effect to prevent further corrosion of the metal. The weight of the corrosion inhibitor is selected to be 3-4 parts, and the amount of the corrosion inhibitor is insufficient, the protection effect is not good, and local corrosion is easy to occur; too much corrosion inhibitor increases the material cost and may cause environmental burden.

[0058] Specifically, the stabilizer is hydroxyl cellulose (CAS: 9004-62-0), which ensures the stability of the coating system and prevents separation or precipitation of components; the weight of the stabilizer is selected to be 2-3 parts. If the amount of the stabilizer is insufficient, the coating will be unstable, and separation may occur during storage. If the amount of the stabilizer is too much, the rheological properties of the coating may be changed, affecting use.

[0059] In the A component, the weight of solvent A is selected to be 10-15 parts. Solvent A acts as a dispersion medium to help mixing and adjust viscosity. If the amount of solvent A is too small, the coating will be too thick and not easy to apply. If the amount of solvent A is too large, it will take longer to evaporate the solvent, increasing drying time and cost.

[0060] Specifically, the curing agent is any one of 3-methyl-1-aziridine and 1-aziridine ethanol. The curing agent reacts with the active functional groups in the A component to promote cross-linking and curing of the coating to form a strong coating layer. If the amount of the curing agent is insufficient, the curing will be incomplete, and the coating hardness will not be enough. If the amount of the curing agent is too much, it may lead to excessive cross-linking, making the coating brittle and fragile.

[0061] Specifically, the pigment includes any one or both of red iron oxide and titanium white powder, which gives the coating color and also serves as a physical barrier to enhance corrosion protection. The weight of the pigment is selected to be 3-5 parts. If the amount of the pigment is too small, the color will be light and the hiding power will be poor. If the amount of the pigment is too much, not only will resources be wasted, but the functions of other components may also be affected.

[0062] Specifically, solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0063] Specifically, the molecular weight of polyvinyl alcohol is 70-100 thousand, providing flexibility and strength to the coating film. The weight of polyvinyl alcohol is 20-25 parts. If it is below this range, the coating may be too fragile to effectively protect the substrate. If it exceeds this range, the coating film may be too soft, affecting its mechanical properties.

[0064] Specifically, the weight of amphoteric polyurethane is 10-15 parts. Amphoteric polyurethane can form a tightly adhered protective film and increase adhesion. If the amount of amphoteric polyurethane is insufficient, the protective layer formed will not be dense enough to fully prevent water and oxygen from contacting the metal. If the amount of amphoteric polyurethane is too much, it will increase the cost and may not necessarily bring additional benefits.

[0065] The weight of the rust converter is 10-12 parts, and the rust converter can convert iron rust into a stable compound to realize rust coating. When the amount of the rust converter is insufficient, it cannot completely convert all iron rust, leaving potential corrosion points; when the amount of the rust converter is too much, it can cause unnecessary chemical reactions, and even side effects.

[0066] As Figure 1 The preparation method of the above-mentioned coating comprises the following steps:

[0067] (1) Preparation of A component

[0068] According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, amphoteric polyurethane, rust converter, accelerator, corrosion inhibitor, stabilizer and solvent A are fully mixed at room temperature (such as mixing at room temperature for 1 h at a stirring speed of 200 r / min), mixed at 50-60°C for 2 h, and then cooled to room temperature to obtain the A component;

[0069] (2) Preparation of B component

[0070] According to the composition of each raw material of the B component, the materials are taken, and then fully mixed (such as mixing at room temperature for 1 h at a stirring speed of 200 r / min), to obtain the B component;

[0071] In use, the A component and the B component are mixed at a weight ratio of 50:2-3 (such as mixing at room temperature for 1 min at a stirring speed of 200 r / min before application).

[0072] The application provides the application of the coating. The coating described above is applied to the rust prevention treatment or corrosion prevention treatment of steel products, and can be applied to large steel structures, buildings, bridges, offshore drilling platforms and cultural relic corrosion prevention engineering and repair work.

[0073] Specifically, the following process can be followed:

[0074] (1) Metal surface treatment: treat the metal surface with severe rust, and ignore the thin rust spots; (2) coating method: brushing or spraying or other coating methods. For example, the thickness of each layer of the sprayed paint film is 20-30 μm, and 3 layers of paint are required for severe corrosion, and the coating curing time is 5-6 h at room temperature;

[0075] The coating for preventing the passivation of the steel surface is further described in the following preparation examples, examples, comparative examples and experimental examples;

[0076] Preparation Example 1

[0077] The preparation method of the amphoteric polyurethane comprises the following steps:

[0078] 1. Material preparation

[0079] Raw materials and chemical names:

[0080] Isophorone diisocyanate (IPDI);

[0081] Polytetramethylene ether glycol (PTMG) with a molecular weight of 1000;

[0082] N-methyldiethanolamine (N-MDEA);

[0083] 2,2-dimethylol propionic acid (DMPA) as a hydrophilic chain extender;

[0084] D-xylose (D-Xylose);

[0085] Dibutyltin dilaurate (DBTDL) as a catalyst;

[0086] Triethylamine (TEA);

[0087] Acetone;

[0088] Deionized water;

[0089] 2. Dosage and dosage ratio:

[0090] The -NCO / OH molar ratio of IPDI to PTMG was set to 3.2.

[0091] N-MDEA accounted for 4% of the total amount of raw materials.

[0092] DMPA accounted for 7% of the total amount of raw materials.

[0093] The amount of D-xylose was 0.003 mol, relative to the total amount of IPDI and PTMG.

[0094] 3. Preparation process:

[0095] (1) Prepolymer synthesis: 1 mol of IPDI and vacuum-dried PTMG were added to a reaction vessel equipped with a stirrer and reflux device, heated to 70°C, and stirred in an oil bath while adding DBTDL catalyst, and reacted for 2 hours to form a polyurethane prepolymer.

[0096] (2) Chain extension reaction: Then heated to 80°C, and N-MDEA and DMPA were added in sequence for chain extension reaction, for 2 hours, to obtain an amphoteric polyurethane prepolymer.

[0097] (3) Modification reaction: The temperature was kept unchanged, and a predetermined amount of D-xylose was continuously added, and reacted for an additional 2 hours, so that the D-xylose reacted with the isocyanate groups in the prepolymer, thereby introducing a polyhydroxy structure, forming a star-shaped amphoteric polyurethane.

[0098] (4) Neutralization and emulsification: After cooling to 40°C, TEA was added dropwise for complete neutralization, and then an appropriate amount of acetone was added according to the viscosity of the system. After that, the temperature was lowered to room temperature, and deionized water was added under rapid stirring to complete the emulsification process, obtaining an emulsion.

[0099] (5) Purification: The emulsion was finally removed from the unreacted small molecule monomers by dialysis bag to obtain pure amphoteric polyurethane. The obtained pure amphoteric polyurethane was in the form of an emulsion.

[0100] The prepared amphoteric polyurethane was subjected to Fourier infrared spectrum test, and it was found that in the infrared spectrum of the amphoteric polyurethane, the strong absorption peak originally belonging to NCO in the IPDI monomer at 2262 cm^ -1 disappeared, and a weak peak appeared near 3320 cm^ -1 , which was caused by N-H stretching vibration. At the same time, the polyhydroxy association peak at 3225-3410 cm^ -1 did not appear, indicating that the polyhydroxy in D-xylose had completely reacted with NCO to form the expected star-shaped structure.

[0101] The amphoteric polyurethane was detected by dynamic light scattering method, and the average particle size was 81.47 nm. The low viscosity and appropriate particle size of the amphoteric polyurethane made it easy to coat and form a continuous and uniform film during the drying process; its good thermal stability and high mechanical strength ensured that the formed protective layer was not easy to break or fall off.

[0102] The amphoteric characteristic of the amphoteric polyurethane could adsorb on the metal surface and form a closely adhered protective film, preventing oxygen and moisture from contacting the steel substrate, thereby delaying the corrosion process. In addition, its hydrophobicity also helped to reduce the possibility of water vapor penetration.

[0103] The small particle size of the amphoteric polyurethane and the presence of the hydrophilic chain extender (2,2-dimethylol propionic acid) increased its permeability, allowing it to penetrate into the micropores of the steel surface, providing better protection. Moreover, its multi-functional structure could establish multiple connection points in the internal space, further enhancing the adhesion.

[0104] The amphoteric polyurethane provided an immediate corrosion protection barrier by increasing the bonding sites with the metal surface, and it could also maintain effective protection for a long time due to the long-term existence of chemical bonding.

[0105] The preparation method of the amphoteric polyurethane involved the following chemical reaction process:

[0106]

[0107] Example 1

[0108] A kind of coating for preventing steel surface oxidation passivation, including A component and B component, the A component includes the following raw materials by weight parts:

[0109] Polyvinyl alcohol 20 parts, amphoteric polyurethane 10 parts, rust converter 10 parts, accelerator 1 part, corrosion inhibitor 3 parts, stabilizer 2 parts, solvent A 10 parts;

[0110] The B component includes the following raw materials by weight parts:

[0111] Curing agent 2 parts, solvent A 10 parts;

[0112] Wherein: the rust converter is composed of phosphoric acid and tannic acid according to weight ratio 1:1;

[0113] The preparation method of the amphoteric polyurethane is carried out according to preparation example 1.

[0114] The accelerator is citric acid;

[0115] The corrosion inhibitor is polyaniline, and the molecular weight of polyaniline is 5000;

[0116] The stabilizer is hydroxyl cellulose;

[0117] The curing agent is 3-methyl-1-aziridine.

[0118] The solvent A is composed of water and ethanol according to weight ratio 3:1.

[0119] The molecular weight of the polyvinyl alcohol is 70,000.

[0120] The preparation method of the above-mentioned coating for preventing steel surface oxidation passivation includes the following steps:

[0121] (1) Preparation of A component

[0122] According to the composition of each raw material of A component, material is taken;Polyvinyl alcohol, amphoteric polyurethane, rust converter, accelerator, corrosion inhibitor, stabilizer, solvent A are fully mixed at room temperature, then mixed at 50 DEG C for 2h, and reduced to room temperature to obtain A component;

[0123] (2) Preparation of B component

[0124] According to the composition of each raw material of B component, material is taken, then fully mixed to obtain B component;

[0125] When used, A component and B component are mixed and applied according to the weight ratio of 50:2.

[0126] Example 2

[0127] A kind of coating for preventing steel surface oxidation passivation, including A component and B component, the A component includes the following raw materials by weight parts:

[0128] Polyvinyl alcohol 25 parts, amphoteric polyurethane 15 parts, rust converter 12 parts, accelerator 2 parts, corrosion inhibitor 4 parts, stabilizer 3 parts, solvent A 15 parts;

[0129] The B component includes the following raw materials by weight parts:

[0130] Curing agent 4 parts, solvent A 15 parts;

[0131] The rust converter is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0132] The preparation method of the amphoteric polyurethane is carried out according to Preparation Example 1.

[0133] The accelerator is citric acid;

[0134] The corrosion inhibitor is polyaniline, and the molecular weight of the polyaniline is 15000;

[0135] The stabilizer is hydroxyl cellulose;

[0136] The curing agent is 1-aziridine ethanol.

[0137] The solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0138] The molecular weight of the polyvinyl alcohol is 100,000.

[0139] The preparation method of the above-mentioned paint for preventing the passivation of the oxidation of the steel surface includes the following steps:

[0140] (1) Preparation of A component

[0141] According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, amphoteric polyurethane, rust converter, accelerator, corrosion inhibitor, stabilizer, and solvent A are fully mixed at room temperature, then mixed at 60°C for 2h, and then cooled to room temperature to obtain the A component;

[0142] (2) Preparation of B component

[0143] According to the composition of each raw material of the B component, the materials are taken and then fully mixed to obtain the B component;

[0144] In use, the A component and the B component are mixed and applied in a weight ratio of 50:3.

[0145] Example 3

[0146] A paint for preventing the passivation of the oxidation of the steel surface includes A component and B component, the A component includes the following raw materials by weight parts:

[0147] Polyvinyl alcohol 22 parts, amphoteric polyurethane 13 parts, rust converter 11 parts, accelerator 1.5 parts, corrosion inhibitor 3.5 parts, stabilizer 2.5 parts, solvent A 13 parts;

[0148] The B component includes the following raw materials by weight parts:

[0149] Curing agent 3 parts, solvent A 13 parts;

[0150] The rust converter is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0151] The preparation method of the amphoteric polyurethane is carried out according to Preparation Example 1.

[0152] The accelerator is citric acid;

[0153] The corrosion inhibitor is polyaniline, and the molecular weight of the polyaniline is 9000;

[0154] The stabilizer is hydroxyl cellulose;

[0155] The curing agent is 3-methyl-1-aziridine.

[0156] The solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0157] The molecular weight of the polyvinyl alcohol is 80,000.

[0158] The preparation method of the above-mentioned paint for preventing the passivation of the oxidation of the steel surface includes the following steps:

[0159] (1) Preparation of A component

[0160] According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, amphoteric polyurethane, rust converter, accelerator, corrosion inhibitor, stabilizer, and solvent A are fully mixed at room temperature, then mixed at 55°C for 2h, and then cooled to room temperature to obtain the A component;

[0161] (2) Preparation of B component

[0162] According to the composition of each raw material of the B component, the materials are taken and then fully mixed to obtain the B component;

[0163] In use, the A component and the B component are mixed and applied in a weight ratio of 50:2.5.

[0164] Example 4

[0165] A paint for preventing the passivation of the oxidation of the steel surface includes A component and B component,

[0166] The A component includes the following raw materials by weight parts:

[0167] Polyvinyl alcohol 21 parts, amphoteric polyurethane 11 parts, rust converter 11 parts, accelerator 1 part, corrosion inhibitor 3 parts, stabilizer 2 parts, solvent A 11 parts;

[0168] The B component includes the following raw materials by weight parts:

[0169] Curing agent 2 parts, solvent A 11 parts;

[0170] The rust converter is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0171] The preparation method of the amphoteric polyurethane is carried out according to Preparation Example 1.

[0172] The accelerator is citric acid;

[0173] The corrosion inhibitor is polyaniline, and the molecular weight of the polyaniline is 7000;

[0174] The stabilizer is hydroxyl cellulose;

[0175] The curing agent is any one of 3-methyl-1-aziridine and 1-aziridine ethanol.

[0176] The solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0177] The molecular weight of the polyvinyl alcohol is 80,000.

[0178] The preparation method of the above-mentioned paint for preventing the passivation of the oxidation of the steel surface includes the following steps:

[0179] (1) Preparation of A component

[0180] According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, the amphoteric polyurethane, the rust converter, the accelerator, the corrosion inhibitor, the stabilizer, and the solvent A are fully mixed at room temperature, then mixed at 50°C for 2h, and then cooled to room temperature to obtain the A component;

[0181] (2) Preparation of B component

[0182] According to the composition of each raw material of the B component, the materials are taken and then fully mixed to obtain the B component;

[0183] In use, the A component and the B component are mixed and applied in a weight ratio of 50:2.

[0184] Example 5

[0185] A paint for preventing the passivation of the oxidation of the steel surface includes A component and B component, and the A component includes the following raw materials by weight parts:

[0186] Polyvinyl alcohol 24 parts, amphoteric polyurethane 14 parts, rust remover 12 parts, accelerator 1.5 parts, corrosion inhibitor 3 parts, stabilizer 3 parts, solvent A 14 parts;

[0187] Component B, by weight, comprises the following raw materials:

[0188] 3 parts curing agent, 14 parts solvent A;

[0189] Wherein: the rust-removing agent is composed of phosphoric acid and tannic acid in a weight ratio of 1:1;

[0190] The preparation method of the amphoteric polyurethane is carried out according to Preparation Example 1.

[0191] The accelerator is citric acid;

[0192] The corrosion inhibitor is polyaniline, which has a molecular weight of 14,000.

[0193] The stabilizer is hydroxycellulose;

[0194] The curing agent is composed of 3-methyl-1-aziridine and 1-aziridine ethanol in a weight ratio of 1:1.

[0195] Solvent A is composed of water and ethanol in a weight ratio of 3:1.

[0196] The molecular weight of the polyvinyl alcohol is 90,000.

[0197] The method for preparing the coating described above to prevent oxidation and passivation of steel surfaces includes the following steps:

[0198] (1) Preparation of component A

[0199] According to the composition of each raw material in component A, the materials are taken out; polyvinyl alcohol, amphoteric polyurethane, rust remover, accelerator, corrosion inhibitor, stabilizer and solvent A are thoroughly mixed at room temperature, and then mixed at 60°C for 2 hours, and then cooled to room temperature to obtain component A.

[0200] (2) Preparation of component B

[0201] According to the composition of each raw material in component B, the materials are taken and then thoroughly mixed to obtain component B;

[0202] When using, mix and apply components A and B in a weight ratio of 50:2.5.

[0203] Comparative Example 1

[0204] A coating to prevent oxidation and passivation of steel surfaces, without the addition of amphoteric polyurethane, and with 30 parts of polyvinyl alcohol, and the remaining conditions are the same as in Example 1.

[0205] Comparative Example 2

[0206] A coating for preventing the passivation of the surface of steel and iron, wherein no rust converter is added to the A component, and the other conditions are the same as in Example 1.

[0207] Comparative Example 3

[0208] A coating for preventing the passivation of the surface of steel and iron, wherein no stabilizer is added to the A component, and the other conditions are the same as in Example 1.

[0209] Comparative Example 4

[0210] A coating for preventing the passivation of the surface of steel and iron, wherein the amphoteric polyurethane is the amphoteric polyurethane prepolymer in Preparation Example 1, and the other conditions are the same as in Example 1.

[0211] Comparative Example 5

[0212] A coating for preventing the passivation of the surface of steel and iron, wherein no polyvinyl alcohol is added, and the amphoteric polyurethane is 30 parts, and the other conditions are the same as in Example 1.

[0213] The coatings prepared in Examples 1-5 and Comparative Examples 1-5 were subjected to the following performance tests.

[0214] Experimental Example

[0215] The coatings prepared in Examples 1-5 and Comparative Examples 1-5 were applied to the surface of a steel structure by brushing to form a coating, and the dry film thickness of the coating was 40-45 μm. The hardness, water resistance, impact resistance, and adhesion of the coating were tested. The salt spray resistance of the coating was also tested, and each test was performed at least three times in parallel, and the average value was taken to obtain the results shown in Table 1.

[0216] The detection standards in the experimental example are as follows:

[0217] Pencil method for determining the hardness of paint film of color and varnish 《GB / T 6739-2022》

[0218] Method for determining the water resistance of paint film 《GB / T 1733-1993》

[0219] Method for determining the impact resistance of paint film 《GB / T 1732-2020》

[0220] Method for determining the neutral salt spray resistance of color and varnish 《GB / T 1771-2007》

[0221] Cross-hatch test for color and varnish 《GB / T 9286-2021》

[0222] Table 1

[0223]

[0224] From Table 1, it can be seen that the coating layers of Examples 1 to 5 perform well in terms of hardness, water resistance, impact strength, adhesion, and salt spray resistance, etc. The specific results are as follows:

[0225] Hardness: The hardness of all examples is 3H, indicating that the coating has good hardness.

[0226] Water resistance (h): ranging from 371 hours to 395 hours, indicating that these coatings can resist the effects of moisture for a long time without losing their performance.

[0227] Impact strength (J / m): the values are between 156 and 167, showing that the coating has sufficient toughness and impact resistance.

[0228] Adhesion: all examples reach level 1, which is the best level, meaning that the coating has very strong adhesion with the substrate.

[0229] Salt spray resistance (h): the test results show that the salt spray resistance time is as long as 1057 hours to 1124 hours, which indicates that the coating can provide long-term protection in corrosive environments.

[0230] From Table 1, it can also be seen that the coating performance of Comparative Example 1, hardness: 2H, water resistance (h): 185 hours, impact strength (J / m): 112, adhesion: level 4, salt spray resistance (h): 586 hours; Comparative Example 1 does not add amphoteric polyurethane, but increases the amount of polyvinyl alcohol. Due to the lack of chemical bonding and tight fitting protection layer provided by amphoteric polyurethane, the overall protective performance of the coating is reduced. Specifically, the water resistance and salt spray resistance are significantly reduced, and the adhesion is also reduced from level 1 of Example 1 to level 4, which indicates that the adhesion between the coating and the substrate is greatly weakened.

[0231] The coating performance of Comparative Example 2, hardness: 1H, water resistance (h): 287 hours, impact strength (J / m): 48, adhesion: level 2, salt spray resistance (h): 247 hours; Comparative Example 2 does not add rust converter in A component. The role of rust converter is to convert iron rust into stable compounds, thereby preventing the development of corrosion. Therefore, without rust converter, the coating cannot effectively treat existing rust, resulting in a significant decrease in water resistance and salt spray resistance, and the adhesion and impact strength are also significantly deteriorated.

[0232] The coating properties of Comparative Example 3, hardness: 3H, water resistance (h): 350 hours, impact resistance (J / m): 85, adhesion: 2nd grade, salt spray resistance (h): 908 hours; Comparative Example 3 did not contain a stabilizer in the A component. Stabilizers (such as hydroxyl cellulose) ensure the stability of the coating system, preventing separation or precipitation of the components. Although the hardness remained at 3H, both the impact resistance and the adhesion decreased, which can be attributed to the lack of a stabilizer, which can cause the coating to delaminate during the storage period, affecting the quality and performance of the final coating film.

[0233] The coating properties of Comparative Example 4, hardness: 2H, water resistance (h): 330 hours, impact resistance (J / m): 75, adhesion: 3rd grade, salt spray resistance (h): 810 hours; Comparative Example 4 used an unmodified amphoteric polyurethane prepolymer instead of the modified amphoteric polyurethane in Preparation Example 1. The modification process introduces multiple hydroxyl structures, increasing the cross-linking density of the polyurethane and its ability to bond to the metal surface. Therefore, the unmodified version did not perform as well as Example 1 in all aspects, particularly in adhesion and impact resistance.

[0234] The coating properties of Comparative Example 5, hardness: 1H, water resistance (h): 310 hours, impact resistance (J / m): 92, adhesion: 1st grade, salt spray resistance (h): 954 hours; Comparative Example 5 did not contain polyvinyl alcohol, but instead increased the amount of amphoteric polyurethane. Polyvinyl alcohol provides flexibility and strength to the coating film, and its absence led to a decrease in hardness, although the adhesion remained at 1st grade, the overall mechanical properties (such as impact resistance) were affected. In addition, water resistance and salt spray resistance also decreased, indicating that polyvinyl alcohol is very important for improving the overall performance of the coating.

[0235] In summary, in the coating described in this application, the amphoteric polyurethane contains abundant multiple hydroxyl functional groups, which can form a strong chemical bond with the metal surface, and due to the presence of hydrophilic chain extenders, it can penetrate into the micropores of the steel surface, enhancing the protective effect; the amphoteric polyurethane not only provides an immediate corrosion barrier, but also maintains effective protection for a long time through long-term chemical bonding.

[0236] Rust converters (phosphoric acid and tannic acid) convert iron rust into a stable, non-toxic filler, enabling rusted surfaces to be painted, thereby preventing the development of corrosion. This feature allows the coating to be used directly on surfaces with slight rust without the need for additional rust removal.

[0237] Polyaniline, as a highly effective corrosion inhibitor, forms a dense film on the metal surface, increasing its oxidation and reduction properties and reducing the likelihood of corrosion. At the same time, it can establish multiple connection points with the metal surface, enhancing adhesion.

[0238] The hydroxyl cellulose as the stabilizer ensures the stability of the coating system, avoids separation or precipitation of the components, and ensures the quality stability and long-lasting performance after construction of the coating.

[0239] The above embodiments are the preferred implementation of the present application, in addition to this, the present application can be implemented in other ways, without departing from the concept of the present application, any obvious replacement within the protection scope of the present application.

Claims

1. A paint for preventing oxidation passivation of a steel surface, characterized by, It comprises A component and B component, the A component comprises the following raw materials by weight parts: Polyvinyl alcohol 20-25 parts, amphoteric polyurethane 10-15 parts, rust converter 10-12 parts, accelerator 1-2 parts, corrosion inhibitor 3-4 parts, stabilizer 2-3 parts, solvent A 10-15 parts; The B component comprises the following raw materials by weight parts: Curing agent 2-4 parts, solvent A 10-15 parts; The rust converter is composed of phosphoric acid and tannic acid according to a weight ratio of 1:1; The preparation method of the amphoteric polyurethane comprises the following steps: using isophorone diisocyanate, polytetrahydrofuran ether diol, N-methyl diethanolamine and 2,2-dimethylol propionic acid as raw materials, an aqueous polyurethane prepolymer is prepared by a prepolymerization method; Then D-xylose with multiple hydroxyl groups is introduced as a crosslinking modifier to react with the isocyanate groups in the aqueous polyurethane prepolymer to graft polymerize and form the amphoteric polyurethane; Among them, the amount of D-xylose is 0.003 mol relative to the total amount of isophorone diisocyanate and polytetrahydrofuran ether diol; the molar ratio of isophorone diisocyanate to polytetrahydrofuran ether diol is 3.2; The corrosion inhibitor is polyaniline; The molecular weight of the polyvinyl alcohol is 70-100 thousand; In use, the A component and the B component are mixed and applied according to a weight ratio of 50:2-3.

2. The coating of claim 1, wherein, The accelerator is citric acid.

3. The coating of claim 1, wherein, The stabilizer is hydroxyl cellulose.

4. The coating of claim 1, wherein, The curing agent is any one of 3-methyl-1-aziridine and 1-aziridine ethanol.

5. The coating of claim 1, wherein, It also comprises pigments, which include any one or both of red iron oxide and titanium white powder.

6. The coating of claim 1, wherein, The solvent A is composed of water and ethanol according to a weight ratio of 3:

1.

7. The method of preparing the coating according to any one of claims 1 to 6, characterized in that, It comprises the following steps: (1) Preparation of the A component According to the composition of each raw material of the A component, the materials are taken; the polyvinyl alcohol, the amphoteric polyurethane, the rust converter, the accelerator, the corrosion inhibitor, the stabilizer and the solvent A are fully mixed at room temperature, and then mixed at 50-60℃ for 2h, and then cooled to room temperature to obtain the A component; (2) Preparation of the B component According to the composition of each raw material of the B component, the materials are taken, and then fully mixed to obtain the B component; In use, the A component and the B component are mixed and applied according to a weight ratio of 50:2-3.

8. Use of a coating, characterized in that The paint of any one of claims 1-6 or the paint prepared by the preparation method of claim 7 is applied to the corrosion prevention of steel products.

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