Antirust agent and preparation method and application method thereof

Abstract

The invention relates to the technical field of metal protection, and provides an antirust agent and a preparation method and application method of the antirust agent, and the antirust agent provided by the invention comprises the following components by weight: 20-30% of inorganic acid, 0.1-1% of a surfactant, 2-5% of a composite corrosion inhibitor, 1-5% of a thickener, and the balance of water. The antirust agent not only can quickly remove rust on the surface of metal, but also can form a new and more friction-resistant protective layer while removing the rust, thereby being beneficial to improving the antirust performance of a metal base material, prolonging the service life of the metal base material and reducing the failure rate and maintenance cost caused by the rust at the same time. In addition, all the components in the antirust agent are environment-friendly and non-toxic substances, so that the antirust agent does not cause harm to human bodies and the environment. The antirust agent does not generate harmful waste gas, waste water and waste residues in the using process, and meets the environmental protection requirement.

Description

Technical Field

[0001] The present application relates to the technical field of metal protection, and in particular to a rust inhibitor and a preparation method and an application method of the rust inhibitor. Background Art

[0002] The corrosion of metal materials not only reduces the strength of metal structures and affects the normal operation of equipment, but also causes waste of resources and environmental pollution. Traditional anti-rust methods mostly rely on heavy metal salts or organic solvent-based rust inhibitors, which are easy to pollute the environment during use and have potential hazards to human health.

[0003] In recent years, with the enhancement of environmental awareness and the continuous advancement of technology, people have begun to explore the use of non-toxic, harmless and biodegradable rust inhibitors. However, the existing rust inhibitors still have some shortcomings in formulation design and preparation process, such as unstable rust prevention effect and short service life. Summary of the invention

[0004] Based on this, the embodiments of the present application provide a rust inhibitor and a preparation method and an application method of the rust inhibitor, aiming to improve the rust prevention effect and service life of the rust inhibitor by optimizing the component ratio and preparation process, while reducing its pollution to the environment and harm to the human body.

[0005] The first aspect of the present application provides a rust inhibitor, which comprises the following components by weight:

[0006] Inorganic acid 20-30%, surfactant 0.1-1%, composite corrosion inhibitor 2-5%, thickener 1-5%, and water as the balance.

[0007] Optionally, the inorganic acid is a combination of one or more of oxalic acid, hydrochloric acid and acetic acid.

[0008] Optionally, the surfactant is a combination of one or more of N-alkyl pyrrolidone, alkyl amine oxide, alkyl alcohol amide, and alkylphenol polyoxyethylene ether.

[0009] Optionally, the thickener is a combination of one or more of gelatin, agar, and sodium carboxymethyl cellulose.

[0010] The second aspect of the present application provides a method for preparing a rust inhibitor, the method for preparing the rust inhibitor comprising:

[0011] Mix oleic acid, diethyleneimine and xylene, heat to reflux and stir, heat to 140-160°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; then heat to 170-180°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; continue to heat to 200-210°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; finally heat to 220-230°C, keep warm for 1-3h, evacuate for 5-10min, return to normal pressure; cool to room temperature to obtain imidazoline intermediate;

[0012] The imidazoline intermediate and glycine are mixed, heated to 80-100°C with stirring, reacted for 30-60 minutes, and then cooled to room temperature to obtain a glycinated imidazoline intermediate;

[0013] 2,3-Epoxypropyltrimethylammonium chloride is added to N,N-dimethylformamide solvent, and glycine imidazoline intermediate is added thereto, stirred evenly, and catalyst sodium hydroxide is added, the temperature is raised to 100-120° C., reacted for 5-8 hours, cooled to room temperature, and the pH is adjusted to neutral to obtain a composite corrosion inhibitor;

[0014] Heat the water to 40-60°C, add the surfactant into the water, stir for 10-20 minutes, then add the composite corrosion inhibitor and thickener, stir for 10-30 minutes, finally slowly add the inorganic acid, stir for 20-30 minutes to obtain the rust inhibitor.

[0015] Optionally, the mass ratio of oleic acid, diethyleneimine and xylene is 1:0.2-0.4:0.5-0.8.

[0016] Optionally, the mass ratio of the imidazoline intermediate to glycine is 1:0.3-0.5.

[0017] Optionally, the mass ratio of the glycinated imidazoline intermediate, 2,3-epoxypropyltrimethylammonium chloride, and sodium hydroxide is 1:0.2-0.4:0.03-0.1.

[0018] The third aspect of the present application provides an application method of a rust inhibitor, the application method of the rust inhibitor comprising:

[0019] The rust inhibitor is applied to the surface of a substrate to form a protective coating.

[0020] Optionally, the rust inhibitor is applied to the surface of the substrate by any one of brushing, spraying and dipping, and the substrate comprises metal.

[0021] The rust preventive provided by the embodiment of the present application can not only quickly remove the rust on the metal surface, but also form a new, more friction-resistant protective layer while removing the rust, or provide more favorable conditions for subsequent secondary rust prevention treatment. The rust preventive helps to improve the rust resistance of the metal substrate, extend its service life, and reduce the failure rate and maintenance cost caused by rust. In addition, since each component in the rust preventive is an environmentally friendly and non-toxic substance, it will not cause harm to the human body and the environment. The rust preventive will not produce harmful waste gas, waste water and waste residue during use, and meets environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 It is a schematic flow chart of the method for preparing the rust inhibitor provided in the examples of the present application.

[0024] Figure 2 This is the anti-rust effect of the rust inhibitor prepared in each embodiment provided in the embodiments of the present application. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] The embodiment of the present application provides a rust inhibitor, which is a chemical agent widely used in the field of metal surface treatment. Its main function is to prevent metals from rusting in humid, oxidative and other environments, thereby extending the service life of the metal and maintaining its original physical and chemical properties.

[0027] The rust inhibitor provided in the embodiment of the present application includes the following components by weight:

[0028] Inorganic acid: 20-30%;

[0029] Surfactant: 0.1-1%;

[0030] Composite corrosion inhibitor: 2-5%;

[0031] Thickener: 1-5%;

[0032] Water: Balance.

[0033] In an optional embodiment, the inorganic acid is a combination of one or more of oxalic acid, hydrochloric acid, and acetic acid. The role of the inorganic acid is to provide an acidic environment, which can effectively remove oxides and dirt on the metal surface, and at the same time form a protective film with subsequent components to improve the anti-rust effect.

[0034] In an optional embodiment, the surfactant is a combination of one or more of N-alkyl pyrrolidone, alkyl amine oxide, alkyl alcohol amide, and alkylphenol polyoxyethylene ether. The role of the surfactant is to reduce the surface tension between the rust inhibitor and the metal surface, so that the rust inhibitor can more easily penetrate into the tiny pores on the metal surface, thereby improving the rust prevention effect.

[0035] The function of composite corrosion inhibitors is to inhibit the corrosion reaction of metals in humid, oxidative and other environments, thereby extending the service life of metals. Composite corrosion inhibitors are usually composed of a combination of multiple corrosion inhibitors to exert a synergistic effect. Corrosion inhibitors may include inorganic corrosion inhibitors (such as silicates, phosphates, etc., which can form a protective film on the metal surface to prevent the contact between the corrosive medium and the metal matrix), organic corrosion inhibitors (such as amines, alcohols, esters, etc., which can combine with the active sites on the metal surface to form a dense protective film to inhibit the corrosion reaction), and polymer corrosion inhibitors (such as polyvinyl alcohol, polyacrylamide, etc., which can form a polymer film on the metal surface with good barrier properties and corrosion resistance).

[0036] In an optional embodiment, the thickener is a combination of one or more of gelatin, agar, and sodium carboxymethyl cellulose. The thickener increases the viscosity of the rust inhibitor, making it easier to adhere to the metal surface and form a uniform rust-proof film.

[0037] Water is the solvent in the rust inhibitor, and its function is to dissolve and disperse the components in the rust inhibitor to form a uniform rust-proof liquid. At the same time, water can also provide the necessary humidity environment for the rust inhibitor, which helps the rust inhibitor to combine with the metal surface.

[0038] The rust preventive provided in the embodiment of the present application can form a dense rust-proof film on the metal surface through a reasonable component ratio, effectively preventing the corrosion reaction of the metal in a humid, oxidized environment. Each component in the rust preventive is an environmentally friendly and non-toxic substance, which will not cause harm to the human body and the environment. At the same time, the rust preventive will not produce harmful waste gas, waste water and waste residue during use, and meets environmental protection requirements. The rust preventive has good fluidity and wettability and can be easily applied to the metal surface. At the same time, the viscosity of the rust preventive is moderate, and will not cause dripping and waste during the coating process. The rust preventive provided in the embodiment of the present application is suitable for rust-proof treatment of various metal materials, such as steel, copper, aluminum, etc. At the same time, the rust preventive is also suitable for different use environments, such as indoors, outdoors, high temperature, low temperature, etc.

[0039] See also Figure 1 , which is a schematic flow diagram of a method for preparing a rust inhibitor provided in an embodiment of the present application. The method for preparing the rust inhibitor comprises the following steps.

[0040] S1, preparation of imidazoline intermediate.

[0041] The preparation of imidazoline intermediates is based on specific chemical reaction principles.

[0042] In a specific embodiment, in order to prepare the imidazoline intermediate, oleic acid, diethyleneimine and xylene can be mixed. Oleic acid (an unsaturated fatty acid) is used as a starting material to undergo a condensation reaction with diethyleneimine, and xylene is used as a solvent to participate in this process, which helps the reactants to fully contact and react.

[0043] Mix oleic acid, diethyleneimine and xylene, heat to reflux and stir, raise the temperature to 140-160°C, keep the temperature for 2-5 hours, evacuate for 3-5 minutes, and return to normal pressure; then raise the temperature to 170-180°C, keep the temperature for 2-5 hours, evacuate for 3-5 minutes, and return to normal pressure; continue to raise the temperature to 200-210°C, keep the temperature for 2-5 hours, evacuate for 3-5 minutes, and return to normal pressure; finally raise the temperature to 220-230°C, keep the temperature for 1-3 hours, evacuate for 5-10 minutes, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0044] Under the conditions of heating to 140-160°C and keeping warm, oleic acid and diethyleneimine begin to undergo condensation reaction to generate preliminary addition products. As the temperature gradually rises to 170-180°C, 200-210°C and finally 220-230°C, the water and other small molecular by-products in the reaction system are gradually removed. The operation of vacuuming and returning to normal pressure helps to accelerate the dehydration process and promote the reaction to generate imidazoline intermediates. Through multi-step heating, heat preservation and vacuuming operations, the raw materials are fully reacted to generate imidazoline intermediates with specific structures, providing a basis for the subsequent preparation of composite corrosion inhibitors.

[0045] In an optional embodiment, the mass ratio of oleic acid, diethyleneimine and xylene can be set to 1:0.2-0.4:0.5-0.8.

[0046] Setting the mass ratio of oleic acid, diethyleneimine and xylene to 1:0.2-0.4:0.5-0.8 can ensure the full reaction of each component during the reaction, reduce the generation of unreacted raw materials and by-products, and thus improve the purity of the imidazoline intermediate. The structure and purity of the imidazoline intermediate directly affect the performance of the rust inhibitor. High-purity imidazoline intermediates can more effectively combine with the metal surface to form a dense protective film and improve the rust prevention effect.

[0047] S2, preparation of glycinated imidazoline intermediate.

[0048] The imidazoline intermediate and glycine are mixed, heated to 80-100° C. with stirring, reacted for 30-60 minutes, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0049] In a specific embodiment, the imidazoline intermediate obtained in step S1 and glycine can be mixed in a mass ratio of 1:0.3-0.5, stirred and heated to 80-100° C., reacted for 30-60 minutes, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0050] When the imidazoline intermediate and glycine are mixed under heating and stirring conditions, the carboxyl group (-COOH) of glycine reacts with the amino group (-NH2) of the imidazoline intermediate, removing a molecule of water to form an amide bond, thereby generating a glycinated imidazoline intermediate. Carrying out the reaction at a temperature of 80 to 100°C can accelerate the reaction rate and ensure complete reaction.

[0051] Glycine is an amino acid containing amino and carboxyl groups. When introduced into the imidazoline intermediate, it not only increases the molecular weight and complexity of the intermediate, but more importantly, introduces functional groups with corrosion inhibition properties. These functional groups can form chemical bonds or adsorption layers with the metal surface, thereby effectively slowing down the corrosion rate of the metal in a corrosive environment.

[0052] The glycine imidazoline intermediate generated by the amidation reaction of glycine and imidazoline intermediate has stronger corrosion inhibition performance. This is mainly due to the introduction of glycine, which enables the intermediate to form a more stable and denser protective film on the metal surface, thereby more effectively preventing the contact between the corrosive medium and the metal surface.

[0053] S3, preparing a composite corrosion inhibitor.

[0054] Add 2,3-epoxypropyltrimethylammonium chloride to N,N-dimethylformamide solvent, add glycine imidazoline intermediate thereto, stir evenly, add catalyst sodium hydroxide, heat to 100-120° C., react for 5-8 hours, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0055] In a specific embodiment, the glycine imidazoline intermediate obtained in step S2 can be mixed with 2,3-epoxypropyltrimethylammonium chloride and sodium hydroxide in a mass ratio of 1:0.2-0.4:0.03-0.1.

[0056] 2,3-Epoxypropyltrimethylammonium chloride is a cationic compound containing an epoxy group. Its epoxy group has high reactivity and can undergo a ring-opening reaction with compounds containing active hydrogen (such as amino, hydroxyl, etc.). Since the glycine imidazoline intermediate contains an amino group, it can react with the epoxy group of 2,3-epoxypropyltrimethylammonium chloride to form a new chemical bond.

[0057] Specifically, when 2,3-epoxypropyltrimethylammonium chloride is added to the N,N-dimethylformamide (DMF) solvent containing the glycine imidazoline intermediate, the epoxy group of 2,3-epoxypropyltrimethylammonium chloride reacts with the amino group of the glycine imidazoline intermediate to form a compound containing a quaternary ammonium salt structure. The quaternary ammonium salt structure has a strong adsorption capacity and film-forming property, and can form a dense protective film on the metal surface, effectively isolating the contact between the corrosive medium and the metal surface, thereby improving the corrosion inhibition performance. At the same time, since 2,3-epoxypropyltrimethylammonium chloride itself carries a positive charge, and the glycine imidazoline intermediate may contain some unreacted carboxyl or amino groups, the entire reaction system may also involve a certain acid-base neutralization reaction, so that the pH value of the final product tends to be neutral. The product under neutral conditions is more stable and is not prone to adverse reactions such as hydrolysis or decomposition.

[0058] During the reaction, adding the catalyst sodium hydroxide (NaOH) can accelerate the ring-opening reaction, increase the reaction rate and product yield. At the same time, the addition of NaOH also helps to adjust the pH value of the reaction system, making the reaction more stable and controllable.

[0059] The prepared composite corrosion inhibitor can be used for the anti-corrosion treatment of various metal materials because it contains a variety of corrosion-inhibiting functional groups and quaternary ammonium salt structures, especially in harsh environments such as high temperature, high humidity, strong acid, and strong alkali, and can still maintain a good corrosion inhibition effect.

[0060] S4, preparing a rust inhibitor.

[0061] In a specific embodiment, water can be heated to 40-60° C., a surfactant can be added to the water and stirred for 10-20 minutes, then a composite corrosion inhibitor and a thickener can be added and stirred for 10-30 minutes, and finally an inorganic acid can be slowly added and stirred for 20-30 minutes to obtain a rust inhibitor.

[0062] Heating the water to 40-60°C helps dissolve the surfactant. Add the surfactant to the water and stir for 10-20 minutes to fully dissolve it. The role of the surfactant is to reduce the surface tension of water and help disperse and mix the subsequent components. After the surfactant is dissolved, add the composite corrosion inhibitor and thickener and stir for 10-30 minutes to evenly disperse them in the water. The composite corrosion inhibitor is the core component of the rust inhibitor and has excellent corrosion inhibition performance; the thickener is used to adjust the viscosity of the rust inhibitor, making it easier to apply and form a stable protective film. Finally, slowly add the inorganic acid and continue stirring for 20-30 minutes. The addition of inorganic acid can adjust the pH value of the rust inhibitor and enhance its anti-rust performance. At the same time, the inorganic acid can also form a chemical bond or adsorption layer with the metal surface to further improve the anti-rust effect.

[0063] Step S4 reasonably controls the order of adding the components: adding the surfactant first helps to disperse and mix the subsequent components; the order of adding the composite corrosion inhibitor and the thickener can affect their dispersion degree and anti-rust performance in water; the last addition of the inorganic acid can ensure its uniform distribution in the rust inhibitor and avoid premature reaction leading to performance degradation.

[0064] In step S4, by controlling the stirring time and speed, sufficient reaction and dispersion between the components of the rust inhibitor can be ensured, thereby forming a stable rust-proof system.

[0065] The above steps S1-S4 describe in detail the entire preparation process of the rust inhibitor, starting from the preparation of the imidazoline intermediate, through the synthesis of the glycine imidazoline intermediate, and then to the generation of the composite corrosion inhibitor, and finally obtaining a rust inhibitor with good rust prevention performance.

[0066] Next, the present application uses a series of examples, adopts different raw material ratios and reaction conditions, and aims to compare the anti-rust effects of the rust inhibitors obtained in different examples.

[0067] Example 1

[0068] S11, mix 10g oleic acid, 2g diethyleneimine and 5g xylene, heat to reflux and stir, raise the temperature to 140°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; then raise the temperature to 170°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; continue to raise the temperature to 200°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; finally raise the temperature to 220°C, keep warm for 1h, evacuate for 5min, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0069] S12, 10 g of the imidazoline intermediate and 3 g of glycine are mixed, heated to 80° C. with stirring, reacted for 30 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0070] S13, add 2g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 0.3g of catalyst sodium hydroxide, heat to 100°C, react for 5h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0071] S14, heat 76.9g of water to 40°C, add 0.1g of surfactant N-alkyl pyrrolidone into the water, stir for 10min, then add 2g of composite corrosion inhibitor and 1g of thickener agar, stir for 10min, finally slowly add 20g of hydrochloric acid, stir for 20min, and obtain a rust inhibitor.

[0072] Example 2

[0073] S21, mix 10g oleic acid, 4g diethyleneimine and 8g xylene, heat to reflux and stir, raise the temperature to 160°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; then raise the temperature to 180°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; continue to raise the temperature to 210°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; finally raise the temperature to 230°C, keep warm for 3h, evacuate for 10min, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0074] S22, 10 g of the imidazoline intermediate and 5 g of glycine are mixed, heated to 100° C. with stirring, reacted for 60 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0075] S23, add 4 g of 2,3-epoxypropyltrimethylammonium chloride to 20 mL of N,N-dimethylformamide solvent, add 10 g of glycine imidazoline intermediate thereto, stir evenly, add 1 g of catalyst sodium hydroxide, heat to 120° C., react for 8 h, cool to room temperature, adjust the pH to neutral, and obtain a composite corrosion inhibitor.

[0076] S24, heat 59g of water to 60°C, add 1g of surfactant N-alkyl pyrrolidone into the water, stir for 20min, then add 5g of composite corrosion inhibitor and 5g of thickener agar, stir for 30min, finally slowly add 30g of hydrochloric acid, stir for 30min, and obtain a rust inhibitor.

[0077] Example 3

[0078] S31, mix 10g oleic acid, 3g diethyleneimine and 6g xylene, heat to reflux and stir, raise the temperature to 150°C, keep warm for 3h, evacuate for 4min, and return to normal pressure; then raise the temperature to 180°C, keep warm for 3h, evacuate for 4min, and return to normal pressure; continue to raise the temperature to 200°C, keep warm for 5h, evacuate for 3min, and return to normal pressure; finally raise the temperature to 230°C, keep warm for 1h, evacuate for 10min, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0079] S32, 10 g of the imidazoline intermediate and 4 g of glycine are mixed, heated to 100° C. with stirring, reacted for 40 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0080] S33, add 3g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 0.5g of catalyst sodium hydroxide, heat to 120°C, react for 6h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0081] S34, heat 69.7g of water to 50°C, add 0.3g of surfactant N-alkyl pyrrolidone into the water, stir for 15min, then add 4g of composite corrosion inhibitor and 2g of thickener agar, stir for 15min, finally slowly add 25g of hydrochloric acid, stir for 30min, and obtain a rust inhibitor.

[0082] Example 4

[0083] S41, mix 10g oleic acid, 4g diethyleneimine and 7g xylene, heat to reflux and stir, raise the temperature to 150°C, keep warm for 4h, evacuate for 4min, return to normal pressure; then raise the temperature to 170°C, keep warm for 3h, evacuate for 4min, return to normal pressure; continue to raise the temperature to 200°C, keep warm for 4h, evacuate for 5min, return to normal pressure; finally raise the temperature to 230°C, keep warm for 2h, evacuate for 10min, return to normal pressure; cool to room temperature to obtain imidazoline intermediate.

[0084] S42, 10 g of the imidazoline intermediate and 4 g of glycine are mixed, heated to 90° C. with stirring, reacted for 50 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0085] S43, add 3g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 0.5g of catalyst sodium hydroxide, heat to 100°C, react for 6h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0086] S44, heat 59.5g of water to 50°C, add 0.5g of surfactant N-alkyl pyrrolidone into the water, stir for 18min, then add 5g of composite corrosion inhibitor and 5g of thickener agar, stir for 30min, finally slowly add 30g of hydrochloric acid, stir for 20min, and obtain a rust inhibitor.

[0087] Example 5

[0088] S51, mix 10g oleic acid, 2g diethyleneimine and 8g xylene, heat to reflux and stir, raise the temperature to 150°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; then raise the temperature to 180°C, keep warm for 5h, evacuate for 3min, and return to normal pressure; continue to raise the temperature to 200°C, keep warm for 2h, evacuate for 5min, and return to normal pressure; finally raise the temperature to 220°C, keep warm for 1h, evacuate for 10min, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0089] S52, 10 g of the imidazoline intermediate and 5 g of glycine are mixed, heated to 100° C. with stirring, reacted for 50 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0090] S53, add 3g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 0.8g of catalyst sodium hydroxide, heat to 120°C, react for 6h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0091] S54, heat 66g of water to 55°C, add 1g of surfactant N-alkyl pyrrolidone into the water, stir for 15min, then add 3g of composite corrosion inhibitor and 5g of thickener agar, stir for 20min, finally slowly add 25g of hydrochloric acid, stir for 30min, and obtain a rust inhibitor.

[0092] Example 6

[0093] S61, mix 10g oleic acid, 4g diethyleneimine and 8g xylene, heat to reflux and stir, raise the temperature to 160°C, keep warm for 4h, evacuate for 4min, and return to normal pressure; then raise the temperature to 180°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; continue to raise the temperature to 210°C, keep warm for 5h, evacuate for 5min, and return to normal pressure; finally raise the temperature to 230°C, keep warm for 3h, evacuate for 10min, and return to normal pressure; cool to room temperature to obtain the imidazoline intermediate.

[0094] S62, 10 g of the imidazoline intermediate and 5 g of glycine are mixed, heated to 100° C. with stirring, reacted for 60 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0095] S63, add 4g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 1g of catalyst sodium hydroxide, heat to 120°C, react for 8h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0096] S64, heat 59g of water to 60°C, add 1g of surfactant alkylamine oxide into the water, stir for 20min, then add 5g of composite corrosion inhibitor and 5g of thickener gelatin, stir for 30min, finally slowly add 30g of acetic acid, stir for 30min, and obtain a rust inhibitor.

[0097] Example 7

[0098] S71, mix 10g oleic acid, 2g diethyleneimine and 5g xylene, heat to reflux and stir, raise the temperature to 140°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; then raise the temperature to 170°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; continue to raise the temperature to 200°C, keep warm for 2h, evacuate for 3min, and return to normal pressure; finally raise the temperature to 220°C, keep warm for 1h, evacuate for 5min, and return to normal pressure; cool to room temperature to obtain an imidazoline intermediate.

[0099] S72, 10 g of the imidazoline intermediate and 3 g of glycine are mixed, heated to 80° C. with stirring, reacted for 300 min, and then cooled to room temperature to obtain a glycinated imidazoline intermediate.

[0100] S73, add 2g of 2,3-epoxypropyltrimethylammonium chloride to 20mL of N,N-dimethylformamide solvent, add 10g of glycine imidazoline intermediate thereto, stir evenly, add 0.3g of catalyst sodium hydroxide, heat to 100°C, react for 5h, cool to room temperature, adjust pH to neutral, and obtain a composite corrosion inhibitor.

[0101] S74, heat 76.9g of water to 40°C, add 0.1g of surfactant alkylphenol polyoxyethylene ether into the water, stir for 10min, then add 2g of composite corrosion inhibitor and 1g of thickener sodium carboxymethyl cellulose, stir for 10min, finally slowly add 20g of oxalic acid, stir for 20min to obtain a rust inhibitor.

[0102] In order to verify the performance of the rust inhibitors prepared in Examples 1 to 7, the present application conducted a salt spray chamber accelerated corrosion test. At the same time, the present application also set up a comparative example to compare the rust prevention effects of different rust inhibitors. The rust prevention effects of the rust inhibitors prepared in each example are as follows: Figure 2 shown.

[0103] Among them, the comparative example is: 64g of water is heated to 50°C, 1g of surfactant N-alkyl pyrrolidone is added to the water, stirred for 20 minutes, then 5g of thickener agar is added, stirred for 30 minutes, and finally 30g of hydrochloric acid is slowly added, and stirred for 30 minutes to obtain a rust inhibitor.

[0104] Among them, salt spray box accelerated corrosion test: the test method refers to SH / T0081-1991, the metal test piece 20 steel 50mm×25mm×2mm is treated according to the method specified in GB / T4879-1999, and then subjected to salt spray box accelerated corrosion test.

[0105] The test results show that by adjusting the ratio of oleic acid, diethyleneimine, and xylene, the amount of glycine, the reaction temperature and time, and other components in the preparation process of the composite corrosion inhibitor and the rust inhibitor, the rust inhibitors prepared in Examples 1 to 7 all have good rust prevention effects, and the time for corrosion to occur is significantly longer than that of the comparative example. This proves the effectiveness and reliability of the preparation method of the rust inhibitor provided in the present application.

[0106] The embodiment of the present application also provides a method for using a rust inhibitor, which includes applying the rust inhibitor to a surface of a substrate to form a protective coating.

[0107] Wherein, the substrate includes metal, for example, common metal materials such as iron, steel, aluminum, copper, etc. These metals are very easy to rust in a humid, oxidative or corrosive environment, and therefore need to be protected by applying a rust inhibitor.

[0108] In order to ensure that the rust inhibitor can be evenly and firmly attached to the surface of the metal substrate, the embodiment of the present application applies the rust inhibitor to the surface of the substrate by any one of brushing, spraying and dipping, ensuring that the rust inhibitor can fully penetrate into the tiny pores on the metal surface. Regardless of the application method, it is necessary to ensure that the rust inhibitor can completely cover the metal surface and form a continuous protective coating. The protective coating can not only isolate the metal from contact with the corrosive medium, but also protect the metal through its internal corrosion inhibitor components, thereby effectively extending the service life of the metal.

[0109] In an optional embodiment, before applying the rust inhibitor, the surface of the metal substrate may be cleaned to remove impurities such as oil, dust, etc. to ensure that the metal surface is dry and free of moisture.

[0110] The thickness and number of times of rust inhibitor coating can be adjusted according to the size, shape and use environment of the metal substrate to achieve the best rust prevention effect. After coating, let the rust inhibitor dry naturally on the metal surface to form a dense rust protection film.

[0111] Through the above application method, the rust inhibitor described in the present application can form a stable and durable rust-proof protective film on the surface of the metal substrate, effectively preventing the performance degradation and shortening of the life of the metal substrate caused by rust, and improving the reliability and safety of the metal substrate. At the same time, the rust inhibitor has the advantages of being environmentally friendly, non-toxic, and easy to operate, and is suitable for rust-proofing various metal materials.

[0112] The preparation method of the rust inhibitor provided in the embodiment of the present application has the following technical effects:

[0113] (1) The rust inhibitor of the present application achieves efficient rust protection for metal surfaces through the selection and scientific proportioning of specific components. The inorganic acid can remove oxides and dirt on the metal surface, the surfactant can improve the wettability and permeability of the rust inhibitor on the metal surface, the composite corrosion inhibitor can significantly improve the rust prevention effect and service life, and the thickener can adjust the viscosity of the rust inhibitor to make it more stable during use.

[0114] (2) The rust inhibitor preparation method of the present application is simple, easy to operate, and easy to industrialize. Through multiple steps of heating, heat preservation and vacuuming, the raw materials are fully reacted to generate an imidazoline intermediate with a specific structure; then, through the reaction of glycine with the imidazoline intermediate, a functional group with corrosion inhibition performance is introduced; finally, through the reaction of epoxypropyltrimethylammonium chloride with the glycinated imidazoline intermediate, a composite corrosion inhibitor with excellent corrosion inhibition performance is generated. The entire preparation process has mild reaction conditions, is environmentally friendly, and is easy to control.

[0115] (3) The rust inhibitor of the present application has good rust prevention performance and service life. The rust inhibitor can form a stable protective film on the metal surface in a harsh environment, effectively preventing the rust and corrosion of the metal. At the same time, the rust inhibitor also has good environmental performance and is easy to use, and can be widely used in the rust prevention protection of various metal materials.

[0116] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

[0117] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A rust inhibitor, characterized in that: The rust inhibitor comprises the following components by weight: Inorganic acid 20-30%, surfactant 0.1-1%, composite corrosion inhibitor 2-5%, thickener 1-5%, and water as the balance.

2. The rust inhibitor according to claim 1, characterized in that The inorganic acid is a combination of one or more of oxalic acid, hydrochloric acid and acetic acid.

3. The rust inhibitor according to claim 1, characterized in that The surfactant is a combination of one or more of N-alkyl pyrrolidone, alkyl amine oxide, alkyl alcohol amide, and alkylphenol polyoxyethylene ether.

4. The rust inhibitor according to claim 3, characterized in that The thickener is a combination of one or more of gelatin, agar and sodium carboxymethyl cellulose.

5. A method for preparing a rust inhibitor according to any one of claims 1 to 4, characterized in that: The preparation method of the rust inhibitor comprises: Mix oleic acid, diethyleneimine and xylene, heat to reflux and stir, heat to 140-160°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; then heat to 170-180°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; continue to heat to 200-210°C, keep warm for 2-5h, evacuate for 3-5min, return to normal pressure; finally heat to 220-230°C, keep warm for 1-3h, evacuate for 5-10min, return to normal pressure; cool to room temperature to obtain imidazoline intermediate; The imidazoline intermediate and glycine are mixed, heated to 80-100°C with stirring, reacted for 30-60 minutes, and then cooled to room temperature to obtain a glycinated imidazoline intermediate; 2,3-Epoxypropyltrimethylammonium chloride is added to N,N-dimethylformamide solvent, and glycine imidazoline intermediate is added thereto, stirred evenly, and catalyst sodium hydroxide is added, the temperature is raised to 100-120° C., reacted for 5-8 hours, cooled to room temperature, and the pH is adjusted to neutral to obtain a composite corrosion inhibitor; Heat the water to 40-60°C, add the surfactant into the water, stir for 10-20 minutes, then add the composite corrosion inhibitor and thickener, stir for 10-30 minutes, finally slowly add the inorganic acid, stir for 20-30 minutes to obtain the rust inhibitor.

6. The method for preparing the rust inhibitor according to claim 5, characterized in that: The mass ratio of the oleic acid, diethyleneimine and xylene is 1:0.2-0.4:0.5-0.

8.

7. The method for preparing the rust inhibitor according to claim 5, characterized in that: The mass ratio of the imidazoline intermediate to glycine is 1:0.3-0.

5.

8. The method for preparing the rust inhibitor according to claim 5, characterized in that: The mass ratio of the glycinated imidazoline intermediate, 2,3-epoxypropyltrimethylammonium chloride and sodium hydroxide is 1:0.2-0.4:0.03-0.

1.

9. A method for applying the rust inhibitor according to any one of claims 1 to 4, characterized in that: The application method of the rust inhibitor comprises: The rust inhibitor is applied to the surface of a substrate to form a protective coating.

10. The method for applying the rust inhibitor according to claim 9, characterized in that: The rust preventive is applied to the surface of the substrate by any one of brushing, spraying and dipping, and the substrate includes metal.

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