Environment-friendly water-based antirust agent, preparation method and application thereof

Abstract

This invention discloses an environmentally friendly water-based rust inhibitor, its preparation method, and its application, relating to the field of rust prevention technology. The rust inhibitor uses water as a solvent and is composed of the following components at the following concentrations: soda ash 5-15 g / L, glycerin 6.3-19 g / L, and sodium gluconate 0.1-0.5 g / L. The preparation steps involve adding the formulated amounts of glycerin, soda ash, and sodium gluconate to water in any order at room temperature with stirring. After stirring until completely dissolved, water is added to bring the volume to the target level, and stirring is continued until homogeneous. In application, iron parts that have undergone paint stripping, pickling, and iron-based phosphating treatment are immersed in the environmentally friendly water-based rust inhibitor for 1-2 minutes, removed, and allowed to air dry naturally before electrostatic powder coating. This invention solves the problems of existing rust inhibitors used in factory repair being highly polluting, and the workpieces easily rusting again between processes, affecting the quality of the coating.

Description

Technical Field

[0001] This invention relates to the field of rust prevention technology, and in particular to an environmentally friendly water-based rust inhibitor, its preparation method, and its application. Background Technology

[0002] According to Clause 1.2.5 of the "Railway Passenger Car Repair Regulations", in cases where the requirements for rust and scale removal are not explicitly defined in the regulations, the cleanliness of the steel surface must meet the St2 or Sa2 standard in GB / T 8923.2 "Treatment Grades after Partial Removal of Original Coating on Coated Steel Surfaces". This means that the steel surface must be thoroughly cleaned of visible grease and dirt, and free of loosely adhering scale, rust, old coatings, and various impurities. This is an important quality requirement for railway passenger car parts repair. Currently, in railway passenger car repair operations, the conventional treatment process for iron parts involves paint removal, inspection, pickling, iron-based phosphating, and then electrostatic powder coating. The mainstream industry processes at present mostly employ traditional oil-based rust-preventive materials and highly polluting pickling and phosphating auxiliaries, resulting in significant environmental shortcomings and application defects. On the one hand, the chemicals used in traditional processes contain volatile organic compounds, heavy metals, and various corrosive pollutants, easily generating waste gas, wastewater, and waste residue during operations. This not only severely pollutes the factory environment but also increases the cost of treating these wastes. On the other hand, the phosphate film formed by existing iron-based phosphate treatment is relatively thin, with insufficient protective performance and extremely poor rust prevention. After pickling and iron-based phosphate treatment, iron parts are highly susceptible to large-scale rusting and corrosion during the interval between transportation and spraying. This not only leads to substandard surface quality and batch quality failures, but also directly damages the foundation for subsequent electrostatic powder coating, causing insufficient adhesion, coating peeling, and other quality defects, significantly reducing the maintenance pass rate and service life of railway passenger car parts. Removing large areas of rust by grinding or reworking and re-pickling and phosphate treatment results in a significant waste of manpower and materials, greatly increasing the production cost of parts repair and reducing maintenance efficiency. To solve these rust prevention problems, some companies have tried using rust-inhibiting oils or rust inhibitors containing nitrites. However, these products easily cause secondary pollution, increase subsequent cleaning processes, and do not conform to the current green and environmentally friendly development direction, failing to fundamentally balance the rust prevention quality of parts, cost reduction and efficiency improvement, and the needs of green production. Summary of the Invention

[0003] The purpose of this invention is to solve the problems of strong pollution and easy rust return between workpiece processes in existing factory repair rust inhibitors, which affect the coating quality. The invention provides a green and environmentally friendly water-based rust inhibitor with excellent rust prevention performance that is suitable for railway passenger car factory repair processes, as well as its preparation method and application.

[0004] To solve the above problems, the technical solution adopted by the present invention is as follows: On the one hand, the present invention provides an environmentally friendly water-based rust inhibitor, which uses water as a solvent and is composed of the following components at the following concentrations: soda ash 5-15 g / L, glycerin 6.3-19 g / L, and sodium gluconate 0.1-0.5 g / L.

[0005] In the above-mentioned technical solution for environmentally friendly water-based rust inhibitor, a more specific technical solution may be: the soda ash is industrial grade with a purity ≥99%; the glycerin is glycerin with a purity ≥99%; and the sodium gluconate is industrial grade with a purity ≥98%.

[0006] In some possible implementations, it consists of the following components: 10 g / L soda ash, 12.6 g / L glycerol, 0.3 g / L sodium gluconate, and the balance being water.

[0007] In some possible implementations, it consists of the following components: 5 g / L soda ash, 6.3 g / L glycerol, 0.1 g / L sodium gluconate, and the balance being water.

[0008] In some possible implementations, it consists of the following components: 15 g / L soda ash, 19 g / L glycerol, 0.5 g / L sodium gluconate, and the balance being water.

[0009] On the other hand, the present invention provides a method for preparing the aforementioned environmentally friendly water-based rust inhibitor, comprising the following steps: at room temperature and under stirring, adding the formulated amounts of glycerin, soda ash and sodium gluconate to water in any order, stirring until completely dissolved, then adding water to make up to the target volume, and continuing to stir until uniform, thereby obtaining the environmentally friendly water-based rust inhibitor.

[0010] In the above-mentioned preparation method of environmentally friendly water-based rust inhibitor, a more specific technical solution may be: the water is tap water.

[0011] On another aspect, the present invention provides an application of the aforementioned environmentally friendly water-based rust inhibitor in the repair and processing of railway passenger car parts. The iron parts, after being stripped of paint, pickled, and treated with iron phosphate, are immersed in the environmentally friendly water-based rust inhibitor for 1 to 2 minutes, removed and air-dried naturally, and then subjected to electrostatic powder coating treatment.

[0012] In the above-mentioned technical solution for the application of environmentally friendly water-based rust inhibitor in the repair and processing of railway passenger car parts, a more specific technical solution could be: immersing parts without interlayers for 1 minute and immersing parts with interlayers for 2 minutes.

[0013] By adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. The rust inhibitor of this invention uses water as a solvent and is composed of only three components: soda ash, glycerin, and sodium gluconate. The components are widely available, green, and non-toxic, and do not contain toxic or harmful components such as nitrites, chromates, phosphates, triethanolamine, and benzotriazole. This eliminates the problems of heavy metal pollution, eutrophication of water bodies, and volatile organic compound emissions, making it highly environmentally friendly. Soda ash can neutralize the hydrogen ions remaining on the surface of iron parts after pickling and phosphating, creating a suitable slightly alkaline environment for subsequent rust prevention. Glycerin can form a dense physical isolation film on the surface of the parts, effectively blocking the contact between oxygen in the air and the metal surface. Sodium gluconate, as a chelating agent, can actively complex iron ions on the metal surface, reducing their activity in electrochemical corrosion. Through the synergistic effect of neutralizing residual acid, physical shielding, and ion passivation, the three components significantly slow down the rusting speed of iron parts after pickling and phosphating without relying on any traditional corrosion inhibitors or oily substances, while not affecting the quality of subsequent electrostatic powder coating, thus balancing rust prevention effect, production efficiency, and green production requirements.

[0014] 2. Further limiting the purity of each component, high-purity industrial-grade soda ash, glycerin, and sodium gluconate are used. Low impurity content avoids residual impurities affecting the formation of the anti-rust film and the adhesion of the coating, ensuring stable and controllable performance of the rust inhibitor. High-purity soda ash can more effectively neutralize residual hydrogen ions on the surface of parts after pickling, preventing secondary contamination of the phosphating film by impurity ions. High-purity glycerin can form a continuous, dense, and uniform physical barrier layer on the surface of parts, enhancing the oxygen isolation effect. High-purity sodium gluconate can more efficiently chelate iron ions, inhibiting their ability to catalyze corrosion reactions. Regarding environmental friendliness, the specified industrial-grade raw materials are all edible substances commonly used in the food or pharmaceutical fields. Their production and use do not produce toxic or harmful byproducts, further strengthening the green attributes of this rust inhibitor, which is harmless to human health and environmentally friendly.

[0015] 3. A synergistic ratio of 10 g / L soda ash, 12.6 g / L glycerin, and 0.3 g / L sodium gluconate achieves an optimal balance between rust prevention performance and raw material economy. At this concentration, the neutralizing ability of soda ash is sufficient to neutralize residual acid radicals without damaging the phosphating film structure; the protective film formed by glycerin has a moderate thickness, dries quickly, and does not affect the adhesion of subsequent powder coatings; and the chelating activity of sodium gluconate is sufficient to inhibit initial rusting. Experimental verification shows that the overall rust area of ​​this formula is 0.000% after 12 hours of storage in an acidic environment. After 10 days of storage, the treated parts show no obvious rust, and it has no adverse effects on the appearance, adhesion, and corrosion resistance of the plastic coating after electrostatic powder spraying. From an environmental perspective, the formula uses a moderate amount of raw materials and has low wastewater treatment costs, fully meeting the green production requirements of railway passenger car repair operations.

[0016] 4. The formulation with the lower limit of components uses simpler materials and lower cost, making preparation and use more economical. While meeting basic rust prevention requirements, it maintains non-toxic and environmentally friendly characteristics. It is suitable for railway passenger car iron parts with short rust prevention cycle requirements and simple structure, and can achieve low-cost and environmentally friendly rust prevention treatment, reducing the input of factory repair materials.

[0017] 5. The formulation with the upper limit of components can form a more dense protective film layer, which can adhere to the surface of components with complex structures, interlayers and dead corners of liquid accumulation to achieve full coverage. For workpieces that are in a humid and static environment for a long time, it can extend the natural storage protection time, adapt to a variety of operating conditions, and has a wider overall application coverage. The formulation is still made with environmentally friendly raw materials and does not contain toxic or harmful components. It will not cause secondary pollution during use and waste liquid disposal. The environmental performance is stable and meets the standards. This ratio is more focused on adapting to the long-term static protection of complex components and is not designed for strong acid short-term accelerated corrosion environment.

[0018] 6. The preparation method of this invention operates at room temperature throughout the process, without heating or pressurization. The process is simple and easy to control, with extremely low energy consumption. The order of adding each component is flexible, reducing the risk of operational errors in the production process and facilitating rapid on-site preparation. The preparation process generates no waste gas, wastewater, or waste residue, making it green and environmentally friendly. The components are only physically mixed without chemical reactions, resulting in stable synergistic rust-preventing effects. It can quickly produce environmentally friendly water-based rust inhibitors with uniform performance, suitable for batch preparation and use on-site.

[0019] 7. Using tap water as a solvent, the raw materials are readily available and inexpensive, avoiding the additional energy consumption and costs associated with using deionized water, further improving the economic efficiency and practicality of the formula, while not affecting the performance and environmental characteristics of the rust inhibitor, making it suitable for large-scale industrial applications.

[0020] 8. The application method of this invention involves soaking iron parts in the railway passenger car repair process for 1-2 minutes. The soaking time is short and the operation is simple. No additional cleaning process is required, which greatly reduces the waste of manpower and materials caused by rust rework and significantly improves maintenance efficiency.

[0021] 9. Set the soaking time according to the differences in the structure of the parts. For simple parts without interlayer, a short soaking time can meet the rust prevention requirements. For complex parts with interlayer, the soaking time should be appropriately extended to ensure that the rust inhibitor is fully in contact with the liquid, so as to balance the rust prevention effect and the processing efficiency, avoid insufficient or excessive soaking, and improve the process adaptability and economy. Attached Figure Description

[0022] Figure 1 These are photographs of the test piece from Example 1-1.

[0023] Figure 2 These are photographs of test pieces from Examples 1-2.

[0024] Figure 3This is a photograph of the test piece from Example 2-1.

[0025] Figure 4 These are photographs of test pieces from Example 2-2.

[0026] Figure 5 This is a photograph of the test piece from Example 3-1.

[0027] Figure 6 These are photographs of test pieces from Example 3-2.

[0028] Figure 7 These are photos of the test piece in comparison 1-1.

[0029] Figure 8 These are photos of test pieces from comparison scale 1-2.

[0030] Figure 9 These are photos of the test piece in Comparative Example 2-1.

[0031] Figure 10 These are photos of the test pieces from Comparative Example 2-2.

[0032] Figure 11 These are photos of the test piece in Comparative Example 3-1.

[0033] Figure 12 These are photos of the test pieces from Comparative Example 3-2.

[0034] Figure 13 This is a sample photo of the test piece in Comparative Example 4-1.

[0035] Figure 14 These are photos of the test pieces from Comparative Example 4-2.

[0036] Figure 15 These are photos of the test pieces in Comparative Example 5.

[0037] Figure 16 These are photos showing the rust prevention effect after 5 days, mimicking Experiment 1.

[0038] Figure 17 These are photos showing the rust prevention effect after 5 days, mimicking Experiment 2.

[0039] Figure 18 These are photos showing the rust prevention effect after 10 days, mimicking Experiment 2.

[0040] Figure 19 These are photos showing the rust prevention effect after 5 days, mimicking Experiment 3.

[0041] Figure 20 These are photos showing the rust prevention effect after 10 days, mimicking Experiment 3.

[0042] Figure 21 These are photos of the test piece cross-cutting experiment.

[0043] Figure 22 These are photos of a cross-cut test on a curved roof slab.

[0044] Figure 23 These are photos of a cross-cut test on iron wall panels.

[0045] Figure 24 These are photos of a cross-cut test on long angle iron.

[0046] Figure 25 These are photos of the partition wall slat test.

[0047] Figure 26 These are photos of a ladder mounting bracket cross-cut test.

[0048] Figure 27 These are photos of the scratch test on the lock guard plate.

[0049] Figure 28 This is a photo taken before the plastic coating was immersed in salt water for testing.

[0050] Figure 29 This is a photo taken after the plastic coating has been soaked in salt water for 24 hours.

[0051] Figure 30 This is a photo of the curved roof of a railway passenger car after phosphating but before it was soaked in rust inhibitor.

[0052] Figure 31 This is a photo of the upper part of the luggage compartment sliding door cover of a railway passenger car after phosphating but before being soaked in rust inhibitor.

[0053] Figure 32 These are photos showing the effect of immersion in rust inhibitor after phosphating the curved roof panels of railway passenger cars.

[0054] Figure 33 This is a photo showing the effect of immersion in rust inhibitor after phosphating the upper part of the luggage compartment sliding door cover of a railway passenger car. Detailed Implementation

[0055] The present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, the raw materials used in the following embodiments are all conventional raw materials conforming to industrial standards, and the operating methods are all conventional methods in the art.

[0056] This invention relates to an environmentally friendly water-based rust inhibitor that uses water as a solvent and is composed of three components: soda ash, glycerin, and sodium gluconate. In the following examples, the soda ash is industrial grade with a purity of not less than 99%, the glycerin is glycerin with a purity of not less than 99%, and the sodium gluconate is industrial grade with a purity of not less than 98%. This invention uses soda ash, glycerin, and sodium gluconate as core raw materials. All raw materials are environmentally friendly, and the overall formula system contains no toxic or harmful additives. Soda ash and glycerin are commonly used in food-related fields, and sodium gluconate can also be used in pharmaceutical applications. These components do not have adverse effects on human health or the natural environment. Compared to the various irritating and environmentally harmful additives commonly used in existing rust-preventing products, the raw materials used in this invention are non-irritating, do not poison aquatic organisms, do not generate harmful waste during use, and the waste liquid treatment is simple and convenient. It fully meets the green and environmentally friendly production standards for railway passenger car repair operations and has outstanding environmental advantages throughout the entire process of raw material storage, on-site use, and subsequent waste liquid disposal.

[0057] To comprehensively verify the performance of rust inhibitors with different formulations, two types of tests were conducted. The first was a short-term accelerated corrosion test, conducted in a formic acid environment with a pH of 4.0–5.0, a temperature of 25–30°C, and a relative humidity of 85% ± 5%, for a continuous test duration of 12 hours. The second was a long-term atmospheric exposure test, in which the surface rust of the workpiece was recorded after 5 and 10 days of exposure. The performance was verified from two dimensions: resistance to short-term organic acid corrosion and long-term rust prevention in the natural environment.

[0058] Example 1 The environmentally friendly water-based rust inhibitor of this embodiment consists of the following components per 1L: 5 g / L soda ash, 6.3 g / L glycerin, 0.1 g / L sodium gluconate, and the balance being tap water.

[0059] The preparation method of the environmentally friendly water-based rust inhibitor in this embodiment is as follows: Under normal temperature and continuous stirring, first add 500mL of tap water to a beaker, then add the formulated amounts of glycerin, soda ash, and sodium gluconate. The order of adding each component can be adjusted. Keep stirring until each component is completely dissolved, then add tap water to make up the volume to 1000mL, and continue stirring until the system is homogeneous to obtain the environmentally friendly water-based rust inhibitor of this embodiment.

[0060] The application method of the environmentally friendly water-based rust inhibitor in this embodiment is as follows: Immerse the iron parts of the railway passenger car repair shop that have been treated by paint removal, pickling, and iron phosphate into the rust inhibitor of this embodiment. Immerse the parts without interlayers for 1 minute and the parts with interlayers for 2 minutes. After taking them out, let them air dry naturally, and then perform electrostatic powder spraying treatment.

[0061] Example 2 The environmentally friendly water-based rust inhibitor of this embodiment consists of the following components per 1L: 10 g / L soda ash, 12.6 g / L glycerin, 0.3 g / L sodium gluconate, and the remainder is tap water.

[0062] The environmentally friendly water-based rust inhibitor in this embodiment differs from that in Example 1 only in component concentration. The rest of the preparation method, application method, raw material specifications, solvent type, stirring conditions, volume adjustment method, soaking time, drying method, and subsequent electrostatic powder spraying process are the same as those in Example 1.

[0063] Example 3 The environmentally friendly water-based rust inhibitor of this embodiment consists of the following components per 1L: 15 g / L soda ash, 19 g / L glycerin, 0.5 g / L sodium gluconate, and the remainder is tap water.

[0064] The environmentally friendly water-based rust inhibitor in this embodiment differs from that in Example 1 only in component concentration. The rest of the preparation method, application method, raw material specifications, solvent type, stirring conditions, volume adjustment method, soaking time, drying method, and subsequent electrostatic powder spraying process are the same as those in Example 1.

[0065] Comparative Example 1 This comparative example is based on Example 2, but without the addition of sodium gluconate. The other components, component amounts, raw material specifications, solvent types, preparation methods, stirring conditions, volume adjustment methods, and operating conditions are exactly the same as in Example 2.

[0066] Comparative Example 2 This comparative example is based on Example 2, but without the addition of soda ash. The other component types, component amounts, raw material specifications, solvent types, preparation methods, stirring conditions, volume adjustment methods, and operating conditions are exactly the same as in Example 2.

[0067] Comparative Example 3 This comparative example is based on Example 2, but without the addition of glycerol. The other component types, component amounts, raw material specifications, solvent types, preparation methods, stirring conditions, volume adjustment methods, and operating conditions are exactly the same as in Example 2.

[0068] Comparative Example 4 This comparative example is based on Example 2, with the addition of 11.3g of 99% pure triethanolamine. The other components, amounts, raw material specifications, solvent types, preparation methods, stirring conditions, volume adjustment methods, and operating conditions are exactly the same as in Example 2.

[0069] Comparative Example 5 This comparative example is a blank control. No rust inhibitor was used. The test pieces after paint removal, pickling, and iron phosphate treatment were directly air-dried. The other pretreatment conditions, placement environment, and observation conditions were the same as those of the test pieces treated in Example 2.

[0070] Performance testing and effect verification 1. Sample preparation All examples and comparative examples used test pieces of the same material and size. The test pieces were made of Q235A and had a size of 70mm×80mm×1.5mm. All test pieces were subjected to the same pretreatment process, which included paint removal, pickling, iron phosphating, water washing, and draining. The pretreated test pieces were immersed in the solution of the corresponding example or comparative example for 1 minute, and then removed and air-dried to obtain the test pieces.

[0071] 2. Rust prevention performance test The prepared test pieces were suspended in an acidic environment at 25℃ for 12 hours. Image analysis software was used to measure the percentage of rust and corrosion area on the surface of each test piece three times. The average of the three measurements was calculated to evaluate the rust prevention performance. The test results are shown in Table 1. Table 1. Rust prevention performance test results Two parallel samples were set up for each formulation. The material, size, pretreatment process, soaking process, test environment and test method of the two samples were exactly the same, and they were only independent parallel test samples. The percentage of rust area of ​​each sample was tested three times, and the average value of the two samples was taken as the comprehensive percentage of rust area of ​​the formulation.

[0072] Figures 1 to 15The images shown are photographs of test pieces from Examples 1 to 3 and Comparative Examples 1 to 5. Test results indicate that the water-based rust inhibitors within the specified formulation range of this invention all possess good rust-preventing capabilities. The three core components work synergistically to form a stable protective system. The absence of any one component disrupts the balance between components, resulting in a significant decrease in overall rust-preventing efficacy. Introducing triethanolamine, a commonly used ingredient in the industry, into the optimized formulation system leads to a decline in overall rust-preventing effect. This is because triethanolamine alters the acid-base balance within the system, interfering with the neutralization and regulation of residual acidic substances on the workpiece surface by soda ash. It also weakens the continuity of glycerol film formation and the metal ion chelation of sodium gluconate, disrupting the synergistic protective mechanism of the original compound system and thus weakening the overall anti-corrosion effect. Furthermore, triethanolamine is a chemical additive that is irritating to the skin and eyes, potentially impacting the health of workers during use, and its waste discharge also increases the environmental burden. This confirms that the present invention can achieve ideal rust prevention without the need for alcohol amine additives. By eliminating such irritating and harmful components, it not only relies on the synergistic effect of the components to ensure stable and reliable rust prevention performance, but also maintains the green and harmless characteristics of the formula throughout the process. This greatly reduces the risks of on-site use and the difficulty of subsequent waste liquid treatment, which fully meets the green and low-carbon production needs of railway passenger car repair. Workpieces that have not been treated with rust inhibitor lack a protective barrier and their corrosion resistance is at the lowest level.

[0073] 3. On-site simulated rust prevention test To verify the rust-preventive effect of the environmentally friendly water-based rust inhibitor of this invention in actual production at railway passenger car repair shops, three sets of on-site simulation tests were set up: Simulation Test 1, Simulation Test 2, and Simulation Test 3. The test objects were iron parts at railway passenger car repair shops that had undergone paint stripping, pickling, and iron-based phosphating treatment. After pickling, phosphating, and water washing, the parts were treated according to the corresponding methods of each group and immersed for 1 minute. After being taken out, they were naturally air-dried and hung in the usual temporary storage location for parts at railway passenger car repair shops. The rust-preventive effect was observed in the natural environment of the workshop. Among them, Simulation Test 1 was a blank control without the use of any rust inhibitor, Simulation Test 2 used the environmentally friendly water-based rust inhibitor of Example 2, and Simulation Test 3 used the environmentally friendly water-based rust inhibitor of Example 3. The rust-preventive effect was observed, and the results are shown in Table 2. Table 2. Results of on-site simulated rust prevention test Figures 16 to 18The following are the photos of the rust prevention effect of the imitation test. It can be seen from the above results of the on-site simulation test that iron fitments for factory repair of passenger cars without rust prevention treatment are extremely prone to rapid rusting under the conventional storage environment in the workshop. Although the rust inhibitor prepared in Example 2 can achieve good protection effects in the short term, slight rust signs will still appear after long-term storage. However, after treating the fitments with the rust inhibitor prepared in Example 3, the surface of the fitments can be maintained in good condition stably for a long period, effectively delaying the occurrence of rust problems, fully proving that the water-based rust inhibitor prepared by the present invention can adapt to the actual on-site storage working conditions and can truly meet the medium- and long-term rust prevention use requirements during the factory repair of railway passenger car fitments.

[0074] 4. Influence Test on the Electrostatic Powder Spraying Plastic Layer The formula of Example 2 was used for the test. Test pieces that had been pickled and phosphated and then soaked in the rust inhibitor of this example for 1 min were subjected to electrostatic powder spraying treatment.

[0075] (1) Appearance test: Detection was carried out in accordance with the requirements of the electrostatic powder spraying operation instruction for factory repair passenger car fitments. The surface of the plastic layer was flat and smooth, allowing slight orange peel, a very small number of inconspicuous fine particles and hanger contact marks. There were no allowed bumps, scratches, obvious flow marks, missed spraying, exposed substrate, delamination, loss of gloss, color difference, large particles, bubbles, pinholes or severe orange peel on the coating surface, and the appearance met the requirements.

[0076] (2) Adhesion test of the plastic layer: The adhesion test was carried out in accordance with GB / T 9286-2021 "Paints and varnishes - Cross-cut test". The rating of the cross-cut test of the test piece was level 2, meeting the use requirements, as shown in Figure 21 .

[0077] The cross-cut test results of factory repair passenger car fitments are shown in Table 3: Table 3 Rating Table of Cross-cut Test for Factory Repair Passenger Car Fitments Figures 22 to 27 The following are the photos of the cross-cut test of the fitments.

[0078] (3) Corrosion resistance test: The corrosion resistance test was carried out in accordance with GB / T 9274 "Paints and varnishes - Determination of resistance to liquid media". A 5% NaCl solution was used to soak for 24 hours at room temperature. There were no phenomena of blistering, peeling or rusting on the plastic layer, and the corrosion resistance was qualified. The test records are as follows: Before the soaking test, the plastic layer was intact and there were no abnormalities, as shown in Figure 28 ; after soaking for 24 h, there were no phenomena of blistering, peeling or rusting, qualified, as shown in Figure 29 .

[0079] 5. On-site Practical Application The environmentally friendly water-based rust inhibitor of this invention has been put into use on the pre-treatment line of the applicant's railway passenger car repair shop. The application process is as follows: iron parts that have undergone paint stripping, pickling, and iron-based phosphating are immersed in the rust inhibitor. Parts without interlayers are immersed for 1 minute, and parts with interlayers are immersed for 2 minutes. After being removed and naturally dried, they are then electrostatically powder-coated. Actual use has verified that the rust problem of iron parts is significantly improved after treatment with the rust inhibitor of this invention. Before use, the parts had extensive rust, posing a high risk of quality failure; after use, the surface of the parts is smooth and rust-free, demonstrating a significant rust-preventive effect. Figures 30 to 33 The photos shown are comparison photos of the two accessories before and after use.

[0080] Field testing has shown that the rust inhibitor of this invention can effectively reduce the need for rework, re-acid pickling and phosphating processes caused by rusting, saving manpower and material costs, and improving maintenance efficiency and product quality.

[0081] This environmentally friendly water-based rust inhibitor can be applied to mainstream iron parts in railway passenger car repair shops. These parts are representative workpieces that are prone to rusting after pickling and phosphating in actual maintenance operations. It has strong versatility and can comprehensively solve the technical problem of easy rusting after pickling and phosphating of these mainstream parts, improve the overall maintenance quality and pass rate of parts, and at the same time maintain the advantages of environmental protection, high efficiency and low cost throughout the process.

Claims

1. An environmentally friendly water-based rust preventive, characterized by comprising: a water-soluble polymer; a water-soluble organic acid; and a water-soluble inorganic salt. Using water as a solvent, it consists of the following components at the following concentrations: soda ash 5–15 g / L, glycerol 6.3–19 g / L, and sodium gluconate 0.1–0.5 g / L.

2. The environmentally friendly water-based rust inhibitor according to claim 1, characterized in that, It is composed of the following components: the soda ash is industrial grade with a purity ≥99%; the glycerol is glycerol with a purity ≥99%; and the sodium gluconate is industrial grade with a purity ≥98%.

3. The environmentally friendly water-based rust inhibitor according to claim 2, characterized in that, It consists of the following components: 10 g / L soda ash, 12.6 g / L glycerol, 0.3 g / L sodium gluconate, and the balance water.

4. The environmentally friendly water-based rust inhibitor according to claim 2, characterized in that, It consists of the following components: 5 g / L soda ash, 6.3 g / L glycerol, 0.1 g / L sodium gluconate and the balance water.

5. The environmentally friendly water-based rust inhibitor according to claim 2, characterized in that, It consists of the following components: 15 g / L soda ash, 19 g / L glycerol, 0.5 g / L sodium gluconate, and the balance water.

6. A method for preparing the environmentally friendly water-based rust inhibitor according to any one of claims 1 to 5, characterized in that, Includes the following steps: At room temperature and under stirring, add the formulated amounts of glycerin, soda ash, and sodium gluconate to water in any order, stir until completely dissolved, then add water to bring the volume to the target level, and continue stirring until homogeneous to obtain the environmentally friendly water-based rust inhibitor.

7. The method for preparing the environmentally friendly water-based rust inhibitor according to claim 6, characterized in that: The water in question is tap water.

8. The application of the environmentally friendly water-based rust inhibitor according to any one of claims 1 to 5 in the repair and processing technology of railway passenger car parts, characterized in that: The iron parts that have undergone paint removal, pickling, and iron phosphate treatment are immersed in the environmentally friendly water-based rust inhibitor for 1 to 2 minutes, then removed and air-dried naturally before being treated with electrostatic powder coating.

9. The application of the environmentally friendly water-based rust inhibitor according to claim 8 in the repair and processing technology of railway passenger car parts, characterized in that: Unlined parts are soaked for 1 minute, while lined parts are soaked for 2 minutes.

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