Pretreatment process before anti-corrosion coating of steel structure

Abstract

The invention relates to a pretreatment process for a steel structure before anti-corrosion coating. At present, the main mode of derusting a steel structure is sand blasting, the operation is flexible, but the defects are that the construction period of large-scale operation is long, and generated sand dust is difficult to completely recover. The invention provides a pretreatment process before anticorrosive coating of a steel structure, which comprises the following steps: degreasing the surface of the steel structure by using a chemical reagent, simultaneously realizing deoiling and derusting of the metal surface, shortening the working period of sand blasting, and finally sealing the derusted surface of the steel structure by using a sealing agent. The adhesive strength of the anticorrosive coating and a matrix can be effectively improved, and the service life of the anticorrosive coating is prolonged. The pretreatment process is applied to coastal area construction and has a wide application prospect.

Description

Technical Field

[0001] The invention relates to the technical field of chemical corrosion rust removal, in particular to a pretreatment process before anti-corrosion painting of a steel structure and an anti-corrosion painting process for a bridge steel structure. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention, and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to a person skilled in the art.

[0003] Steel structures have the advantages of high strength and light weight. They are currently widely used in infrastructure construction, such as roads, bridges, airports, railway stations, etc. The above buildings all involve a large number of steel structures exposed to the outdoors. Anti-corrosion coating is the focus of later maintenance work, especially for steel structures of bridges erected on the sea. Taking the Jiaozhou Bay Bridge as an example, the bridge is located in the northern frozen marine environment, with obvious seasonal changes in climate. There is an ice period of nearly two months each year, and the difference between the highest and lowest temperatures is close to 60°C. It is also a domestic cross-sea bridge project with high salt content. The salinity of seawater in the bridge area is as high as 29.4‰-32.9‰. According to the ISO9223-1992 "Atmospheric Corrosion Resistance Classification of Metals and Alloys" standard, the atmospheric corrosion severity level of the Jiaozhou Bay Bridge is rated as level 4, which belongs to the severe corrosion level. This strong corrosive environment has caused some steel components of the bridge to suffer from corrosion, rust and coating shedding to varying degrees, which seriously threatens the aesthetics, safety and durability of the bridge.

[0004] In the later maintenance of bridge steel structures, in order to ensure the durability of anti-corrosion coatings, the metal surface needs to have good cleanliness and roughness, and the metal structure surface must be pre-treated by rust removal. There is a saying in the anti-corrosion industry that "70% rust removal and 30% coating", which shows the importance of rust removal. For the rust removal of bridge engineering steel structures, the commonly used methods currently include sandblasting and shot blasting, which remove rust, scale and old coatings through impact and friction. Among them, sandblasting is more suitable for cleaning workpieces with complex shapes, cavities and dead corners, with flexible construction locations and a wider range of applications. However, sandblasting also has the following defects and shortcomings: 1) The sand and dust generated during sandblasting is difficult to completely collect and protect, and falling into the ocean will affect the ecological environment; 2) The bridge construction span is large, the trusses and cables are long and detailed, and sandblasting is mainly carried out manually, with a long operation cycle.

[0005] In view of the above technical status, the inventor believes that if the steel structure is pre-cleaned and rust-removed by chemical corrosion method, it is expected to shorten the sandblasting period and reduce the adverse impact on the ecological environment. However, in the later maintenance of bridge steel structure, the research on rust removal by chemical corrosion method is still relatively blank. Summary of the invention

[0006] In view of the above technical background, the purpose of the present invention is to provide a pretreatment process for anti-corrosion coating of steel structures. The main improvement of this process is that a pretreatment step of chemical corrosion and rust removal on the surface of the steel structure is added before sandblasting. This pretreatment can effectively reduce the duration of sandblasting and create appropriate cleanliness and roughness on the surface of the steel structure to cooperate with the subsequent anti-corrosion coating construction.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a pretreatment process for anticorrosive coating of a steel structure, comprising the following steps: (1) surface degreasing treatment: spraying a degreasing agent on the surface of the steel structure to be treated, so that the degreasing agent and the surface of the steel structure are fully infiltrated for at least 3 hours; the formula of the degreasing agent is as follows: 3-6% sodium dodecylbenzene sulfonate, 8-10% alkylphenol polyoxyethylene ether, 5-8% alkyl glycoside, 5-10% fatty alcohol polyoxyethylene ether, 7-10% disodium ethylenediaminetetraacetic acid, 2-4% phytic acid, and 0.5-2% carboxymethyl chitosan; (2) Sandblasting: The steel structure after surface treatment is sandblasted, the sandblasting pressure is 0.6MPa~1.2MPa, and the sandblasting material is 60~200 mesh; (3) Cleaning: The steel structure after sandblasting is rinsed with high-pressure water flow, with a water pressure of about 2~7MPa; (4) Sealing: The cleaned steel structure surface is sealed with a sealant, the formula of which is as follows: 3-6% bis-(γ-trimethoxysilyl) propylamine, 1-3% ethanol, 2-4% gluconic acid, 0.5-1.5% sodium citrate, and the balance is water; the subsequent coating is carried out after the sealing liquid dries.

[0008] Taking bridges as an example, the current service life of bridge construction design is usually one hundred years, while the life cycle of anti-corrosion coating is usually twenty years. The difficulties in subsequent maintenance of bridges mainly lie in: the steel structure cannot be disassembled, so it is impossible to apply chemical reagent infiltration, electrochemical rust removal or hot-dip galvanizing and other rust removal processes that require heating; there is usually not enough working space, and it is impossible to directly use shot blasting machines, lasers and other rust removal equipment; there are many construction details such as cables, flanges, bolts, nuts, etc., which require careful manual processing; it includes a large number of aerial operations, such as bridge trusses, cables, towers, ceilings, etc., and the operating space for these aerial operations is smaller. Therefore, in view of the operational characteristics of subsequent maintenance of steel structures, the present invention designs this pretreatment process. Through the surface treatment of the degreasing agent, the grease and dust on the surface of the steel structure are removed, and the rusty coating will also be fully infiltrated and peeled off. Only quick sandblasting is required to complete the rust removal, and the degreasing agent components are environmentally friendly, and even if they cannot be fully recycled, they will not affect the environment.

[0009] In coastal areas, the air humidity is high and the chloride ion content is high. According to general construction requirements in this field, the metal surface must be subsequently painted within 2 hours after sandblasting, otherwise it will need to be sandblasted again. The present invention seals the surface of the steel structure with a silicon-containing sealant after sandblasting. Through the sealing treatment, the time for subsequent painting does not have to be limited to within 2 hours, and the anti-corrosion coating construction can be postponed to 7 days at most. The sealant can also provide suitable roughness for the anti-corrosion coating, increase the adhesion effect between the coating and the substrate, and extend the life cycle of the anti-corrosion coating.

[0010] Based on the above design ideas, the pretreatment process provided by the first aspect of the present invention is more suitable for the subsequent maintenance of steel structures, especially for the maintenance of steel structures in outdoor infrastructure in coastal areas, such as bridges, roads, gymnasiums, railway stations, etc. Further, in the maintenance of bridges, it is more suitable for the outer side of guardrails, hangers, cables, cable clamps, saddles, towers or traffic signs on bridge decks.

[0011] In the degreasing agent of the above step (1), fatty alcohol polyoxyethylene ether and alkyl polyglycoside belong to the surfactant type, and can achieve the simultaneous removal of grease and rust when combined with phytic acid. Sodium dodecylbenzene sulfonate and alkylphenol polyoxyethylene ether can activate acidic molecules, improve the pickling effect, and increase the pickling speed, thereby effectively removing rust, grease, impurities and oxide scale. Disodium ethylenediaminetetraacetic acid acts as a masking agent for metal ions and plays a role in chelating metal ions, thereby promoting the above-mentioned rust removal process. The main function of carboxymethyl chitosan is to regulate the viscosity of the degreasing agent. When the viscosity is high, the degreasing agent can better adhere to the surface of the steel structure to play a wetting role and also play a corrosion inhibition role. When the viscosity is low, the degreasing agent stays less on the surface of the steel structure, which can reduce the rust removal speed of the degreasing agent.

[0012] Furthermore, the selectable models of the alkylphenol polyoxyethylene ether include but are not limited to one or a combination of OP-4, OP-7, OP-10, OP-15, and OP-40, and more preferably, OP-10, which not only has excellent wettability, emulsification and cleaning power, but also does not gel when used.

[0013] Furthermore, the optional types of the fatty alcohol polyoxyethylene ether include but are not limited to AEO-3, AEO-7, and AEO-9, and more preferably AEO-3, which has good emulsification, decontamination and cleaning properties.

[0014] In the above step (2), the material for sandblasting is selected from all or some of steel sand, steel shot, stainless steel sand / shot, brown corundum, white corundum, silicon carbide, glass beads, ceramic sand, garnet sand, copper ore sand, quartz sand, corundum, iron sand, Hainan sand, plastic sand, walnut shells, and corn cobs.

[0015] In the above step (4), during the preparation of the sealing agent, the above raw materials are added to water according to the ratio, stirred continuously and the solution is heated and kept warm to completely dissolve, wherein the stirring rate is 400-600 rpm, the heating temperature is above 55°C, and the solution temperature is maintained above 50°C by keeping warm.

[0016] The second aspect of the present invention provides an anti-corrosion coating process for a bridge steel structure, comprising using the pretreatment process described in the first aspect to clean and remove rust from the surface of the bridge steel structure, and then coating the surface with a primer and a topcoat.

[0017] In the above-mentioned coating process, the primer and topcoat are preferably anti-corrosion coatings for bridge steel with better salt spray resistance. In a further preferred solution, the primer is sprayed within 2h~100h after the surface of the steel structure is treated by the pretreatment process of the first aspect, and the primer includes epoxy zinc-rich primer, inorganic zinc-rich primer, polyasparagine waterproof anti-corrosion coating, etc., and the coating thickness is 40μm~80μm.

[0018] Furthermore, the optional types of topcoat include but are not limited to fluorocarbon topcoat, acrylic polyurethane topcoat, polyurethane paint, epoxy anti-corrosion paint or gray aluminum powder graphite alkyd topcoat, etc., and the coating thickness is 40μm~100μm.

[0019] Furthermore, the above anti-corrosion coating may also have an intermediate layer as appropriate.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention provides a steel structure surface cleaning and rust removal process that can be used for outdoor and aerial operations, including chemical corrosion using a degreasing agent, sandblasting and sealing. The chemical reagents used in the present invention are environmentally friendly, can effectively reduce the working time of sandblasting operations, and reduce the impact of sand and dust on the environment.

[0021] 2. The present invention uses a silicon-containing reagent to seal the metal surface after sandblasting and rust removal. This treatment method can effectively increase the adhesion strength between the anti-corrosion coating and the metal substrate, enhance the salt spray resistance of the anti-corrosion coating, and extend the service life. In addition, the sealant treatment also makes the construction time of the anti-corrosion coating more flexible. DETAILED DESCRIPTION

[0022] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0023] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0024] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below in combination with specific embodiments and comparative examples.

[0025] Example 1 In this embodiment, a pretreatment process for a steel structure before painting is provided, comprising the following steps: (1) Surface degreasing treatment: Prepare the degreasing agent according to the following formula: 4.5% sodium dodecylbenzene sulfonate, 9.2% alkylphenol polyoxyethylene ether (OP-10), 6.0% alkyl glycoside, 6.2% fatty alcohol polyoxyethylene ether (AEO-3), 8.55% disodium ethylenediaminetetraacetic acid (EDTA-2Na), 3% phytic acid, 1% carboxymethyl chitosan. The above ingredients are calculated by weight, and the balance is water. Spray the above degreasing agent evenly onto the surface of the steel structure to be treated, and control the spraying speed so that the spraying time of a cable or workpiece with a length of 1m is controlled within 60~80s. Depending on the effect of rust removal, the number of spraying can be increased or the key parts can be manually painted. The surface treatment time is at least 3h, and then proceed to the next step.

[0026] (2) Sandblasting for rust removal: The distance between the nozzle and the surface of the steel structure is controlled at 100-300 mm. Before sandblasting, shield and protect the non-sandblasting parts. For cables, spray all around. For flat steel parts, alternately sandblast at angles of 15 and 30 degrees, such as 30 degrees for 15 seconds, 15 degrees for 15 seconds, and so on. The sandblasting materials are 60-200 mesh quartz sand, corundum, and glass beads. The sandblasting pressure is 0.6MPa-1.2MPa.

[0027] (3) Cleaning: Use a high-pressure water gun to rinse the degreased steel structure surface with a water pressure of about 2~7MPa. When the water after rinsing no longer contains sandblasting grit, stop cleaning and let it dry naturally. If construction is carried out in winter, hot air can be used to assist drying.

[0028] (4) Passivation sealing: Prepare the sealant according to the following formula: 5% bis-(γ-trimethoxysilylpropyl)amine, 2% ethanol, 3% gluconic acid, 1% sodium citrate, and the balance is water; when preparing the sealant, add the above ingredients into water and stir continuously to completely dissolve them at a stirring rate of 500 rpm. Heat and keep warm at the same time to make the solution temperature reach above 50°C. Spray or brush the prepared sealant onto the surface of the steel structure and dry it with hot air.

[0029] Example 2 In this embodiment, another pretreatment process for steel structure before painting is provided, comprising the following steps: (1) Surface degreasing treatment: a degreasing agent is prepared according to the following formula: 3% sodium dodecylbenzene sulfonate, 8% alkylphenol polyoxyethylene ether (OP-10), 5% alkyl glycoside, 5% fatty alcohol polyoxyethylene ether (AEO-3), 7% disodium ethylenediaminetetraacetic acid (EDTA-2Na), 2% phytic acid, and 0.5% carboxymethyl chitosan. The above ingredients are calculated by weight, and the balance is water. The remaining operations are the same as in Example 1.

[0030] (2) Sandblasting for rust removal: The distance between the nozzle and the surface of the steel structure is controlled at 100-300 mm. Before sandblasting, shield and protect the non-sandblasting parts. For cables, sandblast all around. For flat steel parts, alternately sandblast at angles of 15 and 30 degrees, such as 30 degrees for 15 seconds, 15 degrees for 15 seconds, and so on. The sandblasting materials are 60-200 mesh silicon carbide, glass beads and ceramic sand particles, and the sandblasting pressure is 0.6MPa-1.2MPa.

[0031] (3) Cleaning: Use a high-pressure water gun to rinse the degreased steel structure surface with a water pressure of 2~7MPa to clean the sand and gravel on the steel structure surface and let it dry naturally.

[0032] (4) Passivation and sealing: A sealing agent was prepared according to the following formula: 3% bis-(γ-trimethoxysilylpropyl)amine, 1% ethanol, 2% gluconic acid, 0.5% sodium citrate, and the balance was water; the rest of the operation was the same as in Example 1.

[0033] Example 3 In this embodiment, another pretreatment process for steel structure before painting is provided, comprising the following steps: (1) Surface degreasing treatment: a degreasing agent is prepared according to the following formula: 6% sodium dodecylbenzene sulfonate, 10% alkylphenol polyoxyethylene ether (OP-10), 8% alkyl glycoside, 10% fatty alcohol polyoxyethylene ether (AEO-3), 10% disodium ethylenediaminetetraacetic acid (EDTA-2Na), 4% phytic acid, and 2% carboxymethyl chitosan. The above ingredients are calculated by weight, and the balance is water. The remaining operations are the same as in Example 1.

[0034] (2) Sandblasting for rust removal: The distance between the nozzle and the surface of the steel structure is controlled at 100-300 mm. Before sandblasting, shield and protect the non-sandblasting parts. For cables, spray all around. For flat steel parts, alternately sandblast at angles of 15 and 30 degrees, such as 30 degrees for 15 seconds, 15 degrees for 15 seconds, and so on. The sandblasting materials are 60-100 mesh copper ore sand, quartz sand, corundum and iron sand particles, and the sandblasting pressure is 0.6MPa-0.8MPa.

[0035] (3) Cleaning: Use a high-pressure water gun to rinse the degreased steel structure surface with a water pressure of 2~7MPa to clean the sand and gravel on the steel structure surface and let it dry naturally.

[0036] (4) Passivation and sealing: A sealing agent was prepared according to the following formula: 6% bis-(γ-trimethoxysilylpropyl)amine, 3% ethanol, 4% gluconic acid, 1.5% sodium citrate, and the balance was water; the rest of the operation was the same as in Example 1.

[0037] Example 4 In this embodiment, another pretreatment process before painting of steel structure is provided, which is different from that in Embodiment 1 in that the model of alkylphenol polyoxyethylene ether in this embodiment is OP-40, and the model of fatty alcohol polyoxyethylene ether is AEO-9.

[0038] Example 5 In this embodiment, another pretreatment process for steel structure before painting is provided, which is different from Embodiment 1 in that the model of alkylphenol polyoxyethylene ether in this embodiment is OP-4, and the model of fatty alcohol polyoxyethylene ether is AEO-7.

[0039] The cleanliness level of the steel structure surface after pretreatment in the above-mentioned embodiments 1-5 can at least reach the Sa2.5 level, and generally can reach the Sa2 level.

[0040] Comparative Example 1 In this embodiment, another pretreatment process for anti-corrosion coating of steel structure is provided, which is different from the first embodiment in that: after cleaning in step (3), no sealing is performed, but the anti-corrosion coating is directly applied.

[0041] Comparative Example 2 In this embodiment, another pretreatment process for anti-corrosion coating of steel structures is provided, which is different from that of Embodiment 1 in that the degreasing surface treatment in step (1) is not performed.

[0042] In this embodiment, the sandblasting time in step (2) is significantly prolonged. Calculated based on the rust removal area, under the same spraying pressure, the sandblasting rust removal in Example 1 to reach Sa2.5 level requires about 3 to 6 minutes per square meter, while in this embodiment, it takes 15 to 20 minutes to reach the same level of cleaning.

[0043] Comparative Example 3 In this embodiment, another pretreatment process for anti-corrosion coating of steel structure is provided, which is different from that of Embodiment 1 in that the formula of the degreasing agent in step (1) is as follows: 6.0% alkyl glycoside, 6.2% fatty alcohol polyoxyethylene ether (AEO-3), 8.55% disodium ethylenediaminetetraacetic acid (EDTA-2Na), and 3% phytic acid.

[0044] Comparative Example 4 In this embodiment, another pretreatment process for anticorrosive coating of steel structure is provided, which is different from that of Embodiment 1 in that the formula of the degreasing agent in step (1) is as follows: 4.5% sodium dodecylbenzene sulfonate, 9.2% alkylphenol polyoxyethylene ether (OP-10), 6.0% alkyl glycoside, 6.2% fatty alcohol polyoxyethylene ether (AEO-3), 8.55% disodium ethylenediaminetetraacetic acid (EDTA-2Na), and 3% phytic acid.

[0045] Verification of steel structure anti-corrosion performance Q235D steel was used as a sample, and the surface treatment was performed using the pretreatment process in the above embodiment and comparative example, and then the coating system shown in Table 1 was used for coating: Table 1 Steel structure surface coating system Adhesion test: According to GBT 9286-2021 "Scratch test for paint and varnish", three parts are randomly selected on the painted surface of the steel sample and repeatedly scratched with a scraper. The line spacing is 2mm, and the distance between the selected parts and the edge of the steel structure is more than 5mm. After the scribing is completed, the cutting area is inspected by visual method, and the painted surfaces in the embodiments and comparative examples are rated according to "Table 1 Test Results Classification" in the standard. The rating is divided into 1 to 6 levels (0, 1, 2, 3, 4, 5), among which the first three levels are passable. The results are shown in Table 2 below: Table 2 Test results of steel structure adhesion in the examples and comparative examples From the results in Table 2, we can see that: (1) In Examples 1-5, the anti-corrosion coating and the substrate have good adhesion, and the two are very tight and can reach level 0-1. This shows that the pretreatment process provided by the present invention can effectively increase the bonding strength of the anti-corrosion coating, which is expected to reduce the probability of the anti-corrosion coating falling off and extend the service life of the anti-corrosion coating.

[0046] (2) The adhesion effect of the anti-corrosion coating in Comparative Example 1 is the worst, and obvious coating shedding occurs under artificial destruction. Compared with Example 1, the metal surface after sandblasting and rust removal is not sealed in Comparative Example 1, so the metal surface cannot reach the corresponding roughness, and the coating lacks strong binding sites on the metal surface. In addition, the process in Comparative Example 1 requires rapid coating after rinsing with clean water, which places higher requirements on the scheduling of the construction period and construction.

[0047] (3) The adhesion effect of the anti-corrosion coating in Comparative Example 2 is also poor. Since no degreasing treatment was performed in Comparative Example 2 and the sandblasting period was relatively long, the inventors speculate that: on the one hand, the extended sandblasting period also prolonged the time the metal surface was exposed to the air after rust removal, resulting in a certain degree of oxidation on the metal surface; on the other hand, the surface treatment with the degreasing agent also plays an auxiliary role in improving the adhesion effect of the anti-corrosion coating.

[0048] (4) In the process of developing the degreasing agent, the present invention has designed the schemes in Comparative Examples 3 and 4. Comparative Example 3 is mainly composed of surfactant components, acid and slow-release components. According to the measurement, it takes about 10 to 15 minutes to complete the rust removal of one square meter of steel structure surface by sandblasting after surface treatment with the degreasing agent in Comparative Example 3. In order to further improve the rust removal efficiency, the present invention proposes the scheme in Comparative Example 4, which adds an acid activator to promote penetration. It takes about 6 to 8 minutes to complete the rust removal of one square meter of steel structure surface, but the construction workers need to repeatedly brush and treat for more than 4 hours. Therefore, the present invention adds a viscosity regulator to the scheme of Comparative Example 4, which effectively reduces the workload of the construction workers and further speeds up the speed of sandblasting rust removal.

[0049] From the adhesion test results, the coating and substrate in Comparative Examples 3 and 4 are well bonded, the main difference being that the sandblasting construction period is longer.

[0050] Corrosion resistance test: According to GB / T1771-2007 "Determination of neutral salt spray resistance of paints and varnishes", three locations are randomly selected on the painted surface of the steel sample and a scratching tool is used to make a scratch with a length of 5 cm, a width of 0.5 mm, and a depth directly reaching the steel surface. According to the standard, the above-mentioned scratched steel structure is placed in a salt spray chamber for exposure. The test time is 200 hours. The corrosion products are removed in the manner described in Appendix C. The steel sample is cleaned and dried, and the mass loss is weighed. The weight is calculated as grams per square meter of exposure area. Compared with the average weight change of the reference sample, the average mass loss in the above-mentioned embodiment or comparative example is 25g / m 2 The results are shown in Table 3 below: Table 3 Corrosion resistance test results of steel samples coated in the examples and comparative examples According to the results in Table 3 above, we can see that: (1) The quality loss of the anti-corrosion coatings in Examples 1-5 under salt spray exposure is generally less than that in the control example, and the scratch width does not change significantly. This shows that the anti-corrosion coatings in the present invention have better salt spray and corrosion resistance. They are applied in coastal areas, especially in the anti-corrosion of steel structures of bridges built on the sea, which will effectively extend the service life of the anti-corrosion coatings.

[0051] (2) In Comparative Example 1-2, the anti-corrosion coating showed obvious rust and peeling on the surface under the influence of salt spray exposure. When the surface was artificially damaged, the corrosion and peeling at the scratches were particularly obvious. Compared with Example 1, the application of the sealant not only effectively increased the adhesion effect between the coating and the substrate, but also significantly improved the salt spray resistance of the anti-corrosion coating.

[0052] (3) In Comparative Examples 3-4, the rust on the paint surface is not obvious, but the degree of rust and peeling at the notch is close to that of Comparative Example 1. It can be considered that when the surface of the steel structure is damaged by external force, the pretreatment method of Example 1 can improve the salt spray corrosion resistance of the damaged area.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A pretreatment process for anti-corrosion coating of steel structure, characterized in that: The steps include: (1) Surface degreasing treatment: spray the degreasing agent on the steel structure to be treated, so that the degreasing agent and the surface of the steel structure are fully infiltrated for at least 3 hours; the formula of the degreasing agent is as follows: 3-6% sodium dodecylbenzene sulfonate, 8-10% alkylphenol polyoxyethylene ether, 5-8% alkyl glycoside, 5-10% fatty alcohol polyoxyethylene ether, 7-10% disodium ethylenediaminetetraacetic acid, 2-4% phytic acid, and 0.5-2% carboxymethyl chitosan; (2) Sandblasting: The steel structure after surface treatment is sandblasted, the sandblasting pressure is 0.6MPa~1.2MPa, and the sandblasting material is 60~200 mesh; (3) Cleaning: The steel structure after sandblasting is rinsed with high-pressure water at a water pressure of 2~7MPa; (4) Sealing: The cleaned steel structure surface is sealed with a sealant, the formula of which is as follows: 3-6% bis-(γ-trimethoxysilyl) propylamine, 1-3% ethanol, 2-4% gluconic acid, 0.5-1.5% sodium citrate, and the balance is water; the subsequent coating is carried out after the sealing liquid dries.

2. The pretreatment process according to claim 1, characterized in that: The pretreatment process is applicable to the maintenance of steel structures in outdoor infrastructure in coastal areas, wherein the infrastructure is selected from bridges, roads, gymnasiums or railway stations; in the maintenance of bridges, the pretreatment process is applicable to the outside of guardrails, hangers, cables, cable clamps, saddles, towers or traffic signs on the bridge deck.

3. The pretreatment process according to claim 1, characterized in that: In step (1), the type of the alkylphenol polyoxyethylene ether is selected from one or a combination of OP-4, OP-7, OP-10, OP-15, and OP-40.

4. The pretreatment process according to claim 3, characterized in that: The model of the alkylphenol polyoxyethylene ether is OP-10.

5. The pretreatment process according to claim 1, characterized in that: In step (1), the type of the fatty alcohol polyoxyethylene ether is selected from AEO-3, AEO-7 or AEO-9.

6. The pretreatment process according to claim 5, characterized in that: The model of the fatty alcohol polyoxyethylene ether is AEO-3.

7. The pretreatment process according to claim 1, characterized in that: In step (2), the material for sandblasting is selected from all or some of steel sand, steel shot, stainless steel sand / shot, brown corundum, white corundum, silicon carbide, glass beads, ceramic sand, garnet sand, copper ore sand, quartz sand, corundum, iron sand, Hainan sand, plastic sand, walnut shells, and corn cobs.

8. The pretreatment process according to claim 1, characterized in that: In step (4), during the preparation of the sealing agent, the above raw materials are added to water according to the proportion, stirred continuously, and the solution is heated and kept warm to completely dissolve, wherein the stirring rate is 400-600 rpm, the heating temperature is above 55°C, and the solution temperature is maintained above 50°C by keeping warm. 9.An anti-corrosion coating process for a bridge steel structure, characterized in that: The method comprises using the pretreatment process described in any one of claims 1 to 8 to clean and remove rust from the surface of the steel structure, and then applying primer and topcoat.

10. The anti-corrosion coating process for bridge steel structure according to claim 9, characterized in that: After the surface of the steel structure is treated by the pretreatment process described in any one of claims 1 to 8, the primer is sprayed within 2h to 100h, the primer is selected from epoxy zinc-rich primer, inorganic zinc-rich primer or polyasparagine waterproof and anti-corrosion coating, and the coating thickness is 40μm to 80μm; the topcoat is selected from fluorocarbon topcoat, acrylic polyurethane topcoat, polyurethane paint, epoxy anti-corrosion paint or gray aluminum powder graphite alkyd topcoat, and the coating thickness is 40μm to 100μm.

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