Environmentally friendly water-based modification agent for improving the surface finish performance of galvanized steel sheets and its use.

Abstract

This invention discloses an environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets and its use. The environmentally friendly aqueous modification agent contains the following components dissolved in water to form a solution: (A) a fluorine-containing compound, with a content of 0.02 to 0.15 mol / L in molar concentration of fluoride ions; (B) a nonionic polyol surfactant, with a content of 0.004 to 0.03 mol / L in molar concentration of hydroxyl groups; (C) an oxidizing agent, with a content of 0.02 to 0.2 mol / L in molar concentration of oxidizing agent; (D) a colloidal dispersion containing colloidal silica particles, with a content of 0.008 to 0.06 mol / L in molar concentration of Si elements; and (E) a hydroxycarboxylic acid group-containing compound, with a content of 0.2 to 2 mol / L in molar concentration of carboxyl groups. This invention can effectively improve the processing performance of the surface of galvanized steel sheets.

Description

Technical Field

[0001] The present invention relates to the technical field of surface treatment of metal materials, and particularly to an environmentally friendly water-based modification treatment agent for improving the surface processing performance of galvanized steel sheets, which is applicable to surface modification treatment when zinc-based galvanized steel sheets such as electro-galvanized steel sheets, hot-dip galvanized steel sheets, and hot-dip zinc-iron alloy galvanized steel sheets are used in the fields of automobiles and household appliances, and to its use.

Background Art

[0002] Galvanized steel sheets are widely used in various fields such as automobiles, household appliances, and construction due to their excellent sacrificial corrosion protection performance. Since the properties of the zinc layer are different from those of cold-rolled carbon steel, there are obvious differences in surface processing performance. Therefore, galvanized steel sheets are supplemented for the deficiencies in high-performance processing processes by various functional coatings on the surface, and various zinc-coated surface functional coating products are used in the market.

[0003] The automobile manufacturing process mainly includes four processes: forming, joining, painting, and assembly. Among them, the processing stages in the three processes of forming, joining, and painting are all related to the requirements for the functions of the surface of automobile body materials. Since the end of the previous century, galvanized steel sheets have gradually become the mainstream material for automobile body parts. In the automobile industry, trends of high-efficiency production, green manufacturing, and safety and reliability have been formed. As a result, the requirements for the surface processing performance of materials mainly appear in the following three aspects: (1) High-efficiency production raises new requirements for the lubricity of the steel sheet surface; (2) In order to be applied to an environmentally friendly pretreatment process due to green manufacturing, the reaction performance of the material surface needs to effectively meet the requirements of the painting pretreatment process; (3) Safety and reliability raise higher requirements for the joining performance of the material surface.

[0004] Surface treatment agents for galvanized steel sheets primarily focus on lubrication performance during forming. These systems mainly include inorganic chromium-containing salts, phosphates, molybdates, silica sols, etc., along with organic silanes, acrylic resins, polyurethane resins, etc., and improve product performance by forming a microscale or submicroscale coating on the steel sheet surface. For example, Chinese Patent Publication No. CN101608311A proposes a self-lubricating galvanized metal material, and its self-lubricating treatment agent mainly consists of trivalent chromium compounds, silica sols, and organic carboxylic acids, and is mainly used to improve the lubricity and corrosion resistance of galvanized surfaces. Chinese Patent Publication No. CN104497827A proposes an aqueous chromium-free lubricating treatment agent for galvanized steel sheet surfaces and a method for producing the same. The treatment agent consists of aqueous polyisocyanate, aqueous polyacrylate emulsion, silica sol, wax emulsion, surfactant, coupling agent, molybdate, and film-forming aid, and improves lubricity and corrosion resistance after treating the galvanized steel sheet surface with the treatment agent. Chinese Patent Publication No. CN1934232A proposes a lubricating aqueous polyurethane resin composition treatment agent, which mainly comprises a special polyurethane resin, polyolefin resin fine particles, and colloidal silica, and the surface of a galvanized steel sheet treated therewith has the functions of corrosion resistance, alkali resistance, paint adhesion, and lubricity.

[0005] While the above-mentioned treatment agents can improve the lubrication performance of galvanized steel sheets, they cannot effectively achieve the bonding performance and pre-painting treatment performance required for galvanized products, and therefore cannot be effectively used in the automotive manufacturing industry, which has higher overall performance requirements.

[0006] Based on the above circumstances, there is a need to develop a surface modification agent for adjusting the lubrication performance, bonding performance, and pre-painting treatment (phosphate treatment, zirconium conversion treatment) performance of galvanized steel sheets, which will also meet the technological trends of high-efficiency production, safety and reliability, and green manufacturing in the automotive manufacturing process. [Overview of the project] [Problems that the invention aims to solve]

[0007] To overcome the shortcomings of conventional technology, the object of the present invention is to provide an environmentally friendly aqueous surface modification agent and its use that improves the surface processing performance of galvanized steel sheets. This agent forms a nanoscale surface modification layer on the surface of galvanized steel sheets that has excellent formability, bonding properties, and phosphate treatment / zirconium chemical conversion treatment properties for painting, thereby effectively improving the processing performance of the surface of galvanized steel sheets and meeting the technological trends of high-efficiency production, safety and reliability, and green manufacturing in the automotive manufacturing process. [Means for solving the problem]

[0008] To achieve the above objectives, the present invention employs the following technical solution: A first aspect of the present invention provides an environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, comprising the following components dissolved in water to form a solution: (A) Fluorine-containing compounds, the content of which is 0.02 to 0.15 mol / L in terms of fluoride ion molar concentration; (B) Nonionic polyol surfactant, the content of which is 0.004 to 0.03 mol / L in terms of hydroxyl group molar concentration; (C) Oxidizing agent, the content of which is 0.02 to 0.2 mol / L in molar concentration of the oxidizing agent; (D) Colloidal dispersion containing colloidal silica particles, the content of which is 0.008 to 0.06 mol / L in molar concentration of element Si; and (E) A compound containing a hydroxycarboxylic acid group, the content of which is 0.2 to 2 mol / L in terms of the molar concentration of the carboxyl group.

[0009] Preferably, the fluorine-containing compound is a chemical substance containing six fluoride ions; and / or, the nonionic polyol surfactant is an organic solvent containing a hydroxyl group; and / or, the oxidizing agent is selected from oxidizing agents with a standard electrode potential of 0.95 to 1.7 V; and / or, the colloidal dispersion containing the colloidal silica particles is a silica sol with a particle size of 5 to 20 nm.

[0010] Preferably, the fluorine-containing compound is a fluorine titanate, silicate, and / or zirconate, and the salt is preferably an ammonium salt, sodium salt, or potassium salt, preferably one or two selected from the group consisting of ammonium fluorotitanate, sodium fluorosilicate, ammonium fluorozirconate, sodium fluorotitanate, sodium fluorozirconate, potassium fluorotitanate, and potassium fluorozirconate, more preferably one or two selected from the group consisting of ammonium fluorotitanate, sodium fluorozirconate, potassium fluorotitanate, and potassium fluorozirconate; and / or, the nonionic polyol surfactant is dipropylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether The oxidizing agent is one selected from the group consisting of ether, triethanolamine, and isopropanol, preferably selected from the group consisting of isopropanol, ethylene glycol ethyl ether, and triethanolamine; and / or the oxidizing agent is one or two selected from the group consisting of sodium nitrate, copper nitrate, potassium nitrate, potassium permanganate, bromate (e.g., sodium bromate), hydrogen peroxide, and ammonium metavanadate, preferably selected from the group consisting of hydrogen peroxide, potassium permanganate, and ammonium metavanadate; and / or the hydroxycarboxylic acid group-containing compound is one or two selected from the group consisting of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, and tannic acid, preferably selected from the group consisting of tannic acid, oxalic acid, and ethylenediaminetetraacetic acid.

[0011] Preferably, the content of the fluorine-containing compound is 0.04 to 0.1 mol / L in terms of the molar concentration of fluoride ions.

[0012] Preferably, the content of the nonionic polyol surfactant is 0.006 to 0.015 mol / L in terms of the molar concentration of hydroxyl groups.

[0013] Preferably, the content of the oxidizing agent is 0.04 to 0.12 mol / L in terms of the molar concentration of the oxidizing agent.

[0014] Preferably, the content of the colloidal dispersion containing the colloidal silica particles is 0.015 to 0.03 mol / L in terms of the molar concentration of Si element.

[0015] Preferably, the content of the hydroxycarboxylic acid group-containing compound is 0.8 to 1.5 mol / L in terms of the molar concentration of the carboxyl group.

[0016] Preferably, the pH of the environmentally friendly aqueous treatment agent is 2 to 5.

[0017] A second aspect of the present invention provides the use of an environmentally friendly aqueous modification agent for galvanized steel sheets to improve the surface processing performance of galvanized steel sheets according to the first aspect of the present invention, and includes use for improving the friction performance, bonding performance, phosphate treatment performance and zirconium conversion treatment performance of galvanized steel sheets.

[0018] A third aspect of the present invention provides a method for improving the friction performance, bonding performance, phosphate treatment performance, and zirconium conversion treatment performance of a galvanized steel sheet, the method comprising the step of applying an environmentally friendly aqueous modification agent for improving the surface processing performance of the galvanized steel sheet according to the present invention to the surface of the galvanized steel sheet. In some embodiments, the environmentally friendly aqueous modification agent may be applied to the surface of the galvanized steel sheet by methods such as impregnation, spraying, or roll coating to form a wet film, which is then dried. For example, it may be dried by blow drying or oven drying. The amount of the environmentally friendly aqueous modification agent according to the present invention to be applied is 100 to 2000 mg / m². 2 This may also be the case. After drying, a nanoscale surface modification layer can be formed on the surface of the galvanized steel sheet. Preferably, the thickness of the nanoscale surface modification layer is 20 to 80 mg / m². 2 That is the case.

[0019] The fourth aspect of the present invention provides a galvanized steel sheet, the surface of which has a nano-scale surface modification layer formed by drying an environmentally friendly water-based modification treatment agent according to the present invention applied to the surface of the galvanized steel sheet.

Advantages of the Invention

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. According to the environmentally friendly water-based modification treatment agent for improving the surface processing performance of the galvanized steel sheet according to the present invention and its use, on the surface of the effectively treated galvanized steel sheet (hot-dip galvanized, electro-galvanized, hot-dip zinc-iron alloy galvanized), the comprehensive optimization of the forming performance, joining performance, and pre-painting treatment (phosphate treatment / zirconium chemical conversion treatment) performance can be realized, and the requirements of an environmentally friendly and highly efficient processing process can be met.

[0021] 2. According to the environmentally friendly water-based modification treatment agent according to the present invention, a wet film can be formed on the surface of the galvanized steel sheet by methods such as impregnation, spraying, roll coating, etc., and a nano-scale surface modification layer can be rapidly formed on the surface of the galvanized steel sheet with the treatment agent by blow drying or oven drying. The surface modification layer can significantly improve the processing performance of the surface of the galvanized steel sheet.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, the present invention will be described in detail based on specific examples. The following examples are helpful for those skilled in the art to further understand the present invention, but do not limit the present invention in any form.

[0023] This invention, after theoretical analysis, extensive laboratory scientific research, and practical verification, has finally determined the technical route for an environmentally friendly aqueous treatment agent for nano-modification of the surface of galvanized steel sheets to achieve good formability, bonding performance, phosphate treatment performance, and zirconium conversion treatment performance. By combining the structural characteristics of the surface of typical hot-dip galvanized / electro-galvanized / and alloyed hot-dip galvanized steel sheets with the basic principles of surface lubrication, bonding, phosphate treatment, and zirconium conversion treatment processes, the mechanism for strengthening the processed surface of galvanized steel sheets was elucidated, and an environmentally friendly aqueous modification treatment agent was developed. This environmentally friendly aqueous modification treatment agent can be used in high-speed continuous coil production processes and parts manufacturing processes for galvanized steel sheet materials. Specifically, the treatment method involves forming a wet film on the steel sheet surface by methods such as impregnation, spraying, and roll coating, and then rapidly forming a surface modification layer on the steel sheet surface by blow drying or oven drying, which can significantly improve the surface processing performance.

[0024] The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets provided by the present invention comprises the following components dissolved in water to form a solution: (A) Fluorine-containing compounds, the content of which is 0.02 to 0.15 mol / L in terms of fluoride ion molar concentration; (B) Nonionic polyol surfactant, the content of which is 0.004 to 0.03 mol / L in terms of the molar concentration of hydroxyl groups (OH); (C) Oxidizing agent, the content of which is 0.02 to 0.2 mol / L in molar concentration of the oxidizing agent; (D) A colloidal dispersion containing colloidal silica particles, the content of which is 0.008 to 0.06 mol / L in molar concentration of element Si; (E) A compound containing a hydroxycarboxylic acid group, the content of which is 0.2 to 2 mol / L in terms of the molar concentration of the carboxyl group (COOH).

[0025] The environmentally friendly aqueous modification agent according to the present invention can be applied to the surface of metal materials such as hot-dip galvanized steel, electro-galvanized steel, and zinc-iron alloy plated steel sheets by mixing the above components in a specific ratio to prepare an acidic solution with a pH of 2 to 5, thereby achieving an optimization effect on processing performance.

[0026] The composition, formulation, and design principle of the environmentally friendly aqueous treatment agent according to the present invention are as follows: (A) A fluorine-containing compound, specifically a chemical substance containing six fluoride ions such as a titanate, silicate, and / or zirconate of fluorine, may be used. The salt is preferably an ammonium salt, sodium salt, or potassium salt. Preferably, the fluorine-containing compound is one or two selected from the group consisting of ammonium fluorotianoate, sodium fluorosilicate, ammonium fluorozirconate, sodium fluorotianoate, sodium fluorozirconate, potassium fluorotianoate, and potassium fluorozirconate; the content of the fluorine-containing compound in the environmentally friendly aqueous modification agent is 0.02 to 0.15 mol / L in molar concentration of fluoride ions (F ions), preferably 0.03 to 0.1 mol / L or 0.04 to 0.1 mol / L. However, the main function of the fluorine-containing compound is to utilize the strong reactivity of F ions in acidic solutions to rapidly induce a film formation reaction by etching the oxide layer on the material surface, and to form a passivation layer with an oxidation shielding function on the surface of the material to be treated, thereby avoiding the impact on surface bonding performance due to the formation of a loosely structured zinc-containing compound. When the content falls below 0.02 mol / L, the oxidation shielding effect is clearly reduced, but when the content exceeds 0.15 mol / L, the stability of the treatment agent is significantly reduced, and the optimization effect of the lubricity of the modified layer surface decreases.

[0027] (B) Nonionic polyol surfactant, specifically an organic solvent containing a hydroxyl group, which may be one selected from the group consisting of dipropylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, triethanolamine, and isopropanol. The content of the nonionic polyol surfactant in the environmentally friendly aqueous modification agent is 0.004 to 0.03 mol / L in terms of the molar concentration of hydroxyl groups (OH), preferably 0.006 to 0.015 mol / L or 0.008 to 0.025 mol / L. The main function of the nonionic polyol surfactant is to adjust the surface leveling performance. If the content is below 0.004 mol / L, the optimization effect of the film formation performance of the treatment agent on the surface of the galvanized steel sheet is significantly reduced, impairing the uniformity of the film and affecting the optimization effect of the processing performance. However, if the content exceeds 0.03 mol / L, there is an excess of adsorbed residue, affecting the adhesion performance of the surface modification layer and causing a decrease in bonding performance and pre-coating treatment performance.

[0028] (C) Oxidizing agent, mainly an oxidizing agent with a standard electrode potential Eθ in the range of 0.95 to 1.7 V, specifically, one or two selected from the group consisting of sodium nitrate, copper nitrate, potassium nitrate, potassium permanganate, bromate, hydrogen peroxide, and ammonium metavanadate. The content of the oxidizing agent in the environmentally friendly aqueous modification treatment agent is 0.02 to 0.2 mol / L in molar concentration of the oxidizing agent, preferably 0.04 to 0.12 mol / L or 0.06 to 0.2 mol / L. The main function of the oxidizing agent is to promote the film formation process of the treatment agent by utilizing its own oxidizing function, to achieve an effective film thickness in a short time, and thereby achieve an optimization effect of surface lubrication performance. If the content is below 0.02 mol / L, it will significantly affect the film formation effect of the treatment agent and the lubrication function of the film layer, but if the content is above 0.2 mol / L, it will impair the stability of the solution system and inhibit the film formation reaction of other components.

[0029] (D) A colloidal dispersion containing colloidal silica particles, specifically a silica sol with a particle size of 5 to 20 nm; the content of the colloidal dispersion containing the colloidal silica particles in the environmentally friendly aqueous modification agent is 0.008 to 0.06 mol / L in terms of the molar concentration of Si element, preferably 0.015 to 0.03 mol / L or 0.015 to 0.04 mol / L. The main function of the colloidal dispersion containing the colloidal silica particles is to enhance the film adhesion performance of the environmentally friendly aqueous modification agent and at the same time improve the surface lubrication performance by utilizing uniformly distributed nanoscale fine particles. If the particle size is less than 5 nm, aggregation is likely to occur, affecting the stability of the environmentally friendly aqueous modification agent, but if the particle size is greater than 20 nm, a decrease in lubrication effect will occur after film formation. In environmentally friendly aqueous modification agent systems, if the content of colloidal dispersion containing colloidal silica particles falls below 0.008 mol / L, the film-forming lubrication function of the treatment agent is significantly reduced. However, if the content exceeds 0.06 mol / L, the treatment agent forms a film bond, significantly detrimental to the pre-treatment performance before painting.

[0030] (E) A hydroxycarboxylic acid group-containing compound, specifically one or two selected from the group consisting of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, and tannic acid; the content of the hydroxycarboxylic acid group-containing compound in the environmentally friendly aqueous modification agent is 0.2 to 2 mol / L in terms of the molar concentration of the carboxyl group (COOH), preferably 0.8 to 1.5 mol / L or 0.7 to 1.2 mol / L. The main function of the hydroxycarboxylic acid group-containing compound is to react with the Zn and Fe metal elements on the surface of the plated layer to produce particulate organic acid salts, thereby improving the lubrication performance of the surface. A large amount of organic acid salt further enriches the chemically active sites on the material surface, achieving an optimization effect for the pre-treatment performance of painting. If the molar concentration of carboxyl groups in the additive in the treatment agent falls below 0.2 mol / L, the number of particulate organic acid salts formed by the film formation of the treatment agent becomes insufficient, preventing the optimization effect of lubrication performance from being achieved. However, if the molar concentration of carboxyl groups exceeds 2 mol / L, the stability of the treatment agent deteriorates, and the size of the organic acid salt particles becomes too large, resulting in insufficient cohesive bonding strength, which affects the surface lubricity and paint adhesion performance.

[0031] In some embodiments, in the environmentally friendly aqueous modification treatment agent for improving the surface processing performance of galvanized steel sheets according to the present invention, the content of the fluorine-containing compound is 0.03 to 0.1 mol / L in terms of the molar concentration of fluorine ions, the content of the nonionic polyol surfactant is 0.008 to 0.025 mol / L in terms of the molar concentration of hydroxyl groups (OH), the content of the oxidizing agent is 0.06 to 0.2 mol / L in terms of the molar concentration of the oxidizing agent, the content of the colloidal dispersion containing colloidal silica particles is 0.015 to 0.04 mol / L in terms of the molar concentration of Si element, and the content of the hydroxycarboxylic acid group-containing compound is 0.7 to 1.2 mol / L in terms of the molar concentration of carboxyl groups (COOH). L is preferably, in these embodiments, the fluorine-containing compound is one or two selected from the group consisting of ammonium fluorotianoate, sodium fluorozirconate, potassium fluorotianoate, and potassium fluorozirconate; the nonionic polyol surfactant is selected from the group consisting of isopropanol, ethylene glycol ethyl ether, and triethanolamine; the oxidizing agent is selected from the group consisting of hydrogen peroxide, potassium permanganate, and ammonium metavanadate; and the hydroxycarboxylic acid group-containing compound is selected from the group consisting of tannic acid, oxalic acid, and ethylenediaminetetraacetic acid.

[0032] The present invention further provides the use of the aforementioned environmentally friendly aqueous modification agent on galvanized steel sheets (hot-dip galvanized, electro-galvanized, hot-dip zinc-iron alloy plated), wherein the environmentally friendly aqueous modification agent can be used to coat the galvanized steel sheet by methods such as impregnation, spraying, and roll coating, and then a nanoscale surface modification layer having excellent formability, bondability, and coating phosphate treatment / zirconium chemical conversion treatment properties can be formed on the surface of the galvanized steel sheet by methods such as blow drying or oven drying; the environmentally friendly aqueous modification agent can provide the surface of the galvanized steel sheet with excellent formability, bondability, and applicability to environmentally friendly coating processes.

[0033] In the present invention, galvanized steel sheets such as hot-dip galvanized, electro-galvanized, and hot-dip zinc-iron alloy plated sheets may be galvanized steel sheets of various types and specifications well known in the art, or galvanized steel sheets used in fields such as automobiles, home appliances, and construction. An exemplary galvanized steel sheet typically contains C, Si, Mn, Ti, and unavoidable impurities such as P and S, with the remainder being Fe. In the substrate of the exemplary galvanized steel sheet, the C content may be 0.01-0.15% by mass, the Si content may be 0.1-0.5%, the Mn content may be 0.1-0.5%, the Ti content may be 0.1-0.4%, the P content is typically ≤0.08%, and the S content is typically ≤0.05%. The exemplary galvanized steel sheet typically has a zinc plating layer thickness of 10-100 g / m². 3 It may also be 20-60 g / m², for example. 3 That is the case.

[0034] The following provides further explanation, based on specific examples, of environmentally friendly water-based modifying agents that improve the surface treatment performance of galvanized steel sheets and their use. [Examples]

[0035] 1) Test sample board: The materials used in the examples include hot-dip galvanized, hot-dip galvanized-iron alloy plated, and electro-galvanized materials, all with a thickness of 0.7 mm, and their composition is shown in Table 1.

[0036] [Table 1]

[0037] 2) Method for processing and cleaning sample plates: The above material was processed into 150mm*70mm sample pieces by shearing and applied to evaluate the performance of phosphate treatment / zirconium conversion treatment for coating, 25.4mm*100mm sample pieces and applied to evaluate bonding performance, and 25mm*400mm sample pieces and applied to evaluate friction performance.

[0038] The surface was rinsed with an alkaline degreasing agent (pH=11-12) to remove dirt and oil, then rinsed with pure water to remove any remaining alkaline components, and finally dried with cool air before being prepared for use.

[0039] 3) Application An environmentally friendly aqueous surface modifier was applied to the surface of a galvanized steel sheet. The substrate type, composition of the environmentally friendly aqueous surface modifier, and application method used in each example and comparative example are shown in Table 2. After application, the sheets were dried by blow drying or oven drying. In each example and comparative example, the amount of aqueous surface modifier applied was as shown in Table 2, resulting in a nanoscale surface modification layer thickness of 20 to 85 mg / m² after drying. 2 It is intended to bring it within the range.

[0040] [Table 2] TIFF2026525413000003.tif167170

[0041] 4) Performance evaluation method The surface-treated sample plates obtained in the above examples and comparative examples were treated with 500 mg / m². 2 After applying the rust-preventive oil treatment, the surface was left for 24 hours before its performance was evaluated.

[0042] (a) Measurement of the coefficient of friction Referring to ASTM D1894, the surface dynamic friction coefficient of galvanized steel sheets with composite nanostructures was measured using the point pressure method with stainless steel balls.

[0043] The evaluation criteria for surface friction performance were as follows: ◎: The reduction in the coefficient of friction is ≥30% compared to an untreated substrate; ○: Compared to an untreated substrate, the reduction in the coefficient of friction is 10% to 30%; Δ: Compared to an untreated substrate, the reduction in the coefficient of friction is 0% to 10%; ×: Compared to an untreated substrate, the coefficient of friction either does not change or increases.

[0044] (b) Measurement of bonding performance Referring to the SAE J1523 standard, a typical structural adhesive, TEROSON EP 5089, was selected as the bonding agent. When preparing the bonded sample, the bonded area was 3.2 cm². 2 The bond thickness was set to 0.2 mm; curing of the bonding agent: curing temperature: 160°C, time: 15 min. After curing, the samples were left for 24 hours, then impregnated in deionized water at 55°C for 7 days, and then removed and subjected to a tensile peel test. Tensile test: Performed in accordance with ASTM D 1002, with a tensile speed of 13 mm / min. The superiority of the bonding effect was evaluated according to the peel mode.

[0045] The delamination mode was analyzed for two sample pieces after tensile delamination was completed (the delamination mode is classified into two types: cohesive delamination, i.e., fracture within the bonding agent; interfacial delamination, i.e., separation of the bonding agent from the metal surface). The bonding performance was evaluated based on the area ratio of cohesive delamination, and the evaluation criteria were as follows: ◎: Aggregation and detachment area = 100%; ○: 85% ≤ Aggregation and detachment area < 100%; Δ: 65% ≦ Cohesive peeling area < 85%; ×: Aggregation and detachment area < 65%.

[0046] (c) Measurement of phosphate treatment performance The phosphate treatment performance was evaluated before painting. The phosphate treatment process, primarily referencing pre-painting treatment processes in automotive factories including degreasing, surface preparation, and phosphate treatment, was simulated in the laboratory. Commercially available Parkerizing products were used for the treatment agents, and specific process parameters are shown in Table 3.

[0047] [Table 3]

[0048] After processing the sample plates using the method described above, the phosphate crystal coverage and crystal size were microscopically observed using a scanning electron microscope, and the weight of the phosphate film was measured by the chemical dissolution film method. The specific method was as follows.

[0049] Evaluation of phosphate crystal coverage Using a scanning electron microscope (Zeiss SIGMA 500), the phosphate-treated surface of the sample was observed at 1000x magnification and evaluated by the phosphate film coverage area ratio. The evaluation criteria were as follows: ◎: Phosphate film coverage = 100%; ○: 80% ≤ Phosphate film coverage < 100%; Δ: 60% ≤ Phosphate film coverage < 80%; ×: Phosphate film coverage < 60%.

[0050] (d) Measurement of zirconium conversion treatment performance The performance of zirconium conversion treatment was evaluated before painting. The process was simulated in the laboratory, referencing the zirconium conversion treatment process used as a pre-painting treatment in automotive factories, primarily including degreasing, rinsing, and zirconium conversion treatment steps. Commercial products from Parkerizing were used as the treatment agents, and specific process parameters are shown in Table 4.

[0051] [Table 4]

[0052] The film thickness of the zirconium conversion treated surface of the sample pieces was measured and evaluated using X-ray fluorescence spectroscopy, and the evaluation criteria were as follows: ◎: The improvement in film thickness due to zirconium conversion treatment is ≥100% compared to an untreated substrate; ○: Compared to an untreated substrate, the improvement in film thickness due to zirconium conversion treatment is 30% to 100%. Δ: Compared to an untreated substrate, the improvement in film thickness due to zirconium conversion treatment is -30% to 30%. ×: The improvement in film thickness due to zirconium conversion treatment compared to an untreated substrate is ≤30%.

[0053] [Table 5]

[0054] As can be seen from Table 5, Examples 1 to 6 all showed good performance in each evaluation item, with Examples 4, 5, and 6 showing particularly excellent overall performance. As can be seen from the comparison between Examples and Comparative Example 1, when the content of the treatment agent components was too high, the treated surface showed significant deterioration in friction performance, bonding performance, phosphate treatment performance, and zirconium conversion treatment performance. As can be seen from the comparison between Examples and Comparative Example 2, when the surfactant content and silica sol addition amount in the treatment agent components were too high, the surface showed excellent friction performance, but significant deterioration in bonding performance and zirconium conversion treatment performance was observed. As can be seen from the comparison between Examples and Comparative Example 3, when the content of the treatment agent components was too low, the treated surface's friction performance, bonding performance, phosphate treatment performance, and zirconium conversion treatment performance were all at the level of the substrate, and no significant optimization effect was observed. As can be seen from the comparison between Example 1 and Comparative Example 4, when the content of the oxidizing agent and the hydroxycarboxylic acid group-containing compound in the treatment agent was too low, the treated surface showed a significant deterioration in friction performance. As can be seen from Examples 3, 4, and 5, the treatment agent can be applied to typical coating methods such as spraying, impregnation, and roll coating, and has broader process compatibility.

[0055] In summary, the above embodiments are for illustrative purposes only and not to limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art will understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and that all such modifications should be included within the scope of the claims of the present invention.

Claims

1. An environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, characterized by containing the following components when dissolved in water to form a solution: (A) Fluorine-containing compounds, the content of which is 0.02 to 0.15 mol / L in terms of fluoride ion molar concentration; (B) Nonionic polyol surfactant, the content of which is 0.004 to 0.03 mol / L in terms of hydroxyl group molar concentration; (C) Oxidizing agent, the content of which is 0.02 to 0.2 mol / L in molar concentration of the oxidizing agent; (D) Colloidal dispersion containing colloidal silica particles, the content of which is 0.008 to 0.06 mol / L in molar concentration of element Si; and (E) A compound containing a hydroxycarboxylic acid group, the content of which is 0.2 to 2 mol / L in terms of the molar concentration of the carboxyl group.

2. The fluorine-containing compound employs a chemical substance containing six fluoride ions, preferably a titanate, silicate, and / or zirconiumate of fluorine, and the salt is preferably an ammonium salt, sodium salt, or potassium salt; and / or The nonionic polyol surfactant is an organic solvent containing a hydroxyl group; and / or, The oxidizing agent is selected from oxidizing agents having a standard electrode potential of 0.95 to 1.7 V; and / or, The colloidal dispersion containing the aforementioned colloidal silica particles employs a silica sol with a particle size of 5 to 20 nm. An environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, as described in claim 1.

3. The fluorine-containing compound is one or two selected from the group consisting of ammonium fluorotitanate, sodium fluorosilicate, ammonium fluorozirconate, sodium fluorotitanate, sodium fluorozirconate, potassium fluorotitanate, and potassium fluorozirconate; and / or, The nonionic polyol surfactant is one selected from the group consisting of dipropylene glycol methyl ether, ethylene glycol ethyl ether, ethylene glycol butyl ether, triethanolamine, and isopropanol; and / or, The oxidizing agent is one or two selected from the group consisting of sodium nitrate, copper nitrate, potassium nitrate, potassium permanganate, bromate, hydrogen peroxide, and ammonium metavanadate; and / or, The hydroxycarboxylic acid group-containing compound is one or two selected from the group consisting of 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, and tannic acid. An environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, as described in claim 1.

4. The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, characterized in that the content of the fluorine-containing compound is 0.04 to 0.1 mol / L in terms of the molar concentration of fluorine ions, as described in claim 1.

5. The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, characterized in that the content of the nonionic polyol surfactant is 0.006 to 0.015 mol / L in terms of the molar concentration of hydroxyl groups, as described in claim 1.

6. The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, characterized in that the content of the oxidizing agent is 0.04 to 0.12 mol / L in terms of the molar concentration of the oxidizing agent, as described in claim 1.

7. The colloidal dispersion containing the colloidal silica particles is characterized in that the content of the colloidal dispersion is 0.015 to 0.03 mol / L in terms of the molar concentration of Si element, wherein the environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets is as described in claim 1.

8. The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, characterized in that the content of the hydroxycarboxylic acid group-containing compound is 0.8 to 1.5 mol / L in terms of the molar concentration of the carboxyl group, as described in claim 1.

9. The environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, as described in claim 1, characterized in that the pH of the environmentally friendly aqueous modification agent is 2 to 5.

10. The content of the aforementioned fluorine-containing compound is 0.03 to 0.1 mol / L in terms of the molar concentration of fluoride ions; The content of the nonionic polyol surfactant is 0.008 to 0.025 mol / L in terms of the molar concentration of hydroxyl groups (OH); The content of the oxidizing agent is 0.06 to 0.2 mol / L in terms of the molar concentration of the oxidizing agent; The content of the colloidal dispersion containing the colloidal silica particles is 0.015 to 0.04 mol / L in terms of the molar concentration of Si element; and The content of the hydroxycarboxylic acid group-containing compound is 0.7 to 1.2 mol / L in terms of the molar concentration of the carboxyl group (COOH). An environmentally friendly aqueous modification agent for improving the surface processing performance of galvanized steel sheets, as described in claim 1.

11. A method for improving the friction performance, bonding performance, phosphate treatment performance, and zirconium conversion treatment performance of a galvanized steel sheet, characterized by comprising the step of applying an environmentally friendly aqueous modification agent for improving the surface processing performance of a galvanized steel sheet, as described in any one of claims 1 to 10, to the surface of the galvanized steel sheet.

12. The method according to claim 11, characterized in that it includes applying the environmentally friendly aqueous modification agent to the surface of the galvanized steel sheet by impregnation, spraying, or roll coating to form a wet film, and then drying to form a nanoscale surface modification layer on the surface of the galvanized steel sheet.

13. A galvanized steel sheet having a nanoscale surface modification layer formed by drying an environmentally friendly aqueous modification agent according to any one of claims 1 to 10 applied to the surface of the galvanized steel sheet, preferably with a thickness of 20 to 80 mg / m². ２ A galvanized steel sheet characterized by the following:

14. The galvanized steel sheet described in claim 13 is a galvanized steel sheet used in the fields of automobiles, home appliances and construction, and is characterized in that it includes hot-dip galvanized steel sheets, electro-galvanized steel sheets and hot-dip zinc-iron alloy plated steel sheets.

15. Use of an environmentally friendly aqueous modification agent for improving the surface processing performance of a galvanized steel sheet according to any one of claims 1 to 10 on a galvanized steel sheet, or use for improving the friction performance, bonding performance, phosphate treatment performance and zirconium conversion treatment performance of a galvanized steel sheet.

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