Water-based surface treatment for surface aluminum-containing magnesium metal sheets and method of use thereof

Abstract

The application discloses a kind of for forming electron beam curing coating coil steel coating, effective component includes: composite matrix resin A: 40-60 parts by weight;Organosilicon compound B: 3-10 parts by weight;Monofunctional olefinic unsaturated polymerizable monomer C: 15-25 parts by weight;Acrylic acid phosphate ester compound D: 5-15 parts by weight;Titanium salt or zirconium salt of acrylic acid compound E: 0.2-3 parts by weight;Wherein, A includes 20-30wt% isobornyl acrylate containing aliphatic polyurethane acrylate oligomer A1 and 30-40wt% dipropylene glycol diacrylate containing amine modified epoxy diacrylate oligomer A2, the mass fraction ratio of A1 and A2 is: 1.0-5.0.Correspondingly, the application also discloses the steel plate with the electron beam curing coating formed by the coil steel coating on the surface.

Description

Technical Field

[0001] This invention relates to a surface treatment agent, and more particularly to a water-based surface treatment agent for metal plates. Background Technology

[0002] Automobile manufacturing is mainly divided into four major processes: forming, joining, painting, and final assembly. The joining process includes three techniques: welding, riveting, and adhesive bonding. The joining performance of body materials directly affects its structural stability and collision safety; therefore, it is essential to ensure the adhesive performance of the body panels. The factors influencing the surface adhesive performance of body materials mainly include physical and chemical properties. Physical properties are primarily affected by the adhesive's bonding strength along the surface physical contours and the adhesion of surface substances, while chemical properties are mainly affected by surface tension and the chemical reactivity of the surface layer.

[0003] On the other hand, multi-element alloy coatings containing Mg and Al are increasingly used in automotive body materials. However, the adhesive properties of these materials are one of the factors hindering their widespread application in the automotive industry. The main reasons are as follows: Al can react rapidly with oxygen in the air to form a stable, inert oxide film. The low chemical activity of this oxide layer is not conducive to interfacial bonding strengthening during the adhesive process. Mg is also a reactive metal, but the oxides it forms in the air are unstable and can further react with water and carbon dioxide in the air to form non-dense carbonate compounds. The insufficient physical bonding force between these substances and the substrate is also not conducive to interfacial bonding strengthening during the adhesive process.

[0004] Therefore, it is desirable to improve the surface adhesive properties of multi-element alloy coatings containing Mg and Al. Currently, there are two main approaches to improving surface adhesive properties: one is to remove oxides that are detrimental to adhesive properties through specific methods, mainly including chemical etching, plasma activation, and laser activation; the other is to optimize adhesive properties mainly through surface oxide layer control and chemical treatment.

[0005] For example, Chinese patent document CN108060382A, published on May 22, 2018, entitled "A Method for Improving the Adhesive Performance of Zinc-Aluminum-Magnesium Alloy Coated Steel Plates", optimizes the poor adhesive performance caused by surface Mg and Al oxides by covering the zinc-aluminum-magnesium coating surface with metallic Zn.

[0006] For example, Chinese patent document with publication number CN113512691A and publication date of October 19, 2021, entitled "A Zinc-Aluminum-Magnesium Coated Steel and Its Preparation Method", proposes to optimize the surface adhesive properties of zinc-aluminum-magnesium coated materials by designing the coating composition, adding rare earth elements and surface treatment (chemical oxidation treatment, high temperature oxidation treatment). Summary of the Invention

[0007] One of the objectives of this invention is to provide a water-based surface treatment agent for aluminum-magnesium-containing metal plates. When applied to coated steel plates or light alloy materials with Al and Mg coatings, this product can optimize the adhesive properties of the coated steel plates or light alloy materials with Al and Mg coatings while meeting the requirements of automotive painting processes.

[0008] To achieve the above objectives, the present invention provides a water-based surface treatment agent for aluminum-magnesium metal plates, the effective components of which include an alkaline aqueous composition A and a hydrate containing hydroxycarboxylic acid B;

[0009] The alkaline aqueous composition A comprises:

[0010] Alkaline compounds containing alkali metal elements, A1;

[0011] Buffer A2: at least one of sodium carbonate, sodium bicarbonate, glycine, and sodium tetraborate;

[0012] The hydrate B containing hydroxycarboxylic acid includes:

[0013] Compound B1 contains a hydroxycarboxylic acid;

[0014] Compound B2 contains six fluoride ions;

[0015] Surface tension modifier B3: at least one of sulfate ester salt, sulfonate salt and quaternary ammonium salt.

[0016] In this invention, the main function of the alkaline compound Al containing alkali metal elements is to etch the Mg and Al oxygen-containing compounds on the surface of Al and Mg coated steel plates or light alloy materials, so as to remove the Mg and Al oxygen-containing compounds that affect the adhesive properties.

[0017] In this invention, the main function of buffer A2 is to ensure the functional stability of the treatment agent. By buffering the pH value, the alkalinity of the alkaline aqueous composition A can be stably controlled during application.

[0018] In this invention, the main function of compound B1 containing hydroxycarboxylic acid is to significantly increase the number of hydroxyl groups on the surface of the treated metal material, thereby improving its adhesive properties, because the surface hydroxyl groups are easy to form strong chemical bonds with the adhesive.

[0019] In this invention, the main function of compound B2 containing six fluoride ions is to form a passivation layer with oxidation barrier function on the surface of the treated material, so as to prevent the surface Mg and Al elements from undergoing further oxidation during storage, transportation and processing, so as to prevent the formation of Mg and Al oxygen-containing compounds that are detrimental to the bonding performance.

[0020] In this invention, the main function of surface tension modifier B3 is to adjust surface tension. As an additive, it can effectively reduce the surface tension of hydrate B containing hydroxycarboxylic acid, enabling it to form a film quickly and uniformly. On the other hand, it can also reduce the surface tension of the modified layer after the treatment agent forms a film, making it more compatible with the adhesive and thus improving the bonding performance.

[0021] Furthermore, in the water-based surface treatment agent of the present invention, the mass ratio of the alkaline aqueous composition A to the hydroxycarboxylic acid hydrate B is 1:10 to 10:1.

[0022] Furthermore, in the water-based surface treatment agent of the present invention, the alkaline compound containing an alkali metal element includes at least one of the following: sodium phosphate, potassium phosphate, sodium silicate, sodium benzoate, sodium nitrite, sodium polyphosphate, and sodium pyrophosphate.

[0023] Furthermore, in the water-based surface treatment agent of the present invention, the molar content of the alkaline compound Al containing alkali metal elements in the alkaline aqueous composition A is 0.1-0.6 mol / L.

[0024] Furthermore, the molar content of the alkaline compound A1 containing alkali metal elements in the alkaline aqueous composition A is 0.25-0.5 mol / L.

[0025] When the content of alkaline compound Al containing alkali metal elements is below 0.1 mol / L, the removal efficiency of Mg and Al oxygen-containing compounds that affect adhesive properties decreases rapidly, thus affecting the adhesive optimization effect. When its content is above 0.6 mol / L, the reaction will be significantly enhanced, and over-etching and unevenness (spotting) are likely to occur.

[0026] Furthermore, in the water-based surface treatment agent of the present invention, the molar content of buffer A2 in the alkaline aqueous composition A is 0.01-0.08 mol / L.

[0027] When the content of buffer A2 is below 0.01 mol / L, it cannot achieve the required pH buffering effect; if the content is above 0.08 mol / L, the efficiency of the treatment agent will decrease significantly.

[0028] Furthermore, the molar content of buffer A2 in the alkaline aqueous composition A is 0.04-0.06 mol / L.

[0029] Furthermore, in the water-based surface treatment agent of the present invention, the pH value of the alkaline aqueous composition A is 8-11.

[0030] Furthermore, the pH value of the alkaline aqueous composition A is 9-10.5.

[0031] In this invention, after the alkaline aqueous composition A completes the mixed hydrolysis of alkaline compound A1 containing alkali metal elements and buffer A2, a sodium hydroxide solution, such as a 0.1 mol / L sodium hydroxide solution, can be used to adjust the pH value so that the pH value of the alkaline aqueous composition A is in the range of 8-11, preferably 9-10.5.

[0032] Furthermore, in the water-based surface treatment agent of the present invention, the compound B1 containing hydroxycarboxylic acid is selected from at least one of the following: 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, tartaric acid, lactic acid, and tannic acid.

[0033] Furthermore, in the water-based surface treatment agent of the present invention, the molar content of the hydroxycarboxylic acid compound B1 in the hydrate B containing hydroxycarboxylic acid, calculated based on the hydroxyl group, is 0.05-1 mol / L.

[0034] When the molar concentration of compound B1 containing hydroxycarboxylic acid in hydrate B is less than 0.05 mol / L, the optimization effect on surface adhesive properties decreases significantly. When the molar concentration of compound B1 containing hydroxycarboxylic acid in hydrate B is greater than 1 mol / L, a non-dense accumulation phenomenon occurs in the surface film, which leads to a decrease in adhesive properties.

[0035] Furthermore, in the water-based surface treatment agent of the present invention, the compound B2 containing six fluoride ions is selected from at least one of the following: ammonium fluorotitanate, sodium fluorosilicate, ammonium fluorozirconate, sodium fluorotitanate, sodium fluorozirconate, potassium fluorotitanate, and potassium fluorozirconate.

[0036] Furthermore, in the water-based surface treatment agent of the present invention, the molar content of the compound B2 containing six fluoride ions in the hydrate B containing hydroxycarboxylic acid, calculated as fluoride ions, is 0.05-0.16 mol / L.

[0037] When the content of compound B2 containing six fluoride ions is below 0.05 mol / L, the oxidative barrier effect decreases significantly. When its content is above 0.16 mol / L, the stability of hydrated hydroxycarboxylic acid B decreases significantly. At the same time, excessively high F ion content will affect the film-forming effect of compound B1 containing hydroxycarboxylic acid on the material surface, leading to a decrease in adhesive properties.

[0038] Furthermore, the molar content of the compound B2 containing six fluoride ions in the hydrate B containing hydroxycarboxylic acid is 0.07-0.11 mol / L.

[0039] Furthermore, in the water-based surface treatment agent of the present invention, the surface tension regulator B3 is selected from at least one of the following: sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

[0040] Furthermore, in the water-based surface treatment agent of the present invention, the molar content of the surface tension modifier B3 in the hydrate B containing hydroxycarboxylic acid is 0.001-0.006 mol / L.

[0041] When the content of surface tension modifier B3 is below 0.001 mol / L, the film-forming performance optimization effect of the treatment agent decreases significantly. When its content is above 0.006 mol / L, it will affect the adhesion performance of the surface modified layer film, resulting in a decrease in adhesive performance.

[0042] Furthermore, the surface tension modifier B3 has a molar content of 0.002-0.004 mol / L in the hydrate B containing hydroxycarboxylic acid.

[0043] Another object of the present invention is to provide a method of using a water-based surface treatment agent.

[0044] To achieve the above objectives, the present invention provides a method for using the water-based surface treatment agent described above, comprising the following steps:

[0045] First, the alkaline aqueous composition A is coated onto the surface of the metal plate and dried to form a film;

[0046] Then, a hydrate B containing hydroxycarboxylic acid is coated onto the coating and dried to form a film.

[0047] The alkaline aqueous composition A can be added to the leveling or tensioning process of a continuous coil steel production line with a surface spraying process, or it can be applied by adding application equipment before the coating process. The hydroxycarboxylic acid hydrate B can be applied in the coating process of the production line.

[0048] Furthermore, the present invention also provides another method for using the water-based surface treatment agent described above, which includes the following steps:

[0049] A mixed water-based surface treatment agent is obtained by mixing alkaline aqueous composition A and hydroxycarboxylic acid hydrate B.

[0050] The mixed water-based surface treatment agent is coated onto the surface of a metal plate and dried to form a film.

[0051] When using a mixed water-based surface treatment agent, the preferred application method is coating. This water-based surface treatment agent can form a film at room temperature, and after coating, it can be dried by blowing or baking, while high-temperature baking is not a necessary drying method.

[0052] As can be seen, the water-based surface treatment agent of this invention comprises two parts: an alkaline aqueous composition A and a hydrate containing hydroxycarboxylic acid B. In use, the material to be treated can be contacted sequentially with the alkaline aqueous composition A first, and then with the hydrate containing hydroxycarboxylic acid B. Alternatively, it can be directly contacted with a mixture of the alkaline aqueous composition A and the hydrate containing hydroxycarboxylic acid B for surface modification treatment. Contact methods can include immersion, spraying, and roller coating.

[0053] Another object of the present invention is to provide a metal plate applied with the water-based surface treatment agent described above.

[0054] Accordingly, the present invention provides a metal plate whose surface contains aluminum and magnesium elements, and the surface of the metal plate has a dry film applied by the method of use described above.

[0055] Furthermore, the metal plate is: a steel plate with a magnesium-aluminum coating, an aluminum alloy plate, or a magnesium alloy plate.

[0056] The water-based surface treatment agent of the present invention has the following characteristics and beneficial effects:

[0057] This invention, through theoretical analysis, extensive laboratory scientific research, and practical verification, ultimately determined the technical route for the nano-modification of typical material adhesive surfaces using an environmentally friendly water-based treatment agent. Combining the characteristics of how the structure of typical Mg and Al element oxides affects surface adhesive properties and the interface strengthening mechanism of the adhesive process, the water-based surface treatment agent described in this invention was obtained. This water-based surface treatment agent can meet the application requirements of materials such as Al and Mg coatings in high-speed continuous coil production processes and component manufacturing processes. Specifically, the treatment can be applied to the steel plate surface by methods such as immersion, spraying, and roller coating to form a wet film. By blowing or drying, the treatment agent can quickly form a surface modification layer of several nanometers thickness on the steel plate surface.

[0058] This modified treatment layer can form a large number of hydroxyl active sites on the material surface, thereby significantly improving the adhesive properties of the material surface, while not affecting the processing performance of molding, joining and painting processes in automobile manufacturing.

[0059] The method described in this invention is essentially a surface modification treatment method for optimizing the adhesive properties of coated steel plates or light alloy materials containing Al, Mg, etc. This method utilizes an economical and environmentally friendly water-based surface treatment agent. The application process of this invention is convenient, and the performance optimization is significant. While significantly improving the adhesive properties of the material surface, it does not affect the processing performance of molding, joining, and painting processes in automobile manufacturing. Detailed Implementation

[0060] The following will further explain and illustrate the water-based surface treatment agent for aluminum-magnesium metal plates and its application method described in this invention with reference to specific embodiments. However, this explanation and illustration do not constitute an undue limitation on the technical solution of this invention.

[0061] The metal plates to be processed selected in the various embodiments and comparative examples of this invention include two types:

[0062] Material 1 is a zinc-aluminum-magnesium coating material for automobiles. Specifically, it uses a commercially available low-aluminum zinc-aluminum-magnesium coating product for automobiles, with a substrate grade of CR4-ZM, a thickness of 1.0 mm, and a coating thickness of 40 g / m. 2 Table 1 lists the content of the basic components of Material 1.

[0063] Table 1

[0064] Content (wt%) 0.007 0.2 0.015 0.010 0.02

[0065] Material 2 is an aluminum sheet material for automobiles, specifically the typical 5182 aluminum alloy used in car bodies, with a thickness of 1.0 mm. Table 2 lists the basic composition of Material 2.

[0066] Table 2

[0067]

[0068] The metal plate to be treated is processed to a size of 100*25.4mm, and the edge burrs are effectively removed. Surface oil is removed by ultrasonic treatment with an organic solvent (acetone), and after drying, it is treated with the water-based surface treatment agent described in the embodiments and comparative examples of this invention.

[0069] Examples 1-8 and Comparative Examples 1-4

[0070] Alkaline aqueous composition A and hydroxycarboxylic acid hydrate B

[0071] Example 1:

[0072] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: first spray the alkaline aqueous composition A onto the surface of the metal plate, then blow dry to form a film; then roll coat the hydrate B containing hydroxycarboxylic acid, and then dry to form a film.

[0073] The alkaline aqueous composition A is prepared by hydrolysis of 0.3 mol / L sodium phosphate and sodium silicate A1 and 0.02 mol / L glycine A2, followed by pH adjustment to 9.5 using 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is composed of: tartaric acid B1 with a hydroxyl molar content of 0.3 mol / L, ammonium fluorotitanate and ammonium fluorozirconate B2 with an F ion content of 0.09 mol / L, and sodium dodecyl sulfate B3.

[0074] Example 2:

[0075] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: after mixing and preparing the alkaline aqueous composition A and the hydrate containing hydroxycarboxylic acid B, a film is formed by roller coating and drying.

[0076] The alkaline aqueous composition A is prepared by hydrolyzing 0.25 mol / L potassium phosphate A1 and 0.03 mol / L glycine A2, followed by pH adjustment to 9.5 using 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is composed of: oxalic acid + citric acid B1 with a hydroxyl molar content of 0.15 mol / L, sodium fluorotitanate B2 with a F ion content of 0.07 mol / L, and sodium dodecyl sulfate B3.

[0077] Example 3:

[0078] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray the alkaline aqueous composition A, then blow it dry to form a film, then spray the hydrate B containing hydroxycarboxylic acid, and blow it dry to form a film.

[0079] The alkaline aqueous composition A consists of 0.6 mol / L sodium pyrophosphate A1 and 0.01 mol / L sodium tetraborate A2, which are hydrolyzed, and then the pH is adjusted to 9 using a 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B comprises: 3,4,5-trihydroxybenzoic acid + lactic acid B1 with a hydroxyl content of 0.08 mol / L, ammonium fluorozirconate B2 with a F ion content of 0.16 mol / L, and sodium dodecylbenzenesulfonate + octadecyltrimethylammonium chloride B3, all mixed together.

[0080] Example 4:

[0081] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0082] The alkaline aqueous composition A is selected from the following: 0.2 mol / L sodium benzoate A1 and 0.08 mol / L sodium tetraborate + glycine A2 are hydrolyzed, and then the pH is adjusted to 10.5 with 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is composed of: citric acid B1 with a hydroxyl molar content of 0.9 mol / L, potassium fluorozirconate + sodium fluorosilicate B2 with an F ion content of 0.14 mol / L, and octadecyltrimethylammonium chloride B3 mixed together.

[0083] Example 5:

[0084] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0085] The alkaline aqueous composition A consists of 0.4 mol / L sodium polyphosphate A1 and 0.04 mol / L sodium carbonate A2, which are hydrolyzed and then the pH is adjusted to 8 using a 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is prepared by mixing and dissolving salicylic acid B1 (0.05 mol / L hydroxyl content), ammonium fluorotitanate B2 (0.05 mol / L F ion content), and sodium dodecyl sulfate B3.

[0086] Example 6:

[0087] Material 2 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: after mixing alkaline aqueous composition A and hydrate containing hydroxycarboxylic acid B, a film is formed by roller coating and drying.

[0088] The alkaline aqueous composition A is prepared by hydrolyzing 0.1 mol / L sodium nitrite A1 and 0.05 mol / L sodium bicarbonate A2, followed by adjusting the pH to 11 with 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is prepared by mixing and dissolving ethylenediaminetetraacetic acid (EDTA) B1 (0.05 mol / L hydroxyl content), ammonium fluorozirconate (0.11 mol / L F ion content) B2, and octadecyltrimethylammonium chloride (0.004 mol / L) B3.

[0089] Example 7:

[0090] Material 2 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0091] The alkaline aqueous composition A is prepared by hydrolyzing 0.5 mol / L sodium pyrophosphate + sodium polyphosphate A1 and 0.065 mol / L sodium tetraborate A2, followed by adjusting the pH to 10 with 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is prepared by mixing and dissolving 1 mol / L lactic acid B1 (hydroxyl content 1 mol / L), 0.12 mol / L sodium fluorosilicate B2 (F ion content 0.12 mol / L), and 0.002 mol / L sodium dodecyl sulfate + sodium dodecylbenzenesulfonate B3.

[0092] Example 8:

[0093] Material 2 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0094] The alkaline aqueous composition A is prepared by hydrolyzing 0.6 mol / L sodium silicate A1 and 0.07 mol / L glycine + sodium carbonate A2, followed by adjusting the pH to 9.5 with 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is prepared by mixing and dissolving 0.5 mol / L tannic acid + salicylic acid B1 (hydroxyl content), 0.06 mol / L sodium fluorotitanate B2 (F ion content), and 0.001 mol / L hexadecyltrimethylammonium chloride B3.

[0095] Comparative Example 1:

[0096] Material 1 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0097] The alkaline aqueous composition A is prepared by hydrolyzing 0.8 mol / L sodium phosphate A1 and 0.08 mol / L glycine A2, followed by adjusting the pH to 9.5 with 0.1 mol / L sodium hydroxide solution. The hydroxycarboxylic acid hydrate B is prepared by mixing and dissolving oxalic acid B1 (1.1 mol / L hydroxyl content), ammonium fluorotitanate B2 (0.18 mol / L F ion content), and sodium dodecylbenzenesulfonate B3.

[0098] Comparative Example 2:

[0099] The metal plate to be processed is material 1, which has not undergone surface modification treatment.

[0100] Comparative Example 3:

[0101] Material 2 is selected for the metal plate to be treated. The method of using the water-based surface treatment agent is as follows: spray alkaline aqueous composition A, then blow dry to form a film; then roll coat hydrate B containing hydroxycarboxylic acid, and dry to form a film.

[0102] The alkaline aqueous composition A is hydrolyzed using 0.08 mol / L sodium pyrophosphate A1 and 0.009 mol / L sodium tetraborate A2. The hydrate containing hydroxycarboxylic acid B is hydrolyzed using ethylenediaminetetraacetic acid B1 with a hydroxyl molar content of 0.04 mol / L and ammonium fluorozirconate B2 with an F ion content of 0.04 mol / L.

[0103] Comparative Example 4:

[0104] The metal plate to be processed is material 2, which has not undergone surface modification treatment.

[0105] Table 3 lists the components and contents of the water-based surface treatment agents in Examples 1-8 and Comparative Examples 1-4.

[0106]

[0107] It should be noted that although the above embodiments 1-8 provide optional single substances or combinations of two substances for A1, A2, B1, B2 and B3, combinations of more than two substances are also feasible within the optional substance range in other embodiments.

[0108] Examples 1-8 and Comparative Examples 1-4 were coated with oil, stacked, and left to stand for one week before being evaluated for adhesive performance. The adhesive and sample preparation method are described below:

[0109] For adhesive bonding, a typical structural adhesive is selected: TEROSON EP 5089;

[0110] The adhesive bonding area for the sample preparation is 3.2 cm², and the adhesive thickness is 0.2 mm, specifically referring to standard SAE J1523;

[0111] Adhesive curing (severe curing conditions): Curing temperature: 160℃, time: 15min.

[0112] The method for evaluating adhesive bonding performance is as follows:

[0113] After curing and bonding, the samples were placed in deionized water at 55°C for 7 days, then removed for tensile peel testing. Tensile test: conducted according to ASTM D 1 002, tensile speed 13 mm / min. The adhesive performance was evaluated by the peel test.

[0114] The two samples after tensile peeling were analyzed for peeling methods (there are two types of peeling methods: cohesive peeling, which is the internal breakage of the adhesive; and interfacial peeling, which is the separation of the adhesive from the metal surface). The adhesive performance was evaluated by the percentage of cohesive peeling area, and the results are listed in Table 4.

[0115] Table 4.

[0116]

[0117]

[0118] The symbols in Table 4 are explained as follows:

[0119] ◎: Cohesion stripping area = 100%

[0120] ○: 85% ≤ cohesive stripping area < 100%

[0121] △: 65% ≤ Phosphating film coverage < 85%

[0122] ×: Phosphating film coverage < 65%

[0123] As can be seen from Table 4, Examples 1-8 of the present invention exhibit good adhesive properties. A comparison of Examples 1-8 with Comparative Examples 2 and 4 shows that the adhesive properties of Materials 1 and 2, after surface modification treatment with a water-based surface treatment agent, are significantly improved.

[0124] As can be seen from the comparison of the various embodiments and Comparative Example 1, when the component content of the water-based surface treatment agent is excessive, the degree of optimization of the adhesive performance of the material surface decreases, and its surface adhesive performance is not as good as that of the embodiments.

[0125] As can be seen from the comparison of the various embodiments and Comparative Example 3, when the water-based surface treatment agent components do not meet the requirements of the present invention, the surface adhesive performance cannot be effectively controlled.

[0126] It should be noted that the embodiments listed above are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and similar changes or modifications made thereto are those that can be directly derived or easily conceived by those skilled in the art from the content disclosed in the present invention, and should all fall within the protection scope of the present invention.

Claims

1. A water-based surface treatment agent for aluminum-magnesium-containing metal plates, characterized in that, Its active ingredients include: alkaline aqueous composition A and hydrate containing hydroxycarboxylic acid B; The alkaline aqueous composition A comprises: The alkaline compound A1 containing an alkali metal element has a molar content of 0.1-0.6 mol / L in the alkaline aqueous composition A; the alkaline compound containing an alkali metal element includes at least one of the following: sodium phosphate, potassium phosphate, sodium polyphosphate, and sodium pyrophosphate. Buffer A2: at least one of sodium carbonate, sodium bicarbonate, glycine, and sodium tetraborate; the molar content of buffer A2 in the alkaline aqueous composition A is 0.01-0.08 mol / L; The hydroxycarboxylic acid hydrate B comprises: Compound B1 containing hydroxycarboxylic acid has a molar content of 0.05-1 mol / L based on the hydroxyl group in the hydrate B containing hydroxycarboxylic acid. The compound B2 containing six fluoride ions has a molar content of 0.05-0.16 mol / L based on fluoride ions in the hydrate B containing hydroxycarboxylic acid; the compound B2 containing six fluoride ions is selected from at least one of the following: ammonium fluorotitanate, sodium fluorosilicate, ammonium fluorozirconate, sodium fluorotitanate, sodium fluorozirconate, potassium fluorozirconate. Surface tension modifier B3: at least one of sulfate ester salt, sulfonate salt and quaternary ammonium salt; the molar content of surface tension modifier B3 in hydrate B containing hydroxycarboxylic acid is 0.001-0.006 mol / L; The mass ratio of the alkaline aqueous composition A to the hydroxycarboxylic acid hydrate B is 1:10 to 10:

1.

2. The water-based surface treatment agent as described in claim 1, characterized in that, The alkaline compound containing an alkali metal element also includes at least one of the following: sodium silicate, sodium benzoate, and sodium nitrite.

3. The water-based surface treatment agent as described in claim 1, characterized in that, The molar content of the alkaline compound A1 containing alkali metal elements in the alkaline aqueous composition A is 0.25-0.5 mol / L.

4. The water-based surface treatment agent as described in claim 1, characterized in that, The molar content of buffer A2 in alkaline aqueous composition A is 0.04-0.06 mol / L.

5. The water-based surface treatment agent as described in claim 1, characterized in that, The pH value of the alkaline aqueous composition A is 8-11.

6. The water-based surface treatment agent as described in claim 5, characterized in that, The pH value of the alkaline aqueous composition A is 9-10.

5.

7. The water-based surface treatment agent as described in claim 1, characterized in that, The compound B1 containing a hydroxycarboxylic acid is selected from at least one of the following: 3,4,5-trihydroxybenzoic acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid, salicylic acid, lactic acid, and tannic acid.

8. The water-based surface treatment agent as described in claim 1, characterized in that, The molar concentration of compound B2 containing six fluoride ions in hydrate B containing hydroxycarboxylic acid is 0.07-0.11 mol / L.

9. The water-based surface treatment agent as described in claim 1, characterized in that, The surface tension modifier B3 is selected from at least one of the following: sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, hexadecyltrimethylammonium chloride, and octadecyltrimethylammonium chloride.

10. The water-based surface treatment agent as described in claim 1, characterized in that, The surface tension modifier B3 has a molar content of 0.002-0.004 mol / L in the hydrate B containing hydroxycarboxylic acid.

11. A method of using the water-based surface treatment agent as described in any one of claims 1-10, characterized in that, Including the following steps: First, the alkaline aqueous composition A is coated onto the surface of the metal plate and dried to form a film; Then, a hydrate B containing hydroxycarboxylic acid is coated onto the coating and dried to form a film.

12. A method of using the water-based surface treatment agent as described in any one of claims 1-10, characterized in that, Including the following steps: A mixed water-based surface treatment agent is obtained by mixing alkaline aqueous composition A and hydroxycarboxylic acid hydrate B. The mixed water-based surface treatment agent is coated onto the surface of a metal plate and dried to form a film.

13. A metal plate, the surface of which contains aluminum and magnesium elements, characterized in that, Its surface has a dry film applied using the method of use as described in claim 11.

14. The metal plate as claimed in claim 13, characterized in that, The metal plate is: a steel plate with a magnesium-aluminum coating, an aluminum alloy plate, or a magnesium alloy plate.

15. A metal plate, the surface of which contains aluminum and magnesium elements, characterized in that, Its surface has a dry film applied using the method of use as described in claim 12.

16. The metal plate as claimed in claim 15, characterized in that, The metal plate is: a steel plate with a magnesium-aluminum coating, an aluminum alloy plate, or a magnesium alloy plate.

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