Water-based ball-milled passivated aluminum paste as well as preparation method and application thereof

Abstract

The invention relates to a water-based ball-milled passivated aluminum paste and a preparation method and application thereof, and the preparation method comprises the following steps: carrying out ball milling on aluminum powder, a surface modifier, a hydrophilic solvent and an inorganic passivator until the target particle size of the aluminum powder is reached, and obtaining preliminarily passivated aluminum paste; carrying out suction filtration on the primarily passivated aluminum paste, uniformly stirring and mixing, adding an organic passivator, continuously stirring to carry out a passivation reaction, adding an auxiliary agent, and continuously stirring to obtain aluminum paste; wherein the organic passivator is a combination of a micromolecular organic passivator and a macromolecular organic passivator. According to the method, the in-situ passivation technology is adopted, the aluminum sheet is passivated in the extension process, the influence of dissolution and auxiliaries on the aluminum sheet is small, a more compact protective film is formed through the synergistic effect of the inorganic passivator and the organic passivator and through the oxidation film layer, chelation and precipitation reaction, corrosion of aluminum powder is greatly inhibited, and the service life of the aluminum sheet is prolonged. And the water-based passivated aluminum paste and a water-based resin system maintain good compatibility, and can show good glossiness.

Description

Technical Field

[0001] This invention belongs to the field of metal coating technology, specifically relating to a water-based ball milling passivation aluminum silver paste, its preparation method, and its application. Background Technology

[0002] Water-based aluminum silver paste uses water as a hydrophilic solvent, is non-toxic, pollution-free, and has low VOCs (volatile organic compounds), meeting environmental protection requirements. In contrast, oil-based aluminum silver paste contains a large amount of organic solvents, resulting in higher VOC emissions, which are detrimental to the environment and human health. Currently, there are generally two methods for preparing water-based aluminum silver paste: Firstly, spherical aluminum powder, surface treatment agents, and hydrophilic solvents are mixed, wet ball milled, and then coated with silicon-containing compounds or passivated with corrosion inhibitors to form a protective layer on the surface of the flake aluminum particles, thereby preventing aluminum metal ions from reacting with the medium. The coating reaction process requires high-precision equipment and precise control and strict operation, so the complexity of the production process leads to generally high production costs.

[0003] Secondly, such as Figure 1 As shown, by adding a passivating agent to perform water-based passivation treatment on oily aluminum silver paste, a passivation film is coated on the surface of aluminum powder, which can prevent aluminum powder from reacting with the external environment to a certain extent. However, it is impossible to completely remove the solvents and additives used in the oily ball milling process, which affects the effectiveness of passivation and easily leads to problems such as large amount of gas release and batch instability during application and storage.

[0004] To address the aforementioned issues, this invention provides an aqueous ball milling passivation aluminum silver paste, its preparation method, and its application. Summary of the Invention

[0005] The purpose of this invention is to provide an aqueous ball milling passivation aluminum silver paste, its preparation method, and its application in order to solve the above-mentioned problems.

[0006] The present invention achieves the above objectives through the following technical solutions: A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: Aluminum powder, surface modifier, hydrophilic solvent, and inorganic passivator are ball-milled in a ball mill with ball milling media to the target particle size of aluminum powder to obtain a pre-passivated aluminum silver paste; During ball milling, the surface of spherical aluminum powder is continuously subjected to mechanical forces. Due to aluminum's excellent ductility, the spherical aluminum powder continuously expands into flakes during milling, resulting in a continuous increase in newly formed surface areas. Inorganic passivating agents and surface modifiers are easily adsorbed onto these highly active surfaces. Specifically, the added inorganic passivating agent initially passivates the newly formed surface of the aluminum powder, forming a dense film layer composed of aluminum oxide, metal hydrates, and metal salts. The functional groups in the added surface modifier react with trace amounts of hydroxyl groups adsorbed on the aluminum powder surface, coupling them to the aluminum flake surface to form a molecular layer, thereby effectively improving the surface morphology of the aluminum powder and providing a better foundation for subsequent passivation. Moreover, the above reaction can continue throughout the entire ball milling process.

[0007] S2: Filter the pre-passivated aluminum silver paste, stir and mix it, then add an organic passivating agent, continue stirring to carry out the passivation reaction, then add an additive and continue stirring to obtain aluminum silver paste; wherein, the organic passivating agent is a combination of small molecule organic passivating agent and large molecule organic passivating agent, the molecular weight of the small molecule organic passivating agent is 210-280, and the molecular weight of the large molecule organic passivating agent is 5000-10000; The corrosion-inhibiting groups in the added organic passivating agent molecules will chelate with the metal ions on the surface of the flake aluminum powder. In addition, the inorganic passivating agent remaining in the silver paste and the precipitation reaction of the metal ions on the surface of the aluminum powder are still ongoing. The synergistic effect of chelation and precipitation forms a denser passivation protective film on the surface of the flake aluminum particles, which can effectively isolate the aluminum particles in the film from external substances and greatly inhibit the occurrence of corrosion. The added organic passivating agents are divided into small molecule organic passivating agents and large molecule organic passivating agents. The advantage of small molecule organic passivating agents is that they can work with the passivation protective film formed on the aluminum sheet surface to have a more obvious effect on inhibiting corrosion. The advantage of large molecule organic passivating agents is that the passivation protective film is thicker and has a stronger protective ability on the aluminum sheet surface. The synergistic effect of small and large molecule organic passivating agents increases the thickness of the protective film on the aluminum sheet surface and also enhances the corrosion inhibition effect. Some groups in small-molecule organic passivating agents can combine with hydroxyl groups on the aluminum sheet surface to form an organic passivation film protective layer. However, because the protective layer built by small-molecule organic passivating agents on the aluminum sheet surface is relatively thin, the aluminum sheet surface cannot be completely passivated. Adding macromolecular organic passivating agents allows the macromolecules in the passivating agent to react with the unpassivated parts of the aluminum sheet surface to generate a passivation film that simultaneously covers the passivation film formed by the small-molecule organic passivating agents. Because the organic passivating agent macromolecules bonded to the aluminum sheet surface are negatively charged, like charges repel each other, resulting in a disordered arrangement. As the passivation layer thickness on the aluminum sheet surface increases, it gradually attracts positive and negative charges within the system to combine, causing the molecules of the protective layer on the aluminum sheet surface to gradually arrange themselves in an orderly manner, thereby making the passivation film formed on the aluminum sheet surface more dense. The added additives can neutralize some of the functional groups in the organic passivating agent molecules, while modifying the surface of the aluminum silver paste. They also prevent the agglomeration of flake aluminum particles through steric hindrance stabilization, increase the leveling properties of the silver paste, and enhance the gloss of the aluminum flake surface, thereby effectively solving problems such as the gloss, storage stability, and dispersibility in water of the silver paste.

[0008] S3: After the aluminum silver paste is encapsulated, it is placed in a room temperature environment for 2-3 days to obtain water-based passivated aluminum silver paste.

[0009] As a further optimization of the present invention, the aluminum powder is spherical aluminum powder; the amount of the hydrophilic solvent is 1.5-5.5 times that of the spherical aluminum powder; the ball milling uses 6-8mm steel balls, and the ball-to-material ratio is (25-48):1; the mass ratio of the spherical aluminum powder to the surface modifier is 100:1-3; and the mass ratio of the spherical aluminum powder to the inorganic passivating agent is 100:1-3.

[0010] As a further optimization of the present invention, in step S1, the hydrophilic solvent is at least one of ethylene glycol ethyl ether, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, and dipropylene glycol dimethyl ether. The surface modifier is at least one of silane coupling agents and titanate coupling agents.

[0011] As a further optimization of the present invention, in step S1, the inorganic passivating agent is at least one of orthophosphoric acid and sodium metavanadate.

[0012] As a further optimization of the present invention, in step S1, the initial ball milling speed is 30-50 r / min; when the particle size of the aluminum silver paste reaches a difference of 2-3 μm from the target particle size of the aluminum powder, the ball milling speed is reduced to 15-25 r / min until the target particle size is reached.

[0013] As a further optimization of the present invention, in step S2, the amount of the organic passivating agent is 3-10% of the solid content of the aluminum silver paste; the amount of the additive is 5-10% of the mass of the aluminum silver paste.

[0014] As a further optimization of the present invention, in step S2, the small molecule organic passivating agent and the macromolecule organic passivating agent are composed in a mass ratio of 1-6:1; Among them, the small molecule organic passivating agent is composed of octyl salicylate and sodium dodecyl sulfonate, and the mass ratio of octyl salicylate to sodium dodecyl sulfonate is 1:3-1:20; The macromolecular organic passivating agent is composed of polydimethylsiloxane and sodium dodecyl sulfonate, with polydimethylsiloxane as the main component and the mass ratio of polydimethylsiloxane to sodium dodecyl sulfonate being 5:1-50:1. As a further optimization of the present invention, in step S2, the auxiliary agent is at least one of palmitic acid, stearic acid, and aspartic acid.

[0015] The present invention also provides an aqueous ball milling passivation aluminum silver paste, which is prepared by the preparation method described above.

[0016] The present invention also provides the application of the above-described water-based ball-milled passivated aluminum silver paste in the preparation of water-based coatings.

[0017] The beneficial effects of this invention are as follows: 1) This invention employs in-situ passivation technology to passivate aluminum sheets during the stretching process. The passivation process is less affected by solvents and additives. Through the synergistic effect of inorganic and organic passivating agents, a denser protective film is formed through oxide film layer, chelation and precipitation reactions, which greatly inhibits the corrosion of aluminum powder. Furthermore, the solvents and additives used are highly hydrophilic, which ensures that the prepared water-based passivated aluminum silver paste maintains good compatibility with the water-based resin system and exhibits good gloss. 2) During the ball milling process, new surfaces are continuously generated, and passivating agents and modifiers can be adsorbed and reacted in a timely manner to form a dynamic protective film construction process, ensuring that the surface of aluminum powder is always in a protected state. 3) This invention increases the thickness of the protective film and enhances the corrosion inhibition effect through the synergistic application of large and small molecule organic passivating agents. At the same time, it makes the protective film more compact through charge action. Attached Figure Description

[0018] Figure 1 This is a technical roadmap for preparing water-based passivated aluminum silver paste (processed using oil-based aluminum silver paste) in the existing technology.

[0019] Figure 2 This is a technical roadmap for preparing water-based passivated aluminum silver paste according to the present invention; Figure 3 These are experimental graphs showing the impact resistance of scraper samples of water-based passivated aluminum silver paste and commercially available aluminum silver paste (standard sample) from Example 3 of this invention, under the same dispersion system. Figure 4 This is an experimental diagram showing the adhesion performance of the water-based passivated aluminum silver paste and commercially available aluminum silver paste (standard sample) of the bottle paint system in Example 3 of this invention. Detailed Implementation

[0020] The present application will now be described in further detail with reference to the accompanying drawings. It should be noted that the following specific embodiments are only used to further illustrate the present application and should not be construed as limiting the scope of protection of the present application. Those skilled in the art can make some non-essential improvements and adjustments to the present application based on the above application content.

[0021] 1. The aluminum powder is spherical with a particle size of 2-19μm; the ball mill uses 6-8mm steel balls with a ball-to-material ratio of (25-48):1 and an initial ball milling speed of 30-50r / min; when the aluminum silver paste particle size reaches the target particle size difference of 2-3μm, the ball milling speed is reduced to 15-25r / min. 2. Hydrophilic solvent: at least one of ethylene glycol ethyl ether, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, and dipropylene glycol dimethyl ether, preferably ethylene glycol butyl ether; 3. Surface modifier: at least one of silane coupling agent (A-171 vinyl silane coupling agent) and titanate coupling agent, wherein the mass ratio of A-171 vinyl silane coupling agent and titanate coupling agent is selected as 1:3-5 (preferably 1:4). 4. Inorganic passivating agent: at least one of orthophosphoric acid and sodium metavanadate; when the two are compounded, the mass ratio of orthophosphoric acid and sodium metavanadate is 1:5-10, preferably 1:7. 5. Organic passivating agent: composed of small molecule organic passivating agent and large molecule organic passivating agent. The molecular weight of the small molecule organic passivating agent is 210-280, and the molecular weight of the large molecule organic passivating agent is 5000-10000. The mass ratio of the small molecule organic passivating agent to the large molecule organic passivating agent is 1-6:1 (preferably 5:1). In this invention, the small molecule organic passivating agent includes octyl salicylate (molecular weight about 222.3) and sodium dodecyl sulfonate (molecular weight about 272.4), with a mass ratio of 1:3 to 1:20 and a molecular weight of 210 to 280, preferably with a mass ratio of 1:3 to 1:10. The macromolecular organic passivating agents include polydimethylsiloxane (molecular weight of 5000-10000, preferably 8352.7) and sodium dodecyl sulfonate (molecular weight of about 272.4), in a mass ratio of 5:1-50:1; preferably 5:1-20:1. 6. Additives: Palmitic acid + aspartic acid (mass ratio 1:6-10, preferably 1:7) or stearic acid + aspartic acid (mass ratio 1:5-10, preferably 1:6); Note: Unless otherwise specified, the preferred schemes were used in the following verification tests; Unless otherwise specified, all methods used in this application are conventional methods known to those skilled in the art, and all reagents and materials used are commercially available products unless otherwise specified.

[0022] Example 1

[0023] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 6.5 kg of spherical aluminum powder, 190 g of surface modifier, 22 kg of hydrophilic solvent, and 120 g of inorganic passivating agent (phosphoric acid) are ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste is 2-3 μm different from the target particle size of the aluminum powder, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 3.2% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 5:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5) and stir continuously at 15 r / min for 40 minutes; finally add 6% of the additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0024] Example 2

[0025] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 6 kg of spherical aluminum powder, 170 g of surface modifier, 20 kg of hydrophilic solvent, and 130 g of inorganic passivating agent (sodium metavanadate) are ball-milled in a ball mill with 225 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 10:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:3) and stir continuously at 15 r / min for 40 minutes; finally add 7.5% additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0026] Example 3

[0027] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivating agent (phosphoric acid and sodium metavanadate in a mass ratio of 1:7) are ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5) and stir continuously at 15 r / min for 40 minutes; finally add 8.2% of the additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0028] Example 4

[0029] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivating agent (phosphoric acid) are ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5) and stir continuously at 15 r / min for 40 minutes; finally add 8.2% of the additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0030] Example 5

[0031] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivating agent (phosphoric acid and sodium metavanadate in a mass ratio of 1:7) are ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:10) and stir continuously at 15 r / min for 40 minutes; finally add 8.2% of the additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0032] Example 6

[0033] A method for preparing an aqueous ball-milled passivated aluminum silver paste includes the following steps: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivating agent (phosphoric acid and sodium metavanadate in a mass ratio of 1:7) are ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed is reduced to 21 r / min until the target particle size of the aluminum powder is reached; S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent based on the solid content of the aluminum silver paste and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 18:1) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5) and stir continuously at 15 r / min for 40 minutes; finally add 8.2% of the additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. S3: After the aluminum silver paste processed in step S2 is taken out and packaged, it is placed in a room temperature environment (20℃±2℃) for 2-3 days to obtain water-based passivated aluminum silver paste.

[0034] Comparative Example 1 Based on the preparation method of Example 3, only step S1 was adjusted in this comparative example, and the adjusted step is as follows: The hydrophilic solvent in Example 3 was replaced with water, while everything else remained the same, as follows: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of water, and 135 g of inorganic passivating agent (phosphoric acid and sodium metavanadate in a mass ratio of 1:7) were ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a preliminarily passivated aluminum silver paste; the rest were consistent with the preparation method of Example 3.

[0035] Comparative Example 2 Based on the preparation method of Example 3, only step S1 was adjusted in this comparative example, and the adjusted step is as follows: The inorganic passivating agent (phosphoric acid and sodium metavanadate in a mass ratio of 1:7) in Example 3 is replaced with a phosphate, with everything else remaining unchanged, as follows: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivating agent (phosphomolybdic acid) were ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a preliminarily passivated aluminum silver paste; the rest were consistent with the preparation method of Example 3.

[0036] Comparative Example 3 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: No organic passivating agent is added, everything else remains the same, as follows: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader to mix for 5-10 minutes. Then add 8.2% of the additive by weight of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. The rest is consistent with the preparation method of Example 3.

[0037] Comparative Example 4 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: Only the macromolecular organic passivating agent remains unchanged, as detailed below: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% of the solid content of the aluminum silver paste as an organic passivating agent and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent and stir continuously at 18 r / min for 55 minutes. Then add the macromolecular organic passivating agent (the amount of which is the same as the amount of small molecule organic passivating agent in Example 3) and stir continuously at 15 r / min for 40 minutes. Finally, add 8.2% of the mass of the aluminum silver paste as an additive and stir continuously at 12 r / min for 35 minutes. The rest is consistent with the preparation method in Example 3.

[0038] Comparative Example 5 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: Only the small molecule organic passivating agent remains unchanged, as detailed below: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% of the solid content of the aluminum silver paste with organic passivating agent and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the small molecule organic passivating agent (the amount of which is the same as the amount of the macromolecular organic passivating agent in Example 3), stir continuously at 18 r / min for 55 minutes, then add the small molecule organic passivating agent, stir continuously at 15 r / min for 40 minutes, and finally add 8.2% of the mass of the aluminum silver paste with additives and stir continuously at 12 r / min for 35 minutes. The rest is consistent with the preparation method in Example 3.

[0039] Comparative Example 6 Based on the preparation method of Example 3, only step S1 was adjusted in this comparative example, and the adjusted step is as follows: No inorganic passivating agent was added for in-situ passivation; everything else remained unchanged, as follows: S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, and 23 kg of hydrophilic solvent were ball-milled in a ball mill with 230 kg of ball milling media to the target particle size of the aluminum powder to obtain a pre-passivated aluminum silver paste; the initial ball milling speed was 42 r / min; when the particle size of the aluminum silver paste reached the target particle size of the aluminum powder minus 2-3 μm, the ball milling speed was reduced to 21 r / min until the target particle size of the aluminum powder was reached; the rest were consistent with the preparation method in Example 3.

[0040] Comparative Example 7 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: Replace the organic passivating agent in step S2 with an equal mass of inorganic passivating agent, while keeping everything else unchanged, as follows: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it evenly. Then add 4.5% inorganic passivating agent based on the solid content of the aluminum silver paste. Add inorganic passivating agent (the amount is the same as the amount of macromolecular organic passivating agent in Example 3). Stir continuously at 18 r / min for 55 minutes. Then add inorganic passivating agent (the amount is the same as the amount of small molecule organic passivating agent in Example 3). Stir continuously at 15 r / min for 40 minutes. Finally, add 8.2% additive based on the mass of the aluminum silver paste and continue stirring at 12 r / min for 35 minutes. The rest is consistent with the preparation method in Example 3.

[0041] Comparative Example 8 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: The molecular weights of the organic passivating agents differ, but other aspects remain the same, as detailed below: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% organic passivating agent of the aluminum silver paste solid content and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the macromolecular organic passivating agent (molecular weight of 15124.3) and stir continuously at 18 r / min for 55 minutes; then add the small molecule organic passivating agent (molecular weight of 397.5) and stir continuously at 15 r / min for 40 minutes; finally add 8.2% of the additives of the aluminum silver paste mass and stir continuously at 12 r / min for 35 minutes. The rest is consistent with the preparation method of Example 3.

[0042] Comparative Example 9 Based on the preparation method of Example 3, only step S2 was adjusted in this comparative example, and the adjusted step is as follows: First add the small-molecule organic passivating agent, then add the large-molecule organic passivating agent, keeping everything else unchanged, as follows: S2: Take out the pre-passivated aluminum silver paste, filter it, and put it into a kneader for 5-10 minutes to mix it. Then add 6.5% of the solid content of the aluminum silver paste as an organic passivating agent and stir continuously at 10-20 r / min for 60-120 minutes to carry out the passivation reaction. Specifically, first add the small molecule organic passivating agent and stir continuously at 15 r / min for 40 minutes; then add the large molecule organic passivating agent and stir continuously at 18 r / min for 55 minutes; finally add 8.2% of the mass of the aluminum silver paste as an additive and stir continuously at 12 r / min for 35 minutes. The rest is consistent with the preparation method in Example 3.

[0043] Comparative Example 10 S1: Add 40 kg of spherical aluminum powder and 80-120 kg (preferably 103 kg) of 90# petroleum ether to a ball mill. Adjust the speed of the ball mill (225 kg of ball milling media) to 5 r / min and stir for 30 min for pre-dispersion. After pre-dispersion, add 0.04-0.1 kg (preferably 0.08 kg) of oleic acid and 0.15-0.2 kg (preferably 0.17 kg) of silicic acid. Adjust the speed of the ball mill to 30-40 r / min and ball mill for 15-20 h (preferably 35 r / min for 18 h). Filter the mixture after discharge to obtain oily aluminum silver paste. Step S2: Use the oily aluminum silver paste obtained in step S1 as raw material to replace the initially passivated aluminum silver paste for subsequent processing steps. All other steps are consistent with the preparation method in Example 3.

[0044] 1. Hydrogen evolution test (1) Test method: Test coating samples (Example 1-6 groups) and control coating samples (Comparative Example 1-10 groups and commercially available aluminum silver paste, i.e. standard samples) were prepared according to 10% of the water-based passivated aluminum silver paste of the Example group / Comparative Example group + 16% water + 74% water-based resin (the water-based resin was from the same batch). The pH was 8.5-8.6. The two groups of ink samples were placed in the same hydrogen evolution device and stored at room temperature (22℃±2℃) and in a 50℃ constant temperature water bath. The observation period was 7 days. The amount of hydrogen produced by the two groups of ink samples was observed (the unit of gas release is ml). The results are shown in Table 1: Table 1. Hydrogen Evolution Test Data Recording Sheet ; Experimental conclusions: As shown in Table 1, the inorganic passivating agent obtained by compounding phosphoric acid and sodium metavanadate can significantly improve the storage stability of the final product by performing in-situ passivation during the ball milling of spherical aluminum powder. Through the synergistic effect of inorganic and organic passivating agents, a denser protective film is formed through oxide film layer, chelation and precipitation reactions, which greatly inhibits the corrosion of aluminum powder and further improves the storage stability of the final product. The preparation process of using small molecule organic passivating agents and large molecule organic passivating agents in combination, as well as the order of adding large molecule organic passivating agents first and then small molecule organic passivating agents, also has obvious advantages.

[0045] 2. Acid resistance test Test method: The aqueous passivated aluminum silver paste and commercially available aluminum silver paste (standard sample) samples of the above-mentioned embodiment 3 of the present invention were respectively immersed in a 5% concentration hydrochloric acid solution until white bubbles appeared in the 5% concentration hydrochloric acid solution.

[0046] Test results: Commercially available aluminum silver paste (standard sample) showed white bubbles after 3 minutes in a 5% hydrochloric acid solution; the water-based passivated aluminum silver paste of Example 3 of this invention showed white bubbles after 7 minutes in a 5% hydrochloric acid solution; This indicates that the water-based passivated aluminum silver paste of this invention has better acid resistance.

[0047] 3. Gloss performance test The water-based passivated aluminum silver paste from Example 3 of this invention and commercially available aluminum silver paste (standard sample) were respectively scraped to obtain scraped samples. The scraped samples were then tested using a BYK six-angle colorimeter (the light source illuminates the tested surface at a fixed 45° angle, and the instrument is equipped with a receiving optical path in each of the six directions of -15°, 15°, 25°, 45°, 75°, and 110°, forming a "45°-six-angle" geometric structure). The test data are shown in Table 2. Table 2 Gloss performance test data ; Experimental conclusion: In the same system, the water-based passivated aluminum silver paste of Example 3 of the present invention has a higher L-value gloss at all angles than commercially available aluminum silver paste.

[0048] 4. Impact resistance test According to the impact resistance test standard GB / T 1732-1993, the scraper samples of the water-based passivated aluminum silver paste and commercially available aluminum silver paste (standard sample) of the above-mentioned Example 3 of the present invention were tested by the drop hammer method, and the forward impact test and reverse impact test were also performed.

[0049] Test results are as follows Figure 3As shown, under a 4x magnifying glass, it was observed that, compared to commercially available aluminum silver paste, the water-based passivated aluminum silver paste of Example 3 of this invention showed no cracks in the coating film of the standard sample of commercially available aluminum silver paste during the forward impact test, while the water-based passivated aluminum silver paste of Example 3 did not. During the reverse impact test, the coating film of the standard sample of commercially available aluminum silver paste completely peeled off, while some of the coating film of the water-based passivated aluminum silver paste of Example 3 remained intact. Overall, the water-based passivated aluminum silver paste of Example 3 of this invention has better impact resistance and less coating film damage.

[0050] 5. Adhesion performance test of wine bottle paint system Primer: 1g aluminum silver paste (water-based passivation aluminum silver paste of Example 3 of this invention, commercially available aluminum silver paste), 1g ethylene glycol monobutyl ether diluted, 8g water-based acrylic resin emulsion, mixed evenly and diluted, then sprayed, flash-dry at 80°C for 5 minutes after spraying, then heat to 170°C and bake for 30 minutes. Topcoat: Mix one part water-based acrylic resin emulsion with 5 wt% red pigment and 20 wt% water, bake at 80℃ for 5 minutes, then increase the temperature to 170℃ and bake for 30 minutes.

[0051] After the primer and topcoat are applied, the interlayer adhesion between the primer and topcoat is tested using the cross-cut test (under the same experimental conditions).

[0052] Test results are as follows Figure 4 As shown, commercially available aluminum silver paste (standard sample) exhibits poor interlayer adhesion when used in a wine bottle paint system, resulting in complete peeling of the red topcoat. In contrast, the water-based passivated aluminum silver paste of Example 3 of this invention demonstrates good interlayer adhesion in the wine bottle paint system, with no peeling of the red topcoat.

[0053] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A method for preparing an aqueous ball-milled passivated aluminum silver paste, characterized in that: Includes the following steps: S1: After ball milling aluminum powder, surface modifier, hydrophilic solvent and inorganic passivator to the target particle size of aluminum powder, a preliminary passivated aluminum silver paste is obtained; S2: Filter the pre-passivated aluminum silver paste, stir and mix it, then add an organic passivating agent, continue stirring to carry out the passivation reaction, then add an additive and continue stirring to obtain aluminum silver paste; wherein, the organic passivating agent is a combination of small molecule organic passivating agent and large molecule organic passivating agent, the molecular weight of the small molecule organic passivating agent is 210-280, and the molecular weight of the large molecule organic passivating agent is 5000-10000; S3: After the aluminum silver paste is encapsulated, it is placed in a room temperature environment for 2-3 days to obtain water-based passivated aluminum silver paste.

2. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: The aluminum powder is spherical; the amount of the hydrophilic solvent is 1.5-5.5 times that of the spherical aluminum powder; the ball milling uses 6-8mm steel balls with a ball-to-material ratio of (25-48):1; the mass ratio of the spherical aluminum powder to the surface modifier is 100:1-3; the mass ratio of the spherical aluminum powder to the inorganic passivating agent is 100:1-3.

3. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S1, the hydrophilic solvent is at least one of ethylene glycol ethyl ether, ethylene glycol ethyl ether acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, and dipropylene glycol dimethyl ether. The surface modifier is at least one of silane coupling agents and titanate coupling agents.

4. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S1, the inorganic passivating agent is at least one of orthophosphoric acid and sodium metavanadate.

5. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S1, the initial ball milling speed is 30-50 r / min; when the aluminum silver paste particle size is 2-3 μm smaller than the target particle size of the aluminum powder, the ball milling speed is reduced to 15-25 r / min until the target particle size is reached.

6. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S2, the amount of the organic passivating agent is 3-10% of the solid content of the aluminum silver paste; the amount of the additive is 5-10% of the mass of the aluminum silver paste.

7. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S2, the small molecule organic passivating agent and the macromolecule organic passivating agent are composed in a mass ratio of 1-6:1; Among them, the small molecule organic passivating agent is composed of octyl salicylate and sodium dodecyl sulfonate, and the mass ratio of octyl salicylate to sodium dodecyl sulfonate is 1:3-1:20; The macromolecular organic passivating agent is composed of polydimethylsiloxane and sodium dodecyl sulfonate, with polydimethylsiloxane as the main component and a mass ratio of 5:1 to 50:1 with sodium dodecyl sulfonate.

8. The method for preparing an aqueous ball-milled passivated aluminum silver paste according to claim 1, characterized in that: In step S2, the auxiliary agent is at least one of palmitic acid, stearic acid, and aspartic acid.

9. A water-based ball-milled passivation aluminum silver paste, characterized in that: It is prepared by any one of the preparation methods described in claims 1-8.

10. The application of the water-based ball-milled passivated aluminum silver paste as described in claim 9 in the preparation of water-based coatings.

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