An aqueous ball-milled passivated aluminum silver paste, a preparation method and application thereof

Abstract

The application relates to a water-based ball-milled passivated aluminum silver paste as well as a preparation method and application thereof, the preparation method comprising the following steps: ball-milling aluminum powder, a surface modifier, a hydrophilic solvent and an inorganic passivating agent to a target particle size of the aluminum powder to obtain a primary passivated aluminum silver paste; performing suction filtration on the primary passivated aluminum silver paste, uniformly stirring and mixing, then adding an organic passivating agent, continuously stirring to perform a passivation reaction, continuously stirring by adding an additive to obtain an aluminum silver paste; wherein the organic passivating agent is a combination of a small-molecule organic passivating agent and a large-molecule organic passivating agent. The in-situ passivation technology is adopted to passivate the aluminum sheet during the extension process, the influence of the solvent and the additive is small, and through the synergistic effect of the inorganic and organic passivating agents, a denser protective film is formed through an oxidation film layer, chelation and precipitation reaction, the corrosion of the aluminum powder is greatly inhibited, the water-based passivated aluminum silver paste has good compatibility with a water-based resin system, and good glossiness can be exhibited.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of metal coating, and particularly relates to a water-based ball-milling passivated aluminum silver paste as well as a preparation method and application thereof. BACKGROUND

[0002] The water-based aluminum silver paste uses water as a hydrophilic solvent, is non-toxic, non-polluting, and low in VOC (volatile organic compound), and meets environmental protection requirements. In comparison, the oily aluminum silver paste contains a large amount of organic solvent and is high in VOC emission, which is harmful to the environment and human health. In the prior art, there are generally two ways to prepare the water-based aluminum silver paste.

[0003] One way is to mix spherical aluminum powder, a surface treatment agent, and a hydrophilic solvent, and then perform wet ball milling, and then perform coating with a silicon compound or passivation with a corrosion inhibitor, so as to form a protective layer on the surface of the flaky aluminum particles, thereby preventing the reaction of aluminum metal ions with the medium. The coating reaction process needs to be implemented by using high-precision equipment, needs to be accurately controlled and strictly operated, and therefore the complexity of the production process leads to generally high production cost.

[0004] The other way is to add a passivation agent to the oily aluminum silver paste to perform water-based passivation treatment, so as to coat a passivation film on the surface of the aluminum powder, which can prevent the reaction of the aluminum powder with the external environment to a certain extent. However, the solvent and the additive used in the oily ball-milling process cannot be completely removed, which affects the effectiveness of the passivation and easily leads to problems such as high air release amount and unstable batch during application and storage. Figure 1

[0005] Based on the above problems, the application provides a water-based ball-milling passivated aluminum silver paste as well as a preparation method and application thereof. SUMMARY

[0006] The application aims to provide a water-based ball-milling passivated aluminum silver paste as well as a preparation method and application thereof to solve the above problems.

[0007] The application achieves the above-mentioned purpose by the following technical solutions.

[0008] A preparation method of a water-based ball-milling passivated aluminum silver paste, comprising the following steps:

[0009] S1: ball-milling aluminum powder, a surface modification agent, a hydrophilic solvent, and an inorganic passivation agent in a ball mill by using a ball-milling medium to obtain a preliminary passivated aluminum silver paste with a target particle size of the aluminum powder;

[0010] ​During the ball milling process, the surface of the aluminum powder is continuously subjected to mechanical force. Due to the good ductility of aluminum, the spherical aluminum powder is continuously elongated into a flaky shape during the ball milling process, and the newly generated surface continuously increases. The inorganic passivation agent and the surface modifier molecules are easily adsorbed by these generated high-activity surfaces. Specifically, the inorganic passivation agent added to the aluminum powder performs preliminary passivation on the newly generated surface of the aluminum powder, forming a dense film layer composed of aluminum oxide, metal hydrates, and metal salts; the functional groups contained in the surface modifier react with the trace amount of hydroxyl groups adsorbed on the surface of the aluminum powder, enabling the coupling of the aluminum flake surface to form a molecular layer, thereby effectively improving the surface morphology of the aluminum powder and providing a better basis for subsequent passivation; and the above reactions can be carried out throughout the entire ball milling process.

[0011] S2: The aluminum paste after the preliminary passivation is suction filtered, stirred and uniformly mixed, and then an organic passivation agent is added. The passivation reaction is continuously stirred, and then an additive is added for continuous stirring to obtain the aluminum paste; wherein the organic passivation agent is a combination of a small-molecule organic passivation agent and a large-molecule organic passivation agent, the molecular weight of the small-molecule organic passivation agent is 210-280, and the molecular weight of the large-molecule organic passivation agent is 5000-10000;

[0012] The corrosion-inhibiting groups in the molecules of the added organic passivation agent will undergo chelation with the metal ions on the surface of the flaky aluminum powder. In addition, the residual inorganic passivation agent in the silver paste and the ongoing precipitation reaction between the metal ions on the surface of the aluminum powder form a synergistic effect through chelation and precipitation, forming a more dense passivation protective film layer on the surface of the flaky aluminum particles, which can effectively isolate the aluminum particles in the film from external substances and greatly inhibit the occurrence of corrosion.

[0013] The added organic passivation agent is divided into a small-molecule organic passivation agent and a large-molecule organic passivation agent. The advantage of the small-molecule organic passivation agent is that it can effectively inhibit corrosion with the passivation protective film generated on the surface of the aluminum flake. The advantage of the large-molecule organic passivation agent is that the passivation protective film is thicker and has stronger protection for the surface of the aluminum flake. The synergistic effect of the small-molecule and large-molecule organic passivation agents increases the thickness of the protective film on the surface of the aluminum flake while also enhancing the corrosion inhibition effect.

[0014] Some groups in the molecules of the small-molecule organic passivation agent will combine with the hydroxyl groups on the surface of the aluminum flake to form an organic passivation film protective layer. However, due to the thin protective layer formed by the small-molecule organic passivation agent on the surface of the aluminum flake, the surface of the aluminum flake cannot be completely passivated. The addition of the large-molecule organic passivation agent enables the large molecules in the passivation agent to react with the unpassivated part of the aluminum flake surface to generate a passivation film, which is also overlaid on the passivation film generated by the small-molecule organic passivation agent.

[0015] Since the macromolecular groups of the organic passivation agent combined with the surface of the aluminum sheet are negatively charged, the same charges repel each other, and the arrangement state is in a disordered state. With the increase of the thickness of the passivation layer on the surface of the aluminum sheet, the positive and negative charges in the system are gradually combined, so that the molecules of the protection layer on the surface of the aluminum sheet are gradually arranged in order, and then the passivation film generated on the surface of the aluminum sheet is more dense;

[0016] The added auxiliary agent can neutralize part of the groups in the organic passivation agent molecules, simultaneously modify the surface of the aluminum silver paste, and prevent the aggregation of the flaky aluminum particles through steric hindrance stabilization, increase the leveling property of the silver paste, and improve the gloss of the surface of the aluminum sheet, thereby effectively solving the problems of gloss, storage stability and dispersion in water of the silver paste.

[0017] S3: after the aluminum silver paste is packaged, it is placed in a normal temperature environment for 2-3 days, and the water-based passivated aluminum silver paste is obtained.

[0018] As a further optimization scheme of the present application, 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 6-8 mm 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 passivation agent is 100:1-3.

[0019] As a further optimization scheme of the present application, in step S1, the hydrophilic solvent is at least one of ethylene glycol ethyl ether, ethylene glycol ethyl acetate, ethylene glycol butyl ether, diethylene glycol butyl ether, propylene glycol methyl ether, and dipropylene glycol dimethyl ether.

[0020] The surface modifier is at least one of a silane coupling agent and a titanate coupling agent.

[0021] As a further optimization scheme of the present application, in step S1, the inorganic passivation agent is at least one of orthophosphoric acid and sodium metavanadate.

[0022] As a further optimization scheme of the present application, 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 um from the target particle size of the aluminum powder, the ball milling speed is reduced to 15-25 r / min, and the ball milling is continued until the target particle size is reached.

[0023] As a further optimization scheme of the present application, in step S2, the amount of the organic passivation agent is 3-10% of the solid content of the aluminum silver paste; and the amount of the auxiliary agent is 5-10% of the mass of the aluminum silver paste.

[0024] As a further optimization scheme of the present application, in step S2, the small molecule organic passivation agent and the macromolecular organic passivation agent are composed in a mass ratio of 1-6:1.

[0025] The small-molecule organic passivation 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.

[0026] The macromolecular organic passivation agent is composed of polydimethylsiloxane and sodium dodecyl sulfonate, and the mass ratio of polydimethylsiloxane to sodium dodecyl sulfonate is 5:1-50:1.

[0027] As a further optimization scheme of the present application, in step S2, the auxiliary agent is at least one of palmitic acid, stearic acid and aspartic acid.

[0028] The present application also provides a water-based ball-milled passivated aluminum silver paste prepared by the preparation method.

[0029] The present application also provides an application of the water-based ball-milled passivated aluminum silver paste in preparing a water-based paint.

[0030] The present application has the following beneficial effects:

[0031] 1) The present application adopts in-situ passivation technology to passivate the aluminum sheet during the extension process, and the passivation process is less affected by the solvent and the auxiliary agent. Through the synergistic effect of the inorganic passivation agent and the organic passivation agent, a more compact protective film is formed through oxidation film layer, chelation and precipitation reaction, which greatly inhibits the corrosion of the aluminum powder. The solvent and the auxiliary agent used have strong hydrophilicity, so that the water-based passivated aluminum silver paste prepared has good compatibility with the water-based resin system and exhibits good gloss.

[0032] 2) In the ball milling process, the new surface is continuously generated, and the passivation agent and the modifier can timely adsorb and react to form a dynamic protective film construction process, so that the surface of the aluminum powder is always in a protected state.

[0033] 3) The present application synergistically applies the small-molecule and macromolecular organic passivation agents, which not only increases the thickness of the protective film, but also enhances the corrosion inhibition effect, and through the charge effect, the protective film is more compact. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a technical route map for preparing a water-based passivated aluminum silver paste (processed by an oily aluminum silver paste) in the prior art.

[0035] Figure 2 is a technical route map for preparing a water-based passivated aluminum silver paste of the present application;

[0036] Figure 3 is an impact resistance experiment diagram of a squeegee sample of the water-based passivated aluminum silver paste of Example 3 group of the present application and a commercially available aluminum silver paste (standard sample) under the same dispersion system;

[0037] Figure 4Figure is the bottle paint system adhesion performance experiment diagram of the water-based passivated aluminum silver paste of the embodiment 3 group of the present application and the commercially available aluminum silver paste (standard sample). DETAILED DESCRIPTION

[0038] It is necessary to point out here that the following detailed description is only used to further illustrate the present application and cannot be understood as limiting the protection scope of the present application, and the skilled in the art can make some non-essential improvements and adjustments to the present application according to the above application content.

[0039] 1. The aluminum powder is spherical aluminum powder with a particle size of 2-19 μm; the ball milling uses 6-8 mm steel balls, the ball-to-material ratio is (25-48):1, and the initial ball milling speed is 30-50 r / min; when the particle size of the aluminum silver paste reaches the target particle size of the aluminum powder with a difference of 2-3 um, the ball milling speed is reduced to 15-25 r / min;

[0040] 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;

[0041] 3. Surface modifier: at least one of silane coupling agent (A-171 vinyl silane coupling agent) and titanate coupling agent, A-171 vinyl silane coupling agent and titanate coupling agent are selected with a mass ratio of 1:3-5 (preferably a mass ratio of 1:4);

[0042] 4. Inorganic passivator: 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 the mass ratio of orthophosphoric acid and sodium metavanadate is 1:7;

[0043] 5. Organic passivator: composed of small molecule organic passivator and macromolecular organic passivator, the molecular weight of the small molecule organic passivator is 210-280, the molecular weight of the macromolecular organic passivator is 5000-10000, and the mass ratio of the small molecule organic passivator and the macromolecular organic passivator is 1-6:1 (preferably the mass ratio is 5:1);

[0044] In the present application, the small molecule organic passivator includes octyl salicylate (molecular weight about 222.3) and sodium dodecyl sulfonate (molecular weight about 272.4), the mass ratio is 1:3-1:20, the molecular weight is 210-280, and preferably the mass ratio is 1:3-1:10;

[0045] The macromolecular organic passivator includes polydimethylsiloxane (molecular weight 5000-10000, preferably molecular weight 8352.7) and sodium dodecyl sulfonate (molecular weight about 272.4), the mass ratio is 5:1-50:1; preferably the mass ratio is 5:1-20:1;

[0046] 6. Auxiliary agent: 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);

[0047] Note: The preferred scheme is used in the following verification test, except as specifically noted;

[0048] The methods used in this application are conventional methods known to those skilled in the art, and the reagents and other materials used are commercially available products, unless otherwise specified.

[0049] Example 1

[0050] A method for preparing a water-based ball-milled passivated aluminum silver paste, comprising the following steps:

[0051] S1: 6.5 kg of spherical aluminum powder, 190 g of surface modifier, 22 kg of hydrophilic solvent, and 120 g of inorganic passivation agent (orthophosphoric acid) are ball milled in a ball mill with 230 kg of ball milling medium to obtain a preliminary passivated aluminum silver paste with target aluminum powder particle size; the initial ball milling speed is 42 r / min; when the particle size of the aluminum silver paste reaches the target aluminum powder particle size with a difference of 2-3 um, the ball milling speed is reduced to 21 r / min until the target aluminum powder particle size is reached;

[0052] S2: The preliminary passivated aluminum silver paste is removed and filtered, then put into a kneader for stirring for 5-10 min to mix, then 3.2% of the solid content of the aluminum silver paste is added as an organic passivation agent, and the stirring speed is 10-20 r / min for 60-120 min for passivation reaction, specifically, first add macromolecular organic passivation agent (mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 5:1), stirring speed is 18 r / min for 55 min; then add small molecule organic passivation agent (mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5), stirring speed is 15 r / min for 40 min; finally, 6% of the mass of the aluminum silver paste is added as an auxiliary agent, and the stirring speed is 12 r / min for 35 min;

[0053] S3: The aluminum silver paste treated in step S2 is removed and packaged, and then placed in a normal temperature environment (20℃±2℃) for 2-3 days to obtain a water-based passivated aluminum silver paste.

[0054] Example 2

[0055] A method for preparing a water-based ball-milled passivated aluminum silver paste, comprising the following steps:

[0056] S1: 6 kg of spherical aluminum powder, 170 g of surface modifier, 20 kg of hydrophilic solvent, 130 g of inorganic passivation agent (sodium metavanadate) are ball milled in a ball mill with 225 kg of ball milling medium balls to obtain a preliminary passivated aluminum slurry after the aluminum powder target particle size is reached; the initial ball milling speed is 42 r / min; when the particle size of the aluminum slurry reaches the aluminum powder target particle size minus 2-3 um, the ball milling speed is reduced to 21 r / min until the aluminum powder target particle size is reached;

[0057] S2: Take out the preliminary passivated aluminum slurry, filter it and put it into a kneader for stirring for 5-10 min, then add 6.5% of the solid content of the aluminum slurry to the organic passivation agent, and continuously stir at a speed of 10-20 r / min for 60-120 min for passivation reaction. Specifically, first add macromolecular organic passivation agent (mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 10:1), continuously stir at a speed of 18 r / min for 55 min; then add small molecule organic passivation agent (mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:3), continuously stir at a speed of 15 r / min for 40 min; finally, add 7.5% of the mass of the aluminum slurry to the additive, and continue to stir at a speed of 12 r / min for 35 min;

[0058] S3: Take out the aluminum slurry treated in step S2, seal and place it in a normal temperature environment (20℃±2℃) for 2-3 days to obtain a water-based passivated aluminum slurry.

[0059] Example 3

[0060] A preparation method of a water-based ball-milled passivated aluminum slurry, comprising the following steps:

[0061] S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, 135 g of inorganic passivation agent (mass ratio of 1:7 of orthophosphoric acid and sodium metavanadate) are ball milled in a ball mill with 230 kg of ball milling medium balls to obtain a preliminary passivated aluminum slurry after the aluminum powder target particle size is reached; the initial ball milling speed is 42 r / min; when the particle size of the aluminum slurry reaches the aluminum powder target particle size minus 2-3 um, the ball milling speed is reduced to 21 r / min until the aluminum powder target particle size is reached;

[0062] S2: Take out the preliminary passivated aluminum silver paste, filter it and put it into the kneader for stirring for 5-10 minutes, mix it, then add 6.5% of the organic passivation agent of the solid content of the aluminum silver paste, continuously stir at the speed of 10-20 r / min for 60-120 minutes for passivation reaction. Specifically, first add the macromolecular organic passivation agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1), continuously stir at the speed of 18 r / min for 55 minutes; then add the small molecular organic passivation agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5), continuously stir at the speed of 15 r / min for 40 minutes; finally, add 8.2% of the additive of the mass of the aluminum silver paste, continuously stir at the speed of 12 r / min for 35 minutes;

[0063] S3: Take out the aluminum silver paste treated in step S2, package it and place it in the normal temperature environment (20℃±2℃) for 2-3 days, and the water-based passivated aluminum silver paste can be obtained.

[0064] Example 4

[0065] A preparation method of a water-based ball-milling passivated aluminum silver paste, comprising the following steps:

[0066] S1: Obtain the preliminary passivated aluminum silver paste by ball-milling 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent and 135 g of inorganic passivation agent (orthophosphoric acid) in a ball mill with 230 kg of ball-milling medium until the aluminum powder reaches the target particle size; 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 um, the ball-milling speed is reduced to 21 r / min until the aluminum powder reaches the target particle size.

[0067] S2: Take out the preliminary passivated aluminum silver paste, filter it and put it into the kneader for stirring for 5-10 minutes, mix it, then add 6.5% of the organic passivation agent of the solid content of the aluminum silver paste, continuously stir at the speed of 10-20 r / min for 60-120 minutes for passivation reaction. Specifically, first add the macromolecular organic passivation agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1), continuously stir at the speed of 18 r / min for 55 minutes; then add the small molecular organic passivation agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5), continuously stir at the speed of 15 r / min for 40 minutes; finally, add 8.2% of the additive of the mass of the aluminum silver paste, continuously stir at the speed of 12 r / min for 35 minutes;

[0068] S3: Take out the aluminum silver paste treated in step S2, package it and place it in the normal temperature environment (20℃±2℃) for 2-3 days, and the water-based passivated aluminum silver paste can be obtained.

[0069] Example 5

[0070] A preparation method of an aqueous ball-milled passivated aluminum silver paste, comprising the following steps:

[0071] S1: 7 kg of spherical aluminum powder, 205 g of a surface modifier, 23 kg of a hydrophilic solvent, and 135 g of an inorganic passivation agent (mass ratio of 1:7 orthophosphoric acid and sodium metavanadate) are ball-milled in a ball mill with 230 kg of ball milling medium to obtain a preliminarily passivated aluminum silver paste after the aluminum powder reaches the target particle size; 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 um, the ball milling speed is reduced to 21 r / min until the aluminum powder reaches the target particle size;

[0072] S2: The preliminarily passivated aluminum silver paste is taken out, filtered, and then put into a kneader for stirring for 5-10 min to mix, and then 6.5% of the solid content of the aluminum silver paste is added to the organic passivation agent, and the stirring speed is continuously 10-20 r / min for 60-120 min for passivation reaction, specifically, first, 18 r / min stirring speed is continuously stirred for 55 min by adding macromolecular organic passivation agent (mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 12:1); then, 15 r / min stirring speed is continuously stirred for 40 min by adding small molecular organic passivation agent (mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:10); finally, 8.2% of the mass of the aluminum silver paste is added to the auxiliary agent, and the stirring speed is continuously 12 r / min for 35 min;

[0073] S3: The aluminum silver paste treated in step S2 is taken out, packaged, and placed in a normal temperature environment (20℃±2℃) for 2-3 days to obtain the aqueous passivated aluminum silver paste.

[0074] Example 6

[0075] A preparation method of an aqueous ball-milled passivated aluminum silver paste, comprising the following steps:

[0076] S1: 7 kg of spherical aluminum powder, 205 g of a surface modifier, 23 kg of a hydrophilic solvent, and 135 g of an inorganic passivation agent (mass ratio of 1:7 orthophosphoric acid and sodium metavanadate) are ball-milled in a ball mill with 230 kg of ball milling medium to obtain a preliminarily passivated aluminum silver paste after the aluminum powder reaches the target particle size; 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 um, the ball milling speed is reduced to 21 r / min until the aluminum powder reaches the target particle size;

[0077] S2: The primary passivated aluminum paste is taken out, filtered and put into a kneader for stirring for 5-10 minutes, then 6.5% of the solid content of the aluminum paste of the organic passivation agent is added, and the stirring is continuously carried out at a speed of 10-20 r / min for 60-120 minutes for passivation reaction. Specifically, first, the macromolecular organic passivation agent (the mass ratio of polydimethylsiloxane and sodium dodecyl sulfonate is 18:1) is added, and the stirring is continuously carried out at a speed of 18 r / min for 55 minutes; then, the small-molecule organic passivation agent (the mass ratio of octyl salicylate and sodium dodecyl sulfonate is 1:5) is added, and the stirring is continuously carried out at a speed of 15 r / min for 40 minutes; finally, 8.2% of the mass of the aluminum paste of the additive is added, and the stirring is continuously carried out at a speed of 12 r / min for 35 minutes.

[0078] S3: The aluminum paste treated in step S2 is taken out, packaged and placed in a normal temperature environment (20℃±2℃) for 2-3 days, and the water-based passivated aluminum paste is obtained.

[0079] Comparative Example 1

[0080] Based on the preparation method of Example 3, in this comparative example, only step S1 is adjusted, and the adjustment is as follows:

[0081] The hydrophilic solvent in Example 3 is replaced with water, and the others remain unchanged, and the specific process is as follows:

[0082] S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of water, and 135 g of inorganic passivation agent (the mass ratio of orthophosphoric acid and sodium metavanadate is 1:7) are milled in a ball mill with 230 kg of ball milling medium to obtain a primary passivated aluminum paste; the rest is consistent with the preparation method of Example 3.

[0083] Comparative Example 2

[0084] Based on the preparation method of Example 3, in this comparative example, only step S1 is adjusted, and the adjustment is as follows:

[0085] The inorganic passivation agent (the mass ratio of orthophosphoric acid and sodium metavanadate is 1:7) in Example 3 is replaced with phosphate, and the others remain unchanged, and the specific process is as follows:

[0086] S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, 23 kg of hydrophilic solvent, and 135 g of inorganic passivation agent (phosphomolybdic acid) are milled in a ball mill with 230 kg of ball milling medium to obtain a primary passivated aluminum paste; the rest is consistent with the preparation method of Example 3.

[0087] Comparative Example 3

[0088] Based on the preparation method of Example 3, in this comparative example, only step S2 is adjusted, and the adjustment is as follows:

[0089] Without adding organic passivation agent, other unchanged, as follows:

[0090] S2: take out the preliminary passivated aluminum silver paste, after suction filtration, put it into the kneader for stirring 5-10min mixing, then add 8.2% of the aluminum silver paste mass of auxiliary agent, continue stirring at 12r / min for 35min; the rest is consistent with the preparation method of example 3.

[0091] Comparative example 4

[0092] Based on the preparation method of example 3, in this comparative example, only step S2 is adjusted, and the adjustment is as follows:

[0093] Only macromolecular organic passivation agent, other unchanged, as follows:

[0094] S2: take out the preliminary passivated aluminum silver paste, after suction filtration, put it into the kneader for stirring 5-10min mixing, then add 6.5% of the solid content of the aluminum silver paste of organic passivation agent, continue stirring at 10-20r / min for 60-120min for passivation reaction, specifically, first add macromolecular organic passivation agent, continue stirring at 18r / min for 55min, then add macromolecular organic passivation agent (its dosage is consistent with that of small molecular organic passivation agent in example 3), continue stirring at 15r / min for 40min, finally add 8.2% of the aluminum silver paste mass of auxiliary agent, continue stirring at 12r / min for 35min; the rest is consistent with the preparation method of example 3.

[0095] Comparative example 5

[0096] Based on the preparation method of example 3, in this comparative example, only step S2 is adjusted, and the adjustment is as follows:

[0097] Only small molecular organic passivation agent, other unchanged, as follows:

[0098] S2: take out the preliminary passivated aluminum silver paste, after suction filtration, put it into the kneader for stirring 5-10min mixing, then add 6.5% of the solid content of the aluminum silver paste of organic passivation agent, continue stirring at 10-20r / min for 60-120min for passivation reaction, specifically, first add small molecular organic passivation agent (its dosage is consistent with that of macromolecular organic passivation agent in example 3), continue stirring at 18r / min for 55min, then add small molecular organic passivation agent, continue stirring at 15r / min for 40min, finally add 8.2% of the aluminum silver paste mass of auxiliary agent, continue stirring at 12r / min for 35min; the rest is consistent with the preparation method of example 3.

[0099] Comparative example 6

[0100] Based on the preparation method of Example 3, in this comparative example, only step S1 is adjusted, and the adjustment is as follows:

[0101] No in-situ passivation with inorganic passivator is added, and the rest remains unchanged, and the details are as follows:

[0102] S1: 7 kg of spherical aluminum powder, 205 g of surface modifier, and 23 kg of hydrophilic solvent are ball milled in a ball mill with 230 kg of ball milling medium balls to obtain a preliminary passivated aluminum paste after the aluminum powder reaches the target particle size; the initial ball milling speed is 42 r / min; when the particle size of the aluminum paste reaches the target particle size of the aluminum powder minus 2-3 um, the ball milling speed is reduced to 21 r / min until the aluminum powder reaches the target particle size; the rest remains unchanged with the preparation method of Example 3.

[0103] Comparative Example 7

[0104] Based on the preparation method of Example 3, in this comparative example, only step S2 is adjusted, and the adjustment is as follows:

[0105] The inorganic passivator is used instead of the organic passivator in step S2, and the rest remains unchanged, and the details are as follows:

[0106] S2: The preliminary passivated aluminum paste is taken out and filtered, then put into a kneader for stirring for 5-10 min, then 4.5% of the inorganic passivator of the solid content of the aluminum paste is added, the inorganic passivator is added (the amount is the same as that of the macromolecular organic passivator in Example 3), and the stirring speed is 18 r / min for 55 min, then the inorganic passivator is added (the amount is the same as that of the small molecular organic passivator in Example 3), and the stirring speed is 15 r / min for 40 min, finally 8.2% of the additive of the mass of the aluminum paste is added, and the stirring speed is 12 r / min for 35 min; the rest remains unchanged with the preparation method of Example 3.

[0107] Comparative Example 8

[0108] Based on the preparation method of Example 3, in this comparative example, only step S2 is adjusted, and the adjustment is as follows:

[0109] The molecular weight of the organic passivator is different, and the rest remains unchanged, and the details are as follows:

[0110] S2: The primary passivated aluminum paste is taken out, filtered and put into a kneader for stirring for 5-10 min for mixing, then 6.5% of the organic passivation agent of the solid content of the aluminum paste is added, and stirring is continuously carried out at a speed of 10-20 r / min for 60-120 min for passivation reaction. Specifically, first, the macromolecular organic passivation agent (molecular weight 15124.3) is added, stirring is continuously carried out at a speed of 18 r / min for 55 min; then the small-molecule organic passivation agent (molecular weight 397.5) is added, stirring is continuously carried out at a speed of 15 r / min for 40 min; finally, 8.2% of the additive of the mass of the aluminum paste is added, and stirring is continuously carried out at a speed of 12 r / min for 35 min; the rest is consistent with the preparation method of Example 3.

[0111] Comparative Example 9

[0112] Based on the preparation method of Example 3, in this comparative example, only step S2 is adjusted, and after the adjustment, it is:

[0113] First, the small-molecule organic passivation agent is added, and then the macromolecular organic passivation agent is added, and the rest remains unchanged, and the specific process is as follows:

[0114] S2: The primary passivated aluminum paste is taken out, filtered and put into a kneader for stirring for 5-10 min for mixing, then 6.5% of the organic passivation agent of the solid content of the aluminum paste is added, and stirring is continuously carried out at a speed of 10-20 r / min for 60-120 min for passivation reaction. Specifically, first, the macromolecular organic passivation agent (molecular weight 15124.3) is added, stirring is continuously carried out at a speed of 18 r / min for 55 min; then the small-molecule organic passivation agent (molecular weight 397.5) is added, stirring is continuously carried out at a speed of 15 r / min for 40 min; finally, 8.2% of the additive of the mass of the aluminum paste is added, and stirring is continuously carried out at a speed of 12 r / min for 35 min; the rest is consistent with the preparation method of Example 3.

[0115] Comparative Example 10

[0116] S1: 40 kg of spherical aluminum powder, 80-120 kg (preferably 103 kg) of 90# petroleum ether are added into a ball mill, the stirring speed of the ball mill (225 kg of ball milling medium) is adjusted to 5 r / min for 30 min for pre-dispersion, then 0.04-0.1 kg (preferably 0.08 kg) of oleic acid and 0.15-0.2 kg (preferably 0.17 kg) of stearic acid are added, and the stirring speed of the ball mill is adjusted to 30-40 r / min, and the ball milling is carried out for 15-20 h (preferably 35 r / min for 18 h), and then the oil-based aluminum paste is obtained by pressure filtration;

[0117] Step S2: The oil-based aluminum paste prepared in step S1 is used as the raw material to replace the primary passivated aluminum paste for subsequent processing steps, and the rest is consistent with the preparation method of Example 3.

[0118] 1. Hydrogen evolution test

[0119] (1) Test method: The test paint samples (Examples 1-6) and control paint samples (Comparative Examples 1-10 and commercially available aluminum silver paste, i.e., standard sample) were prepared according to 10% of the Example group / Comparative Example group of water-based passivated aluminum silver paste + 16% water + 74% water-based resin (water-based resin was the same batch), with pH of 8.5-8.6, and the two groups of ink samples were placed in the same hydrogen evolution device and stored in a constant temperature water bath at room temperature (22℃±2℃) and 50℃, with 7 days as an observation period, the amount of hydrogen generated by the two groups of ink samples was observed (gas emission amount: ml), and the results are shown in Table 1:

[0120] Table 1 Hydrogen evolution test data record

[0121] ;

[0122] Experimental conclusion: From the data in Table 1, it can be seen that the in-situ passivation of the inorganic passivator obtained by compounding orthophosphoric acid and sodium metavanadate during the ball milling of spherical aluminum powder can significantly improve the storage stability of the final product, and through the synergistic effect of the inorganic passivator and the organic passivator, a more dense protective film is formed through oxidation film layer, chelation and precipitation reaction, which greatly inhibits the corrosion of aluminum powder and further improves the storage stability of the final product. The preparation process of the combination of small molecule organic passivator and large molecule organic passivator and the addition sequence of large molecule organic passivator first and small molecule organic passivator later also has obvious advantages.

[0123] 2. Acid resistance test

[0124] Test method: The water-based passivated aluminum silver paste of Example 3 of the present application and the commercially available aluminum silver paste (standard sample) were immersed in 5% concentration hydrochloric acid solution until white bubbles appeared in the 5% concentration hydrochloric acid solution.

[0125] Test results: The commercially available aluminum silver paste (standard sample) will produce white bubbles in 5% concentration hydrochloric acid solution in 3 minutes; the water-based passivated aluminum silver paste of Example 3 of the present application will produce white bubbles in 5% concentration hydrochloric acid solution in 7 minutes; thus, it is shown that the water-based passivated aluminum silver paste of the present application has better acid resistance.

[0126] 3. Gloss performance test

[0127] The water-based passivated aluminum silver paste of the inventive example 3 group and the commercially available aluminum silver paste (standard sample) sample were respectively scraped to obtain scraped samples, and the scraped samples were tested, and the values were measured by using a BYK-hexagonal colorimeter (the light source irradiated the measured surface at a fixed 45° angle, and the instrument was equipped with a set of receiving light paths in-15°, 15°, 25°, 45°, 75° and 110° directions, forming a “45°-hexagonal” geometric structure), and the test data are shown in Table 2:

[0128] Table 2: Gloss performance test data

[0129] ;

[0130] Experimental conclusion: in the same system, the L value gloss of the water-based passivated aluminum silver paste of the inventive example 3 group at each angle is greater than that of the commercially available aluminum silver paste.

[0131] 4. Impact resistance performance test

[0132] According to the impact resistance test standard “GB / T 1732-1993”, the scraped samples of the water-based passivated aluminum silver paste of the inventive example 3 group and the commercially available aluminum silver paste (standard sample) were tested by drop hammer method, and the positive impact test and the reverse impact test were simultaneously performed.

[0133] The test results are shown in Table 3. Figure 3 Under four times magnifying glass observation, it was found that, compared with the commercially available aluminum silver paste, when the positive impact test was performed, the standard sample of the commercially available aluminum silver paste had cracks in the paint film, while the water-based passivated aluminum silver paste sample of the inventive example 3 group had no cracks; when the reverse impact test was performed, the standard sample of the commercially available aluminum silver paste had completely fallen off the paint film, while the water-based passivated aluminum silver paste sample of the inventive example 3 group still had part of the sample not falling off. Overall, the water-based passivated aluminum silver paste of the inventive example 3 group has better impact resistance performance of the paint film, and the damage degree of the paint film is small.

[0134] 5. Adhesion performance test of wine bottle paint system

[0135] Primer: 1g of aluminum silver paste (water-based passivated aluminum silver paste of the inventive example 3 group, commercially available aluminum silver paste), 1g of ethylene glycol monobutyl ether was diluted, then 8g of water-based acrylic resin emulsion was added, and after uniform mixing and dilution, it was sprayed, and after spraying, it was flash dried at 80℃ for 5min, and then heated to 170℃ and baked for 30min;

[0136] Topcoat: one part of water-based acrylic resin emulsion, 5wt% of red color paste and 20wt% of water were added, and after uniform mixing, it was baked at 80℃ for 5min, and then heated to 170℃ and baked for 30min.

[0137] After the primer and topcoat were sprayed, the interlayer adhesion between the primer and the topcoat was tested by grid method (under the same experimental conditions).

[0138] The test results are shown in Table 1. Figure 4 As shown in Table 1, the commercially available aluminum paste (standard sample) is used in the wine bottle paint system, and the interlayer adhesion is poor, and the red topcoat is completely peeled off; the water-based passivated aluminum paste of Example 3 of the present application is used in the wine bottle paint system, and the interlayer adhesion is good, and the red topcoat is not peeled off.

[0139] The above-described examples only express several embodiments of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for ordinary skilled persons in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application.

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.

Images