High-density environment-friendly passivating agent for aluminum can with easy-to-open cover and preparation method of high-density environment-friendly passivating agent

Abstract

The invention relates to the field of passivating agents, in particular to a high-compactness environment-friendly passivating agent for an aluminum can with an easy-to-open cover and a preparation method of the high-compactness environment-friendly passivating agent. The high-compactness environment-friendly passivating agent for the aluminum can with the easy-to-open cover, provided by the invention, is prepared from the following raw materials in parts by mass: 10 to 15 parts of a film-forming agent, 4 to 8 parts of a stabilizer, 0.1 to 1 part of a coalescing agent, 0.5 to 2 parts of a hole sealing agent, 0.3 to 1 part of a flatting agent and 80 to 100 parts of water. The high-density environment-friendly passivating agent for the aluminum can with the easy-to-open cover has excellent passivation performance, no residue is generated after washing due to the fact that no resin or silane is added, and the using effect is excellent.

Description

Technical Field

[0001] The present invention relates to the field of passivators, and more specifically, to a highly dense and environmentally friendly passivator for aluminum easy-open cans and a preparation method thereof. Background Art

[0003] As the core component of two-piece cans, the manufacturing process of aluminum can bodies involves key processes such as precision stamping of aluminum can body materials, chemical passivation, coating and printing, and high-temperature curing. According to the provisions of Clause 6.6 of GB / T 9106.1-2019 "Packaging Containers - Aluminum Easy-Open Cans", after the can body is subjected to high-pressure steaming at 121°C for 30 minutes, the coating adhesion needs to be maintained at ≥4.5 N / cm, and there should be no discoloration, blistering or metal exposure on the surface. In the existing process, passivation treatment, as the interface engineering connecting the metal substrate and the organic coating, its film-forming quality directly affects the safety performance of the final product.

[0004] The current mainstream chromium-free passivation technology is mainly based on zirconium salt systems, such as ammonium hexafluorozirconate, potassium hexafluorozirconate, etc., which form a nano-level protective film through the deposition of zirconium oxide polymers. Although this technology has passed the ISO 15726:2009 environmental protection certification, there are still the following technical bottlenecks in industrial applications:

[0005] 1. Sensitivity of process parameters: The concentration of the passivation solution needs to be precisely controlled within a narrow range of 0.30% - 0.45%: when the concentration is greater than 0.45%, the rapid polycondensation of zirconium salts causes the porosity of the film layer to increase to 15% - 20%, resulting in a decrease in coating adhesion; when the concentration is less than 0.30%, the film-forming continuity is damaged and the corrosion resistance fails to meet the standard.

[0006] 2. Defect in aluminum ion tolerance: During continuous production, the dissolution of the aluminum substrate causes the aluminum ion concentration in the bath to accumulate at a rate of 5 - 8 ppm / min: when the Al 3 + concentration is greater than 200 ppm, the colloidal stability of zirconium salts drops sharply, resulting in deterioration of the film layer uniformity; to maintain process stability, 8% - 10% of the bath needs to be replaced every hour, which not only increases production costs but also poses a problem in the treatment of heavy metal-containing waste zirconium water.

[0007] 3. Defect in high-temperature energy consumption: The activation energy of the hydrolysis reaction of zirconium salts is as high as 85 kJ / mol, and a constant temperature environment of 40 ± 2°C needs to be maintained.

[0008] Based on this, the industry has also implemented many improvement and optimization measures, such as adding silane or resin to the zirconium salt chromium-free passivation system. Chinese invention patent CN109468624B discloses a high-adhesion chromium-free color coating passivator and its preparation method. The raw materials for the preparation of the passivator include, by mass percentage, citric acid 15-25%, fluorozirconate 1-6%, aminosilane 1-6%, corrosion-resistant additive 0.5-3%, wetting agent 0.1-0.5% and deionized water as the balance; the product does not contain chromium and other toxic heavy metals, is green and environmentally friendly, and the introduction of aminosilane has improved the problem of narrow quality control window to a certain extent, and the concentration control window has been expanded to 0.3%-1.0%, but it also causes new problems such as difficulty in rinsing aminosilane after passivation and easy generation of water stains that affect the appearance of the tank.

[0009] Therefore, there is an urgent need for an environmentally friendly passivating agent with a high concentration window that is not easy to leave residue on the surface of the can and affect the appearance of the can, which has important practical significance for broadening the application scope of aluminum easy-open aluminum cans. Summary of the invention

[0010] In order to solve the above technical problems, the first aspect of the present invention provides a high-density environmentally friendly passivator for aluminum cans with easy-open lids. The raw materials for its preparation, calculated by weight, include: 10-15 parts of a film-forming agent, 4-8 parts of a stabilizer, 0.1-1 parts of a film-forming aid, 0.5-2 parts of a sealing agent, 0.3-1 parts of a leveling agent and 80-100 parts of water.

[0011] As an implementable example, the film-forming agent includes fluorozirconic acid and fluorotitanate.

[0012] Furthermore, the mass ratio of fluorozirconic acid to fluorotitanate is (6-8):(3-5).

[0013] Furthermore, the mass ratio of fluorozirconic acid to fluorotitanate is 7.2:3.4.

[0014] Furthermore, the fluorotitanate includes one or more of potassium fluorotitanate, sodium fluorotitanate, ammonium fluorotitanate or magnesium fluorotitanate.

[0015] Furthermore, the fluorotitanate is potassium fluorotitanate.

[0016] In the present invention, fluorozirconic acid and potassium fluorotitanate are selected as stabilizers, wherein the hexafluorotitanate ion [TiF6] of potassium fluorotitanate 2-In an acidic medium, a nano-scale TiO2-ZrO2 co-deposited film is formed through a hydrolysis polycondensation reaction; compared with a single zirconium salt system, the zirconium-titanium synergy broadens the film-forming temperature window to 10 - 30 °C, and the aluminum ion tolerance threshold is increased to 900 ppm. Specifically, the introduction of potassium fluotitanate promotes the molar ratio of titanium to zirconium in the passivation film to stabilize at 1:(2.5 - 3.0), and its d-orbital vacancy characteristics effectively capture Al 3+ , combined with the complexing effect of the stabilizer, resulting in a high film-forming uniformity when the aluminum ions in the bath are enriched. This formulation can achieve stable control of the film thickness within a wide concentration range of 0.3 - 1.0%, meeting the performance requirements of beverage cans for pasteurization at 68 °C / 30 min and high-temperature cooking cans for 121 °C / 0.25 MPa, and at the same time meeting the environmental emission standards of HJ 2538 - 2018.

[0017] As an implementable case, the stabilizer includes one or more of phytic acid, citric acid, sodium silicate, and aluminum silicate.

[0018] Furthermore, the stabilizer is phytic acid.

[0019] The 6 phosphoric acid groups in phytic acid (C6H 18 O 24 P6) can strongly complex with aluminum ions to form stable complexes, inhibiting the interference of aluminum ion enrichment on the passivation film. Even when the aluminum ion concentration is as high as 900 ppm, an effective film can still be formed, reducing the replacement rate of the passivation bath from 100% in the traditional system to 10 - 20%, significantly reducing resource consumption and the pressure of wastewater treatment. Secondly, phytic acid has weak acidity and dynamic buffering ability, which can neutralize the acid-base fluctuations caused by metal hydrolysis in the bath or external factors, maintaining the pH value in a stable range of 4.5 - 6.5, ensuring the uniformity of the film-forming reaction and the process continuity. In addition, phytic acid chelates Ti 4+ and Zr 4+ ions, regulating their hydrolysis polycondensation rate, avoiding the film layer being too thick or loose caused by rapid polycondensation, promoting the formation of a dense and uniform zirconium-titanium composite film, and enhancing the corrosion resistance and coating adhesion. In terms of synergistic effect, phytic acid and the zirconium-titanium film-forming agent optimize the release of metal ions, and together with the sealing agent, fill the pores of the film layer to enhance the density, and cooperate with the leveling agent to improve the wettability of the passivation solution. When the content of phytic acid is insufficient, the enrichment of aluminum ions causes a decrease in corrosion resistance, and yellowing or blackening will occur at the bottom of the can. When the phytic acid is excessive, the film formation is inhibited, resulting in a too thin film layer. Therefore, the preferred addition amount in this invention is 4 - 8 parts, that is, the mass concentration of phytic acid is 4 - 8 wt%, which can balance the aluminum ion complexation and the film thickness requirement, and achieve the comprehensive performance of high anti-pollution, wide process window and low environmental load.

[0020] As an implementable case, the film-forming aid includes one or more of cerium nitrate, lanthanum nitrate, ammonium fluoride, or ammonium molybdate.

[0021] Furthermore, the film-forming auxiliary is cerium nitrate.

[0022] Cerium nitrate promotes the adsorption of cerium ions on the surface of the aluminum substrate through catalytic film formation and self-healing functions, accelerates the oxidation of aluminum to generate an alumina base layer, and simultaneously releases oxygen free radicals to repair the microscopic defects of the film layer, improving the continuity and compactness of the passivation film. Different from the traditional zirconium salt system that requires heating at 40°C, cerium nitrate can activate the hydrolysis and polycondensation reactions of zirconium and titanium ions at room temperature, increasing the film-forming rate by 30%-50%, and ensuring uniform film thickness by regulating the ion concentration gradient to avoid the decrease in coating adhesion caused by local over-thickness. When combined with zirconium-titanium film-forming agents, the CeO2 nanocrystallites formed by the oxidation of cerium can enable the orderly deposition of zirconium-titanium oxides, enhancing the interfacial bonding force; synergistically optimizing the metal ion release rate with the stabilizer phytic acid to avoid rapid polycondensation; jointly filling the pores with the sealing agent hydrophilic fumed silica to form a "chemical-physical" double sealing structure, significantly improving the corrosion resistance, with the aluminum ion tolerance concentration reaching 900 ppm and the bath replacement rate reduced to 10%-20%; however, the addition amount of cerium nitrate should not be excessive. In the present invention, its addition amount is preferably 0.5-2 parts, that is, the mass concentration is 0.5-2 wt%. If added in excess, the film layer will be loose due to the accumulation of CeO2 particles, the coating is prone to peeling off, and the practicability of the product will be significantly reduced.

[0023] As an implementable case, the sealing agent includes hydrophilic fumed silica.

[0024] As an implementable case, the sealing agent includes hydrophilic fumed silica.

[0025] Furthermore, the particle size of the hydrophilic fumed silica is 5-100 nm.

[0026] Furthermore, the particle size of the hydrophilic fumed silica is 5-10 nm.

[0027] In this application, hydrophilic fumed silica is selected as the sealing agent. The main reason is that the particle size of its nanoparticles is relatively small, being 5 - 10 nm. Therefore, it has excellent dispersion performance and can be evenly filled in the microscopic pores of the titanium-zirconium passivation film to form a stable suspension, thereby significantly improving the densification and corrosion resistance of the film layer. At the same time, the high bond energy Si - O bond in the fumed silica can significantly enhance the interfacial bonding strength and further improve the adhesion of the coating. In addition, the synergistic effect of fumed silica and the titanium-zirconium film layer, combined with the rapid film-forming effect of cerium nitrate, can form a dense and uniform passivation film under normal temperature conditions. In addition, the addition of phytic acid and leveling agent further improves the wettability of the passivation solution and the uniformity of the film layer. Therefore, it avoids the problem of insufficient corrosion resistance caused by too thin film formation under low concentration conditions, as well as the problems of loose film layer and decreased adhesion caused by too thick film formation. At the same time, the control window of the usage concentration is expanded to 0.30% - 1.00%, which is 4 - 5 times higher than the traditional zirconium salt system, thus ensuring the stability and reliability of the film-forming quality.

[0028] As an implementable case, the leveling agent described includes fatty alcohol polyoxyethylene ether.

[0029] Furthermore, the grade of the fatty alcohol polyoxyethylene ether is Plurafac LF221, which can be purchased from BASF Co., Ltd.

[0030] The hydrophilic chain segment in the molecule of Plurafac LF221 can effectively reduce the surface tension of the passivation solution, greatly improve the wettability and penetration ability, enable the passivation solution to quickly and evenly cover the surface of the aluminum substrate, fully fill the microscopic pores, and ensure the close contact and uniform film formation between the passivation film and the substrate. Secondly, the leveling agent combines with the hydrophobic components in the passivation film through polar groups, converting the surface of the film layer from hydrophobic to hydrophilic, enabling the rinsing water to quickly penetrate and wash away the residues, avoiding local water stains or spots caused by the retention of residues, and ensuring the bright and clean appearance of the tank body after passivation. At the same time, after adding the leveling agent, the amount of rinsing water can be significantly reduced, the surface finish of the tank body is improved after drying, and there is no visible water stain residue. If the leveling agent is not added, it will lead to insufficient wettability of the passivation solution, resulting in uneven film formation and local blackening of the tank body after rinsing.

[0031] The second aspect of the present invention provides a preparation method of a highly dense and environmentally friendly passivation agent for aluminum easy-open lid cans, including: mixing a film-forming agent, a stabilizer, a film-forming aid, a sealing agent, a leveling agent and water evenly to obtain the highly dense and environmentally friendly passivation agent for aluminum easy-open lid cans.

[0032] Furthermore, the preparation method of the highly dense and environmentally friendly passivation agent for aluminum easy-open lid cans includes: adding the film-forming agent, the stabilizer, the film-forming aid, the sealing agent and the leveling agent into water in sequence and mixing evenly to obtain the highly dense and environmentally friendly passivation agent for aluminum easy-open lid cans.

[0033] Beneficial effects

[0034] (1) Through the aluminum ion complexation of phytic acid, the redox catalysis of cerium nitrate, and the wettability optimization of the leveling agent, the passivator provided by the present invention can form a dense and uniform zirconium-titanium composite film within the range of 0.30% to 1.00% of the grooving concentration, and the adhesion and corrosion resistance of the passivation film both meet the requirements of the GB / T 9106.1-2019 standard. Therefore, the same passivation parameters can be used for beverage cans and high-temperature cooking cans without adjusting the process, significantly improving production continuity and reducing the cost of line change.

[0035] (2) Compared with the traditional zirconium salt system with a concentration control window of only 0.30% to 0.45%, through the pH buffering and metal ion chelation of phytic acid, the room-temperature film-forming catalysis of cerium nitrate, and the pore filling of fumed silica in coordination, the present invention expands the concentration window to 0.30% to 1.00%. Even at the highest concentration, it can still avoid the film layer from being too thick or loose, ensuring the stability of the film-forming quality.

[0036] (3) In the present invention, the stabilizer phytic acid can complex aluminum ions up to 900 ppm and still effectively form a film. The replacement rate of the passivation bath solution is reduced from 100% in 8 hours in the traditional method to 10% to 20%, reducing the consumption of the passivator by more than 40%. At the same time, the wastewater discharge is reduced by 80%, greatly saving resources and costs.

[0037] (4) The synergistic effect of cerium nitrate and phytic acid in the present invention enables the passivation reaction to proceed efficiently at room temperature without the heating energy consumption of maintaining 40±2°C in the traditional process, effectively saving energy and reducing emissions.

[0038] (5) In the present invention, a specific leveling agent, fatty alcohol polyoxyalkylene ether, is selected, which can convert the surface of the passivation film from hydrophobic to hydrophilic. The penetration efficiency of the rinsing water, the removal rate of residues, and the surface finish after the tank body is dried are significantly improved, and there are no visible water stains or spots, and the appearance quality meets the requirements of food-grade packaging. Compared with the passivator containing resin or silane coupling agent raw materials, the passivator of the present invention can still achieve zero-defect rinsing at a high production line speed of 3000 cans / min, significantly improving production efficiency. Detailed implementation methods

[0039] In the following implementation cases, the fumed silica with hydrophilicity has the brand number AEROSIL 380 and is purchased from Evonik Industries AG; the leveling agent of fatty alcohol polyoxyethylene ether with the brand number Plurafac LF221 is purchased from BASF Co., Ltd.

[0040] Example 1

[0041] The first aspect of this example provides a high-density environmentally friendly passivator for aluminum cans with easy-open lids. The raw materials for its preparation are, in terms of mass percentage, 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 0.6 parts of film-forming aid, 1 part of sealing agent, 0.5 parts of leveling agent and 81.8 parts of water; the mass concentration of the high-density environmentally friendly passivator for aluminum cans with easy-open lids is 0.3wt%.

[0042] The film-forming agent is a compound of fluorozirconic acid and potassium fluorotitanate, and the mass ratio of fluorozirconic acid to potassium fluorotitanate is 7.2:3.4.

[0043] The stabilizer is phytic acid.

[0044] The film-forming aid is cerium nitrate.

[0045] The sealing agent is hydrophilic fumed silica with a particle size of 5-10 nm.

[0046] The grade of the leveling agent is Plurafac LF221.

[0047] The second aspect of this example provides a method for preparing a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans, specifically: adding a film-forming agent, a stabilizer, a film-forming aid, a sealing agent and a leveling agent to water in sequence, and mixing them evenly to obtain a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans.

[0048] Example 2

[0049] The first aspect of this example provides a high-density environmentally friendly passivator for aluminum cans with easy-open lids. The raw materials for its preparation are, by weight, 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 0.6 parts of film-forming aid, 1 part of sealing agent, 0.5 parts of leveling agent and 81.8 parts of water; the mass concentration of the high-density environmentally friendly passivator for aluminum cans with easy-open lids is 1wt%.

[0050] The film-forming agent is a compound of fluorozirconic acid and potassium fluorotitanate, and the mass ratio of fluorozirconic acid to potassium fluorotitanate is 7.2:3.4.

[0051] The stabilizer is phytic acid.

[0052] The film-forming aid is cerium nitrate.

[0053] The sealing agent is hydrophilic fumed silica with a particle size of 5-10 nm.

[0054] The grade of the leveling agent is Plurafac LF221.

[0055] The second aspect of this example provides a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans, specifically: adding a film-forming agent, a stabilizer, a film-forming auxiliary agent, a sealing agent, and a leveling agent into water in sequence, and mixing evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans.

[0056] Example 3

[0057] The first aspect of this example provides a highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans. The preparation raw materials are as follows by mass fraction: 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 0.6 part of film-forming auxiliary agent, 1 part of sealing agent, 0.5 part of leveling agent, and 81.8 parts of water; the slotted use mass concentration of the highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans is 0.5 wt%.

[0058] The film-forming agent is a compound of zirconium fluoride acid and potassium fluotitanate, and the mass ratio of zirconium fluoride acid to potassium fluotitanate is 7.2:3.4.

[0059] The stabilizer is phytic acid.

[0060] The film-forming auxiliary agent is cerium nitrate.

[0061] The sealing agent is hydrophilic fumed silica with a particle size of 5 - 10 nm.

[0062] The leveling agent has the brand number of Plurafac LF221.

[0063] The second aspect of this example provides a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans, specifically: adding a film-forming agent, a stabilizer, a film-forming auxiliary agent, a sealing agent, and a leveling agent into water in sequence, and mixing evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans.

[0064] Comparative Example 1

[0065] The first aspect of this example provides a highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans. The preparation raw materials are as follows by mass fraction: 10.6 parts of film-forming agent, 3 parts of stabilizer, 0.6 part of film-forming auxiliary agent, 1 part of sealing agent, 0.5 part of leveling agent, and 84.3 parts of water; the slotted use mass concentration of the highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans is 0.5 wt%.

[0066] The film-forming agent is a compound of zirconium fluoride acid and potassium fluotitanate, and the mass ratio of zirconium fluoride acid to potassium fluotitanate is 7.2:3.4.

[0067] The stabilizer is phytic acid.

[0068] The film-forming auxiliary agent is cerium nitrate.

[0069] The sealing agent is hydrophilic fumed silica with a particle size of 5 - 10 nm.

[0070] The grade of the leveling agent is Plurafac LF221.

[0071] The second aspect of this example provides a method for preparing a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans, specifically: adding a film-forming agent, a stabilizer, a film-forming aid, a sealing agent and a leveling agent to water in sequence, and mixing them evenly to obtain a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans.

[0072] Comparative Example 2

[0073] The first aspect of this example provides a high-density environmentally friendly passivator for aluminum cans with easy-open lids. The raw materials for its preparation are, in terms of mass percentages, 10.6 parts of film-forming agent, 9 parts of stabilizer, 0.6 parts of film-forming aid, 1 part of sealing agent, 0.5 parts of leveling agent and 78.3 parts of water; the mass concentration of the high-density environmentally friendly passivator for aluminum cans with easy-open lids is 0.5wt%.

[0074] The film-forming agent is a compound of fluorozirconic acid and potassium fluorotitanate, and the mass ratio of fluorozirconic acid to potassium fluorotitanate is 7.2:3.4.

[0075] The stabilizer is phytic acid.

[0076] The film-forming aid is cerium nitrate.

[0077] The sealing agent is hydrophilic fumed silica with a particle size of 5-10 nm.

[0078] The grade of the leveling agent is Plurafac LF221.

[0079] The second aspect of this example provides a method for preparing a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans, specifically: adding a film-forming agent, a stabilizer, a film-forming aid, a sealing agent and a leveling agent to water in sequence, and mixing them evenly to obtain a high-density environmentally friendly passivator for aluminum easy-open lid aluminum cans.

[0080] Comparative Example 3

[0081] The first aspect of this example provides a high-density environmentally friendly passivator for aluminum cans with easy-open lids. The raw materials for its preparation are, in terms of mass percentage, 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 1 part of sealing agent, 0.5 part of leveling agent and 82.4 parts of water; the mass concentration of the high-density environmentally friendly passivator for aluminum cans with easy-open lids is 0.5wt%.

[0082] The film-forming agent is a compound of fluorozirconic acid and potassium fluorotitanate, and the mass ratio of fluorozirconic acid to potassium fluorotitanate is 7.2:3.4.

[0083] The stabilizer is phytic acid.

[0084] The sealing agent is hydrophilic fumed silica with a particle size of 5-10 nm.

[0085] The leveling agent has the brand number Plurafac LF221.

[0086] In the second aspect of this example, a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is provided. Specifically: in water, a film-forming agent, a stabilizer, a sealing agent, and a leveling agent are added in sequence and mixed evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy-open end cans.

[0087] Comparative Example 4

[0088] In the first aspect of this example, a highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is provided. Its preparation raw materials are calculated according to mass parts and are specifically: 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 0.6 part of film-forming auxiliary agent, 0.5 part of leveling agent, and 82.8 parts of water; the mass concentration for slotting use of the highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is 0.5 wt%.

[0089] The film-forming agent is a compound of zirconium fluoride acid and potassium fluotitanate, and the mass ratio of zirconium fluoride acid to potassium fluotitanate is 7.2:3.4.

[0090] The stabilizer is phytic acid.

[0091] The film-forming auxiliary agent is cerium nitrate.

[0092] The leveling agent has the brand number Plurafac LF221.

[0093] In the second aspect of this example, a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is provided. Specifically: in water, a film-forming agent, a stabilizer, a film-forming auxiliary agent, and a leveling agent are added in sequence and mixed evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy-open end cans.

[0094] Comparative Example 5

[0095] In the first aspect of this example, a highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is provided. Its preparation raw materials are calculated according to mass parts and are specifically: 10.6 parts of film-forming agent, 5.5 parts of stabilizer, 0.6 part of film-forming auxiliary agent, 3 parts of sealing agent, 0.5 part of leveling agent, and 79.8 parts of water; the mass concentration for slotting use of the highly dense and environmentally friendly passivating agent for aluminum easy-open end cans is 0.5 wt%.

[0096] The film-forming agent is a compound of zirconium fluoride acid and potassium fluotitanate, and the mass ratio of zirconium fluoride acid to potassium fluotitanate is 7.2:3.4.

[0097] The stabilizer is phytic acid.

[0098] The film-forming auxiliary agent is cerium nitrate.

[0099] The sealing agent is hydrophilic fumed silica with a particle size of 5 - 10 nm.

[0100] The leveling agent has the brand number Plurafac LF221.

[0101] In the second aspect of this example, a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans is provided. Specifically: in water, a film - forming agent, a stabilizer, a film - forming auxiliary agent, a sealing agent and a leveling agent are added in sequence and mixed evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans.

[0102] Comparative Example 6

[0103] In the first aspect of this example, a highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans is provided. Its preparation raw materials are as follows by mass fraction: 10.6 parts of film - forming agent, 5.5 parts of stabilizer, 0.6 part of film - forming auxiliary agent, 1 part of sealing agent and 82.3 parts of water; the use mass concentration of the highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans for grooving is 0.5 wt%.

[0104] The film - forming agent is a compound of zirconium fluoride acid and potassium fluotitanate, and the mass ratio of zirconium fluoride acid to potassium fluotitanate is 7.2:3.4.

[0105] The stabilizer is phytic acid.

[0106] The film - forming auxiliary agent is cerium nitrate.

[0107] The sealing agent is hydrophilic fumed silica with a particle size of 5 - 10 nm.

[0108] In the second aspect of this example, a preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans is provided. Specifically: in water, a film - forming agent, a stabilizer, a film - forming auxiliary agent and a sealing agent are added in sequence and mixed evenly to obtain the highly dense and environmentally friendly passivating agent for aluminum easy - open lid cans.

[0109] Comparative Example 7

[0110] This example provides an environmentally friendly passivating agent for aluminum easy - open lid cans. The brand number of the product is ACP404R, which is purchased from Taishan Kemei Chemical Industry Co., Ltd. The grooving concentration of ACP404R is 0.3 - 0.45%, and the specific use concentration in this example is 0.33%.

[0111] Comparative Example 8

[0112] This example provides an environmentally friendly passivating agent for aluminum easy - open lid cans. The brand number of the product is ACP404R, which is purchased from Taishan Kemei Chemical Industry Co., Ltd. The specific use concentration in this example is 0.45%.

[0113] Performance evaluation

[0114] For Examples 1 - 3 and Comparative Examples 1 - 8, performance tests were conducted on the passivators described, including the treatment effect of high - temperature tanks, the treatment effect of beverage cans, the resistance to aluminum ion pollution, the content of passivation film - forming substances, and the water consumption of passivation overflow. The test methods and results of the experiments are shown in Tables 1 - 3.

[0115] The test conditions were a cleaning line for 330 mL aluminum cans at a line speed of 3000 cans / min.

[0116] Table 1

[0117]

[0118]

[0119] Table 2

[0120]

[0121]

[0122] Table 3

[0123]

[0124]

[0125] Table 4

[0126]

[0127]

[0128] Note: In Tables 1 - 4, qualified means: no foaming, no discoloration, and no peeling of the coating.

[0129] From the experimental results in Tables 1 - 4, it can be seen that the environmentally friendly passivators corresponding to Examples 1 - 3 of the present invention have excellent passivation effects. The aluminum can products are qualified after use, and since no resin or silane is used, the products are not likely to produce water stain residues.

[0130] In Comparative Example 1, due to the low addition amount of the stabilizer phytic acid, the anti - pollution property of the passivator decreased significantly.

[0131] In Comparative Example 2, due to the high addition amount of the stabilizer phytic acid, the anti - pollution property of the passivator decreased significantly.

[0132] In Comparative Example 3, due to the lack of film - forming aids, the film - forming speed was slow and the film - forming thickness was thin under normal temperature conditions.

[0133] In Comparative Example 4, since the sealing agent was not added, after the aluminum ion concentration increased, the microscopic pores were filled with aluminum compounds, resulting in the appearance of dot-like white particles at the bottom of the can and the phenomenon of coating blistering.

[0134] In Comparative Example 5, since the sealing agent was added in excess, the hydrophilic fumed silica was adsorbed on the passivation layer to form a powdery and loose layer, so the coating was prone to peeling off.

[0135] In Comparative Example 6, since the leveling agent was not added, water stain residues were likely to occur after the aluminum ion concentration increased, and at the same time, the uneven film formation led to a decrease in corrosion resistance and coating adhesion.

[0136] In Comparative Examples 7-8, the grooving use concentration of the ACP404R passivator was 0.3-0.45%, and it needed to be used under the heating condition of 40 °C. And at the aluminum ion content of 900 ppm, the stability of the coating was poor, so the practicability was relatively weak.

Claims

1. A highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans, characterized in that, The preparation raw materials, by mass parts, include 10-15 parts of film-forming agent, 4-8 parts of stabilizer, 0.1-1 part of film-forming aid, 0.5-2 parts of sealing agent, 0.3-1 part of leveling agent and 80-100 parts of water; The sealing agent includes fumed silica.

2. The highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans according to claim 1, characterized in that, The film-forming agent includes zirconium fluoride and fluorotitanate.

3. The highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans according to claim 2, characterized in that, The mass ratio of the zirconium fluoride to the fluorotitanate is (6-8):(3-5).

4. The highly dense and environmentally friendly passivating agent for aluminum easy-open end aluminum cans according to claim 3, characterized in that, The fluorotitanate includes one or more of potassium fluorotitanate, sodium fluorotitanate, ammonium fluorotitanate or magnesium fluorotitanate.

5. The high-density environmental protection passivating agent for aluminum easy-open lids of aluminum cans according to claim 1, characterized in that The stabilizer includes one or more of phytic acid, citric acid, sodium silicate or aluminum silicate.

6. The highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans according to claim 1, characterized in that, The film-forming aid includes one or more of cerium nitrate, lanthanum nitrate, ammonium fluoride or ammonium molybdate.

7. The highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans according to claim 1, characterized in that, The sealing agent includes hydrophilic fumed silica.

8. The high-density environmental protection passivating agent for aluminum easy-open lids of aluminum cans according to claim 7, characterized in that, The particle size of the hydrophilic fumed silica is 5-100 nm.

9. The high-density environmental protection passivating agent for aluminum easy-open lids of aluminum cans according to any one of claims 1-8, characterized in that The leveling agent includes fatty alcohol polyoxyethylene ether.

10. A preparation method of a highly dense and environmentally friendly passivating agent for aluminum easy-open lids of aluminum cans according to any one of claims 1-9, characterized in that, Including: Mix the film-forming agent, stabilizer, film-forming aid, sealing agent, leveling agent and water evenly to obtain the high-density environmental protection passivator for aluminum easy-open lids of aluminum cans.

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