Medium-temperature nickel-free hole sealing agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of hole sealing reagents, in particular to a medium-temperature nickel-free hole sealing agent and a preparation method and application thereof. The invention provides a nickel-free hole sealing treatment fluid, which comprises the following components by mass concentration: 0.1-30 g / L of a main hole sealing agent; 0.01 to 30 g / L of polyol fatty acid ester; 0.1 g / L to 10 g / L of an accelerant; a pH buffer agent is 0.05 to 5 g / L; wherein the main hole sealing agent comprises alkali metal salt and / or alkaline earth metal salt and lays a hole sealing core foundation; the polyol fatty acid ester is used as a coalescing agent and can form an organic film on the outer surface of a film layer to further obstruct a medium and improve the smoothness; the accelerant can further improve the corrosion resistance and the color fixing property; and the pH buffering agent ensures that the functions of all the components are fully exerted. All the components of the treating fluid cooperate with one another, so that the hole sealing quality, the salt mist tolerance and the color fixing performance of the treating fluid can be comparable with those of a commercially available nickel-containing hole sealing agent, and the treating fluid shows excellent comprehensive performance.

Description

Technical Field

[0001] This application relates to the field of sealing agent technology, and in particular to a medium-temperature nickel-free sealing agent, its preparation method and application. Background Technology

[0002] Aluminum and its alloys are widely used in aerospace, transportation, building decoration, and 3C electronic products due to their outstanding advantages of being lightweight, having high specific strength, good electrical and thermal conductivity, and being easy to form. However, aluminum alloys are chemically active and have poor corrosion resistance. In practical applications, anodizing is required to form a porous alumina (Al2O3) film on their surface. While this film can improve hardness and wear resistance, its porous structure makes it easy for corrosive media to penetrate and corrode the substrate. Therefore, sealing the pores of the anodized film is crucial. The sealing effect directly determines the corrosion resistance and service life of aluminum alloy products. Only by ensuring that the pores are effectively sealed can the penetration of corrosive media be prevented, ensuring that the product does not experience problems such as substrate corrosion and performance failure during long-term use. In addition, for colored aluminum alloy products that need to meet appearance requirements, the color fixation effect is also a core indicator. If dye loss, discoloration, or significant color difference (ΔE) occurs during the sealing process, it will directly damage the product's appearance consistency, reduce the product's aesthetics and market competitiveness, and even lead to product scrapping. Both of these factors together constitute the key support for the use value and market acceptance of aluminum alloy products.

[0003] In the field of pore sealing technology, traditional solutions have obvious limitations: boiling water and steam pore sealing are not only energy-intensive, but also prone to defects such as "powder bloom" and "pore sealing dust" during the process. These defects not only affect the appearance of the product, but also lead to poor pore sealing effect due to the unsealed pores at the defect points, which cannot meet the long-term corrosion resistance requirements; although pore sealing with heavy metal salts (nickel salts, cobalt salts, chromates) can achieve excellent pore sealing effect, the heavy metal ions such as nickel, cobalt, and chromium are highly toxic, and the subsequent wastewater treatment process is complex and costly, and has been strictly restricted by environmental regulations.

[0004] In response to environmental protection requirements, nickel-free sealing agents have emerged. Although they can avoid the toxicity and environmental risks of traditional heavy metal salt sealing agents, their overall performance is still difficult to compete with nickel-containing sealing technology. For example, a Chinese patent application provides a room-temperature stable and efficient environmentally friendly sealing agent for aluminum and aluminum alloys. This sealing agent has advantages such as good sealing penetration and anti-pollution, but it has the shortcoming of poor color fixation. This will affect the stability and inhibition of mass production of the product, making it difficult to realize the widespread implementation and industrial application of the technology.

[0005] Therefore, there is an urgent need to develop a nickel-free sealing agent that combines excellent color fixation, efficient sealing, and superior anti-fouling properties, with overall performance comparable to nickel-containing sealing technology. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the defects and shortcomings of existing nickel-free sealing agents that cannot simultaneously achieve color fixation, sealing and anti-fouling effects, and to provide the application of polyol fatty acid esters in the preparation of nickel-free sealing treatment solutions.

[0007] Another object of the present invention is to provide a nickel-free sealing solution.

[0008] Another object of the present invention is to provide a method for preparing the above-mentioned nickel-free sealing solution.

[0009] Another object of the present invention is to provide the application of the aforementioned nickel-free sealing solution in the preparation of aluminum or aluminum alloy anodic oxide films.

[0010] Another object of the present invention is to provide a nickel-free sealing method.

[0011] Another object of the present invention is to provide a method for preparing anodized films of aluminum or aluminum alloys.

[0012] Another object of the present invention is to provide an aluminum or aluminum alloy anodic oxide film prepared by the above preparation method.

[0013] The above-mentioned objective of this invention is achieved through the following technical solution: This invention protects the use of polyol fatty acid esters in the preparation of nickel-free sealing solutions, wherein the polyol fatty acid esters include one or more of polysorbate, polyglycerol fatty acid ester, and monoglyceride stearate.

[0014] In nickel-free sealing solutions, polyol fatty acid esters are high-performance film-forming aids. Their unique hydrophilic / hydrophobic balance structure brings multiple core advantages: on the one hand, they can significantly optimize the wetting and penetration performance of the solution, ensuring that the sealing solution uniformly covers the film surface and fully fills the pores, laying the foundation for high-quality sealing; on the other hand, after sealing, a dense and continuous organic protective film can be formed on the film surface, which can effectively block the intrusion of external corrosive media, greatly improve the corrosion resistance of the film, and significantly improve the surface finish, making the film appearance smoother and more even, thus comprehensively enhancing the overall effect of sealing treatment.

[0015] This invention protects a nickel-free sealing solution, which, by mass concentration, comprises the following components: Primary sealing agent: 0.1~30 g / L; Polyol fatty acid esters: 0.01~30 g / L; Accelerator 0.1~10 g / L; pH buffer 0.05~5 g / L; The primary sealing agent comprises alkali metal salts and / or alkaline earth metal salts.

[0016] This invention provides a nickel-free sealing solution, comprising the following components by mass concentration: 0.1~30 g / L of primary sealing agent; 0.01~30 g / L of polyol fatty acid ester; 0.1~10 g / L of accelerator; and 0.05~5 g / L of pH buffer. In this treatment solution system, the components function synergistically: the main sealing agent, including alkali metal salts and / or alkaline earth metal salts, lays the core foundation for sealing under the synergistic environment of the system, accelerating the hydration of the membrane layer to form boehmite and achieving pore deposit sealing; the polyol fatty acid ester, as a film-forming aid, improves the wetting and permeability of the treatment solution during the sealing process, ensuring uniform distribution of the sealing solution on the membrane surface and inside the pores, and forms a continuous organic film on the membrane surface after sealing, further blocking external media and improving surface smoothness; the accelerator promotes the directional arrangement or cross-linking of film-forming aid molecules on the membrane surface through complexation, permeation, or hydrogen bonding, enhancing the bonding force between the organic membrane and the boehmite layer, making the resulting composite sealing layer denser, and further improving corrosion resistance and dyeing and color-fixing performance; the pH buffer stabilizes the overall environment in the system, ensuring that other components can fully function. It is the precise synergy and functional complementarity of the components in this treatment liquid system that enables its sealing quality, salt spray resistance and color fixing performance to be comparable to commercially available nickel-containing sealing agents, demonstrating excellent comprehensive application performance.

[0017] In this invention, the mass concentration of the main sealing agent can specifically be 0.1, 0.5, 1, 3, 5, 9, 10, 13, 15, 19, 23, 26, 28, or 30 g / L, or any range formed by any two of the above values. The mass concentration of the film-forming aid can specifically be 0.01, 0.05, 0.1, 0.8, 2, 5, 7, 8, 9, 10, 12, 13, 15, 18, 21, 25, 29, or 30 g / L, or any range formed by any two of the above values. The mass concentration of the accelerator can specifically be 0.1, 0.3, 0.6, 0.9, 1, 1.5, 2, 3, 5, 8, or 10 g / L, or any range formed by any two of the above values. The mass concentration of the pH buffer can specifically be 0.05, 0.1, 0.5, 0.8, 1, 2, 3, 4, or 5 g / L, or any range formed by any two of the above values.

[0018] Preferably, the nickel-free sealing solution comprises, by mass concentration, the following components: Primary sealing agent: 0.5~10 g / L; Polyol fatty acid esters 1~20 g / L; Accelerator 0.5~8 g / L; pH buffer 0.6~3 g / L; The primary sealing agent comprises alkali metal salts and / or alkaline earth metal salts.

[0019] More preferably, the nickel-free sealing solution comprises, by mass concentration, the following components: Primary sealing agent: 0.8~5 g / L; Polyol fatty acid esters 5~15 g / L; Accelerator 0.8~4 g / L; pH buffer 0.8~2 g / L; The primary sealing agent comprises alkali metal salts and / or alkaline earth metal salts.

[0020] Furthermore, the primary sealing agent includes one or more of the following (1) to (3): (1) The alkali metal in the alkali metal salt is lithium; (2) The alkaline earth metal in the alkaline earth metal salt is calcium and / or magnesium; (3) The salts in the alkali metal salts and / or alkaline earth metal salts are one or more of acetate, nitrate, sulfate, and lactate.

[0021] Furthermore, the promoter is a monosaccharide and / or a sugar alcohol compound. These two types of compounds have low molecular weight and good hydrophilicity, and can complex or regulate the film-forming agent in the sealing liquid system, thereby ensuring the stable achievement of the target effect.

[0022] Furthermore, the monosaccharide compound is one or more of fructose, mannose, xylose, ribose, glucose, and galactose.

[0023] More preferably, the sugar alcohol compound is one or more of erythritol, isomaltitol, and xylitol.

[0024] Furthermore, the pH buffer includes one or more of ammonium acetate, triethanolamine, sodium citrate, and pyridine.

[0025] Preferably, the nickel-free sealing solution further includes water.

[0026] This invention protects the preparation method of the aforementioned nickel-free sealing solution, comprising the following steps: Mix the components according to the formula to obtain the nickel-free sealing solution.

[0027] This invention protects the application of the aforementioned nickel-free sealing solution in the preparation of aluminum or aluminum alloy anodic oxide films.

[0028] This invention protects a nickel-free sealing method, which uses the aforementioned nickel-free sealing solution for sealing treatment.

[0029] This invention protects a method for preparing an anodic oxide film on aluminum or aluminum alloy, comprising the following steps: After the aluminum workpiece undergoes pretreatment, it is anodized to form an initial oxide film layer. The aluminum workpiece containing the initial oxide film layer is then immersed in the aforementioned nickel-free sealing solution for sealing treatment. The posttreatment forms an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece.

[0030] Furthermore, the pretreatment includes degreasing, water washing, alkaline etching, water washing, dust removal, and water washing.

[0031] Furthermore, the degreasing process involves immersing the aluminum workpiece in an alkaline degreasing agent with a working solution concentration of 20~50g / L, and treating it at 55±2℃ until the stains on the sample surface are completely removed.

[0032] Preferably, the alkaline degreasing agent is an aluminum alloy degreasing agent.

[0033] More preferably, the aluminum alloy degreaser is TAC Alclean161.

[0034] Preferably, the concentration of the working solution is 25~35 g / L.

[0035] Furthermore, the alkaline etching involves immersing the washed aluminum workpiece in a 50-70 g / L sodium hydroxide solution and treating it at 60±2 ℃ until the surface exhibits a uniform matte finish.

[0036] Preferably, the concentration of the sodium hydroxide solution is 55~65 g / L.

[0037] Furthermore, the ash removal process involves immersing the aluminum workpiece, after alkaline etching and water washing, in a 20-35 wt% nitric acid solution at room temperature until the sample surface is smooth and clean.

[0038] Preferably, the nitric acid solution has a mass fraction of 25-32 wt%.

[0039] Furthermore, the pH of the nickel-free sealing solution is 4.5 to 6.5.

[0040] Furthermore, the pH of the nickel-free sealing solution can be adjusted by acetic acid and / or ammonia.

[0041] Furthermore, the sealing temperature is 50~80 ℃.

[0042] Furthermore, the sealing process is carried out at a temperature of 70~80 ℃.

[0043] Furthermore, the sealing process takes 10 to 40 minutes.

[0044] Furthermore, the sealing process takes 15 to 30 minutes.

[0045] Furthermore, the post-processing includes washing with water and drying.

[0046] Furthermore, the drying process is natural air drying.

[0047] Preferably, the aluminum or aluminum alloy anodized film further includes a dyeing treatment, specifically comprising the following steps: After the aluminum workpiece undergoes pretreatment, it is anodized to form an initial oxide film layer. The aluminum workpiece containing the initial oxide film layer is then immersed in dye. After dyeing, it is washed and then immersed in the aforementioned nickel-free sealing solution for sealing treatment. This posttreatment forms a dyed aluminum or aluminum alloy anodized film on the surface of the aluminum or aluminum workpiece.

[0048] Furthermore, the dye includes one or more of black dye, orange dye, yellow dye, and blue dye.

[0049] Furthermore, the staining time is 0.5 to 30 minutes.

[0050] Furthermore, the washing is a water wash.

[0051] This invention protects the aluminum or aluminum alloy anodic oxide film prepared by the aforementioned preparation method.

[0052] Furthermore, the thickness of the aluminum or aluminum alloy anodic oxide film is 8~20µm.

[0053] Furthermore, the thickness of the undyed aluminum or aluminum alloy anodized film is 8~12 µm.

[0054] Furthermore, the thickness of the dyed aluminum or aluminum alloy anodic oxide film is 13~17 µm. Compared with the prior art, the present invention has the following beneficial effects: This invention provides a nickel-free sealing solution, comprising the following components by mass concentration: a primary sealing agent (0.1-30 g / L); a polyol fatty acid ester (0.01-30 g / L); an accelerator (0.1-10 g / L); and a pH buffer (0.05-5 g / L). The primary sealing agent comprises alkali metal salts and / or alkaline earth metal salts, forming the core foundation for sealing. The polyol fatty acid ester, as a film-forming aid, can form an organic film on the film surface to further block the medium and improve smoothness. The accelerator further enhances corrosion resistance and colorfastness. The pH buffer ensures that each component functions fully. The synergistic effect of the components in this solution results in sealing quality, salt spray resistance, and colorfastness comparable to commercially available nickel-containing sealing agents, exhibiting superior overall performance. Detailed Implementation

[0055] The present invention will be further illustrated below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field.

[0056] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.

[0057] Degreasing: Immerse the aluminum workpiece in alkaline degreasing agent TAC Alclean161 (purchased from Okuno Pharmaceutical Co., Ltd.) with a working solution concentration of 30 g / L and treat at 55±2 ℃ until the stains on the sample surface are completely removed. Alkaline etching: Immerse the washed aluminum workpiece in a 60 g / L sodium hydroxide solution and treat it at 60±2 ℃ until the surface shows a uniform matte effect; Dust removal: Immerse the aluminum workpieces after alkaline etching and water washing in a 30wt% nitric acid solution and treat at room temperature until the sample surface is smooth and clean. Commercially available nickel-containing sealant: DX-500, purchased from Okuno Corporation.

[0058] Example 1: A method for preparing and dyeing a nickel-free sealing solution, an aluminum or aluminum alloy anodic oxide film. 1. A nickel-free sealing solution, comprising the following components by mass concentration: Main sealing agent: Calcium acetate 1 g / L; Polyol fatty acid esters: Polysorbate 8 g / L; Accelerator: Galactose 1.5 g / L; pH buffer: Ammonium acetate 1 g / L; The remainder is water.

[0059] 2. A method for preparing a nickel-free sealing solution, comprising the following steps: Mix the components according to the formula to obtain a nickel-free sealing solution.

[0060] 3. A method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film, comprising the following steps: (1) Pretreatment and anodizing: Aluminum workpieces were sequentially degreased, washed with water, alkali etched, washed with water, degreased, and washed with water. They were then placed in a sulfuric acid solution (180±5 g / L) and anodized by electrolysis. The anodizing conditions were: electrolyte temperature 19±1 ℃, constant voltage mode, voltage set at 15 V, current density controlled at 1.0 A / dm², electrolysis for 20 minutes, and water washing after oxidation. The resulting workpiece (natural color sample) had an initial anodized film thickness of 10.1 µm. For the dyed samples, aluminum workpieces were treated with the same pretreatment process as described above, and then electrolyzed in the same sulfuric acid anodizing system for 30 minutes. After washing with water, a dyeing substrate workpiece with an initial anodized film thickness of 15.2 µm was obtained. (2) Sealing treatment: Immerse the anodized workpiece obtained in step (1) into a nickel-free sealing solution at 80 °C for 20 minutes (during which the pH is adjusted to 5.5 with acetic acid and ammonia, and the workpiece is stirred regularly to ensure uniform temperature and full contact between the workpiece surface and the treatment solution); after sealing, remove the workpiece and rinse it quickly with deionized water, and air dry it to form an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece. (3) Sealing treatment of stained samples: The substrate workpiece obtained in step (1) is immersed in the corresponding dye for dyeing (dye and usage conditions: commercially available Tac Black-GLH (402) black dye 1 g / L, soaking for 10 min; TAC-ORANG-LH (301) orange dye 10 g / L, soaking for 1 min; TAC YELLOW SGL 203 yellow dye 5 g / L, soaking for 5 min; TAC BLUE BRL 507 blue dye 1 g / L, soaking for 3 min); after dyeing, it is thoroughly washed with water, and then the pores are sealed according to the method in step (2) to obtain a dyed aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece.

[0061] Example 2: A method for preparing and dyeing a nickel-free sealing solution, an aluminum or aluminum alloy anodic oxide film. 1. A nickel-free sealing solution, comprising the following components by mass concentration: Primary sealing agent: Lithium acetate 3 g / L; Polyol fatty acid esters: polyglycerol fatty acid esters 12 g / L; Accelerator: 1 g / L glucose; pH buffer: Ammonium acetate 1 g / L; The remainder is water.

[0062] 2. A method for preparing a nickel-free sealing solution, comprising the following steps: Mix the components according to the formula to obtain a nickel-free sealing solution.

[0063] 3. A method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film, comprising the following steps: (1) Pretreatment and anodizing: Aluminum workpieces were sequentially degreased, washed with water, alkali etched, washed with water, degreased, and washed with water. They were then placed in a sulfuric acid solution (180±5 g / L) and anodized by electrolysis. The anodizing conditions were: electrolyte temperature 19±1 ℃, constant voltage mode, voltage set at 15 V, current density controlled at 1.0 A / dm², electrolysis for 20 minutes, and water washing after oxidation. The resulting workpiece (natural color sample) had an initial anodized film thickness of 10.5 µm. For the dyed samples, aluminum workpieces were treated with the same pretreatment process as described above, and then electrolyzed in the same sulfuric acid anodizing system with the same parameters for 30 minutes. After washing with water, a dyeing substrate workpiece with an initial anodized film thickness of 15.4 µm was obtained. (2) Sealing treatment: Immerse the anodized workpiece obtained in step (1) into a nickel-free sealing solution at 80 °C for 20 minutes (during which the pH is adjusted to 5.5 with acetic acid and ammonia, and the workpiece is stirred regularly to ensure uniform temperature and full contact between the workpiece surface and the treatment solution); after sealing, remove the workpiece and rinse it quickly with deionized water, and air dry it to form an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece. (3) Sealing treatment of stained samples: The base workpiece obtained in step (1) is immersed in the corresponding dye for dyeing (dye and usage conditions: commercially available Tac Black-GLH (402) black dye 1 g / L, soaking for 10 min; TAC-ORANG-LH (301) orange dye 10 g / L, soaking for 1 min; TAC YELLOW SGL 203 yellow dye 5 g / L, soaking for 5 min; TAC BLUE BRL 507 blue dye 1 g / L, soaking for 3 min); after dyeing, it is thoroughly washed with water, and then sealed according to the method in step (2), that is, a dyed aluminum or aluminum alloy anodized film is formed on the surface of the aluminum workpiece.

[0064] Example 3: A method for preparing and dyeing a nickel-free sealing solution, an aluminum or aluminum alloy anodic oxide film. 1. A nickel-free sealing solution, comprising the following components by mass concentration: Main sealing agent: Magnesium acetate 1 g / L; Polyol fatty acid esters: Stearic acid monoglyceride 10 g / L; Accelerator: Galactose 3 g / L; pH buffer: Ammonium acetate 1 g / L; The remainder is water.

[0065] 2. A method for preparing a nickel-free sealing solution, comprising the following steps: Mix the components according to the formula to obtain a nickel-free sealing solution.

[0066] 3. A method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film, comprising the following steps: (1) Pretreatment and anodizing: Aluminum workpieces were sequentially degreased, washed with water, alkali etched, washed with water, degreased, and washed with water. They were then placed in a sulfuric acid solution (180±5 g / L) and anodized by electrolysis. The anodizing conditions were: electrolyte temperature 19±1 ℃, constant voltage mode, voltage set at 15 V, current density controlled at 1.0 A / dm², electrolysis for 20 minutes, and water washing after oxidation. The resulting workpiece (natural color sample) had an initial anodized film thickness of 10.5 µm. For the dyed samples, aluminum workpieces were treated with the same pretreatment process as described above, and then electrolyzed in the same sulfuric acid anodizing system for 30 minutes. After washing with water, a dyeing substrate workpiece with an initial anodized film thickness of 15.3 µm was obtained. (2) Sealing treatment: Immerse the anodized workpiece obtained in step (1) into a nickel-free sealing solution at 80 °C for 20 minutes (during which the pH is adjusted to 5.5 with acetic acid and ammonia, and the workpiece is stirred regularly to ensure uniform temperature and full contact between the workpiece surface and the treatment solution); after sealing, remove the workpiece and rinse it quickly with deionized water, and air dry it to form an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece. (3) Sealing treatment of stained samples: The base workpiece obtained in step (1) is immersed in the corresponding dye for dyeing (dye and usage conditions: commercially available Tac Black-GLH (402) black dye 1 g / L, soaking for 10 min; TAC-ORANG-LH (301) orange dye 10 g / L, soaking for 1 min; TAC YELLOW SGL 203 yellow dye 5 g / L, soaking for 5 min; TAC BLUE BRL 507 blue dye 1 g / L, soaking for 3 min); after dyeing, it is thoroughly washed with water, and then sealed according to the method in step (2), that is, a dyed aluminum or aluminum alloy anodized film is formed on the surface of the aluminum workpiece.

[0067] Comparative Example 1: A Traditional Boiling Water Sealing Method The difference from Example 1 is that in step (2) of a method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film, the nickel-free sealing solution is replaced with deionized water, as shown in the following steps: (1) Pretreatment and anodizing: Aluminum workpieces were sequentially degreased, washed with water, etched with alkali, washed with water, degreased, and washed with water. They were then placed in a sulfuric acid solution (180±5 g / L) and anodized by electrolysis. The anodizing conditions were: electrolyte temperature 19±1 ℃, constant voltage mode, voltage set at 15 V, current density controlled at 1.0 A / dm², electrolysis for 20 minutes, and water washing after oxidation. The resulting workpiece had an initial anodized film thickness of 10.2 µm. For the dyed samples, aluminum workpieces were treated with the same pretreatment process as described above, and then electrolyzed in the same sulfuric acid anodizing system for 30 minutes. After washing with water, a dyeing substrate workpiece with an initial anodized film thickness of 15.1 µm was obtained. (2) Sealing treatment: Immerse the anodized workpiece obtained in step (1) in deionized water at 90 °C for traditional boiling water sealing treatment (treatment time is 20 minutes); after sealing, take out the workpiece and rinse it quickly with deionized water, and air dry it to form an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece. (3) Sealing treatment of stained samples: The base workpiece obtained in step (1) is immersed in the corresponding dye for dyeing (dye and usage conditions: commercially available Tac Black-GLH (402) black dye 1 g / L, soaking for 10 min; TAC-ORANG-LH (301) orange dye 10 g / L, soaking for 1 min; TAC YELLOW SGL 203 yellow dye 5 g / L, soaking for 5 min; TAC BLUE BRL 507 blue dye 1 g / L, soaking for 3 min); after dyeing, it is thoroughly washed with water, and then sealed according to the method in step (2), that is, a dyed aluminum or aluminum alloy anodized film is formed on the surface of the aluminum workpiece.

[0068] Comparative Example 2: A nickel-containing sealing agent and its application method The difference from Example 1 is that, in the steps of preparing and dyeing an aluminum or aluminum alloy anodic oxide film with a nickel-free sealing solution, the nickel-free sealing solution is replaced with commercially available nickel-containing sealing agent DX-500 (7 g / L, which is the applicable concentration for which it has better performance).

[0069] The other steps and conditions are the same as in Example 1.

[0070] Comparative Example 3: A nickel-free sealing solution, and a method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film. The difference from Example 1 is that polyglycerol fatty acid esters are not added in the nickel-free sealing solution step.

[0071] The other steps and conditions are the same as in Implementation 1.

[0072] Comparative Example 4: A nickel-free sealing solution, and a method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film. The difference from Example 1 is that, in a nickel-free sealing solution step, polyglycerol fatty acid ester is replaced with sodium fatty alcohol polyoxyethylene ether sulfate (this salt form is commonly used in sealing agent formulations).

[0073] The other steps and conditions are the same as in Example 1.

[0074] Comparative Example 5: A nickel-free sealing solution, and a method for preparing and dyeing an aluminum or aluminum alloy anodic oxide film. The difference from Example 1 is that, in a nickel-free sealing solution step, the polyglycerol fatty acid ester is replaced with 2-ethylhexyl mercaptoacetate.

[0075] The other steps and conditions are the same as in Example 1.

[0076] Experimental example of sealing quality, anti-fouling properties and color-fixing performance of nickel-free sealing solution 1. Experimental Methods (1) Mass loss test All examples and comparative examples were conducted according to GB / T 8753.1-2017: "Evaluation of the sealing quality of anodized oxide films on aluminum and aluminum alloys - Part 1: Phosphoric acid-chromic acid method without nitric acid pre-impregnation". The sealing quality of the oxide films was tested, and the solution preparation and specific steps are as follows: Preparation of chromic phosphate solution: Weigh 20 g of chromium trioxide and 35 mL of 85% phosphoric acid (ρ = 1.7 g / mL) into 500 mL of pure water. After complete dissolution, transfer the solution to a 1000 mL volumetric flask, dilute to the mark with pure water, and mix well. Specific steps: First, dry and weigh the aluminum workpiece sample to form an aluminum or aluminum alloy anodized film. Then, immerse the sample upright and completely into a phosphoric acid solution preheated to 38±1 ℃. After soaking for 15 minutes, remove the sample, rinse it clean, dry it again, weigh it, and calculate the mass loss of the oxide film per square decimeter. The smaller the weight loss value, the less the mass loss and the better the sealing quality.

[0077] (2) Color difference (ΔE) test For the aluminum workpiece test pieces with dyed aluminum or aluminum alloy anodic oxide films formed in Examples 1-3 and Comparative Examples 1-5, the brightness (L), red-green axis (a), and yellow-blue axis (b) values ​​before and after sealing were measured using a DS400 spectrophotometer. ΔL, Δa, and Δb were calculated respectively, and the following results were obtained: The smaller the ΔE value, the less the sealing process affects the color, and the better the colorfastness.

[0078] (3) Neutral Salt Spray (NSS) Resistance Test All embodiments and comparative examples were tested according to GB / T 10125-2021: "Artificial Atmosphere Corrosion Test (Salt Spray Test)" to determine the quality of oxide film sealing. The specific steps are as follows: This method is carried out in a dedicated salt spray chamber. Under the condition of (35±2) ℃, a neutral sodium chloride solution (with a concentration of 50 g / L±5 g / L) is atomized by compressed air and then deposited on the surface of the aluminum workpiece sample with an aluminum or aluminum alloy anodized film. The evaluation criteria refer to GB / T 6461-2002: "Rating of specimens and test pieces of metal and other inorganic coatings on metal substrates after corrosion test". If there is no obvious change on the surface after 48 hours, it is considered as passing; otherwise, it is considered as failing.

[0079] (4) Copper-accelerated acetic acid salt spray (CASS) test All embodiments and comparative examples were tested according to GB / T 12967.3-2022: "Test methods for anodic oxide films and organic polymer films of aluminum and aluminum alloys - Part 3: Salt spray test", and the specific steps are as follows: This method utilizes a dedicated CASS salt spray chamber. At 50 ± 2 °C, an acidic solution with pH = 3.05 ± 0.05 is atomized and continuously sprayed using compressed air. The acid mist settles on the sample surface, causing certain changes in the aluminum workpiece sample with the aluminum or aluminum alloy anodized film. The acidic solution is prepared as follows: a 50 ± 5 g / L sodium chloride solution is prepared, and 0.26 ± 0.02 g / L copper chloride is added. Then, an appropriate amount of glacial acetic acid is added to adjust the pH to approximately 3.05 ± 0.05.

[0080] The evaluation criteria refer to GB / T 6461-2002: "Rating of specimens and test pieces of metal and other inorganic coatings on metal substrates after corrosion test"; no obvious change on the surface after 24 hours is considered as passing, otherwise it is considered as failing.

[0081] (5) Stain resistance test In all embodiments and comparative examples, aluminum workpieces with anodized aluminum or aluminum alloy films were coated with Zebra brand black ink. After standing for 30 seconds, they were wiped with a wet paper towel. The more obvious the staining, the worse the sealing performance, and vice versa. The sealing quality was judged by observing the depth of the stain color, and evaluated according to the following 5 levels: Level 1: Can be completely erased without leaving any trace; Level 2: Erasable, leaving very slight marks; Level 3: Most of it can be erased, but some obvious traces remain; Level 4: Only partially erasable, traces are severe; Level 5: Almost impossible to erase.

[0082] (6) Appearance and feel test Appearance test: Visual inspection is used. The dried anodized film is considered qualified if there is no obvious white dust, discoloration, water stains, or corrosion marks. Tactile test: The smoothness of the dried anodized film surface is judged by touching it with your hand; Roughness judgment criteria: Gently sweep your fingertip along the surface of the workpiece and perceive the "rough / fine" state of the surface's micro-undulations by touch. If the surface has no obvious resistance, a smooth feel, and no grainy or uneven feel, it is judged as smooth and meets the process requirements; if the surface has resistance, a slight grainy feel, or a slight unevenness, it is judged as rough and does not meet the process requirements. Definition of color bleeding degree: The surface color of the part, the state of the dye layer coverage, and the color change before and after sealing are observed visually. The defects are classified into the following levels according to their severity, as shown in Table 1: Table 1. Criteria for Judging the Degree of Flow

[0083] 2. Experimental Results Table 2 Summary of performance data for each embodiment and comparative example

[0084] In the table, "natural color" represents the color of the aluminum alloy parts themselves; "-" indicates that it was not tested. The nickel-free sealing solution in Comparative Example 4 was judged to be unqualified due to poor performance in weight loss and appearance tests, so CASS and NSS tests were not carried out further.

[0085] As shown in Table 2, the nickel-free sealing solution in Examples 1-3, through the synergistic effect of multiple components, enabled aluminum alloy parts to exhibit excellent sealing quality, anti-fouling properties, and color-fixing effects. The specific functions of each component are as follows: The main sealing agent, as the core of the sealing process, can accelerate the hydration of the film layer to form boehmite and achieve pore deposit sealing, laying the foundation for the core of the sealing process; the polyol fatty acid ester, as a film-forming aid, with its hydrophilic / hydrophobic balanced structure, can not only improve the wettability and permeability of the liquid, making the sealing solution evenly distributed on the film surface and inside the pores, but also form a continuous organic film on the surface of the film layer after sealing, further blocking external media and improving surface smoothness; the accelerator promotes the directional arrangement or cross-linking of film-forming aid molecules on the film surface through complexation, penetration, or hydrogen bonding, enhancing the bonding force between the organic film and the boehmite layer, making the resulting composite sealing layer denser, and further improving corrosion resistance and color-fixing performance; the pH buffer stabilizes the overall environment, providing a guarantee for the other components to fully play their roles. Specific performance indicators are as follows: Sealing effect: The weight loss of the oxide film test pieces was ≤8.9 mg / dm², and both the neutral salt spray test (NSS) and copper accelerated acetic acid salt spray test (CASS) were passed. The oxide film after sealing had a uniform color and a smooth surface; Anti-fouling: The staining spot test was all at level 1 (no obvious staining defects); Fixing effect: The color difference ΔE ≤3.41, demonstrating stable fixing ability. Further comparison shows that the sealing quality, anti-fouling and fixing performance of the sealing treatment solutions of Examples 1-3 of this invention are comparable to commercially available nickel-containing sealing agents (DX-500 used in Comparative Example 2).

[0086] Compared to Example 1, Comparative Example 1 uses traditional boiling water sealing, where the process relies solely on the hydration transformation of Al2O3 in 90°C hot water to generate platy / coral-like boehmite for pore reduction. However, this process is highly sensitive to water quality and time, easily leading to pre-hydration at the pore opening, hindering diffusion and resulting in incomplete hydration deep within the pores. It also causes the formation of sealing frost / white mist and dye leaching in hot water, ultimately resulting in significant deterioration of sealing quality, antifouling properties, and color-fixing performance. Comparative Example 3, lacking the film-forming aid polysorbate, cannot form a continuous organic sealing film, exposing surface pores. This allows contaminants to easily adhere and corrosive media to penetrate, leading to increased sealing weight loss, decreased antifouling and corrosion resistance, insufficient dye binding, and significantly deteriorated color-fixing effect. 4. Replacing the film-forming aid polysorbate with sodium fatty alcohol polyoxyethylene ether sulfate (SO4) easily leads to ion exchange and coordination precipitation in systems containing alkali metals or alkaline earth metals, resulting in a turbid and unstable sealing solution that is unsuitable for continuous sealing operations. Simultaneously, the sealing weight loss and color difference of the treated samples increase, and white spots appear on the surface, severely affecting the appearance quality. Comparative Example 5: Replacing the film-forming aid polysorbate with 2-ethylhexyl mercaptoacetate (2-HJTA) presents challenges. Firstly, this aid has low water solubility, making it difficult to form a stable adsorption film on the boehmite layer. Secondly, its thiol groups react with the main sealing salt CaO in the system. 2+ / Mg 2+ / Li + Poor coordination affinity leads to a loose sealing layer, poor sealing quality, easy color bleeding, poor color fixation, and poor resistance to contamination.

[0087] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. The application of polyol fatty acid esters in the preparation of nickel-free sealing solutions, characterized in that, The polyol fatty acid esters include one or more of polysorbate, polyglycerol fatty acid ester, and monoglyceride stearate.

2. A nickel-free sealing solution, characterized in that, Based on mass concentration, it includes the following components: Primary sealing agent: 0.1~30 g / L; Polyol fatty acid esters: 0.01~30 g / L; Accelerator 0.1~10 g / L; pH buffer 0.05~5 g / L; The primary sealing agent comprises alkali metal salts and / or alkaline earth metal salts.

3. The nickel-free sealing solution according to claim 2, characterized in that, The primary sealing agent includes one or more of the following (1) to (3): (1) The alkali metal in the alkali metal salt is lithium; (2) The alkaline earth metal in the alkaline earth metal salt is calcium and / or magnesium; (3) The salts in the alkali metal salts and / or alkaline earth metal salts are one or more of acetate, nitrate, sulfate, and lactate.

4. The nickel-free sealing solution according to claim 2, characterized in that, The promoter is a monosaccharide and / or a sugar alcohol compound.

5. The nickel-free sealing solution according to claim 2, characterized in that, The pH buffer includes one or more of ammonium acetate, triethanolamine, sodium citrate, and pyridine.

6. The method for preparing the nickel-free sealing solution according to any one of claims 2 to 5, characterized in that, Includes the following steps: Mix the components according to the formula to obtain the nickel-free sealing solution.

7. The use of the nickel-free sealing solution according to any one of claims 2 to 5 in the preparation of aluminum or aluminum alloy anodic oxide films.

8. A nickel-free sealing method, characterized in that, The sealing process is performed using the nickel-free sealing solution described in any one of claims 2 to 5.

9. A method for preparing an anodized film of aluminum or aluminum alloy, characterized in that, Includes the following steps: After the aluminum workpiece undergoes pretreatment, it is anodized to form an initial oxide film layer. The aluminum workpiece containing the initial oxide film layer is then immersed in the nickel-free sealing solution described in any one of claims 2 to 5 for sealing treatment. The posttreatment forms an aluminum or aluminum alloy anodized film on the surface of the aluminum workpiece.

10. The aluminum or aluminum alloy anodic oxide film prepared by the preparation method of claim 9.

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