Metal pickling agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of metal cleaning, and particularly relates to a metal pickling agent and a preparation method and application thereof. The metal pickling agent comprises an acid solution, a corrosion inhibitor, a surfactant, an antioxidant and a complexing agent. According to the metal pickling agent, a complete oxidation film can be formed on the surface of a copper material during pickling, the copper material cannot be corroded and discolored under the condition that the surface of the copper material is acid for 30 min, and the requirement of automatic production can be met. After pickling treatment with a metal pickling agent and rinsing cleaning, a formed oxidation film uniformly covers the surface of a workpiece, the texture form is uniform, it can be ensured that the copper material is not corroded or discolored after being naturally stored for at least 3 days, and good oxidation resistance is achieved. Meanwhile, the uniform oxidation film can provide certain lubricity and reduce friction force, the subsequent extrusion or drawing process is facilitated, cracks and mottles are prevented from being generated on the surface of a product, and it is ensured that the workpiece cannot be corroded and discolored before extrusion or drawing.

Description

Technical Field

[0001] This invention belongs to the field of metal cleaning technology, and specifically relates to a metal pickling agent, its preparation method, and its application. Background Technology

[0002] Copper is an amphoteric metal, easily losing electrons and oxidizing in oxidizing environments, leading to discoloration and even blackening of the copper surface. Commercially available pickling agents typically use chromic acid, hydrogen peroxide, or nitric acid to prevent oxidation and discoloration of the copper surface. However, these methods all have certain problems. For example, while chromic acid pickling is fast, it is environmentally unfriendly; hydrogen peroxide pickling agents have high hardness, and nitric acid pickling agents are easily decomposed. Furthermore, pickling with these agents can corrode the workpiece, causing mottled spots, thus only meeting the requirements of traditional processes and not automated production. Therefore, developing a metal pickling solution that contains acid but does not corrode copper is crucial for automated production.

[0003] In practical applications, additional anti-oxidation treatment is usually performed on copper materials after pickling, such as using copper passivating agents and antioxidants. These antioxidants react with the copper surface to form a thin and dense passivation film or protective film, isolating the copper substrate from air and other corrosive media, thereby effectively improving the copper's oxidation resistance and preventing oxidation and discoloration during subsequent storage, transportation, and use. However, two pickling and passivation treatments inevitably increase production costs.

[0004] Therefore, it is of great significance to provide a pickling agent that has good pickling effect, good antioxidant properties, is non-corrosive to copper, and is environmentally friendly and safe. Summary of the Invention

[0005] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial solution. Specifically, the present invention provides a metal pickling agent that is non-corrosive to copper, environmentally friendly and safe; and has good pickling effect and excellent anti-oxidation properties, making it difficult for copper to oxidize again after pickling.

[0006] The inventive concept of this invention: The metal pickling agent of this invention includes acid, corrosion inhibitor, surfactant, antioxidant, and complexing agent.

[0007] This invention utilizes the synergistic effect of acid, corrosion inhibitor, surfactant, antioxidant, and complexing agent to form a complete oxide film on the copper surface during pickling. This film can prevent corrosion for 30 minutes on an acidic copper surface, thus meeting the needs of automated production. After pickling and cleaning, the resulting oxide film uniformly covers the workpiece surface, exhibiting excellent anti-corrosion and discoloration resistance for more than 3 days. Furthermore, the uniform morphology of the oxide film formed by pickling reduces friction, which is beneficial for subsequent extrusion or drawing processes, preventing cracks and spots on the workpiece surface, and ensuring no corrosion or discoloration before extrusion or drawing.

[0008] Therefore, a first aspect of the present invention provides a metal pickling agent.

[0009] Specifically, the metal pickling agent includes acid, corrosion inhibitor, surfactant, antioxidant, and complexing agent.

[0010] In some embodiments, the metal pickling agent is a copper pickling agent used for pickling copper materials.

[0011] In some embodiments, the metal pickling agent comprises, by mass percentage, 5-10% acid, 0.1-2% corrosion inhibitor, 0.2-5% surfactant, 0.1-3% antioxidant, and 0.1-0.5% complexing agent.

[0012] In some embodiments, the mass percentage of the acid solution that enables the present invention to achieve its objective is 5-10%; such as 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5%, 10%, etc.

[0013] In some embodiments, the corrosion inhibitor that achieves the purpose of the present invention has a mass percentage of 0.1-2%; such as 0.1%, 0.5%, 1%, 1.5%, 2%, etc.

[0014] In some embodiments, the surfactant that achieves the purpose of the present invention has a mass percentage of 0.2-5%; such as 0.2%, 1%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, etc.

[0015] In some embodiments, the antioxidant that achieves the purpose of the present invention has a mass percentage of 0.1-3%; such as 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2.5%, 3%, etc.

[0016] In some embodiments, the mass percentage of the complexing agent that can achieve the purpose of the present invention is 0.1-0.5%; such as 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, etc.

[0017] This invention ensures the pickling effect of the pickling agent by reasonably limiting the mass ratio of acid, corrosion inhibitor, surfactant, antioxidant and complexing agent.

[0018] In some embodiments, the acid solution includes sulfuric acid and phosphoric acid.

[0019] In some embodiments, the mass ratio of sulfuric acid to phosphoric acid in the acid solution is (1-4):1; such as 1:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, etc.

[0020] In some embodiments, after pickling with a metal pickling agent, the mass ratio of copper ions precipitated from the copper material to sulfuric acid is 1:(4-6); such as 1:4, 1:4.5, 1:5, 1:5.5, 1:6, etc.

[0021] Specifically, by limiting the mass ratio of copper ions precipitated from copper materials to sulfuric acid, the stability of the pickling system can be monitored, process parameters optimized, product quality ensured, and production costs and environmental risks reduced. For example, it can determine the aging degree and service life of the pickling bath; control the corrosion rate and surface quality of copper materials; optimize acid replenishment strategies to reduce production costs; and assess the difficulty and environmental risks of wastewater treatment.

[0022] In some embodiments, the corrosion inhibitor includes benzotriazole compounds.

[0023] In some embodiments, the corrosion inhibitor includes at least one of benzotriazole (BTA) and methylbenzotriazole (TTA).

[0024] In some embodiments, the surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

[0025] In some embodiments, the antioxidant includes at least one of hexamethylenetetramine (urotropine) and gelatin.

[0026] In some embodiments, the complexing agent includes at least one of citric acid and sodium gluconate.

[0027] In some embodiments, the metal pickling agent further includes a balance of solvent.

[0028] In some embodiments, the solvent includes water.

[0029] A second aspect of the present invention provides a method for preparing the metal pickling agent described in the first aspect of the present invention.

[0030] Specifically, the preparation method of the metal pickling agent includes the following steps:

[0031] The raw material components are mixed to obtain the product.

[0032] In some embodiments, the method for preparing the metal pickling agent includes the following steps: Water is heated and an antioxidant is added to obtain a mixture; the mixture is added to the acid solution; then the corrosion inhibitor, surfactant and complexing agent are added and mixed to obtain the metal pickling agent.

[0033] In some embodiments, the water is heated to a temperature of 50-60°C; such as 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, etc.

[0034] In some embodiments, the method for preparing the metal pickling agent includes the following steps: (1) Mix sulfuric acid and phosphoric acid, cool, and obtain an acid solution; (2) Heat the water and add an antioxidant to obtain mixture 1; add the mixture to the acid solution to obtain mixture 2; (3) The corrosion inhibitor, surfactant and complexing agent are mixed and added to the mixture 2 to obtain the metal pickling agent.

[0035] Specifically, in step (1), the purpose of cooling the mixture of sulfuric acid and phosphoric acid is to avoid a violent reaction after adding other substances.

[0036] A third aspect of the present invention provides a method for pickling metal.

[0037] Specifically, the method of pickling metal includes immersing the metal in the metal pickling agent described in the first aspect of the present invention.

[0038] In some embodiments, the soaking temperature is room temperature.

[0039] In some embodiments, the soaking time is 8-12 minutes, such as 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, etc.

[0040] A fourth aspect of the present invention provides the application of the metal pickling agent described in the first aspect of the present invention in the pickling of copper materials.

[0041] In some embodiments, the copper material includes any one of pure copper or copper alloy.

[0042] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows: (1) By using the metal pickling agent of the present invention, a complete oxide film can be formed on the surface of copper material during pickling. It can be maintained for 30 minutes without corrosion or discoloration on the copper surface under acid conditions, which is beneficial to meet the needs of automated production.

[0043] (2) After being pickled with a metal pickling agent and washed with water, the resulting oxide film uniformly covers the surface of the workpiece and has a uniform structure, which can ensure that the copper material will not corrode or discolor after being stored naturally for at least 3 days and has good oxidation resistance. At the same time, the uniform oxide film can provide a certain degree of lubrication, reduce friction, and facilitate subsequent extrusion or drawing, avoid cracks and spots on the surface of the product, and ensure that it will not corrode or discolor before extrusion or drawing.

[0044] (3) The surface gloss of copper material treated with the metal pickling agent of the present invention is more than 95% similar to the surface color of copper material treated with chromic acid polishing liquid, which is an ideal alternative to chromic acid polishing agent.

[0045] (4) The method of pickling metal in this invention is simple to operate and easy to promote and apply. Attached Figure Description

[0046] Figure 1 Metallographic image of copper material after being pickled, rinsed with water, and air-dried naturally using a metal pickling agent according to Example 1 of the present invention, and then placed in a dry environment at room temperature for 3 days; Figure 2 This is a picture of a copper material pickled with the metal pickling agent of Example 1 of the present invention. The copper material is pickled without being rinsed with water after pickling and left to stand for 30 minutes. Figure 3 The image shows the copper material pickled with the metal pickling agent of Comparative Example 1 of this invention. After pickling, the material was not rinsed with water and left to stand for 30 minutes. Figure 4 This is a picture of a copper material after it has been polished with chromic acid polishing solution. Figure 5 The image shows the actual product after the copper material was pickled, rinsed with water, and air-dried using the metal pickling agent of Example 1, and then placed in a dry environment at room temperature for 3 days. Detailed Implementation

[0047] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0048] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0049] Example 1 This embodiment provides a metal pickling agent, which, by mass percentage, consists of 8% acid (sulfuric acid and phosphoric acid), 1% corrosion inhibitor BTA, 2% surfactant sodium dodecyl sulfate, 2.5% antioxidant hexamethylenetetramine, 0.3% complexing agent citric acid, and the balance deionized water. In the acid solution, the mass ratio of sulfuric acid to phosphoric acid is 3:1.

[0050] After being pickled with a metal pickling agent, the mass ratio of copper ions precipitated from the copper material to sulfuric acid is 1:5.

[0051] This embodiment also provides a method for preparing the above-mentioned metal pickling agent, the specific process of which is as follows: (1) Mix sulfuric acid with a mass concentration of 98% and phosphoric acid with a mass concentration of 85%, and then cool to 25°C to avoid vigorous reaction after adding other substances, and obtain an acid solution; (2) Dissolve the antioxidant hexamethylenetetramine in water heated to 55°C, and then add it to the acid solution obtained in step (1) to obtain mixture 1; (3) The corrosion inhibitor BTA, surfactant sodium dodecyl sulfate and complexing agent citric acid are stirred and mixed evenly, and then added to the mixture 1 obtained in step (2), and stirred evenly to obtain the metal pickling agent.

[0052] Example 2 This embodiment provides a metal pickling agent, which, by mass percentage, consists of 10% acid (sulfuric acid and phosphoric acid), 0.15% corrosion inhibitor BTA, 0.2% surfactant sodium dodecyl sulfate, 0.3% antioxidant gelatin, 0.3% complexing agent citric acid, and the balance deionized water. In the acid solution, the mass ratio of sulfuric acid to phosphoric acid is 1:1.

[0053] This embodiment also provides a method for preparing the above-mentioned metal pickling agent, the specific process of which is as follows: (1) Mix sulfuric acid with a mass concentration of 98% and phosphoric acid with a mass concentration of 85%, and then cool to 25°C to avoid violent reaction after adding other additives, and obtain acid solution; (2) Dissolve the antioxidant gelatin in water heated to 55°C, and then add it to the acid solution obtained in step (1) to obtain mixture 1; (3) Stir the corrosion inhibitor BTA, surfactant sodium dodecyl sulfate and complexing agent citric acid evenly, add them to the mixture 1 obtained in step (2), stir evenly, and prepare metal pickling agent.

[0054] Example 3 This embodiment provides a metal pickling agent, which, by mass percentage, consists of 8% acid (sulfuric acid and phosphoric acid), 0.3% corrosion inhibitor BTA, 0.2% surfactant sodium dodecylbenzenesulfonate, 0.1% antioxidant gelatin, 0.5% complexing agent sodium gluconate, and the balance deionized water. In the acid solution, the mass ratio of sulfuric acid to phosphoric acid is 3:1.

[0055] This embodiment also provides a method for preparing the above-mentioned metal pickling agent, the specific process of which is as follows: (1) Mix sulfuric acid with a mass concentration of 98% and phosphoric acid with a mass concentration of 85%, and then cool to 25°C to avoid violent reaction after adding other additives, and obtain acid solution; (2) Dissolve the antioxidant gelatin in water heated to 55°C, and then add it to the acid solution obtained in step (1) to obtain mixture 1; (3) Stir the corrosion inhibitor BTA, surfactant sodium dodecylbenzenesulfonate and complexing agent sodium gluconate evenly, add them to the mixture 1 obtained in step (2), stir evenly, and prepare metal pickling agent.

[0056] Comparative Example 1 A metal pickling agent, by mass percentage, consists of 8% acid (sulfuric acid and phosphoric acid), 1% corrosion inhibitor BTA, 2% surfactant sodium dodecyl sulfate, 0.3% complexing agent citric acid, and the balance deionized water. In the acid solution, the mass ratio of sulfuric acid to phosphoric acid is 3:1.

[0057] The preparation method of the metal pickling agent in Comparative Example 1 is as follows: (1) Mix sulfuric acid with a mass concentration of 98% and phosphoric acid with a mass concentration of 85%, and then cool to 25°C to avoid violent reaction after adding other additives, and obtain acid solution; (2) Add water heated to 55°C to acid solution and mix to obtain mixture 1; mix surfactant, complexing agent and corrosion inhibitor evenly, then add to mixture 1 and stir evenly to obtain metal pickling agent.

[0058] Performance testing 1. Under room temperature conditions, the copper material was immersed in the metal pickling agent prepared in Example 1 for 10 minutes for pickling, then rinsed with water, air-dried naturally, and placed in a dry environment at room temperature for 3 days before metallographic observation. The results are as follows. Figure 1 As shown.

[0059] Depend on Figure 1It can be seen that after treatment with metal pickling agent, the oxide film formed on the surface of copper material is uniformly covered on the workpiece surface, with uniform structure and no corrosion or discoloration. It has good oxidation resistance, which is greater than 3 days, and can ensure that it will not corrode or discolor before subsequent extrusion or drawing processes.

[0060] 2. The copper materials were immersed in the metal pickling agents prepared in Example 1 and Comparative Example 1 for 10 minutes each. After pickling, they were not rinsed with water. The actual products after 30 minutes are shown in the following figure. Figure 2 , 3 As shown.

[0061] Depend on Figure 2-3 It can be seen that after pickling with the metal pickling agent of this invention without rinsing with water, the copper surface can remain uncorroded and discolored for 30 minutes in an acidic environment, exhibiting oxidation resistance for more than 30 minutes, which is beneficial for meeting the needs of automated production. In contrast, after treatment with the metal pickling agent of Comparative Example 1, corrosion and discoloration occurred within 30 minutes, and the oxidation resistance was less than 30 minutes.

[0062] 3. The coefficient of friction was tested on copper materials that had not been pickled with the metal pickling agent, and on copper materials that had been pickled with the metal pickling agent of Example 1, rinsed with water, air-dried, and placed in a dry environment at room temperature for 3 days. The test method for the coefficient of friction can refer to GB / T 12444.2-2006. The pickling process involved immersing the copper material in the metal pickling agent prepared in Example 1 for 10 minutes at room temperature.

[0063] Friction coefficient tests showed that the coefficient of friction for copper without pickling with the metal pickling agent was 0.53, while the coefficient of friction for copper after pickling with the metal pickling agent was 0.38. This indicates that the oxide film formed on the surface of the copper after pickling with the metal pickling agent of this invention can provide a certain degree of lubrication and reduce friction. This will be beneficial for subsequent extrusion or drawing, and will prevent cracks and spots from forming on the surface of the product.

[0064] 4. Polish the copper material using chromic acid polishing solution. After polishing, rinse with water, air dry naturally, and then place in a dry environment at room temperature for 3 days. (See attached image for the final product.) Figure 4 As shown.

[0065] The copper material was immersed in the pickling agent of Example 1 for pickling, rinsed with water, air-dried, and then placed in a dry environment at room temperature for 3 days. The actual product image is shown below. Figure 5 As shown, the pickling process involves immersing the copper material in the metal pickling agent prepared in Example 1 for 10 minutes at room temperature for pickling.

[0066] Depend on Figure 4 and Figure 5It can be seen that the pickling effect (visual surface brightness of copper material) of the metal pickling agent of this invention can reach 95% of that of chromic acid polishing liquid, making it an ideal alternative to chromic acid polishing agents.

[0067] In summary, the metal pickling agent of this invention can form a complete oxide film on the surface of copper during pickling. Even with acid on the copper surface for 30 minutes, the copper will not corrode or discolor, which is beneficial for meeting the needs of automated production. After pickling with the metal pickling agent and rinsing with water, the formed oxide film uniformly covers the workpiece surface with a uniform morphology, ensuring that the copper will not corrode or discolor after natural storage for at least 3 days, exhibiting excellent oxidation resistance. Simultaneously, the uniform oxide film provides a certain degree of lubrication, reducing friction and facilitating subsequent extrusion or drawing processes, preventing cracks and spots on the product surface, and ensuring that the workpiece will not corrode or discolor before extrusion or drawing.

[0068] Furthermore, the surface gloss of copper treated with the metal pickling agent of this invention is more than 95% similar to the surface color of copper treated with chromic acid polishing liquid, making it an ideal substitute for chromic acid polishing agents.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A metal pickling agent, characterized in that, The metal pickling agent includes acid, corrosion inhibitor, surfactant, antioxidant, and complexing agent.

2. The metal pickling agent according to claim 1, characterized in that, The metal pickling agent comprises, by mass percentage, 5-10% acid, 0.1-2% corrosion inhibitor, 0.2-5% surfactant, 0.1-3% antioxidant, and 0.1-0.5% complexing agent.

3. The metal pickling agent according to claim 1, characterized in that, The acid solution includes sulfuric acid and phosphoric acid; and / or, the corrosion inhibitor includes benzotriazole compounds.

4. The metal pickling agent according to claim 3, characterized in that, In the acid solution, the mass ratio of sulfuric acid to phosphoric acid is (1-4):

1.

5. The metal pickling agent according to claim 1, characterized in that, The surfactant includes at least one of sodium dodecyl sulfate and sodium dodecylbenzene sulfonate.

6. The metal pickling agent according to claim 1, characterized in that, The antioxidant includes at least one of hexamethylenetetramine and gelatin; and / or the complexing agent includes at least one of citric acid and sodium gluconate.

7. The metal pickling agent according to claim 2, characterized in that, The metal pickling agent also includes a balance of solvent.

8. The method for preparing the metal pickling agent according to any one of claims 1-7, characterized in that, The preparation method includes the following steps: The raw material components are mixed to obtain the product.

9. A method for pickling metal, characterized in that, The method includes immersing the metal in the metal pickling agent according to any one of claims 1-7.

10. The application of the metal pickling agent according to any one of claims 1-7 in the pickling of copper materials.

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