A cleaning agent for copper strip surface and a preparation method thereof

Abstract

The application discloses a copper strip surface cleaning agent, which is composed of the following components in percentage by mass: 10-20% of citric acid, 5-10% of ammonium oxalate, 5-10% of disodium ethylenediaminetetraacetate, 1-5% of polyhydroxy alcohol, 0.5-2% of persulfate, 0.5-1.5% of surfactant, and the balance of water. Compared with traditional strong acid cleaning, the copper strip surface cleaning agent is safe and environmentally friendly, has no damage to human body and clothes, has no irritating odor, has no pollution to the environment, and has the removal effect of the oxide on the surface of the copper strip reaching the effect of the strong acid cleaning. In the case that degreasing is not complete, the cleaning effect is even better than that of the strong acid cleaning. The copper strip surface is not damaged, the strip surface is not corroded by over pickling, and the copper strip surface has a certain passivation effect.

Description

Technical Field

[0001] This invention belongs to the field of cleaning agent technology, specifically relating to a copper strip surface cleaning agent and its preparation method. Background Technology

[0002] The production of copper and copper alloy strip typically involves multiple cold rolling and annealing processes. During production, various organic and inorganic contaminants accumulate on the strip surface. After rolling, rolling oil residue remains on the copper strip surface. If the copper strip is exposed to high-temperature air after annealing, oxidation will occur. If not cleaned promptly, this will affect subsequent processes and product surface quality. Therefore, cleaning between secondary rolling processes and after annealing is an indispensable and crucial step. Currently, copper strip cleaning is completed on automated, continuous cleaning machines, typically including degreasing, pickling, grinding, passivation, and drying.

[0003] The purpose of degreasing is primarily to remove organic contaminants from the surface of copper strips, especially rolling oil and mixed machine oil. Common degreasing methods include solvent degreasing, electrolytic degreasing, and alkaline degreasing. Solvent degreasing mainly uses various petroleum-based, chlorine-based, and fluorine-based compounds that are compatible with lubricating oil, as well as emulsifying activators. Solvent degreasing has a strong ability to dissolve lubricating oil and is rapid and thorough, but it has drawbacks such as the flammability of petroleum-based substances, the carcinogenicity of chlorine-based substances, the ozone-depleting nature of fluorine-based substances, and the difficulty in removing reaction products of emulsifying activators and oil. Electrolytic degreasing works by passing an electric current through an alkaline solution, using the copper strip as the cathode, and utilizing the hydrogen bubbles generated at the cathode during electrolysis to peel off surface contaminants and residual oil. Because hydrogen is a very strong reducing and activating agent, it has a good degreasing effect and a surface polishing effect. However, metallic impurities in the electrolyte are prone to precipitate and deposit on the surface of the copper strip, and over-degreasing is very likely to occur, deteriorating the surface of the strip. Currently, the most widely used method is alkaline degreasing. Alkaline solution reacts with lubricating oil through surfactants to form substances such as sodium fatty acids, which dissolve in water to remove oil stains. However, there are problems with the collection and treatment of alkaline mist, and the removed oil stains may reduce the degreasing effect. Therefore, it is necessary to add an oil-water separation device.

[0004] Pickling is primarily for removing oxides; if degreasing is incomplete, the oxides cannot be completely removed by pickling. Grinding, on the other hand, is for better removal of the oxide layer and is usually prepared simultaneously with pickling to improve the surface quality of the copper strip. The pickling solution is mainly a sulfuric acid solution, and oxidants such as nitric acid and hydrogen peroxide are often added to enhance the pickling effect. Strong acid cleaning is low-cost and highly efficient, but the reaction process is difficult to control, easily leading to over-pickling, corrosion of the strip surface, and also causing environmental pollution and skin irritation.

[0005] Copper is reducing and readily oxidizes, especially in copper alloys where the potential differences between alloying elements make them more susceptible to oxidation and discoloration in humid and hot environments. Therefore, passivation is a crucial step in surface cleaning. Traditional passivation treatments primarily include chromate passivation and benzotriazole (BTA) passivation. Chromates, with their strong oxidizing properties, form an inactive passivation layer on the copper surface, providing protection and exhibiting excellent passivation effects. However, their use is restricted due to the presence of hexavalent chromium ions in their wastewater, causing significant environmental pollution. Benzotriazole and its derivatives are highly effective at inhibiting copper corrosion, exhibiting low pollution and good resistance to discoloration, making them the most widely used passivating agents currently.

[0006] Currently, the strong acid pickling process for copper strip is low-cost, efficient, and technically mature, but it still has problems such as environmental pollution and skin irritation. Some studies have explored the use of organic acid for cleaning, but the effect is difficult to reach the level of traditional acid pickling processes. Summary of the Invention

[0007] In view of the shortcomings of the prior art, the purpose of this invention is to provide a copper strip surface cleaning agent to replace the traditional strong acid pickling solution.

[0008] To achieve the above objectives, the present invention adopts the following technical solution.

[0009] The present invention provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0010] Citric acid 10-20%, ammonium oxalate 5-10%, disodium ethylenediaminetetraacetate 5-10%, polyhydroxy alcohol 1-5%, persulfate 0.5-2%, surfactant 0.5-1.5%, balance water.

[0011] Preferably, the mass ratio of citric acid, ammonium oxalate, and disodium ethylenediaminetetraacetate is 2-2.5:1:1.

[0012] Preferably, the polyhydroxy alcohol is one or both of ethylene glycol and glycerol.

[0013] Preferably, the persulfate is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0014] Preferably, the surfactant is an anionic surfactant and / or a nonionic surfactant.

[0015] More preferably, the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate.

[0016] More preferably, the nonionic surfactant is one of fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

[0017] The preparation method of the copper strip surface cleaning agent provided by the present invention is as follows:

[0018] First, dissolve ammonium oxalate and disodium ethylenediaminetetraacetate in water, then add polyhydroxy alcohol, then add citric acid to dissolve, and finally add persulfate and surfactant. Stir well to obtain a copper strip surface cleaning agent.

[0019] The method of using the copper strip surface cleaning agent provided by the present invention is as follows:

[0020] After degreasing, place the copper strip in a copper strip surface cleaning agent and immerse it at room temperature for 2 minutes. After rinsing with deionized water, remove it and dry it at low temperature.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] Compared with traditional strong acid cleaning, the copper strip surface cleaning agent provided by this invention is safe and environmentally friendly, does not damage the human body or clothing, has no irritating odor, and does not pollute the environment; it can remove oxides from the surface of copper strips to the same effect as strong acid cleaning, and even has a better cleaning effect than strong acid cleaning when degreasing is not thorough; it does not damage the surface of copper strips, will not cause over-acid corrosion of the strip surface, and also has a certain passivation effect on the surface of copper strips. Detailed Implementation

[0023] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention. In the embodiments of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; unless specifically specified, the technical means used are all conventional means well known to those skilled in the art.

[0024] The copper strip surface cleaning agent provided in this embodiment of the invention is composed of the following components by mass percentage:

[0025] Citric acid 10-20%, ammonium oxalate 5-10%, disodium ethylenediaminetetraacetate 5-10%, polyhydroxy alcohol 1-5%, persulfate 0.5-2%, surfactant 0.5-1.5%, balance water.

[0026] In some preferred embodiments, the mass ratio of citric acid, ammonium oxalate, and disodium ethylenediaminetetraacetate is 2–2.5:1:1.

[0027] In some preferred embodiments, the polyhydroxy alcohol is one or both of ethylene glycol and glycerol.

[0028] In some preferred embodiments, the persulfate is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

[0029] In some preferred embodiments, the surfactant is anionic surfactant and / or nonionic surfactant.

[0030] In some preferred embodiments, the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or sodium fatty alcohol polyoxyethylene ether sulfate.

[0031] In some preferred embodiments, the nonionic surfactant is one of fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, or polyoxyethylene sorbitan fatty acid ester.

[0032] The preparation method of the copper strip surface cleaning agent provided in this embodiment of the invention is as follows:

[0033] First, dissolve ammonium oxalate and disodium ethylenediaminetetraacetate in water, then add polyhydroxy alcohol, then add citric acid to dissolve, and finally add persulfate and surfactant. Stir well to obtain a copper strip surface cleaning agent.

[0034] Example 1

[0035] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0036] Citric acid 10%, ammonium oxalate 5%, disodium ethylenediaminetetraacetate 5%, ethylene glycol 1%, sodium persulfate 1.5%, sodium dodecyl sulfate 0.5%, water 77%.

[0037] Example 2

[0038] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0039] Citric acid 20%, ammonium oxalate 10%, disodium ethylenediaminetetraacetate 10%, ethylene glycol 2%, glycerol 3%, sodium persulfate 2%, sodium dodecyl sulfate 0.5%, fatty alcohol polyoxyethylene ether 1%, water 51.5%.

[0040] Example 3

[0041] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0042] Citric acid 20%, ammonium oxalate 8%, disodium ethylenediaminetetraacetate 8%, ethylene glycol 2%, glycerol 2%, sodium persulfate 1%, ammonium persulfate 0.5%, sodium fatty alcohol polyoxyethylene ether sulfate 0.5%, polyoxyethylene sorbitan fatty acid ester 1%, water 57%.

[0043] Example 4

[0044] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0045] Citric acid 14%, ammonium oxalate 6%, disodium ethylenediaminetetraacetate 8%, ethylene glycol 2%, glycerol 2%, sodium persulfate 1%, ammonium persulfate 0.5%, sodium fatty alcohol polyoxyethylene ether sulfate 0.5%, polyoxyethylene sorbitan fatty acid ester 1%, water 65%.

[0046] Example 5

[0047] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0048] Citric acid 16%, ammonium oxalate 8%, disodium ethylenediaminetetraacetate 6%, ethylene glycol 2%, glycerol 2%, potassium persulfate 1%, ammonium persulfate 0.5%, sodium fatty alcohol polyoxyethylene ether sulfate 0.5%, sorbitan fatty acid ester 1%, water 63%.

[0049] Example 6

[0050] This embodiment provides a copper strip surface cleaning agent, which is composed of the following components by mass percentage:

[0051] Citric acid 20%, ammonium oxalate 6%, disodium ethylenediaminetetraacetate 6%, ethylene glycol 2%, glycerol 2%, potassium persulfate 1%, ammonium persulfate 0.5%, sodium fatty alcohol polyoxyethylene ether sulfate 0.5%, sorbitan fatty acid ester 1%, water 61%.

[0052] Comparative Example 1

[0053] The copper strip surface cleaning agent provided in this comparative example is composed of the following components by mass percentage:

[0054] Citric acid 20%, ammonium oxalate 10%, ethylene glycol 2%, glycerol 3%, sodium persulfate 2%, sodium dodecyl sulfate 0.5%, fatty alcohol polyoxyethylene ether 1%, water 61.5%.

[0055] Comparative Example 2

[0056] The copper strip surface cleaning agent provided in this comparative example is composed of the following components by mass percentage:

[0057] Citric acid 20%, disodium ethylenediaminetetraacetate 10%, ethylene glycol 2%, glycerol 3%, sodium persulfate 2%, sodium dodecyl sulfate 0.5%, fatty alcohol polyoxyethylene ether 1%, water 61.5%.

[0058] Comparative Example 3

[0059] The surface cleaning agent for the copper strip in this comparative example is 13% sulfuric acid.

[0060] Cleaning performance test:

[0061] Slightly oxidized copper strips after annealing were used for testing. Samples were cut into 100×100mm pieces and divided into two groups for degreasing treatment. The first group had a degreasing rate of 95%, and the second group 83%. After weighing, the samples were immersed in the cleaning agents described in the above examples and comparative examples for 2 minutes each, with 10 samples in each group. After removal, the samples were rinsed with deionized water, dried at low temperature, and weighed. The average weight loss ratio was calculated. The magnitude of the weight loss ratio reflects the cleaning ability of the cleaning agent. The experimental results are shown in Table 1.

[0062] Table 1

[0063] Example First group of weight loss ratios Second group of weight loss ratios Example 1 1.75％ 1.74％ Example 2 1.84％ 1.82％ Example 3 1.82％ 1.81％ Example 4 1.78％ 1.75％ Example 5 1.79％ 1.77％ Example 6 1.76％ 1.75％ Comparative Example 1 0.48％ 0.36％ Comparative Example 2 0.52％ 0.38％ Comparative Example 3 1.86％ 1.62％

[0064] In the first group, the copper strip surface cleaning agents of Examples 1-6 of the present invention and the strong acid cleaning of Comparative Example 3 completely removed the oxides from the strip surface, resulting in a bright color; while the cleaning agents of Comparative Examples 1 and 2 could not completely remove the oxides from the strip surface. In the second group, the degreasing of the copper strip was incomplete. The cleaning agents of Examples 1-6 of the present invention were still able to completely remove the oxides from the strip surface, while the strong acid cleaning of Comparative Example 3 showed incomplete removal of oxides.

[0065] The samples of the first group of Examples 3 and Comparative Examples 3 after cleaning were subjected to a damp heat resistance test at 50°C. The sample of Comparative Example 3 after acid pickling showed corrosion and discoloration after 48 hours, while the sample of Example 3 after cleaning only showed discoloration after 168 hours, indicating that the surface cleaning agent of this application has a certain passivation effect on the surface of copper strip.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A copper strip surface cleaning agent, characterized in that, It consists of the following components by mass percentage: Citric acid 10-20%, ammonium oxalate 5-10%, disodium ethylenediaminetetraacetate 5-10%, polyhydroxy alcohol 1-5%, persulfate 0.5-2%, surfactant 0.5-1.5%, balance water; The polyhydroxy alcohol is one or both of ethylene glycol and glycerol.

2. The copper strip surface cleaning agent according to claim 1, characterized in that, The mass ratio of citric acid, ammonium oxalate, and disodium ethylenediaminetetraacetate is 2~2.5:1:

1.

3. The copper strip surface cleaning agent according to claim 1, characterized in that, The persulfate is one or more of sodium persulfate, potassium persulfate, and ammonium persulfate.

4. The copper strip surface cleaning agent according to claim 1, characterized in that, The surfactant is an anionic surfactant and / or a nonionic surfactant.

5. The copper strip surface cleaning agent according to claim 4, characterized in that, The anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium fatty alcohol polyoxyethylene ether sulfate.

6. The copper strip surface cleaning agent according to claim 4, characterized in that, The nonionic surfactant is one of fatty alcohol polyoxyethylene ether, sorbitan fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

7. The method for preparing the copper strip surface cleaning agent according to any one of claims 1 to 6, characterized in that, Includes the following steps: First, ammonium oxalate and disodium ethylenediaminetetraacetate are dissolved in water. Then, polyhydroxy alcohol is added, followed by citric acid, and finally persulfate and surfactant are added. The mixture is stirred until homogeneous to obtain the copper strip surface cleaning agent.