A method for degreasing and whitening battery aluminum casings

Abstract

This invention provides a method for degreasing and whitening battery aluminum casings. The method includes the following steps: preparing a degreasing and whitening solution from powder and water; using the degreasing and whitening solution to degrease and whiten the battery aluminum casing; rinsing the degreased and whitened aluminum casing to obtain a clean battery aluminum casing. The powder is potassium pyrophosphate, and the water includes sodium hydroxyethylidene diphosphonate, surfactant, organic solvent, and deionized water. This invention combines degreasing and whitening, effectively reducing the cleaning process of battery aluminum casings and improving production efficiency. This method does not require the use of a special PVC tank; only a stainless steel tank commonly used in industrial cleaning is needed.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy surface treatment technology, and relates to a method for degreasing and whitening aluminum battery casings. Background Technology

[0002] The aluminum casings of new energy batteries are made from aluminum sheets through a stamping and stretching process, followed by degreasing and whitening processes. The surface of the stretched casing not only has severe oil residue but also a large amount of fine metal shavings, making cleaning extremely difficult. Furthermore, the degreasing and whitening processes are currently performed separately. The common battery aluminum casing cleaning processes in China are lengthy and cumbersome, affecting production efficiency; the whitening agents used are high-concentration hydrofluoric acid, and may also be used in conjunction with strong acids such as nitric acid and sulfuric acid, which inevitably produces serious acid fumes, harming human health and the environment.

[0003] CN103305857A discloses a whitening solution for aluminum alloy surfaces and a surface treatment method thereof. The solution uses water as a solvent, and each liter of the whitening solution contains: 8-10g ammonium chloride; 40-50g ammonium sulfate; 50-60g ammonium fluoride; and 90-100g ammonium bifluoride. This invention uses ammonium fluoride and ammonium bifluoride instead of traditional liquid hydrofluoric acid to whiten aluminum parts, which can reduce the generation of acid mist. However, this agent cannot avoid the problem of separate degreasing and whitening processes in traditional methods.

[0004] CN106757094A discloses a whitening agent for aluminum mobile phone battery covers and its preparation method, comprising the following components in the indicated mass ratios: sodium silicate 15-18%, sodium gluconate 1.5-2.5%, sodium hydroxyethylidene diphosphonate 2-4%, sodium benzoate 1.2-1.6%, sodium citrate monohydrate 4-6%, triethanolamine 1.0-3.0%, non-foaming amphoteric surfactant 4-6%, and deionized water to 100%. This invention overcomes the drawbacks of traditional methods that involve separate cleaning with two different cleaning agents for degreasing and whitening. However, this invention is not suitable for cleaning aluminum casings of new energy batteries because the non-foaming amphoteric surfactant used in this invention has very weak degreasing ability. After the stretching process, the surface of the battery aluminum casing has a lot of viscous oil residue, which ordinary cleaning agents cannot clean effectively.

[0005] The surface treatment method described above separates the degreasing and whitening processes, resulting in a long process time and affecting production efficiency. The aluminum shell of the battery has serious oil residue and a large amount of metal shavings, which requires a particularly high degreasing and cleaning ability of the cleaning agent. At the same time, the traditional whitening agent is a high-concentration hydrofluoric acid, which is extremely harmful.

[0006] Therefore, developing an agent that has both high degreasing ability and can whiten the aluminum casing of batteries during degreasing is of great significance and has great application prospects. Summary of the Invention

[0007] The purpose of this invention is to provide a method for degreasing and whitening battery aluminum casings. The method of this invention combines degreasing and whitening, effectively reducing the cleaning process of battery aluminum casings and improving production efficiency. The method does not require the use of special PVC tanks, but only stainless steel tanks commonly used in industrial cleaning.

[0008] To achieve this objective, the present invention employs the following technical solution:

[0009] In a first aspect, the present invention provides a method for degreasing and whitening a battery aluminum casing, the method comprising the following steps:

[0010] The powder and water are combined to form a degreasing and whitening solution, which is then used to degrease and whiten the aluminum casing of the battery.

[0011] The aluminum casing obtained after degreasing and bleaching is rinsed to obtain a clean battery aluminum casing;

[0012] The powder is potassium pyrophosphate, and the aqueous solution includes sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water.

[0013] The degreasing and whitening method for battery aluminum shells described in this invention combines degreasing and whitening, effectively reducing the cleaning process of battery aluminum shells and improving production efficiency. The selected surfactants not only have excellent performance themselves, but also have good compatibility and synergistic effects. When compounded in a certain way, they have extremely strong cleaning ability, which can well ensure the production yield. The main whitening raw material, potassium pyrophosphate, is a common industrial cleaning raw material. It is easy to obtain, low in cost, and safer than traditional hydrofluoric acid whitening agents.

[0014] Preferably, based on the total mass of the aqueous and powder components in the degreasing and whitening solution as 100%, the mass fraction of the powder is 5% to 40%, for example: 5%, 8%, 10%, 20%, or 40%.

[0015] The powder used in this invention is potassium pyrophosphate. When heated, the potassium pyrophosphate reacts with aluminum, not only giving the aluminum a white appearance but also forming a phosphate film on the surface of the aluminum parts, thus giving the aluminum parts excellent corrosion resistance and wear resistance. Simultaneously, potassium pyrophosphate also softens water and disperses solid particles.

[0016] Preferably, based on the total mass of the aqueous and powdered agents in the degreasing and whitening solution as 100%, the mass fraction of the aqueous agent is 60-95%, for example: 60%, 70%, 80%, 90% or 95%, etc.

[0017] The powder and liquid formulations described in this invention need to be stored separately and are only mixed together during production. An example of their usage is as follows:

[0018] Add 100kg of tap water and 0.5-2kg of powder to the degreasing tank, dissolve it, then add 3-10kg of liquid agent, heat to the appropriate temperature and it is ready to use.

[0019] Preferably, the surfactant includes Berol 226 and / or Softanol-90.

[0020] Preferably, the mass ratio of Berol 226 to Softanol-90 is 1:(0.5~2), for example: 1:0.5, 1:0.8, 1:1, 1:1.5 or 1:2, etc.

[0021] This invention selects suitable compound surfactants. Berol 226 is a cationic / non-cationic surfactant compound, which not only has a very strong tearing and peeling ability for oil stains, but also has an excellent cleaning effect on metal shavings due to its cationic nature. Softanol-90 is a secondary alcohol polyoxyethylene ether, which is an excellent penetrant, emulsifier, wetting and detergent. Under medium and high temperature conditions, it has a better cleaning, decontamination and penetrating wetting emulsification ability than the traditional emulsifier TX-10.

[0022] Preferably, the organic solvent includes any one or a combination of at least two of isopropanol, isohexanediol, or diethylene glycol monobutyl ether.

[0023] Preferably, the sodium hydroxyethylidene diphosphonate has a mass fraction of 1-4% based on 100% of the aqueous agent, for example: 1%, 2%, 2.5%, 3% or 4%.

[0024] The sodium hydroxyethylidene diphosphonate used in this invention will further improve the agent's ability to soften water and disperse solid particles, so that the metal shavings on the aluminum shell surface can be effectively and quickly peeled off and uniformly dispersed in the liquid, preventing solid re-settling.

[0025] Preferably, based on the mass of the aqueous agent as 100%, the mass fraction of the surfactant is 15-25%, for example: 15%, 18%, 20%, 22% or 25%, etc.

[0026] Preferably, based on the mass of the aqueous agent as 100%, the mass fraction of the organic solvent is 3-6%, for example: 3%, 3.5%, 4%, 5% or 6%, etc.

[0027] The organic solvent used in this invention can improve the cleaning ability of the agent and make the agent easier to rinse.

[0028] Preferably, based on the mass of the aqueous agent as 100%, the mass fraction of the deionized water is 65% to 81%, for example: 65%, 68%, 72%, 75% or 81%, etc.

[0029] Preferably, the degreasing and bleaching treatment includes at least three ultrasonic degreasing and bleaching processes.

[0030] Preferably, the temperature of the degreasing and bleaching treatment is 60-70°C, for example: 60°C, 62°C, 65°C, 68°C or 70°C.

[0031] Preferably, the time for each ultrasonic degreasing and whitening is 1 to 2 minutes, for example: 1 minute, 1.2 minutes, 1.5 minutes, 1.8 minutes or 2 minutes.

[0032] Preferably, the rinsing includes rinsing with pure water.

[0033] Preferably, the rinsing temperature is 50-60°C, for example: 50°C, 52°C, 55°C, 58°C or 60°C.

[0034] Preferably, the time for each pure water rinse is 1 to 2 minutes, for example: 1 minute, 1.2 minutes, 1.5 minutes, 1.8 minutes or 2 minutes.

[0035] Preferably, the rinsing process is followed by spin-drying and drying.

[0036] As a preferred embodiment of the present invention, the method includes the following steps:

[0037] The powder and water are used to prepare a degreasing and whitening solution. The aluminum shell of the battery is subjected to at least three ultrasonic degreasing and whitening treatments at 60-70°C, with each ultrasonic degreasing and whitening treatment lasting 1-2 minutes.

[0038] The aluminum shell obtained after degreasing and whitening is rinsed with pure water at least three times at 50-60℃, with each rinse lasting 1-2 minutes, to obtain a clean battery aluminum shell.

[0039] The powder is potassium pyrophosphate, and the aqueous solution includes sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water. The mass of the powder accounts for 0.5 to 2% of the total mass of the powder and aqueous solution. The mass ratio of sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water in the aqueous solution is (1 to 4):(15 to 25):(3 to 6):(65 to 81).

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) The method of the present invention combines degreasing and whitening, which effectively reduces the cleaning process of battery aluminum shell and improves production efficiency. The method does not require the use of special PVC tanks, but only stainless steel tanks commonly used in industrial cleaning.

[0042] (2) The degreasing and whitening method described in this invention produces battery aluminum shells with suitable whiteness, and the whitening yield can reach more than 98.86%, and the cleaning yield can reach more than 98.48%. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the process flow for the degreasing and whitening method for the aluminum casing of the battery described in this invention.

[0044] Figure 2 This is a surface quality assessment diagram for aluminum shells obtained by degreasing and bleaching using the method described in this invention. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] Unless otherwise specified, all proportions in the embodiments and comparative examples of this invention refer to parts by mass.

[0047] Example 1

[0048] This embodiment provides a method for degreasing and whitening battery aluminum casings, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0049] Sodium hydroxyethylidene diphosphonate, surfactants (Berol 226 and Softanol-90 in a mass ratio of 8:10), organic solvent (isopropanol), and deionized water were mixed in a mass ratio of 4:20:5:71 to prepare an aqueous solution. Potassium pyrophosphate was used as a powder. 100 kg of tap water was added to the degreasing tank, followed by 1 kg of powder to dissolve, and then 4 kg of the aqueous solution was added to obtain a degreasing and whitening solution. The degreasing and whitening solution was used to perform four ultrasonic degreasing and whitening treatments on the aluminum shell of the battery. The ultrasonic degreasing and whitening treatment temperature was 65°C, and the time for each ultrasonic degreasing and whitening treatment was 1.5 min.

[0050] The battery aluminum casing was rinsed with pure water at 55°C for 3 times, with each rinse lasting 1.5 minutes. After spin-drying and drying, a pure battery aluminum casing was obtained.

[0051] Example 2

[0052] This embodiment provides a method for degreasing and whitening battery aluminum casings, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0053] Sodium hydroxyethylidene diphosphonate, surfactants (Berol 226 and Softanol-90 in a mass ratio of 8:10), organic solvent (isohexanediol), and deionized water were mixed in a mass ratio of 1:15:3:81 to prepare an aqueous solution. Potassium pyrophosphate was used as a powder. 100 kg of tap water was added to the degreasing tank, followed by the addition of 0.5 kg of powder to dissolve it, and then 9.5 kg of the aqueous solution was added to obtain a degreasing and whitening solution. The degreasing and whitening solution was used to perform four ultrasonic degreasing and whitening treatments on the aluminum shell of the battery. The ultrasonic degreasing and whitening treatment temperature was 60°C, and the time for each ultrasonic degreasing and whitening treatment was 2 min.

[0054] The battery aluminum casing was rinsed with pure water at 50°C for 3 times, with each rinse lasting 2 minutes. After spin-drying and drying, a pure battery aluminum casing was obtained.

[0055] Example 3

[0056] This embodiment provides a method for degreasing and whitening battery aluminum casings, and the process flow diagram of the method is shown below. Figure 1 As shown, the method includes the following steps:

[0057] Sodium hydroxyethylidene diphosphonate, surfactants (Berol 226 and Softanol-90 in a mass ratio of 8:15), organic solvent (diethylene glycol monobutyl ether), and deionized water were mixed in a mass ratio of 4:25:6:65 to prepare an aqueous solution. Potassium pyrophosphate was used as a powder. 100 kg of tap water was added to the degreasing tank, followed by 2 kg of powder to dissolve, and then 3 kg of aqueous solution was added to obtain a degreasing and whitening solution. The degreasing and whitening solution was used to perform four ultrasonic degreasing and whitening treatments on the aluminum shell of the battery. The temperature of the ultrasonic degreasing and whitening treatment was 70°C, and the time of each ultrasonic degreasing and whitening treatment was 1 min.

[0058] The battery aluminum casing was rinsed with pure water at 60°C for 3 times, with each rinse lasting 1 minute. After spin-drying and drying, a pure battery aluminum casing was obtained.

[0059] Example 4

[0060] The only difference between this embodiment and Example 1 is that the proportion of surfactant in the aqueous solution is 10 (the remainder is made up with deionized water). All other conditions and parameters are exactly the same as in Example 1.

[0061] Example 5

[0062] The only difference between this embodiment and Example 1 is that the proportion of surfactant in the aqueous solution is 30 (the remainder is made up with deionized water). All other conditions and parameters are exactly the same as in Example 1.

[0063] Example 6

[0064] The only difference between this embodiment and Example 1 is that in the aqueous solution, only Berol 226 is used as the surfactant; all other conditions and parameters are exactly the same as in Example 1.

[0065] Example 7

[0066] The only difference between this embodiment and Example 1 is that the surfactant used in the aqueous solution is Softanol-90; all other conditions and parameters are exactly the same as in Example 1.

[0067] Comparative Example 1

[0068] The only difference between this comparative example and Example 1 is that the powder component is replaced with traditional sodium metasilicate instead of potassium pyrophosphate; all other conditions and parameters are exactly the same as in Example 1.

[0069] Comparative Example 2

[0070] The only difference between this comparative example and Example 1 is that the surfactant component in the aqueous solution is replaced with a traditional surfactant (nonylphenol polyoxyethylene ether, fatty alcohol polyoxyethylene ether and 2-octyl alcohol polyoxyethylene ether in a mass ratio of 10:6:4). All other conditions and parameters are exactly the same as in Example 1.

[0071] Performance testing:

[0072] After cleaning and drying, place the battery aluminum casing under the light on the inspection table and observe whether the whiteness of the outer surface and inner cavity of the battery aluminum casing is sufficient and uniform, and whether there is any oil stains or black lines remaining. The standard for judging a well-washed product is: compared with a standard qualified product whose whiteness is within the upper or lower limit, if the whiteness of the battery aluminum casing is observed to be within the range and uniform, it is judged as a well-washed product (see the judgment diagram). Figure 2 (As shown); The standard for judging whether a product is cleaned well is: draw a No. 38 dyne pen on the surface of the battery's aluminum casing or on an area suspected of being oily. If the dyne pen does not shrink, the product is judged to be cleaned well. The whitening yield and cleaning yield are statistically analyzed, and the test results are shown in Table 1:

[0073] Table 1. Whitening and cleaning yield data for the examples and comparative examples.

[0074]

[0075]

[0076] As can be seen from Table 1, the degreasing and whitening method of the present invention produces a battery aluminum shell with suitable whiteness, a whitening yield of over 98.86%, and a cleaning yield of over 98.48%.

[0077] A comparison of Examples 1 and 4-5 shows that in the degreasing and whitening method of the present invention, the proportion of surfactant in the aqueous solution affects the degreasing and whitening effect. Controlling the surfactant mass proportion to 15-25% of the aqueous solution mass results in a better degreasing and whitening effect. If the surfactant proportion is too low, the wetting and cleaning ability of the solution is insufficient, leading to incomplete cleaning of oil stains. If the surfactant proportion is too high, although the cleaning effect is good, it increases the difficulty of rinsing, resulting in solution residue on the battery aluminum shell after cleaning, thus causing poor cleaning.

[0078] Comparing Examples 1 and 6-7, it can be seen that the present invention selects a suitable compound surfactant. Berol226 is a cationic / non-cationic surfactant compound, which not only has a very strong tearing and peeling ability for oil stains, but also has an excellent cleaning effect on metal shavings due to its cationic nature. Softanol-90 is a secondary alcohol polyoxyethylene ether, which is an excellent penetrant, emulsifier, wetting and detergent. The combination of the two can significantly improve the whitening yield and cleaning yield.

[0079] As can be seen from the comparison between Example 1 and Comparative Example 1, sodium metasilicate is a commonly used powder component for cleaning aluminum battery casings. Its main function is to improve the alkaline cleaning environment of the cleaning solution and enhance the cleaning ability. However, sodium metasilicate does not have a corrosive effect on aluminum battery casings. If potassium pyrophosphate is not used, the aluminum casing cannot be whitened.

[0080] As can be seen from the comparison between Example 1 and Comparative Example 2, the present invention uses potassium pyrophosphate as the main whitening agent, and the whiteness of the aluminum shell surface is suitable. However, the traditional surfactant has poor cleaning and decontamination ability, so its cleaning yield is low and there are many black oil stains. Therefore, the whiteness of the workpiece surface is not uniform.

[0081] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for degreasing and whitening battery aluminum casings, characterized in that, The method includes the following steps: The powder and water are combined to form a degreasing and whitening solution, which is then used to degrease and whiten the aluminum casing of the battery. The aluminum casing obtained after degreasing and bleaching is rinsed to obtain a clean battery aluminum casing; The powder is potassium pyrophosphate, and the aqueous solution includes sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water; Based on the mass of the aqueous agent being 100%, the mass fraction of the surfactant is 15-25%. The surfactants are Berol 226 and Softanol-90; The mass ratio of Berol 226 to Softanol-90 is 1:(0.5~2); Based on the total mass of the aqueous and powder components in the degreasing and whitening solution being 100%, the mass fraction of the powder component is 5-40%.

2. The method as described in claim 1, characterized in that, The organic solvent includes any one or a combination of at least two of isopropanol, isohexanediol, or diethylene glycol monobutyl ether.

3. The method as described in claim 1, characterized in that, Based on the mass of the aqueous agent as 100%, the mass fraction of sodium hydroxyethylidene diphosphonate is 1-4%.

4. The method as described in claim 1, characterized in that, Based on the mass of the aqueous agent as 100%, the mass fraction of the organic solvent is 3-6%.

5. The method as described in claim 1, characterized in that, Based on the mass of the aqueous agent being 100%, the mass fraction of the deionized water is 65-81%.

6. The method as described in claim 1, characterized in that, The degreasing and bleaching process includes at least three ultrasonic degreasing and bleaching processes.

7. The method as described in claim 1, characterized in that, The temperature for the degreasing and bleaching process is 60~70℃.

8. The method as described in claim 6, characterized in that, Each ultrasonic degreasing and whitening session lasts 1-2 minutes.

9. The method as described in claim 1, characterized in that, The rinsing includes rinsing with pure water.

10. The method as described in claim 1, characterized in that, The rinsing temperature is 50~60℃.

11. The method as described in claim 9, characterized in that, Each rinse with pure water should last 1-2 minutes.

12. The method as described in claim 1, characterized in that, After rinsing, the water is spun out and dried.

13. The method according to any one of claims 1-12, characterized in that, The method includes the following steps: The powder and water are used to prepare a degreasing and whitening solution. The aluminum shell of the battery is subjected to at least three ultrasonic degreasing and whitening treatments at 60-70°C, with each ultrasonic degreasing and whitening treatment lasting 1-2 minutes. The aluminum shell obtained after degreasing and whitening is rinsed with pure water at least three times at 50~60℃, with each rinse lasting 1~2 minutes, to obtain a clean battery aluminum shell. The powder is potassium pyrophosphate, and the aqueous solution includes sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water. The mass of the powder accounts for 5-40% of the total mass of the powder and aqueous solution. The mass ratio of sodium hydroxyethylidene diphosphonate, surfactant, organic solvent and deionized water in the aqueous solution is (1-4):(15-25):(3-6):(65-81).

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