Cleaning agent for removing polyester insulating coating on surface of lithium ion battery shell as well as preparation method and use method of cleaning agent

Abstract

The invention discloses a cleaning agent for removing a polyester insulating coating on the surface of a lithium ion battery shell as well as a preparation method and a use method of the cleaning agent. The cleaning agent is prepared from the following raw materials in percentage by weight: 30-40% of a main solvent, 5-10% of a cosolvent, 3-5% of a corrosion inhibitor, 1-2% of a surfactant and the balance of acetic acid and deionized water, acetic acid can adjust the pH of the cleaning agent to 7; the main solvent is composed of ethyl acetate and ethanol according to a mass ratio of 1: (1-2); the cosolvent is propylene glycol diacetate; the cleaning agent provided by the invention is safe and environment-friendly, can quickly remove a polyester insulating coating on the surface of the lithium ion battery shell, is high in removal efficiency and non-corrosive, and does not influence secondary spraying of the lithium ion battery shell after the coating is removed.

Description

Technical Field

[0001] The invention belongs to the technical field of coating cleaning, and in particular relates to a cleaning agent for cleaning a polyester insulating coating on the surface of a lithium ion battery shell, and a preparation method and a use method thereof. Background Art

[0002] During the production process of lithium-ion aluminum shell batteries, the aluminum shell of the battery needs to be wrapped with a layer of blue film. It is a single-sided tape made of a PET substrate and PSA (pressure-sensitive adhesive). In addition to having certain isolation properties, this material also has the characteristics of being waterproof, rust-proof, insulating, and resistant to high temperatures. Therefore, it has always been the best solution for the electrical insulation and physical protection of lithium-ion aluminum shell batteries. However, the thickness of this blue film is small, only between 0.015mm and 0.20mm, and it is prone to scratches, breakages, wrinkles and other defects during the production process. Some of these defects will affect the appearance of the product and even damage the product function. For this reason, a new battery cell insulation solution was born - a new UV insulating coating material.

[0003] The main components of UV insulating coating are composed of oligomers such as epoxy acrylate, polyurethane acrylate, polyether polyurethane and photoinitiator. For example, Chinese patent CN 114773984 A discloses an environmentally friendly flame-retardant insulating UV curing coating resin for battery packaging, which is composed of the following components by weight: 10-30 parts of acrylic resin, 10-30 parts of polyurethane acrylic resin, 5-20 parts of trimethylolpropane triacrylate, 5-20 parts of tripropylene glycol diacrylate, 5-20 parts of hexanediol diacrylate, 0-3 parts of photoinitiator, 0-3 parts of cationic initiator, 1-5 parts of ethyl acetate, and 5-20 parts of flame retardant. At present, polyurethane insulating coating is commonly used in the prior art.

[0004] Compared with blue film, polyester insulation coating has no volatile organic compounds, no solvents, and has good insulation, adhesion, low flammability, and high durability after curing. In addition, UV coating can realize fully automatic production line, simple production process, low labor cost, and high comprehensive coating efficiency. In addition, polyester insulation coating can be seamlessly connected with the battery, and has the advantages of excellent insulation performance and safety and environmental protection, and is expected to replace blue film.

[0005] However, the current method of coating to form a protective coating on the surface of the lithium-ion battery shell faces a problem. Compared with the blue film, the UV spraying process has higher requirements for the flatness of the workpiece. The low flatness of the aluminum shell will lead to uneven spraying of the paint. In addition, the coating effect is also affected by the coating material, which will cause bubbles, cracks and color differences on the surface of the sprayed battery cell. In order to avoid the scrapping of the finished battery cell due to poor painting, the sprayed paint needs to be removed.

[0006] Existing paint removal technologies have different methods according to different requirements, different substrates and different coatings, mainly including combustion technology, laser removal technology, mechanical or manual treatment technology and chemical removal technology. Combustion technology is used to remove surface coatings, which is easy to damage the battery cells and cause safety hazards; laser, mechanical and manual removal methods are time-consuming and labor-intensive, and some are easy to cause mechanical damage to the surface of the substrate, affecting its secondary coating. Therefore, in order to avoid these influencing factors, the use of chemical methods (paint strippers) for removal has become and will continue to be a hot topic of research in this field.

[0007] Although the chlorinated hydrocarbon organic cleaning agents commonly used in the market can effectively complete the paint stripping work, chlorinated hydrocarbon cleaning agents have many disadvantages: high toxicity, easy combustion, chemical instability, damage to the user's body and unfriendly to the environment. Summary of the invention

[0008] In order to solve the above technical problems, the present invention provides a cleaning agent for removing the polyester insulating coating on the surface of the lithium-ion battery shell, and a preparation method and a use method thereof. The cleaning agent is safe and environmentally friendly, can quickly remove the polyester insulating coating on the surface of the lithium-ion battery shell, has high cleaning efficiency, and is non-corrosive. After removing the coating, it does not affect the secondary spraying of the lithium-ion battery shell.

[0009] To achieve the above object, the technical solution adopted by the present invention is:

[0010] A cleaning agent for removing polyester insulating coating on the surface of lithium ion battery shell, the cleaning agent is composed of the following raw materials in weight percentage: 30-40% of main solvent, 5-10% of auxiliary solvent, 3-5% of corrosion inhibitor, 1-2% of surfactant, and the rest are acetic acid and deionized water; acetic acid can adjust the pH of the cleaning agent to 7.

[0011] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:(1-2).

[0012] The cosolvent is propylene glycol diacetate.

[0013] The mass ratio of the main solvent to the auxiliary solvent is preferably 3.5:1.

[0014] The corrosion inhibitor is sodium molybdate.

[0015] The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:3.

[0016] The cleaning agent is preferably composed of the following raw materials in percentage by weight: 35% of main solvent, 10% of auxiliary solvent, 3% of corrosion inhibitor, 2% of surfactant, and the rest of acetic acid and deionized water.

[0017] The present invention also provides a method for preparing the cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery shell, which comprises adding a formulated amount of a main solvent, a co-solvent, a corrosion inhibitor, and a surfactant into deionized water, stirring and mixing until the raw materials are completely dissolved, and then adding acetic acid to adjust the pH to 7.0.

[0018] The present invention also provides a method for using the cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery shell, the cleaning agent is mixed with deionized water in a weight ratio of 1:15 to 20, and then sprayed onto the surface of the lithium ion battery shell with the polyester insulating coating, waited for 2 to 5 minutes, and then washed with deionized water.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The invention provides a cleaning agent for removing polyurethane insulating coating on the surface of lithium ion battery shell, which has low volatility, is harmless to human body when used, is safe and environmentally friendly, can quickly remove polyurethane insulating coating on the surface of lithium ion battery shell, and will not damage the surface of aluminum alloy shell of lithium ion battery, has high cleaning efficiency, low cost and simple use method. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The morphology of the surface of the aluminum alloy test piece after being cleaned with the cleaning agent in Example 1;

[0022] Figure 2 The morphology of the surface of the aluminum alloy test piece after being cleaned with the cleaning agent in Comparative Example 1;

[0023] Figure 3 The morphology of the surface of the aluminum alloy test piece after being cleaned by the cleaning agent in Comparative Example 2;

[0024] Figure 4 The morphology of the surface of the aluminum alloy test piece after cleaning with the cleaning agent in Comparative Example 3;

[0025] Figure 5 The morphology of the surface of the aluminum alloy test piece after cleaning with the cleaning agent in Comparative Example 4;

[0026] Figure 6 The morphology of the surface of the aluminum alloy specimen after cleaning with the remover in Comparative Example 5. DETAILED DESCRIPTION

[0027] The present invention is described in detail below with reference to the embodiments.

[0028] Example 1

[0029] A cleaning agent for removing polyurethane insulating coating on the surface of lithium-ion battery shell, the cleaning agent is composed of the following raw materials in percentage by weight: 35% of main solvent, 10% of auxiliary solvent, 3% of corrosion inhibitor, 2% of surfactant, and the rest of acetic acid and deionized water;

[0030] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0031] The cosolvent is propylene glycol diacetate;

[0032] The corrosion inhibitor is sodium molybdate;

[0033] The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:3.

[0034] The preparation method of the cleaning agent is: adding the main solvent, auxiliary solvent, corrosion inhibitor and surfactant in the formula amount into deionized water, stirring and mixing until the raw materials are completely dissolved, and then adding acetic acid to adjust the pH to 7.0.

[0035] Comparative Example 1

[0036] A cleaning agent, the cleaning agent is composed of the following raw materials in percentage by weight: 35% of a main solvent, and the rest of acetic acid and deionized water;

[0037] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0038] The preparation method of the cleaning agent is: adding a main solvent of a formula amount into deionized water, and then adding acetic acid to adjust the pH to 7.0.

[0039] Comparative Example 2

[0040] A cleaning agent, the cleaning agent is composed of the following raw materials in percentage by weight: 35% of a main solvent, 10% of a co-solvent, and the rest being acetic acid and deionized water;

[0041] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0042] The cosolvent is propylene glycol diacetate;

[0043] The preparation method of the cleaning agent is as follows: adding the main solvent and the auxiliary solvent in the formula amount into deionized water, stirring and mixing evenly, and then adding acetic acid to adjust the pH to 7.0.

[0044] Comparative Example 3

[0045] A cleaning agent, the cleaning agent is composed of the following raw materials in percentage by weight: 35% of a main solvent, 10% of a co-solvent, 3% of a corrosion inhibitor, 2% of a surfactant, and the rest being deionized water;

[0046] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0047] The cosolvent is propylene glycol diacetate;

[0048] The corrosion inhibitor is sodium molybdate;

[0049] The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:3.

[0050] The preparation method of the cleaning agent is as follows: adding the main solvent, the auxiliary solvent, the corrosion inhibitor and the surfactant in the formula amount into deionized water, and stirring and mixing until the raw materials are completely dissolved.

[0051] Comparative Example 4

[0052] A cleaning agent, the cleaning agent is composed of the following raw materials in percentage by weight: 20% of a main solvent, 10% of a co-solvent, 3% of a corrosion inhibitor, 2% of a surfactant, and the rest being acetic acid and deionized water;

[0053] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0054] The cosolvent is propylene glycol diacetate;

[0055] The corrosion inhibitor is sodium molybdate;

[0056] The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:3.

[0057] The preparation method of the cleaning agent is: adding the main solvent, auxiliary solvent, corrosion inhibitor and surfactant in the formula amount into deionized water, stirring and mixing until the raw materials are completely dissolved, and then adding acetic acid to adjust the pH to 7.0.

[0058] Comparative Example 5

[0059] A cleaning agent, the cleaning agent is composed of the following raw materials in percentage by weight: 40% of a main solvent, 10% of a co-solvent, 3% of a corrosion inhibitor, 2% of a surfactant, and the rest being acetic acid and deionized water;

[0060] The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:1;

[0061] The cosolvent is propylene glycol diacetate;

[0062] The corrosion inhibitor is sodium molybdate;

[0063] The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:3.

[0064] The preparation method of the cleaning agent is: adding the main solvent, auxiliary solvent, corrosion inhibitor and surfactant in the formula amount into deionized water, stirring and mixing until the raw materials are completely dissolved, and then adding acetic acid to adjust the pH to 7.0.

[0065] Test Case

[0066] The cleaning effect, wettability, corrosion effect, secondary spray cleaning effect, and secondary spray cleaning effect of the cleaning agents in the above-mentioned Example 1 and each comparative example on the polyester coating were tested.

[0067] Here’s how:

[0068] Polyester coating removal efficiency test: Select 3 aluminum alloy test pieces and weigh them as m 0 (g) The test piece is sprayed with the same polyester coating and UV cured, and its mass is m 1 (g), then use solvent to remove the coating and weigh it again, record it as m 2 , calculate the removal efficiency η(%) and removal time, η=(m 1 -m 2 ) / (m 1 -m 0 ), tested 3 times in parallel and took the average value;

[0069] Workpiece surface wettability test: Use a contact angle tester to observe the water contact angle of the aluminum alloy specimen after removing the coating;

[0070] Corrosion effect test: Use scanning electron microscope to observe the surface morphology of aluminum alloy specimens after removing the coating;

[0071] Secondary spraying effect test: After removing the coating, spray the same coating again on the aluminum alloy test piece and record the success rate after spraying.

[0072] Three-time spraying effect test: For the aluminum alloy test piece after the coating is removed twice, the same coating is sprayed again, and the success rate after spraying is recorded.

[0073] The test results of polyester coating removal efficiency are shown in Tables 1 to 3.

[0074] Table 1

[0075]

[0076] For the aluminum alloy test pieces with polyester coating in Table 1, after the coating was removed by using the cleaning agents in Example 1 of the present invention and the comparative examples, the water contact angle of the aluminum alloy test piece was tested. The test results are shown in Table 2.

[0077] Table 2

[0078]

[0079] From the data in the table, it can be seen that the wettability efficiency of the aluminum alloy surface after cleaning with the cleaning agent in Example 1 is better; although the contact angle of Comparative Example 3 is the smallest, the standard deviation is large, indicating that the surface of the aluminum alloy is uneven; the comparison of the data of Comparative Example 1, Comparative Example 2 and Example 1 shows that with the continuous addition of components, the wettability is better; the comparison of the data of Comparative Example 4, Comparative Example 5 and Example 1 shows that the wetting effect is best when the main solvent is 35%.

[0080] For the aluminum alloy test pieces with polyester coating in Table 1, after the coating was removed by the cleaning agents in Example 1 and Comparative Examples 1 to 5 of the present invention, the surface morphology of the aluminum alloy test pieces after cleaning was observed using a scanning electron microscope to evaluate the corrosion of the cleaning agents on the surface of the aluminum alloy test pieces. The results are as follows: Figures 1 to 6 As shown, it can be seen from the scanning electron microscope image that the paint removal effects of Comparative Examples 1 and 2 are not good, and some coatings still remain on the aluminum alloy surface; the aluminum alloy surface of Comparative Example 3 is corroded; there is no residue on the surface of Comparative Example 4; there is unwashed solvent on the surface of Comparative Example 5; Example 1 has the best effect.

[0081] For the aluminum alloy test piece with polyester coating in Table 1, after the coating was removed by the cleaning agent in Example 1 of the present invention and the comparative example, the same coating was sprayed on the surface of the aluminum alloy test piece again, and the success rate of the spraying was recorded. The results are shown in Table 3.

[0082] Table 3

[0083]

[0084] It can be seen from the data in the table that compared with the comparative examples, the secondary spraying success rate of Example 1 is the highest.

[0085] It can be seen from the above data that the use of the remover provided by the present invention has the best effect in removing the polyester coating, and after removal, it is beneficial to repaint the aluminum shell.

[0086] In actual use, the cleaning agent is mixed with deionized water in a weight ratio of 1:15 to 20, and then sprayed onto the surface of the lithium-ion battery shell with a polyester insulating coating. Wait for 2 to 5 minutes, and then rinse with deionized water to complete the removal of the surface coating of the lithium-ion battery shell.

[0087] The above-mentioned reference embodiments provide a detailed description of a cleaning agent for removing the polyester insulating coating on the surface of the lithium-ion battery housing, its preparation method and its use method, which are illustrative rather than restrictive, and several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A cleaning agent for removing polyester insulating coating on the surface of lithium ion battery housing, characterized in that: The cleaning agent is composed of the following raw materials in weight percentage: 30-40% of main solvent, 5-10% of auxiliary solvent, 3-5% of corrosion inhibitor, 1-2% of surfactant, and the rest of acetic acid and deionized water; acetic acid can adjust the pH of the cleaning agent to 7.

2. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to claim 1, characterized in that: The main solvent is composed of ethyl acetate and ethanol in a mass ratio of 1:(1-2).

3. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to claim 1, characterized in that: The cosolvent is propylene glycol diacetate.

4. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to claim 1, characterized in that: The mass ratio of the main solvent to the auxiliary solvent is 3.5:

1.

5. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to claim 1, characterized in that: The corrosion inhibitor is sodium molybdate.

6. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to claim 1, characterized in that: The surfactant is composed of sodium alkylbenzene sulfonate and octylphenol polyoxyethylene ether in a mass ratio of 7:

3.

7. The cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to any one of claims 1 to 6, characterized in that: The cleaning agent is composed of the following raw materials in percentage by weight: 35% of a main solvent, 10% of an auxiliary solvent, 3% of a corrosion inhibitor, 2% of a surfactant, and the rest being acetic acid and deionized water.

8. The method for preparing a cleaning agent for removing polyester insulating coating on the surface of a lithium ion battery housing according to any one of claims 1 to 6, characterized in that: Add the formulated amount of main solvent, co-solvent, corrosion inhibitor and surfactant into deionized water, stir and mix until the raw materials are completely dissolved, and then add acetic acid to adjust the pH to 7.

0.

9. The method for using the cleaning agent for removing the polyester insulating coating on the surface of the lithium ion battery housing according to any one of claims 1 to 6, characterized in that: The cleaning agent is mixed with deionized water in a weight ratio of 1:15-20, and then sprayed onto the surface of the lithium-ion battery housing with a polyurethane insulating coating, and then waited for 2-5 minutes, and then rinsed with deionized water.

Images