UV coating composition applied to battery cell shell and preparation method of insulating coating of UV coating composition

Abstract

The invention relates to a UV coating composition applied to a cell shell and a preparation method of an insulating coating of the UV coating composition, the coating composition comprises aliphatic polyurethane acrylate resin, an aromatic acrylate active monomer, a photoinitiator and the like, the adhesive force of the insulating coating formed after the cell shell is subjected to single UV curing can reach grade 0, and the insulating coating has good shear strength and good insulation performance. The hardness reaches 2H, and meanwhile, due to the relatively high film thickness, the insulating property and the voltage-resistant property are good.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of coating materials, and particularly relates to a UV coating composition applied to an electric core shell and a preparation method of an insulating coating thereof. BACKGROUND

[0002] In recent years, the new energy automobile industry has developed rapidly, and the safety performance of power batteries has undoubtedly become the focus of manufacturers and consumers. Insulating materials play a crucial role in the safety of batteries by isolating different potential conductors, preventing short circuits, providing mechanical support and protection, participating in heat dissipation, etc. As the smallest unit of a battery, the common insulation treatment scheme for the electric core is to wrap it with PET film, PP film, etc. (mostly dark blue, so it is called "blue film"). However, with the continuous upgrading of battery capacity, high-voltage battery modules require better insulation and voltage resistance, and the "blue film" has disadvantages such as poor insulation performance and low shear strength. At the same time, the wrapping method of "blue film" is complex and has low production efficiency.

[0003] In order to solve the problems of low shear strength and poor insulation performance of "blue film", Chinese patent CN 118577463A uses a spraying process to replace the traditional cladding film method. It uses UV coating to spray on the surface of the electric core, first pre-cures at low energy, and then finalizes at high energy. The insulating coating prepared by this technology has good adhesion between the insulating coating and the electric core, and improves the voltage resistance and insulation performance of the electric core. However, this technology needs to be cured multiple times by UV, which seriously affects the production efficiency.

[0004] Chinese patent CN 112322182A directly sprays the coating on the surface of the electric core and obtains an insulating coating by high-temperature curing. However, the formula of this patent contains volatile solvents such as propylene glycol methyl ether, and needs to be baked at 150℃ for 30min during the curing process. This process has problems such as high energy consumption, low efficiency, and environmental pollution.

[0005] Chinese patent CN 115806764A uses a cationic photoinitiator to initiate the UV polymerization of an alicyclic epoxy resin to obtain an insulating coating. The insulating coating obtained by this technology has good adhesion to the substrate, but the active groups of the alicyclic epoxy resin in the formula are connected to the alicyclic ring, so the reaction activity is low. Therefore, preheating (baking at 40-60℃ for 3-5min) is required before curing, and the hardness of the final insulating coating is general (H), which will cause the insulating coating to be prone to cracking, short circuiting, etc. when the battery is subjected to external impact.

[0006] Chinese patent CN 119019926 A uses a large amount of phenolic epoxy resin in the formula to prepare an insulating coating, which has excellent insulation performance and high temperature resistance. However, the extremely high cross-linking density and rigid aromatic structure result in low impact strength and fracture toughness, making it prone to cracking and causing insulation failure.

[0007] The insulating coating of the battery cell prepared by Chinese patent CN 116656217 A with acrylate, epoxy propylene resin, etc. as the base material has poor hardness (HB). Moreover, due to the low activity of the resin and monomer used, preheating and secondary curing are required, which seriously affects production efficiency. In addition, in order to increase the reaction degree, excessive use of initiator will increase material cost and the risk of side reactions.

[0008] The present invention is achieved to solve the problem of coating on existing battery cell shells. Summary of the Invention

[0009] To address the above-mentioned technical problems, the present invention provides a UV coating composition for battery cell casings and a method for preparing the insulating coating. The insulating coating formed by the UV coating composition provided by the present invention after a single UV curing step on the battery cell casing achieves adhesion of Class 0, exhibits excellent shear strength, and achieves a hardness of 2H. Furthermore, the high film thickness provides excellent insulation and voltage resistance. Furthermore, this process does not require additional baking equipment, resulting in a simple production process, high overall coating efficiency, and safety and environmental protection.

[0010] The present invention first provides a UV coating composition for a battery cell shell. The coating composition comprises the following components: 30-70% of an aliphatic polyurethane acrylate resin; 10-40% of an aromatic acrylate active monomer; 2-7% of a photoinitiator; 0.2-1.6% of a leveling agent; 0.1-2% of a wetting and dispersing agent; 0.1-2% of a color paste; and 10-30% of a filler such as quartz powder. The percentages are by weight.

[0011] The aliphatic polyurethane acrylate resin selected in the present invention has good flexibility, which makes the insulating coating less likely to crack when subjected to external force impact and increased ambient temperature under high film thickness conditions, effectively avoiding the risks of battery cell insulation failure, battery short circuit, etc. Aromatic acrylate active monomers can significantly reduce the viscosity of the formula system, which helps the coating to penetrate the microscopic surface of the battery cell shell, form mechanical interlocking after curing, and improve the adhesion and shear strength of the coating. In addition, aromatic acrylate active monomers contain a large number of rigid structures such as benzene rings, which can reduce the volume shrinkage of the coating during light curing, while improving the hardness of the insulating coating and ensuring good adhesion between the battery cell surface and the coating. The aliphatic polyurethane acrylate resin is used as the main film-forming material, and is matched with aromatic acrylate active monomers. The high reactivity enables it to be quickly cured under high film thickness conditions, forming a relatively dense network structure, thereby improving the insulation resistance and corrosion resistance of the coating.

[0012] Furthermore, the aliphatic polyurethane acrylate resin is preferably one or a combination of at least two of Changxing 61280, Changxing 61660, Sartomer CN8003NS, and Sartomer CN996NS.

[0013] Furthermore, the total content of the aliphatic polyurethane acrylate resin is 35%-60%, or 35%, 40%, 45%, 50%, or 53.5%.

[0014] Furthermore, the aromatic acrylate active monomer is preferably one or a combination of at least two of Changxing EM210, Changxing EM2265, Changxing EM3265, and Sartomer SR602NS.

[0015] Furthermore, the total content of the aromatic acrylate active monomers is 15%-30%, or 12%, 20%, 30%, or 35%.

[0016] Furthermore, the photoinitiator is selected from one or a combination of at least two of 1-hydroxycyclohexylphenyl ketone (184), 2-hydroxy-methylphenylpropane-1-one (1173), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) or 2,4,6-trimethylbenzoyldiphenylphosphine oxide benzophenone (BP).

[0017] Furthermore, the photoinitiator is preferably one of 184 and TPO, or a combination of both.

[0018] Furthermore, the added amount of the photoinitiator is preferably 3%, 5%, or 6%.

[0019] Furthermore, the leveling agent is preferably a silicone leveling agent.

[0020] Further, the content of the leveling agent is 0.5%-1.5%, or 0.2%, 0.4%, 0.5%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.5%.

[0021] Further, the wet dispersant is a high molecular weight block copolymer solution containing a pigment affinity group.

[0022] Further, the wet dispersant is preferably one or a combination of BYK163, BYK2000, YCK2680, and the addition amount is preferably 1%-1.5%, or 0.8%, 1.2%.

[0023] Further, the color paste is preferably a blue oily UV color paste, and the addition amount is preferably 1%-1.5%, or 0.8%, 1.2%.

[0024] Further, the filler is quartz powder, glass powder, alumina, etc.

[0025] Further, the quartz powder is preferably a silica powder 925. The quartz powder can further improve the insulation of the coating, while also reducing the volume shrinkage when the glue is cured, thereby reducing the paint film shrinkage stress and improving the adhesion of the coating;

[0026] Further, the quartz powder can also be replaced by glass powder, alumina, silica, etc. insulating fillers.

[0027] Further, the addition amount of the filler is preferably 12%-29%, or 13%, 15.5%, 16.5%, 17.5%, 19.5%, 25%, 27.5%.

[0028] The application also provides a preparation method of the UV coating composition, comprising the following steps:

[0029] S1. The aliphatic polyurethane acrylate resin, aromatic acrylate active monomer, color paste, filler, and wet dispersant are added to the dispersing kettle according to their weight proportions, and dispersed at 800-2000r / min for 10-40min until uniform dispersion;

[0030] S2. The photoinitiator and leveling agent are added to the mixed solution obtained in step S1 according to their weight proportions, and dispersed at 300-800r / min for 5-20min; to obtain the UV coating composition.

[0031] Further, the mixed UV coating composition is sealed and stored for standby.

[0032] Furthermore, in step S2, low-speed stirring can prevent high shear forces from destroying the surface activity of the leveling agent, thereby ensuring the leveling effect. At the same time, it can prevent high shear forces from destroying the initiator structure, thereby preventing the photosensitive component from decomposing prematurely.

[0033] The present invention also provides a method for preparing an insulating coating formed by curing the above-mentioned UV coating composition on the surface of a battery cell housing, the preparation method comprising the following steps:

[0034] S1. The aliphatic polyurethane acrylate resin, aromatic acrylate reactive monomer, paste, filler, wetting and dispersing agent according to their weight ratio are added to the dispersion kettle, 800-2000r / min dispersion 10-40min, until uniformly dispersed;

[0035] S2. The photoinitiator and the leveling agent are added to the mixed solution obtained in step S1 in accordance with their weight ratio, and dispersed at 300-800 r / min for 5-20 min; obtaining the UV coating composition;

[0036] S3. Spray the UV coating composition evenly on the spraying surface of the battery shell at 500-3000mJ / cm 2 The curing energy is 2-6 seconds, and after curing, an insulating coating with a thickness of 70-150μm is formed.

[0037] Furthermore, before spraying, the surface of the cell casing should be laser pre-treated. The laser beam is used to structure the surface and reduce the surface tension of the aluminum shell. Then, plasma cleaning is used to remove dust particles and oxides. After pre-treatment, the surface roughness of the sprayed surface meets the following requirements: 0.5μm ≤ Ra ≤ 5μm, 5μm ≤ Rz ≤ 20μm, and the dyne value of the sprayed surface is ≥ 52.

[0038] Furthermore, the spraying process adopts UV spraying process and uses a spray gun to spray evenly.

[0039] Furthermore, the area of ​​the spraying surface is S, the spraying amount is M, and 80 μm≤M / S≤200 μm.

[0040] Furthermore, the UV energy during the photocuring process is 500-3000 mj / cm 2 .

[0041] Furthermore, the UV energy during the photocuring process is preferably 1000-2000 mj / cm 2 .

[0042] Furthermore, the UV curing time in the light curing process is preferably 5 seconds.

[0043] The application also provides a method for improving the performance of the insulation coating of the battery cell shell, wherein the adhesion of the insulation coating reaches 0 level, the hardness reaches 2H, the voltage resistance performance is >11.6kV, the volume resistivity is >9.1x10 14 Ω·cm, and the shear strength is >8.4kPa.

[0044] In summary, the application provides a UV coating composition applied to the surface of the battery cell shell and a preparation method of the insulation coating of the UV coating composition. The UV coating composition uses aliphatic polyurethane acrylate resin and aromatic acrylate active monomer as the base material for curing reaction at room temperature, and has fast reaction speed, good adhesion, shear strength and insulation performance under the condition of high film thickness, and high hardness. The technology does not need baking and multiple curing, has simple production process, no volatile organic compounds, and is safe and environmentally friendly. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 The application provides a UV coating composition applied to the surface of the battery cell shell and a preparation method of the insulation coating of the UV coating composition.

[0046] Figure 2 The chemical structural formula of the aliphatic polyurethane acrylate resin is shown in the following figure.

[0047] Figure 3 The chemical structural formula of the aromatic acrylate active monomer is shown in the following figure. DETAILED DESCRIPTION

[0048] In order to better illustrate the purpose, technical scheme and advantages of the application, the application will be further described below in combination with the drawings and specific examples. The test methods used in the examples of the application are conventional methods, and the materials and reagents used in the examples of the application are commercially available, unless otherwise specified.

[0049] The technical schemes provided by the application will be described in detail below in combination with examples, but they should not be understood as limitations on the protection scope of the application.

[0050] Example 1:

[0051] The present invention provides a UV coating composition for battery cell housing and a method for preparing the insulating coating thereof. The components of the UV coating are shown in Table 1. In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate active monomer is Changxing EM210, accounting for 50% and 25% of the total weight of the formula, respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3%, respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula, respectively. Quartz powder 925 accounts for 17.5% of the total weight of the formula. Aliphatic polyurethane acrylate resin, aromatic acrylate active monomer, color paste, wetting dispersant, and quartz powder are added to a dispersion kettle according to their weight proportions, and dispersed at 1000r / min for 20 minutes until uniformly dispersed. Then, photoinitiator and leveling agent are added to the mixed solution according to their weight proportions and dispersed at 400r / min for 10 minutes to obtain the UV coating composition of the present invention. The prepared UV coating composition is evenly sprayed on the surface of the battery shell that has been pre-treated by laser, and the dispersion is carried out at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing for 5 seconds with an energy of .

[0052] Example 2:

[0053] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 45% and 30% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 17.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0054] Example 3:

[0055] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 35% and 40% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 17.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0056] Example 4:

[0057] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 60% and 15% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 17.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0058] Example 5:

[0059] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 45% and 20% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 27.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2The UV coating composition prepared in this example was uniformly sprayed on the surface of the battery shell which had been preprocessed by laser, and the battery shell was cured for 5 seconds with an energy of 1000 mJ / cm

[0060] Example 6

[0061] In this example, the aliphatic polyamino acrylate resin was Changxing 61660, the aromatic acrylate active monomer was Changxing EM210, and the proportions in the total weight of the formula were 53.5% and 29% respectively. The dosages of the 184 photoinitiator and the TPO initiator were 2% and 3% respectively. The proportions of the silicone leveling agent BYK333, the Mitsubishi PN-4008F color paste, and the wet dispersing agent BYK163 in the total weight of the formula were 0.5%, 1%, and 1% respectively. The quartz powder 925was 10% of the total weight of the formula. The preparation method of the coating was the same as the preparation method of the coating in Example 1. The UV coating composition prepared in this example was uniformly sprayed on the surface of the battery shell which had been preprocessed by laser, and the battery shell was cured for 5 seconds with an energy of 1000 mJ / cm 2 The UV coating composition prepared in this example was uniformly sprayed on the surface of the battery shell which had been preprocessed by laser, and the battery shell was cured for 5 seconds with an energy of 1000 mJ / cm

[0062] Example 7

[0063] In this example, the aliphatic polyamino acrylate resin was Changxing 61660, the aromatic acrylate active monomer was Changxing EM210, and the proportions in the total weight of the formula were 50% and 25% respectively. The dosages of the 184 photoinitiator and the TPO initiator were 1% and 2% respectively. The proportions of the silicone leveling agent BYK333, the Mitsubishi PN-4008F color paste, and the wet dispersing agent BYK163 in the total weight of the formula were 0.5%, 1%, and 1% respectively. The quartz powder 925was 19.5% of the total weight of the formula. The preparation method of the coating was the same as the preparation method of the coating in Example 1. The UV coating composition prepared in this example was uniformly sprayed on the surface of the battery shell which had been preprocessed by laser, and the battery shell was cured for 5 seconds with an energy of 1000 mJ / cm 2 The UV coating composition prepared in this example was uniformly sprayed on the surface of the battery shell which had been preprocessed by laser, and the battery shell was cured for 5 seconds with an energy of 1000 mJ / cm

[0064] Example 8

[0065] In this example, the aliphatic polyamino acrylate resin was Changxing 61660, the aromatic acrylate active monomer was Changxing EM210, and the proportions in the total weight of the formula were 50% and 25% respectively. The dosages of the 184 photoinitiator and the TPO initiator were 3% and 4% respectively. The proportions of the silicone leveling agent BYK333, the Mitsubishi PN-4008F color paste, and the wet dispersing agent BYK163 in the total weight of the formula were 0.5%, 1%, and 1% respectively. The quartz powder 925 is 15.5% of the total weight of the formula. The preparation method of the coating is the same as the preparation method of the coating in Example 1. The UV coating composition prepared in this example is uniformly sprayed on the surface of the laser pretreated battery shell, and an insulating coating of the battery with a thickness of 100 μm is prepared by curing at an energy of 1000 mJ / cm 2 for 5 seconds.

[0066] Example 9:

[0067] In this example, the aliphatic polyamino acrylate resin is selected as Changxing 61660, and the aromatic acrylate active monomer is selected as Changxing EM210, which accounts for 50% and 25% of the total weight of the formula, respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3%, respectively. The proportions of silicone leveling agent BYK333, Mitsubishi PN-4008F color paste, and wet dispersing agent BYK163 in the total weight of the formula are 1.5%, 1%, and 1%, respectively. The proportion of quartz powder in the total weight of the formula is 1.5%. 925 is 16.5% of the total weight of the formula. The preparation method of the coating is the same as the preparation method of the coating in Example 1. The UV coating composition prepared in this example is uniformly sprayed on the surface of the laser pretreated battery shell, and an insulating coating of the battery with a thickness of 100 μm is prepared by curing at an energy of 1000 mJ / cm 2 for 5 seconds.

[0068] Example 10:

[0069] In this example, the aliphatic polyamino acrylate resin is selected as Changxing 61660, and the aromatic acrylate active monomer is selected as Changxing EM210, which accounts for 50% and 25% of the total weight of the formula, respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3%, respectively. The proportions of silicone leveling agent BYK333, Mitsubishi PN-4008F color paste, and wet dispersing agent BYK163 in the total weight of the formula are 0.5%, 1.5%, and 1%, respectively. The proportion of quartz powder in the total weight of the formula is 1.5%. 925 is 16.5% of the total weight of the formula. The preparation method of the coating is the same as the preparation method of the coating in Example 1. The UV coating composition prepared in this example is uniformly sprayed on the surface of the laser pretreated battery shell, and an insulating coating of the battery with a thickness of 100 μm is prepared by curing at an energy of 1000 mJ / cm 2 for 5 seconds.

[0070] Example 11:

[0071] The aliphatic polyamino acrylate resin in this embodiment is selected from Changxing 61660, the aromatic acrylate active monomer is selected from Changxing EM210, the proportion of the total weight of the formula is 50%, 25% respectively, the amount of 184 photoinitiator and TPO initiator is 2%, 3% respectively. The proportion of the total weight of the formula of the organic silicon leveling agent BYK333, the Mitsubishi PN-4008F color paste, the wet dispersing agent BYK163 is 0.5%, 1%, 1.5% respectively, the proportion of the total weight of the formula of the quartz powder 925 is 16.5%. The preparation method of the coating is the same as the preparation method of the coating in example 1. The UV coating composition prepared in this embodiment is uniformly sprayed on the surface of the laser pretreated battery shell, and the energy of 1000mJ / cm 2 is used to cure for 5 seconds to obtain a battery insulation coating with a thickness of 100μm.

[0072] Example 12:

[0073] The aliphatic polyamino acrylate resin in this embodiment is selected from Changxing 61660, the aromatic acrylate active monomer is selected from Changxing EM210, the proportion of the total weight of the formula is 50%, 25% respectively, the amount of 184 photoinitiator and TPO initiator is 2%, 3% respectively. The proportion of the total weight of the formula of the organic silicon leveling agent BYK333, the Mitsubishi PN-4008F color paste, the wet dispersing agent BYK163 is 0.5%, 1%, 1% respectively, the proportion of the total weight of the formula of the quartz powder 925 is 17.5%. The preparation method of the coating is the same as the preparation method of the coating in example 1. The UV coating composition prepared in this embodiment is uniformly sprayed on the surface of the laser pretreated battery shell, and the energy of 500mJ / cm 2 is used to cure for 5 seconds to obtain a battery insulation coating with a thickness of 100μm.

[0074] Example 13:

[0075] The aliphatic polyamino acrylate resin in this embodiment is selected from Changxing 61660, the aromatic acrylate active monomer is selected from Changxing EM210, the proportion of the total weight of the formula is 50%, 25% respectively, the amount of 184 photoinitiator and TPO initiator is 2%, 3% respectively. The proportion of the total weight of the formula of the organic silicon leveling agent BYK333, the Mitsubishi PN-4008F color paste, the wet dispersing agent BYK163 is 0.5%, 1%, 1% respectively, the proportion of the total weight of the formula of the quartz powder 925 is 17.5%. The preparation method of the coating is the same as the preparation method of the coating in example 1. The UV coating composition prepared in this embodiment is uniformly sprayed on the surface of the laser pretreated battery shell, and the energy of 3000mJ / cm 2The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0076] Example 14:

[0077] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 50% and 25% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 17.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The energy of the film was cured for 5 seconds to obtain a battery core insulation coating with a thickness of 150 μm.

[0078] Example 15:

[0079] In this embodiment, the aliphatic polyamino acrylate resin is Changxing 61660, and the aromatic acrylate reactive monomer is Changxing EM210, accounting for 50% and 25% of the total weight of the formula respectively. The amount of 184 photoinitiator and TPO initiator is 2% and 3% respectively. The silicone leveling agent BYK333, Mitsukoshi PN-4008F color paste, and wetting and dispersing agent BYK163 account for 0.5%, 1%, and 1% of the total weight of the formula respectively. Quartz powder The proportion of 925 in the total weight of the formula is 17.5%. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The energy of the coating was cured for 5 seconds to obtain a battery core insulation coating with a thickness of 70 μm.

[0080] In comparative examples 1-7, the aliphatic polyamino acrylate resin is selected from Changxing 61660, the aromatic acrylate reactive monomer is selected from Changxing EM210, the silicone leveling agent is selected from BYK333, the color paste is selected from Mitsukoshi PN-4008F color paste, the wetting and dispersing agent is selected from BYK163, and the quartz powder is selected from 925, and the proportions of each component in the total weight of the formula are shown in Table 2. The preparation method of the coating is the same as the preparation method of the coating in Example 1. The curing energy and coating thickness are shown in Table 2.

[0081] In Comparative Example 8, aromatic polyurethane acrylic resin (DRU028FS) and aromatic acrylate reactive monomer (EM210) were selected as the base materials, silicone leveling agent was BYK333, color paste was Mitsukoshi PN-4008F color paste, wetting and dispersing agent was BYK163, and quartz powder was selected. 925, the proportion of each component in the total weight of the formula is shown in Table 3. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this comparative example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0082] In Comparative Example 9, aliphatic polyurethane acrylic resin (61660) and aliphatic acrylate active monomer (EM2192) were selected as the base materials, BYK333 was selected as the silicone leveling agent, Mitsukoshi PN-4008F color paste was selected, BYK163 was selected as the wetting and dispersing agent, and quartz powder was selected. 925, the proportion of each component in the total weight of the formula is shown in Table 3. The preparation method of the coating is the same as that of the coating in Example 1. The UV coating composition prepared in this comparative example is evenly sprayed on the surface of the battery shell that has been pretreated by laser, and the UV coating composition is sprayed at 1000mJ / cm 2 The battery core insulation coating with a thickness of 100 μm was obtained by curing with an energy of 5 seconds.

[0083] The UV insulating coating provided by the present invention is applied to the surface of the battery cell housing and its performance is tested according to the following method:

[0084] Adhesion test: Carry out in accordance with the national standard "GBT 9286-1998 Cross-cut test for paint and varnish films".

[0085] The specific method is to use a grid knife to mark 10*10 (100) small squares of 1mm*1mm on the coating surface. Each grid line should be deep enough to reach the bottom layer of paint. Then, use a brush to gently brush away any debris from the test area. Use 3M No. 600 tape or equivalent to firmly adhere to the small grid to be tested. Use an eraser to rub the tape vigorously to increase the contact area and strength between the tape and the test area. Firmly grasp one end of the tape and quickly pull it off vertically (90°). Repeat the test twice at the same location. The coating adhesion level is determined by the degree of coating shedding within the grid.

[0086] Hardness test: Test the coating hardness using a pencil hardness tester in accordance with Chapter 4 of GB / 6739T. Use a Japanese Mitsubishi pencil, 750g.

[0087] Shear strength test: The shear strength of the insulating coating on the surface of the cell shell was tested according to GB / T7124-2008.

[0088] Volume resistivity test: The volume resistivity of the coating was tested using a volume resistivity meter according to the method specified in GB / T 1410-2006.

[0089] Insulation test: The test was performed using a GJW-50kV voltage breakdown test instrument from Changchun Intelligent Instrument Equipment Co., Ltd. according to the method specified in GB / T 1408.1-2006, with a voltage rise speed set to 1 kV / s.

[0090] Acid resistance test: The cell shell coated with the insulating coating was immersed in 5% HC1 for 2h, and no deformation, shrinkage, bulging, cracking, paint peeling, etc. should occur.

[0091] Alkali resistance test: The cell shell coated with the insulating coating was immersed in 5% NaOH for 2h, and no deformation, shrinkage, bulging, cracking, paint peeling, etc. should occur.

[0092] High temperature and high humidity resistance test: The cell shell coated with the insulating coating was placed in a constant temperature and humidity chamber at a temperature of 85°C and a humidity of 85%, and no deformation, shrinkage, bulging, cracking, paint peeling, etc. should occur after 1000h.

[0093] Salt spray resistance: The reliability of the insulating coating was tested using a salt spray test chamber according to ASTM B117 (neutral salt spray, NSS) standard. Chamber temperature: 35±2°C. Neutral salt spray (NSS): 5±1% NaCl solution, pH 6.5-7.2 (25°C). Spray amount: 1.0-2.0 mL / (h·80 cm 2 ). No deformation, shrinkage, bulging, cracking, paint peeling, etc. should occur after 24h.

[0094] Electrolyte resistance test: The electrolyte was composed of ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, methyl ethyl carbonate, lithium hexafluorophosphate, phosphorus pentafluoride, etc. The electrolyte was purchased from the market and tested. The cell shell coated with the insulating coating was immersed in the electrolyte for 24h, then taken out and the surface was wiped dry. No deformation, shrinkage, bulging, cracking, paint peeling, etc. should occur and the adhesion test should be 0 level.

[0095] Table 1 Components, curing energy and coating thickness of the UV coating composition provided in the examples

[0096]

[0097] Table 2 Components, curing energy and coating thickness of the UV coating composition provided in Comparative Examples 1-7

[0098]

[0099] Table 3 Components, curing energy and coating thickness of the UV coating compositions provided in Comparative Examples 8-10

[0100]

[0101] Table 4 Physical property test results of UV insulation coatings obtained under the conditions provided in the examples and comparative examples

[0102]

[0103] Table 5 Reliability test results of UV insulation coatings prepared under the conditions provided in the examples and comparative examples

[0104]

[0105]

[0106] Comparison between Comparative Example 1 and Examples shows that when the content of aliphatic polyurethane acrylic resin is too low and the amount of aromatic acrylate reactive monomer is too high, the coating will not be fully cured and various properties will be significantly deteriorated.

[0107] Comparison between Comparative Example 2 and Example 1 shows that reducing the amount of aromatic acrylate reactive monomer will lead to a significant decrease in the hardness and voltage resistance of the coating.

[0108] Comparison between Comparative Example 3 and Example 1 shows that when the amount of initiator is too low, the degree of cross-linking will be low, the curing will not be complete, and the physical properties and reliability of the coating will be poor.

[0109] Comparison of Comparative Examples 4 and 5 with the embodiment shows that increasing the amount of quartz powder can improve the hardness, voltage resistance and volume resistivity of the coating to a certain extent, but too high an amount will lead to a significant decrease in the adhesion and shear strength of the coating.

[0110] Comparison between Comparative Example 6 and the embodiment shows that when the curing energy is low, the paint film fails to cure completely, resulting in poor adhesion, hardness, voltage resistance, shear strength and other properties.

[0111] Comparison of Comparative Example 7 with the embodiment shows that reducing the coating thickness will significantly reduce the voltage resistance performance of the coating.

[0112] Comparison between Comparative Example 8 and Example 1 shows that when aromatic polyurethane acrylic resin and aromatic acrylate reactive monomer are used as the base material, the adhesion and shear strength of the coating are poor, which may lead to the risk of cracking of the coating under extreme conditions.

[0113] Comparison of Comparative Example 9 with the Examples shows that when aliphatic polyurethane acrylic resin and aliphatic acrylate reactive monomer are used as the base materials of the formulation, the insulation performance of the coating is relatively poor.

[0114] From the test results of the above embodiments and comparative examples, it can be concluded that the UV insulating coating for the battery shell provided by the present invention can achieve a 0-level adhesion after a single UV curing, has good shear strength (>8.4kPa), and a hardness of 2H. At the same time, the high film thickness (70-150μm) makes it have good insulation performance (volume resistivity>9.1×10 14 Ω·cm) and voltage resistance (>11.6kV).

[0115] Finally, it should be noted that 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. All equivalent changes and modifications made based on the content of the present invention are included in the patent scope of the present invention.

Claims

1. A UV coating composition for a battery cell housing, comprising the following components: 30-70% aliphatic polyurethane acrylate resin; 10%-40% aromatic acrylate active monomer; Photoinitiator: 2-7%; Leveling agent: 0.2-1.6%; Wetting and dispersing agent: 0.1%-2%; Color paste: 0.1%-2%; Filler: 10-30%; the percentages are by weight.

2. The UV coating composition according to claim 1, characterized in that The aliphatic polyurethane acrylate resin is preferably one or a combination of at least two of Changxing 61280, Changxing 61660, Sartomer CN8003NS, and Sartomer CN996NS.

3. The UV coating composition according to claim 1, characterized in that The aromatic acrylate active monomer is preferably one or a combination of at least two of Changxing EM210, Changxing EM2265, Changxing EM3265, and Sartomer SR602NS.

4. The UV coating composition according to claim 1, characterized in that The photoinitiator is selected from one or a combination of at least two of 1-hydroxycyclohexyl phenyl ketone (184), 2-hydroxy-methylphenylpropane-1-one (1173), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO) or 2,4,6-trimethylbenzoyldiphenylphosphine oxide benzophenone (BP).

5. The UV coating composition according to claim 1, characterized in that The leveling agent is preferably an organosilicon leveling agent.

6. The UV coating composition according to claim 1, characterized in that The wetting and dispersing agent is preferably one of BYK163, BYK2000, BYK2680, or a combination of two thereof.

7. The UV coating composition according to claim 1, characterized in that The filler is quartz powder, glass powder, and aluminum oxide.

8. The method for preparing the UV coating composition according to any one of claims 1 to 7, comprising the steps of: S1. The aliphatic polyurethane acrylate resin, aromatic acrylate reactive monomer, paste, filler, wetting and dispersing agent according to their weight ratio are added to the dispersion kettle, 800-2000r / min dispersion 10-40min, until uniformly dispersed; S2. Add the photoinitiator and leveling agent according to their weight ratio to the mixed solution obtained in step S1, and disperse at 300-800 r / min for 5-20 min; obtain the UV coating composition.

9. A method for preparing an insulating coating formed by curing the UV coating composition according to any one of claims 1 to 7 on the surface of a battery cell housing, the method comprising the following steps: S1. The aliphatic polyurethane acrylate resin, aromatic acrylate reactive monomer, paste, filler, wetting and dispersing agent according to their weight ratio are added to the dispersion kettle, 800-2000r / min dispersion 10-40min, until uniformly dispersed; S2. The photoinitiator and leveling agent are added to the mixed solution obtained in step S1 according to their weight ratio, and dispersed at 300-800r / min for 5-20min; Obtaining the UV coating composition; S3. Spray the UV coating composition evenly on the spraying surface of the battery shell at 500-3000mJ / cm 2 The curing energy is 2-6 seconds, and after curing, an insulating coating with a thickness of 70-150μm is formed.

10. The preparation method according to claim 9, characterized in that Before the spraying operation, the spraying surface of the battery cell shell is first laser pre-treated.

11. The preparation method according to claim 9, characterized in that The area of ​​the spraying surface is S, the spraying amount is M, 80μm≤M / S≤200μm.

12. A method for improving the performance of an insulating coating on a battery cell housing, wherein the insulating coating is prepared according to the coating composition of any one of claims 1 to 7, has an adhesion of level 0, a hardness of 2H, a withstand voltage of >11.6 kV, and a volume resistivity of >9.1×10 14 Ω·cm, shear strength>8.4kPa.

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