A uv insulating glue for improving the insulation performance of a battery case and a preparation method thereof

Abstract

The application relates to the technical field of adhesives, and discloses a UV insulating adhesive for improving the insulation performance of a battery shell and a preparation method thereof. The UV insulating adhesive comprises 100 parts by weight of UV epoxy acrylate, 28-36 parts by weight of active diluent, 2.5-3.3 parts by weight of photoinitiator and the like. The active diluent is composed of acrylate active diluent and di(acrylate benzoate butyl siloxane). The di(acrylate benzoate butyl siloxane) and the UV epoxy acrylate are subjected to a photocuring reaction, the siloxane with flexibility and electrical insulation is grafted into the epoxy acrylate adhesive, the impact strength and volume resistivity of the adhesive are improved, and the adhesive bonding performance with a PET base material is improved. The adhesive can be better applied to the bonding and insulation of a battery cell shell, and the electrical insulation and safety performance of the battery shell are improved.

Description

Technical Field

[0001] This invention relates to the field of adhesive technology, specifically to a UV insulating adhesive for improving the insulation performance of battery casings and its preparation method. Background Technology

[0002] To improve the safety performance of battery cells in new energy vehicles, an insulating material is typically coated onto the battery casing to prevent short circuits caused by contact between the conductive metal casing and external components, thus ensuring electrical safety. This insulating material is mainly composed of PET polyester and PSA pressure-sensitive adhesive. Traditional PSA pressure-sensitive adhesives suffer from poor adhesion, are prone to peeling, and have poor insulation properties, which hinders their practical application in high-voltage platform new energy vehicle batteries. Therefore, the development of novel insulating adhesives is a key research focus.

[0003] Epoxy resins possess high insulation, good waterproofing, and high strength, and are mainly used in products such as insulating adhesives, structural adhesives, and anti-corrosion adhesives. Epoxy acrylates contain active alkenyl groups, allowing for UV curing with fast curing speed and convenient application, making them widely used in new energy vehicles, electronics, machinery, and construction. However, epoxy resins and UV-cured adhesives have poor toughness and are prone to cracking, severely affecting their bonding and other properties. Summary of the Invention

[0004] This invention provides a UV insulating adhesive for improving the insulation performance of battery casings and its preparation method, which solves the problem of poor toughness of UV epoxy acrylate adhesives and improves both bonding and insulation performance.

[0005] The technical solution of the present invention is: a UV insulating adhesive for improving the insulation performance of battery casing and its preparation method. The UV insulating adhesive comprises 100 parts by weight of UV epoxy acrylate, 28-36 parts by weight of reactive diluent, 0.4-0.8 parts by weight of defoamer, and 2.5-3.3 parts by weight of photoinitiator; the reactive diluent is composed of 13-30 parts by weight of acrylate reactive diluent and 6-15 parts by weight of di(butylsiloxane acrylate benzoate).

[0006] The preparation method of UV insulating adhesive is as follows: UV epoxy acrylate, defoamer, and reactive diluent are added to a container, stirred, and then a photoinitiator is added. The container is then sealed and stored in a light-proof environment to obtain UV insulating adhesive that improves the insulation performance of the battery casing.

[0007] Furthermore, the acrylate reactive diluent includes any one or a combination of dipropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate.

[0008] Furthermore, photoinitiators include photoinitiator TPO and photoinitiator 184.

[0009] Furthermore, the preparation method of di(butylsiloxane acrylate) includes:

[0010] (1) Add sodium hydroxide solution with a concentration of 1.6-2 mol / L and 4-hydroxybenzoic acid to the reaction vessel, stir, add acryloyl chloride in an ice-water bath, stir for 40-60 min, and then stir the reaction at 15-25℃ for 1-1.5 h. Add hydrochloric acid solution with a mass fraction of 5-8% to adjust the pH to 4-5, precipitate out, filter, wash with water, and dry to obtain 4-acrylate benzoic acid.

[0011] (2) Add dichloromethane, 4-acrylate benzoic acid, and 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to the reaction vessel. Add dicyclohexylcarbodiimide and 4-dimethylaminopyridine in an ice-water bath. After stirring, react at 20-35℃ for 12-18h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(acrylate benzoate butylsiloxane).

[0012] Furthermore, in (1), the mass ratio of 4-hydroxybenzoic acid to acryloyl chloride is 100:(66-72).

[0013] Furthermore, (2) the mass ratio of 4-acrylate benzoic acid, 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is (152-180):100:(190-208):(1-1.6).

[0014] The beneficial technical effects of this invention are as follows: This invention adds di(butyl methacrylate benzoate) to the epoxy acrylate UV adhesive. Its two ends contain acrylate groups, which can replace part of the dipropylene glycol diacrylate as an active diluent and react with the UV epoxy acrylate to undergo a photocuring reaction. This grafts a flexible and electrically insulating siloxane into the epoxy acrylate adhesive, which significantly improves the impact strength and volume resistivity of the adhesive.

[0015] The bis(butyl acrylate benzoate) of the present invention contains a benzoate structure similar to that of polyester PET, which improves the affinity and interfacial strength between the adhesive and the PET substrate, and is beneficial to improving the bonding performance with the PET substrate. It has higher peel strength and can be better applied to the bonding and insulation of battery cell shells, thereby improving the electrical insulation and safety performance of the battery shell. Detailed Implementation

[0016] The following describes specific embodiments of the present invention in detail. It should be noted that the technical features or combinations of technical features described in the following embodiments should not be considered in isolation; they can be combined with each other to achieve better technical effects.

[0017] The following UV epoxy acrylate is model number Haolong 2222, with an active ingredient content of 99%, and is sourced from Jiangsu Haolong Chemical Co., Ltd.

[0018] Example 1:

[0019] (1) Add 360 mL of 2 mol / L sodium hydroxide solution and 50 g of 4-hydroxybenzoic acid to a reaction vessel. After stirring, add 33 g of acryloyl chloride in an ice-water bath and stir for 60 min. Then, stir the reaction at 25 °C for 1 h. Adjust the pH to 4 by adding 8% hydrochloric acid solution dropwise, precipitate the product, filter, wash with water, and dry to obtain 4-acrylate benzoic acid. The preparation reaction formula is:

[0020]

[0021] (2) Add 800 mL of dichloromethane, 72 g (375 mmol) of 4-acrylate benzoic acid, and 40 g of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to a reaction vessel. Add 76 g of dicyclohexylcarbodiimide and 0.4 g of 4-dimethylaminopyridine to an ice-water bath. After stirring, react at 35 °C for 12 h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(acrylate benzoate butylsiloxane). The preparation reaction formula is:

[0022]

[0023] (3) Add 1kg of UV epoxy acrylate, 5g of defoamer DAPRO AP7072, 300g of tripropylene glycol diacrylate, and 60g of di(butyl methacrylate benzoate) to a container, stir, add 27g of photoinitiator TPO, seal and store in a light-proof container to obtain UV insulating adhesive that improves the insulation performance of the battery case.

[0024] Example 2:

[0025] (1) Add 400 mL of 1.6 mol / L sodium hydroxide solution and 50 g of 4-hydroxybenzoic acid to the reaction vessel. After stirring, add 36 g of acryloyl chloride in an ice-water bath and stir for 40 min. Then stir the reaction at 15 °C for 1.5 h. Add 8% hydrochloric acid solution to adjust the pH to 5. The precipitate will precipitate. After filtration, wash with water and dry to obtain 4-acrylate benzoic acid.

[0026] (2) Add 700 mL of dichloromethane, 60.8 g of 4-acrylate benzoic acid, and 40 g (143.6 mmol) of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to the reaction vessel. Add 83.2 g of dicyclohexylcarbodiimide and 0.64 g of 4-dimethylaminopyridine to the reaction vessel in an ice-water bath. After stirring, react at 20 °C for 18 h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(acrylate benzoate butylsiloxane).

[0027] (3) Add 1kg of UV epoxy acrylate, 8g of defoamer DAPRO AP7072, 240g of pentaerythritol triacrylate, and 90g of di(butyl methacrylate benzoate) to a container, stir, add 25g of photoinitiator TPO, seal and store in the dark to obtain UV insulating adhesive that improves the insulation performance of battery casing.

[0028] Example 3:

[0029] (1) Add 1kg of UV epoxy acrylate, 5g of defoamer DAPRO AP7072, 190g of dipropylene glycol diacrylate, and 120g of di(acrylate benzoate butylsiloxane) (prepared according to the method of Example 1) to a container, stir, add 33g of photoinitiator 184, seal and store in the dark to obtain UV insulating adhesive that improves the insulation performance of battery shell.

[0030] Example 4:

[0031] (1) Add 1kg of UV epoxy acrylate, 4g of defoamer DAPRO AP7072, 130g of trimethylolpropane triacrylate, and 150g of di(acrylate benzoate butylsiloxane) (prepared according to the method of Example 1) to a container, stir, add 26g of photoinitiator TPO, seal and store in the dark to obtain UV insulating adhesive that improves the insulation performance of battery shell.

[0032] Comparative Example 1 differs from Example 1 in that it uses tripropylene glycol diacrylate instead of di(acrylate benzoate butylsiloxane).

[0033] (1) Add 1kg of UV epoxy acrylate, 5g of defoamer DAPRO AP7072 and 360g of tripropylene glycol diacrylate to a container, stir, add 28g of photoinitiator TPO, seal and store in a light-proof container to obtain UV insulating adhesive.

[0034] Comparative Example 2 differs from Example 1 in that acrylic acid is used instead of 4-acrylate benzoic acid.

[0035] (1) Add 800 mL of dichloromethane, 27 g (375 mmol) of acrylic acid, and 40 g of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to a reaction vessel. Then, add 76 g of dicyclohexylcarbodiimide and 0.4 g of 4-dimethylaminopyridine in an ice-water bath. After stirring, react at 35 °C for 12 h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(butyl acrylate siloxane), with the structural formula:

[0036]

[0037] (2) Add 1kg of UV epoxy acrylate, 5g of defoamer DAPRO AP7072, 300g of tripropylene glycol diacrylate and 60g of di(butyl acrylate) to a container, stir, add 27g of photoinitiator TPO, seal and store in a light-proof container to obtain UV insulating adhesive.

[0038] Comparative Example 3 differs from Example 1 in that 1,8-octanediol is used instead of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane.

[0039] (1) Add 800 mL of dichloromethane, 72 g of 4-acrylate benzoic acid, and 21 g of 1,8-octanediol (143.6 mmol) to a reaction vessel. Then add 76 g of dicyclohexylcarbodiimide and 0.4 g of 4-dimethylaminopyridine in an ice-water bath. After stirring, react at 35 °C for 12 h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(acrylate benzoate octane). The structural formula is...

[0040] (2) Add 1kg of UV epoxy acrylate, 5g of defoamer DAPRO AP7072, 300g of tripropylene glycol diacrylate and 60g of di(acrylate octane) to a container, stir, add 27g of photoinitiator TPO, seal and store in a light-proof container to obtain UV insulating adhesive.

[0041] UV insulating adhesive was applied between two transparent polyester PET sheets, cured in a 2kW UV curing machine for 50 seconds, left at room temperature for 24 hours, and the T-peel strength was tested according to the method of GB / T 2791-1995.

[0042] The insulating adhesive was poured into the mold and cured in a 2kW UV curing machine for 180 seconds. After being left at room temperature for 24 hours, a casting sample was prepared. The volume resistivity was tested according to the method of GB / T 1410-2006.

[0043] The impact strength of the cast specimens was tested according to the method of GB / T 2567-2021.

[0044] Table 1: Performance of UV Insulating Adhesive

[0045]

[0046]

[0047] Compared to Comparative Examples 1-3, the epoxy acrylate UV insulating adhesives of Examples 1-4 simultaneously exhibit good peel strength, volume resistivity, and impact strength, as well as excellent adhesion, insulation, and toughness. This is mainly due to the addition of di(butyl acrylate benzoate), which contains acrylate groups at both ends. This replaces part of the dipropylene glycol diacrylate as an active diluent, undergoing a photocuring reaction with the UV epoxy acrylate. This grafts a flexible and electrically insulating siloxane into the epoxy acrylate adhesive, significantly improving the adhesive's impact strength and volume resistivity. Furthermore, di(butyl acrylate benzoate) contains a benzoate structure similar to PET, thereby improving the affinity and interfacial strength between the adhesive and the PET substrate, which is beneficial for enhancing adhesion to the PET substrate and resulting in higher peel strength.

[0048] While this application has provided several embodiments of the present invention, those skilled in the art should understand that changes can be made to the embodiments herein without departing from the spirit of the invention. The above embodiments are merely exemplary and should not be construed as limiting the scope of the invention.

Claims

1. A UV insulating adhesive for improving the insulation performance of battery casings, characterized in that, The UV insulating adhesive comprises 100 parts by weight of UV epoxy acrylate, 28-36 parts by weight of reactive diluent, 0.4-0.8 parts by weight of defoamer, and 2.5-3.3 parts by weight of photoinitiator; The reactive diluent is composed of 13-30 parts by weight of acrylate reactive diluent and 6-15 parts by weight of di(butyl acrylate benzoate); The structural formula of the di(butyl acrylate butylsiloxane) reactive diluent is as follows: ； The acrylate reactive diluent includes any one or a combination of tripropylene glycol diacrylate, dipropylene glycol diacrylate, trimethylolpropane triacrylate, and pentaerythritol triacrylate.

2. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 1, characterized in that, The photoinitiator includes photoinitiator TPO or photoinitiator 184.

3. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 1, characterized in that, The preparation method of the di(butyl acrylate benzoate) includes: (1) Add sodium hydroxide solution and 4-hydroxybenzoic acid to the reaction vessel, stir, add acryloyl chloride in an ice-water bath, stir for 40-60 min, then stir the reaction at 15-25℃ for 1-1.5 h, add hydrochloric acid solution to adjust the pH, precipitate the precipitate, filter, wash with water, and dry to obtain 4-acrylate benzoic acid. (2) Add dichloromethane, 4-acrylate benzoic acid, and 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane to the reaction vessel. Add dicyclohexylcarbodiimide and 4-dimethylaminopyridine in an ice-water bath. After stirring, react at 20-35℃ for 12-18h. Filter, evaporate the filtrate by rotary evaporation, and purify the crude product by silica gel column chromatography to obtain di(acrylate benzoate butylsiloxane).

4. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 3, characterized in that, The concentration of sodium hydroxide in (1) is 1.6-2 mol / L.

5. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 3, characterized in that, The mass ratio of 4-hydroxybenzoic acid to acryloyl chloride in (1) is 100:(66-72).

6. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 3, characterized in that, In step (1), hydrochloric acid solution is added dropwise to adjust the pH to 4-5; the mass fraction of the hydrochloric acid solution is 5-8%.

7. The UV insulating adhesive for improving the insulation performance of battery casing according to claim 3, characterized in that, The mass ratio of (2) 4-acrylate benzoic acid, 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is (152-180):100:(190-208):(1-1.6).

8. A method for preparing a UV insulating adhesive for improving the insulation performance of a battery casing as described in any one of claims 1-7, characterized in that, The preparation method includes: adding UV epoxy acrylate, defoamer, and reactive diluent to a container, stirring, adding a photoinitiator, and sealing and storing in a light-proof container to obtain a UV insulating adhesive that improves the insulation performance of the battery casing.

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