UV light-cured lithium battery insulating coating and preparation method thereof

Abstract

The invention relates to the technical field of lithium battery insulating materials, and particularly discloses a UV light-cured lithium battery insulating coating and a preparation method thereof. The coating is prepared from the following components in parts by mass: 20 to 30 parts of bisphenol A type epoxy acrylic resin, and the bisphenol A type epoxy acrylic resin is prepared by a controlled ring-opening reaction of DYD-128 epoxy resin and acrylic acid; 6-8 parts of a photoinitiator; 5-6 parts of an adhesion promoter; 1-2 parts of a defoaming agent; and 6-10 parts of an inorganic filler. The invention provides a high-performance, environment-friendly and economical solution, the prepared UV light-cured lithium battery insulating coating has the performance advantages of high strength, high wear resistance, high adhesive force and good flexibility and water resistance, the safety of a lithium battery is remarkably improved, and the service life of the lithium battery is remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery insulating materials, and particularly discloses a UV light-cured lithium battery insulating coating and a preparation method thereof. Background Art

[0002] With the continuous advancement of technology, lithium batteries, as efficient and environmentally friendly energy storage devices, have been widely used in electric vehicles, energy storage systems, consumer electronics, and other fields. However, lithium batteries face numerous safety issues during use, among which the insulation performance of internal battery components is particularly important. Good insulation performance can effectively prevent internal short circuits in the battery, avoiding safety accidents such as thermal runaway, fire, and explosion caused by short circuits, thereby ensuring the safe operation and service life of the battery.

[0003] Traditional lithium battery insulation materials mainly use polyethylene terephthalate (PET) film. PET film has good chemical resistance, tensile strength and insulation properties, and has low equipment investment and material costs. However, PET film also has some obvious shortcomings. First, the adhesion performance of PET film is poor, and gaps are easily generated during the bonding process, resulting in unsatisfactory insulation between the internal components of the battery. Second, PET film is prone to multi-layer stacking at closed joints, which not only affects the overall structure of the battery, but may also cause problems such as local overheating. In addition, soft-pack batteries with PET film are susceptible to external impact or physical damage due to their relatively fragile plastic film structure, thereby increasing the risk of internal short circuits in the battery. Once a short circuit occurs, thermal runaway may occur, causing the battery temperature to rise uncontrollably, thereby generating smoke, fire, or even explosion, posing serious safety hazards to personnel and equipment.

[0004] To overcome these shortcomings of traditional PET film, researchers have begun searching for more efficient and safer lithium battery insulation materials. UV light-curing technology has gained widespread application in the polymer industry due to its advantages, including rapid curing, low energy consumption, room-temperature processing, pollution-free, solvent-free formulation, and low material cost. UV light-curable coatings not only provide excellent insulation properties but also boast superior adhesion, wear resistance, and durability. Compared to traditional thermally cured coatings, UV light-curable coatings have a shorter curing time, forming a hard protective layer in a short period of time, effectively improving production efficiency. Furthermore, the solvent-free formulation of UV light-curable coatings makes them more environmentally friendly, meeting modern society's requirements for green manufacturing. However, existing UV coatings still have some shortcomings in practical applications, such as insufficient adhesion, wear resistance, and water resistance. Furthermore, the complex and costly preparation process of modifying them by adding various additives and modifiers limits their large-scale application. Therefore, the development of a high-performance, low-cost, and simple-to-manufacture UV light-curable lithium battery insulation coating and its preparation method is of great practical significance for improving the safety and service life of lithium batteries. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a UV light-curable lithium battery insulating coating and a preparation method thereof.

[0006] On the one hand, the present invention discloses a UV light-cured lithium battery insulating coating, which adopts the following technical solution:

[0007] A UV light-curable lithium battery insulating coating, the coating comprising the following components in parts by mass:

[0008] 20-30 parts of bisphenol A epoxy acrylic resin, wherein the bisphenol A epoxy acrylic resin is prepared by a controlled ring-opening reaction of DYD-128 epoxy resin and acrylic acid;

[0009] 6-8 parts of photoinitiator;

[0010] 5-6 parts adhesion promoter;

[0011] 1-2 parts of defoaming agent;

[0012] 6 to 10 parts of inorganic filler.

[0013] By using bisphenol A epoxy acrylate resin as the main resin, which has flexible fatty chains compared to conventional rigid epoxy acrylate resins, the coating's adhesion can be prevented from being too brittle and causing reduced adhesion. Furthermore, bisphenol A epoxy acrylate resin itself has a certain degree of polymerization, which can improve the overall degree of polymerization during the curing process. Furthermore, by leveraging the bisphenol A epoxy acrylate resin's molecular chain, which combines rigid benzene rings with flexible fatty chains, the coating maintains its adhesion while improving its mechanical strength and wear resistance after curing.

[0014] Preferably, the bisphenol A epoxy acrylic resin is prepared from the following components in parts by mass:

[0015] 50-70 parts of DYD-128 epoxy resin;

[0016] 30-50 parts of acrylic acid;

[0017] 0.1-1 part of inhibitor;

[0018] 0.5 to 2 parts of catalyst.

[0019] The preparation of bisphenol A epoxy acrylate resin through controlled ring-opening reaction can precisely control the ring-opening and esterification reactions of the epoxy group, ensure the uniformity of the reaction and the molecular weight distribution of the product, effectively avoid the occurrence of side reactions, and improve the purity and performance stability of the product.

[0020] Preferably, the adhesion promoter is trimethylolpropane triacrylate, which is prepared from the following components:

[0021] 8-12 parts of trimethylolpropane;

[0022] 14-18 parts of acrylic acid;

[0023] 0.2-0.4 parts of catalyst;

[0024] 0.02-0.03 parts of free radical inhibitors.

[0025] By using trimethylolpropane triacrylate (TMPTA) as an adhesion promoter, it has three acrylate groups and can simultaneously undergo polymerization reactions with the three acrylate groups to form a highly cross-linked three-dimensional network structure, increasing the connection strength between layers and reducing interlayer gaps. This structure not only enhances the mechanical properties of the coating, but also improves the adhesion between the coating and the substrate. The multi-reaction site characteristics of TMPTA enable it to undergo cross-linking reactions with multiple reactants during the curing process to form a dense cross-linked network, thereby improving the wear resistance and water resistance of the coating.

[0026] Preferably, the defoamer is a polyether-modified silicone oil defoamer, which is prepared from the following components:

[0027] 15-25 parts of polyether-modified polysiloxane copolymer, which is prepared by the following raw materials in parts by weight: 0.5-1.5 parts of hydrogenated silicone oil; 15-25 parts of polyether; 0.1-0.3 parts of acid catalyst;

[0028] 10-15 parts of silicone paste, which is prepared by the following raw materials in parts by weight: 90-95 parts of dimethyl silicone oil; 5-10 parts of hydrophobic white carbon black;

[0029] 2-4 parts of emulsifier;

[0030] 50-70 parts of water.

[0031] Polyether-modified silicone oil defoamer has excellent defoaming and anti-foaming properties, which can effectively prevent the generation of bubbles in the coating during stirring and coating. It has low surface tension and good dispersibility, and can be evenly distributed in the coating system, thereby improving the defoaming effect. In addition, the defoamer has good chemical stability and compatibility and will not affect other properties of the coating.

[0032] Preferably, the coating further comprises:

[0033] 2-adamantyl methacrylate 2-8 parts;

[0034] 3 to 10 parts of fatty chain acrylic acid.

[0035] The addition of 2-adamantyl methacrylate balances the flexibility and wear resistance of the cured coating, allowing it to maintain high strength while also exhibiting good flexibility. The addition of aliphatic chain acrylic acid further enhances the coating's wear and chemical resistance, making it more adaptable to complex operating environments.

[0036] Preferably, the inorganic filler comprises:

[0037] 1-2 parts calcium carbonate;

[0038] 5-8 parts of kaolin.

[0039] The addition of calcium carbonate and kaolin can increase the density and wear resistance of the coating, while reducing the hydrophilicity of the coating and improving its water resistance. These inorganic fillers can also improve the thermal stability and mechanical properties of the coating, allowing it to maintain good performance under high temperature and mechanical stress.

[0040] On the other hand, the present invention discloses a method for preparing a UV-curable lithium battery insulating coating, which adopts the following technical solution:

[0041] A method for preparing a UV-curable lithium battery insulating coating comprises the following steps:

[0042] (1) In a light-shielding condition, bisphenol A epoxy acrylic resin, a photoinitiator, a defoaming agent, an adhesion promoter, and an inorganic filler are added to a reaction vessel, stirred at room temperature for 30 minutes, and then the mixture is filtered to obtain a UV coating;

[0043] (2) After coating the UV coating on the surface of the lithium battery, the coating is cured under a medium-pressure mercury lamp at room temperature to obtain a UV light-cured lithium battery insulating coating.

[0044] The preparation method of the present invention is simple and efficient, enabling rapid curing at room temperature without the need for high-temperature baking, thus saving energy and reducing costs. The solvent-free formulation ensures environmental friendliness and complies with modern environmental protection requirements. By precisely controlling the ratios of the components and reaction conditions, a high-performance UV-curable lithium battery insulating coating can be produced, significantly improving the safety and service life of lithium batteries.

[0045] Preferably, the preparation steps of the bisphenol A type epoxy acrylic resin include:

[0046] (1) Place the mixture of DYD-128 epoxy resin and inhibitor in a four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel, and thermometer and heat to 75 ± 2 °C;

[0047] (2) adding a mixture of acrylic acid and catalyst dropwise, controlling the dropwise acceleration rate to maintain the temperature below 75°C;

[0048] (3) After the addition is complete, heat to 95±2°C and react for 1 h, then heat to 105±2°C and react for 2 h;

[0049] (4) The product was dissolved in chloroform and washed three times with aqueous sodium hydroxide solution to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

[0050] Preferably, the preparation steps of the adhesion promoter include:

[0051] Trimethylolpropane, acrylic acid, a catalyst and a free radical inhibitor were placed in a flask, placed in a preheated oil bath at 120±2°C, and reacted for 15 minutes under magnetic stirring to obtain a trimethylolpropane triacrylate adhesion promoter.

[0052] Preferably, the preparation steps of the defoaming agent include:

[0053] (1) Add hydrogenated silicone oil, polyether, solvent and acid catalyst into a four-necked flask according to the proportion, slowly heat to 105±2°C under stirring, reflux, and react for 10 hours; neutralize with alkali, remove the acid catalyst by suction filtration, and then remove the solvent by reduced pressure distillation to obtain a polyether-modified polysiloxane copolymer;

[0054] (2) Weighing dimethyl silicone oil and hydrophobic silica according to the ratio, placing them in a round-bottom flask, stirring and slowly heating to 190-200°C, keeping the temperature constant for 3-5 hours, and then cooling to 50-60°C to obtain a silicone paste, and then adding a polyether-modified polysiloxane copolymer for compounding, stirring thoroughly, cooling and discharging to obtain a compound;

[0055] (3) Mix the Span emulsifier and the Tween emulsifier, adjust the HLB value to 7-10, stir evenly and set aside;

[0056] (4) Add the compound according to the ratio into a four-necked bottle, add the prepared emulsifier, stir and heat to 60-80°C;

[0057] (5) Slowly add a small amount of water to dissolve the emulsifier, continue stirring at a constant temperature for 2 hours, then slowly add the remaining water, and then use a homogenizer to stir at high speed for about 10 minutes to obtain a polyether modified silicone oil defoamer.

[0058] Compared with the prior art, the present invention has at least the following beneficial effects:

[0059] The UV light-curing lithium battery insulating coating of the present invention and the preparation method thereof provide a high-performance, environmentally friendly and economical insulating solution, which significantly improves the safety and service life of lithium batteries. The coating adopts bisphenol A epoxy acrylic resin as the main body, and by adding specific adhesion promoters and defoaming agents and other components, it achieves high strength, high wear resistance, high adhesion, good flexibility and water resistance. The curing process only takes 1 minute, which is fast and efficient, and does not require high-temperature baking, saving energy and reducing costs. The solvent-free formula ensures green environmental protection and meets modern environmental protection requirements. The coating of the present invention performs well in the voltage resistance test, with a current of less than 0.5mA at 3kV, a tensile strength of 22MPa, a shear strength of 16MPa, and outstanding water resistance and high temperature resistance. The preparation process of the present invention is simple, low-cost, and easy to promote on a large scale. Its broad application prospects cover fields such as electric vehicles, energy storage systems and consumer electronics, providing a strong guarantee for the safe operation and performance improvement of lithium batteries, and has significant economic and social benefits. DETAILED DESCRIPTION

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific embodiments.

[0061] Example 1

[0062] A UV light-curable lithium battery insulating coating, the preparation method of which is as follows:

[0063] Preparation of bisphenol A epoxy acrylic resin:

[0064] (1) A mixture of 50 g of DYD-128 epoxy resin and 0.25 g of inhibitor (hydroquinone) was placed in a 100 ml four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel, and thermometer and heated to 75°C;

[0065] (2) A mixture of 30 g of acrylic acid and 0.5 g of a catalyst (p-toluenesulfonic acid (p-TsOH)) was added dropwise to a four-necked round-bottom flask, and the dropping rate was controlled to keep the temperature below 75°C;

[0066] (3) After the addition is complete, the temperature is raised to 95°C for reaction for 1 hour, and then raised to 105°C for reaction for 2 hours;

[0067] (4) The product was dissolved in chloroform and washed three times with a sodium hydroxide aqueous solution (5 wt %) to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

[0068] Preparation steps of trimethylolpropane triacrylate adhesion promoter:

[0069] 10.3 g of trimethylolpropane, 16.6 g of acrylic acid, 0.3 g of catalyst (Amberlite TM 120IR(H)) and a free radical inhibitor (4-methoxyphenol (MEHQ)) were charged into a flask, placed in a preheated oil bath at 120°C, and reacted for 15 minutes under magnetic stirring to obtain trimethylolpropane triacrylate adhesion promoter.

[0070] Preparation steps of polyether modified silicone oil defoamer:

[0071] (1) Hydrogenated silicone oil, polyether, acid catalyst (HCl), and solvent (ethylene glycol) were added to a four-necked flask in a mass ratio of (1:20:0.2:78.8), slowly heated to 105°C under stirring, refluxed, and reacted for 10 hours; alkali was added for neutralization, the acid catalyst was removed by suction filtration, and the solvent was removed by reduced pressure distillation to obtain a polyether-modified polysiloxane copolymer;

[0072] (2) Dimethyl silicone oil and hydrophobic silica (94:6) were weighed according to the mass ratio, placed in a round-bottom flask, stirred and slowly heated to 190-200°C, kept constant for 3-5 hours, and then cooled to 50-60°C to obtain a silicone paste, and then polyether-modified polysiloxane copolymer was added for compounding (the mass ratio of silicone paste to polyether-modified polysiloxane copolymer was 10:20), stirred thoroughly, cooled and discharged to obtain a compound;

[0073] (3) Mix a span emulsifier and a tween emulsifier with different hydrophilic-lipophilic balance (HLB) values, adjust the HLB value to 7-10, stir well and set aside;

[0074] (4) Add the compound to a four-necked bottle, add the prepared emulsifier (the mass ratio of the compound to the emulsifier is 30:3), stir and heat to 60-80°C;

[0075] (5) Take a certain amount of water according to the ratio (the mass ratio of the compound to water is 30:67), slowly add a small amount of water (about 30% of the total water) to dissolve the emulsifier, continue stirring at a constant temperature for 2 hours, then slowly add the remaining water (about 70% of the total water), and then use a homogenizer to stir at high speed for about 10 minutes to obtain a polyether modified silicone oil defoamer.

[0076] Preparation of UV light-cured lithium battery insulating coating:

[0077] (1) Under light-shielding conditions, 25 g of bisphenol A epoxy acrylic resin, 5 g of 2-adamantyl methacrylate, 6 g of fatty chain acrylic acid, 6 g of diethoxyacetophenone photoinitiator, 1 g of polyether-modified silicone oil defoamer, 5 g of trimethylolpropane triacrylate adhesion promoter, 1 g of calcium carbonate, and 6 g of kaolin were added to a reaction container in sequence, stirred at room temperature for 30 min, and the mixture was filtered to obtain a UV coating;

[0078] (2) After the UV coating is applied to the surface of the lithium battery, it is placed under a medium-pressure mercury lamp (main wavelength: 365nm, lamp power: 1000W, ultraviolet energy per second: 1000J / s) for curing for 1 minute at room temperature to obtain a UV light-cured lithium battery insulating coating.

[0079] Example 2

[0080] A UV light-curable lithium battery insulating coating, the preparation method of which is as follows:

[0081] Preparation of bisphenol A epoxy acrylic resin:

[0082] A mixture of 60 g of DYD-128 epoxy resin and 0.5 g of inhibitor (hydroquinone) was placed in a 100 ml four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel and thermometer and heated to 75°C;

[0083] A mixture of 35 g of acrylic acid and 1.0 g of a catalyst (p-toluenesulfonic acid (p-TsOH)) was added dropwise to a four-necked round-bottom flask, and the dropping rate was controlled to keep the temperature below 75°C;

[0084] After the addition was completed, the temperature was raised to 95°C for reaction for 1 hour, and then raised to 105°C for reaction for 2 hours;

[0085] The product was dissolved in chloroform, washed three times with aqueous sodium hydroxide solution (5 wt %) to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

[0086] Preparation steps of trimethylolpropane triacrylate adhesion promoter:

[0087] 11g of trimethylolpropane, 17g of acrylic acid, 0.35g of catalyst (Amberlite TM 120IR(H)) and a free radical inhibitor (4-methoxyphenol (MEHQ)) were charged into a flask, placed in a preheated oil bath at 120°C, and reacted for 15 minutes under magnetic stirring to obtain trimethylolpropane triacrylate adhesion promoter.

[0088] Preparation steps of polyether modified silicone oil defoamer:

[0089] Hydrogenated silicone oil, polyether, acid catalyst (HCl), and solvent (ethylene glycol) were added to a four-necked flask in a mass ratio of (1:22:0.25:76.75), slowly heated to 105°C under stirring, refluxed, and reacted for 10 hours; alkali was added for neutralization, the acid catalyst was removed by filtration, and the solvent was removed by distillation under reduced pressure to obtain a polyether-modified polysiloxane copolymer;

[0090] Weigh dimethyl silicone oil and hydrophobic silica (90:10) according to the mass ratio, place them in a round-bottom flask, stir and slowly heat to 190-200°C, keep constant temperature for 3-5 hours, and then cool to 50-60°C to obtain a silicone paste, then add a polyether-modified polysiloxane copolymer for compounding (the mass ratio of the silicone paste to the polyether-modified polysiloxane copolymer is 15:15), stir thoroughly, cool and discharge to obtain a compound;

[0091] Mix Span emulsifiers and Tween emulsifiers with different hydrophilic-lipophilic balance (HLB) values, adjust the HLB value to 7-10, stir well and set aside;

[0092] The compound was added to a four-necked bottle, and the prepared emulsifier was added (the mass ratio of the compound to the emulsifier was 30:2), and the mixture was stirred and heated to 60-80°C;

[0093] Take a certain amount of water according to the ratio (the mass ratio of the compound to water is 30:68), slowly add a small amount of water (about 30% of the total water) to dissolve the emulsifier, continue stirring at a constant temperature for 2 hours, then slowly add the remaining water (about 70% of the total water), and then use a homogenizer to stir at high speed for about 10 minutes to obtain a polyether modified silicone oil defoamer.

[0094] Preparation of UV light-cured lithium battery insulating coating:

[0095] Under light-shielding conditions, 28 g of bisphenol A epoxy acrylic resin, 6 g of 2-adamantyl methacrylate, 7 g of fatty chain acrylic acid, 7 g of diethoxyacetophenone photoinitiator, 1.2 g of polyether-modified silicone oil defoamer, 5.5 g of trimethylolpropane triacrylate adhesion promoter, 1.5 g of calcium carbonate and 7 g of kaolin were added to a reaction container in sequence, stirred at room temperature for 30 min, and then the mixture was filtered to obtain a UV coating;

[0096] After the UV coating is applied to the surface of the lithium battery, it is placed under a medium-pressure mercury lamp (main wavelength: 365nm, lamp power: 1000W, ultraviolet energy per second: 1000J / s) for curing for 1 minute at room temperature to obtain a UV light-cured lithium battery insulating coating.

[0097] Example 3

[0098] A UV light-curable lithium battery insulating coating, the preparation method of which is as follows:

[0099] Preparation of bisphenol A epoxy acrylic resin:

[0100] A mixture of 65 g of DYD-128 epoxy resin and 0.75 g of inhibitor (hydroquinone) was placed in a 100 ml four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel and thermometer and heated to 75°C;

[0101] A mixture of 40 g of acrylic acid and 1.5 g of a catalyst (p-toluenesulfonic acid (p-TsOH)) was added dropwise to a four-necked round-bottom flask, and the dropping rate was controlled to keep the temperature below 75°C;

[0102] After the addition was completed, the temperature was raised to 95°C for reaction for 1 hour, and then raised to 105°C for reaction for 2 hours;

[0103] The product was dissolved in chloroform, washed three times with aqueous sodium hydroxide solution (5 wt %) to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

[0104] Preparation steps of trimethylolpropane triacrylate adhesion promoter:

[0105] 12g of trimethylolpropane, 18g of acrylic acid, 0.4g of catalyst (Amberlite TM 120IR(H)) and a free radical inhibitor (4-methoxyphenol (MEHQ)) were charged into a flask, placed in a preheated oil bath at 120°C, and reacted for 15 minutes under magnetic stirring to obtain trimethylolpropane triacrylate adhesion promoter.

[0106] Preparation steps of polyether modified silicone oil defoamer:

[0107] Hydrogenated silicone oil, polyether, acid catalyst (HCl), and solvent (ethylene glycol) were added to a four-necked flask in a mass ratio of (0.8:18:0.2:71), slowly heated to 105°C under stirring, refluxed, and reacted for 10 hours; alkali was added for neutralization, the acid catalyst was removed by filtration, and the solvent was removed by reduced pressure distillation to obtain a polyether-modified polysiloxane copolymer;

[0108] Weigh dimethyl silicone oil and hydrophobic silica (95:5) according to the mass ratio, place them in a round-bottom flask, stir and slowly heat to 190-200°C, keep constant temperature for 3-5 hours, and then cool to 50-60°C to obtain a silicone paste, then add a polyether-modified polysiloxane copolymer for compounding (the mass ratio of the silicone paste to the polyether-modified polysiloxane copolymer is 10:25), stir thoroughly, cool and discharge to obtain a compound;

[0109] Mix Span emulsifiers and Tween emulsifiers with different hydrophilic-lipophilic balance (HLB) values, adjust the HLB value to 7-10, stir well and set aside;

[0110] The compound was added to a four-necked bottle, and the prepared emulsifier was added (the mass ratio of the compound to the emulsifier was 35:4), and the mixture was stirred and heated to 60-80°C;

[0111] Take a certain amount of water according to the ratio (the mass ratio of the compound to water is 35:61), slowly add a small amount of water (about 30% of the total water) to dissolve the emulsifier, continue stirring at a constant temperature for 2 hours, then slowly add the remaining water (about 70% of the total water), and then use a homogenizer to stir at high speed for about 10 minutes to obtain a polyether modified silicone oil defoamer.

[0112] Preparation of UV light-cured lithium battery insulating coating:

[0113] Under light-shielding conditions, 30 g of bisphenol A epoxy acrylic resin, 8 g of 2-adamantyl methacrylate, 10 g of aliphatic chain acrylic acid, 8 g of diethoxyacetophenone photoinitiator, 1.5 g of polyether-modified silicone oil defoamer, 6 g of trimethylolpropane triacrylate adhesion promoter, 2 g of calcium carbonate, and 8 g of kaolin were added to a reaction container in sequence, stirred at room temperature for 30 min, and then the mixture was filtered to obtain a UV coating;

[0114] After the UV coating is applied to the surface of the lithium battery, it is placed under a medium-pressure mercury lamp (main wavelength: 365nm, lamp power: 1000W, ultraviolet energy per second: 1000J / s) for curing for 1 minute at room temperature to obtain a UV light-cured lithium battery insulating coating.

[0115] Example 4

[0116] The difference from Example 1 is that an equal amount of KH560 epoxy silane adhesion promoter is used instead of trimethylolpropane triacrylate adhesion promoter.

[0117] Example 5

[0118] The difference from Example 1 is that an equal amount of polydimethylsiloxane organic silicon defoaming agent is used instead of the polyether modified silicone oil defoaming agent.

[0119] Comparative Example 1

[0120] The difference from Example 1 is that an equal amount of epoxy acrylic resin is used instead of bisphenol A epoxy acrylic resin as the main resin.

[0121] Comparative Example 2

[0122] The difference from Example 1 is that the bisphenol A epoxy acrylic resin is prepared by direct esterification reaction, and the preparation steps are as follows:

[0123] (1) A mixture of 50 g of E-51 epoxy resin and 0.25 g of inhibitor (hydroquinone) was placed in a 100 ml four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel, and thermometer and heated to 60°C;

[0124] (2) A mixture of 30 g of acrylic acid and 0.5 g of a catalyst (p-toluenesulfonic acid (p-TsOH)) was added dropwise to a four-necked round-bottom flask, and the dropping rate was controlled to maintain the temperature below 75°C.

[0125] (3) After the addition was complete, the temperature was raised to 70°C and the reaction was continued for 2 h.

[0126] (4) The product was dissolved in chloroform and washed three times with a sodium hydroxide aqueous solution (5 wt %) to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

[0127] Performance testing

[0128] The UV coatings prepared in Examples 1-5 and Comparative Examples 1-2 were cured on substrates in the same coating manner to prepare corresponding test samples for performance testing, including voltage resistance test, tensile strength, shear strength, water resistance, and high temperature resistance.

[0129] 1. Voltage resistance test

[0130] Test method: Place the coating sample between electrodes, apply the specified voltage (3kV) for 1 minute, and record the current value. If the current is less than 0.5mA, it is judged to have passed the voltage withstand test.

[0131] 2. Tensile strength performance test

[0132] Test method: Cut the prepared coating sample into dumbbell-shaped specimens of standard size and perform a tensile test using an electronic universal material testing machine. Record the maximum tensile force when the specimen breaks and calculate the tensile strength.

[0133] 3. Shear strength performance test

[0134] Test method: Prepare the coating sample into a shear specimen of standard size, use an electronic universal material testing machine to perform a shear test, record the maximum shear force when the sample breaks, and calculate the shear strength.

[0135] 4. Water resistance performance test

[0136] Testing method: Immerse the coating sample completely in distilled water and maintain it at a constant temperature of 23±2℃. Observe the changes in the coating surface within 7 days and record whether there is blistering, peeling or cracking.

[0137] 5. High temperature resistance test

[0138] Testing method: Place the coating sample in an oven at 100°C for 10 minutes, observe the changes on the coating surface, and record whether there is blistering, peeling or cracking.

[0139] The test results are shown in Table 1:

[0140]

[0141]

[0142] As shown in Table 1, the UV-cured coatings produced using the formulation and preparation method of the present invention exhibit excellent adhesion, abrasion resistance, and water resistance. The superior performance of Example 1 compared to Example 4 demonstrates that the coating produced by the present invention, using trimethylolpropane triacrylate as an adhesion promoter, exhibits superior performance. Furthermore, a comparison of Example 1 with Example 5 demonstrates that the coating produced by the present invention, using a polyether-modified silicone oil as a defoamer, exhibits even greater performance advantages.

[0143] In addition, a comparison of the performance results of Comparative Example 1 and Example 1 shows that the present invention's use of bisphenol A epoxy acrylic resin as the main resin not only improves the coating's flexibility, thereby improving its adhesion, but also exhibits higher mechanical strength and wear resistance compared to conventional epoxy acrylic resins. A comparison of Comparative Example 2 and Example 1 shows that the bisphenol A epoxy acrylic resin prepared by the present invention through a controlled ring-opening reaction of DYD-128 epoxy resin and acrylic acid has a significant impact on coating performance. This is because the bisphenol A epoxy acrylic resin prepared by the controlled ring-opening reaction method has advantages such as uniform molecular chain distribution and controllable molecular weight, which enable the resin to better exert a synergistic effect when used in conjunction with TMPTA. The controlled ring-opening reaction method can precisely control the ring-opening degree of the epoxy resin, thereby adjusting the resin's molecular weight and molecular chain structure, making its cross-linking reaction with TMPTA more complete, forming a denser cross-linked network, and further improving the coating's adhesion and mechanical properties.

[0144] The technical solution provided by the present invention is introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of the present invention, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A UV light-curable lithium battery insulating coating, characterized in that: The coating consists of the following components in parts by mass: 20-30 parts of bisphenol A epoxy acrylic resin, wherein the bisphenol A epoxy acrylic resin is prepared by a controlled ring-opening reaction of DYD-128 epoxy resin and acrylic acid; 6-8 parts of photoinitiator; 5-6 parts adhesion promoter; 1-2 parts of defoaming agent; 6 to 10 parts of inorganic filler.

2. The UV light-curable lithium battery insulating coating according to claim 1, characterized in that: The bisphenol A epoxy acrylic resin is prepared from the following components in parts by mass: 50-70 parts of DYD-128 epoxy resin; 30-50 parts of acrylic acid; 0.1-1 part of inhibitor; 0.5 to 2 parts of catalyst.

3. The UV light-curable lithium battery insulating coating according to claim 1, characterized in that: The adhesion promoter is trimethylolpropane triacrylate, which is prepared from the following components: 8-12 parts of trimethylolpropane; 14-18 parts of acrylic acid; 0.2-0.4 parts of catalyst; 0.02-0.03 parts of free radical inhibitors.

4. The UV light-curable lithium battery insulating coating according to claim 1, characterized in that: The defoamer is a polyether modified silicone oil defoamer, which is prepared from the following components: 15-25 parts of polyether-modified polysiloxane copolymer, which is prepared by the following raw materials in parts by weight: 0.5-1.5 parts of hydrogenated silicone oil; 15-25 parts of polyether; 0.1-0.3 parts of acid catalyst; 10-15 parts of silicone paste, which is prepared by the following raw materials in parts by weight: 90-95 parts of dimethyl silicone oil; 5-10 parts of hydrophobic white carbon black; 2-4 parts of emulsifier; 50-70 parts of water.

5. The UV light-curable lithium battery insulating coating according to claim 1, characterized in that: The coating further comprises: 2-adamantyl methacrylate 2-8 parts; 3 to 10 parts of fatty chain acrylic acid.

6. The UV light-curable lithium battery insulating coating according to claim 1, characterized in that: The inorganic filler includes: 1-2 parts calcium carbonate; 5-8 parts of kaolin.

7. A method for preparing a UV-curable lithium battery insulating coating, characterized in that: The following steps are involved: (1) In a light-shielding condition, bisphenol A epoxy acrylic resin, a photoinitiator, a defoaming agent, an adhesion promoter, and an inorganic filler are added to a reaction vessel, stirred at room temperature for 30 minutes, and then the mixture is filtered to obtain a UV coating; (2) After coating the UV coating on the surface of the lithium battery, the coating is cured under a medium-pressure mercury lamp at room temperature to obtain a UV light-cured lithium battery insulating coating.

8. The method for preparing a UV-curable lithium battery insulating coating according to claim 7, wherein: The preparation steps of the bisphenol A type epoxy acrylic resin include: (1) Place the mixture of DYD-128 epoxy resin and inhibitor in a four-necked round-bottom flask equipped with a mechanical stirrer, reflux condenser, addition funnel, and thermometer and heat to 75 ± 2 °C; (2) adding a mixture of acrylic acid and catalyst dropwise, controlling the dropwise acceleration rate to maintain the temperature below 75°C; (3) After the addition is complete, heat to 95±2°C and react for 1 h, then heat to 105±2°C and react for 2 h; (4) The product was dissolved in chloroform and washed three times with aqueous sodium hydroxide solution to remove acrylic acid residues, inhibitors and catalysts, and finally dried in a vacuum oven to remove chloroform.

9. The method for preparing a UV-curable lithium battery insulating coating according to claim 7, wherein: The preparation steps of the adhesion promoter include: Trimethylolpropane, acrylic acid, a catalyst and a free radical inhibitor were placed in a flask, placed in a preheated oil bath at 120±2°C, and reacted for 15 minutes under magnetic stirring to obtain a trimethylolpropane triacrylate adhesion promoter.

10. The method for preparing a UV-curable lithium battery insulating coating according to claim 7, characterized in that: The preparation steps of the defoamer include: (1) Add hydrogenated silicone oil, polyether, solvent and acid catalyst into a four-necked flask according to the proportion, slowly heat to 105±2°C under stirring, reflux, and react for 10 hours; neutralize with alkali, remove the acid catalyst by suction filtration, and then remove the solvent by reduced pressure distillation to obtain a polyether-modified polysiloxane copolymer; (2) Weighing dimethyl silicone oil and hydrophobic silica according to the ratio, placing them in a round-bottom flask, stirring and slowly heating to 190-200°C, keeping the temperature constant for 3-5 hours, and then cooling to 50-60°C to obtain a silicone paste, and then adding a polyether-modified polysiloxane copolymer for compounding, stirring thoroughly, cooling and discharging to obtain a compound; (3) Mix the Span emulsifier and the Tween emulsifier, adjust the HLB value to 7-10, stir evenly and set aside; (4) Add the compound according to the ratio into a four-necked bottle, add the prepared emulsifier, stir and heat to 60-80°C; (5) Slowly add a small amount of water to dissolve the emulsifier, continue stirring at a constant temperature for 2 hours, then slowly add the remaining water, and then use a homogenizer to stir at high speed for about 10 minutes to obtain a polyether modified silicone oil defoamer.

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