An insulating material for the casing of a new energy battery and its preparation method

Abstract

This invention discloses an insulating material for new energy battery casings and its preparation method, relating to the field of polymer insulating materials technology. The preparation method is as follows: Bisphenol A type epoxy resin is melted, and under nitrogen protection and stirring, a 2-(pentadecylfluorooctyl)methyl glycidyl ether solution in butanone is added dropwise. A triphenylphosphine catalyst is added, and the mixture is heated to obtain a fluorinated modified epoxy resin prepolymer. Polyamide particles react with this prepolymer at high temperature in a mixer, and the mixture is cooled and crushed to obtain a fluorinated epoxy / polyamide composite resin matrix. Boron nitride nanosheets are ultrasonically dispersed, and a tetraethyl orthosilicate solution and ammonia are added dropwise. After reaction and treatment, BN@SiO2 core-shell powder is obtained. This powder is refluxed with hexadecyltrimethoxysilane to obtain hydrophobically modified BN@SiO2 particles. The matrix, particles, antioxidant, and zinc stearate are premixed, and then extruded by a twin-screw extruder, cooled, pelletized, and dried to obtain the insulating material. The new energy battery casing material prepared by this invention has excellent insulating properties.

Description

Technical Field

[0001] This invention relates to the field of polymer insulating materials technology, specifically to an insulating material for the casing of new energy batteries and its preparation method. Background Technology

[0002] With the rapid development of new energy batteries towards higher voltage and higher energy density, the battery casing, as a core protective and structural component, directly affects the operational safety and lifespan of the battery system. Currently, common insulation treatment methods for new energy battery casings mainly include bonding Mylar sheets such as PET, PC, and PI; assembling epoxy boards, mica sheets, or foam; and electrostatically spraying resin or dip-coating metal surfaces.

[0003] However, existing insulating materials and processing methods generally suffer from insufficient insulation performance, specifically in the following aspects: First, core insulation parameters are substandard. Some resin materials have low dielectric strength and volume resistivity, which can easily lead to increased leakage current under high-voltage conditions, and even pose a risk of breakdown. Second, insulation performance stability is poor. Traditional materials have limited temperature resistance; PVC materials typically withstand only 105℃, and most resin materials withstand no more than 150℃. They are prone to softening and deformation under high-temperature environments, directly losing their insulating protective function. Furthermore, they are susceptible to chemical degradation in contact with electrolytes or in humid environments, further reducing insulation performance. Third, insulation reliability is easily affected by processes and usage. Adhesive materials such as Mylar sheets have low peel strength and weak abrasion resistance, making them prone to wear and damage under battery assembly and vibration conditions. If pretreatment defects or metallic foreign matter are present in spray coating processes, hidden conductive channels can form, leading to insulation failure and causing risks of casing corrosion, leakage, and even fire.

[0004] The aforementioned insulation performance defects have become a key bottleneck restricting the improvement of the safety performance of new energy batteries. Therefore, developing an insulating material for battery casings with excellent and stable insulation performance is an urgent practical need and has important application value. Summary of the Invention

[0005] The purpose of this invention is to provide an insulating material for the casing of new energy batteries and its preparation method, so as to solve the technical problem of insufficient insulation performance of new energy battery casings mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0008] S1. The bisphenol A type epoxy resin is heated to melt, and under nitrogen protection and stirring, a butanone solution of 2-(pentadecylfluorooctyl)methyl glycidyl ether is slowly added dropwise. Then, a triphenylphosphine catalyst is added, and the temperature is raised to carry out the reaction to obtain a fluorinated modified epoxy resin prepolymer.

[0009] S2. Polyamide particles and fluorinated modified epoxy resin prepolymer are reacted in an internal mixer at high temperature to obtain a fluorinated epoxy / polyamide composite resin matrix, which is then cooled, crushed, and set aside for later use.

[0010] S3. Disperse boron nitride nanosheets in anhydrous ethanol and sonicate them to obtain a suspension. Under constant temperature stirring, slowly add anhydrous ethanol solution of tetraethyl orthosilicate and ammonia catalyst to the suspension to carry out the silica coating reaction. After the reaction is completed, centrifuge, wash and dry to obtain BN@SiO2 core-shell powder.

[0011] S4. Disperse BN@SiO2 core-shell powder in toluene, add hexadecyltrimethoxysilane, and react under reflux conditions. After the reaction is completed, centrifuge, wash and dry to obtain surface hydrophobically modified BN@SiO2 insulating composite particles.

[0012] S5. Fluorinated epoxy / polyamide composite resin matrix, BN@SiO2 insulating composite particles, antioxidant 1010 and zinc stearate lubricant are mixed and premixed. The premixed material is fed into a twin-screw extruder and subjected to melt extrusion, cooling traction, pelletizing and drying to obtain the insulating material for the outer shell of the new energy battery.

[0013] In this invention, the insulating material for the outer shell of a new energy battery uses epoxy resin and polyamide as the main components of the composite resin matrix. Epoxy resin itself has the potential to form a three-dimensional cross-linked network, and the movement of molecular chain segments is difficult, thus providing the material with extremely high volume resistivity, surface resistivity, and dielectric strength. This forms a high-strength insulating skeleton that ensures the stability of the battery shell under high temperature and high electric field conditions. The main function of polyamide is to toughen and improve mechanical properties. Its flexible long-chain structure can effectively absorb and disperse external impact energy, prevent crack propagation, and significantly improve the impact resistance of the composite material, making the shell less prone to breakage. However, the simple physical blending of epoxy resin and polyamide can easily lead to phase separation problems, resulting in interface defects. These defects are usually the starting points of electric field concentration and breakdown, thereby reducing its insulation performance. To improve the insulation performance of the material, this invention first utilizes the epoxy group of 2-(pentadecylfluorooctyl)methyl glycidyl ether to undergo ring-opening copolymerization with the hydroxyl groups on the epoxy resin skeleton, firmly attaching highly electronegative fluorine atoms to the polymer backbone in the form of covalent bonds. The introduction of fluorine atoms produces two key effects: First, the extremely high CF bond energy strongly binds electrons, greatly increasing the energy barrier for charge migration, thereby directly and effectively improving the volume resistivity and dielectric strength of the material, making the matrix itself more difficult to break down by an electric field. Second, the fluorinated segments tend to migrate to the material surface, forming a low surface energy layer, endowing the material with excellent hydrophobicity, effectively blocking the adsorption and penetration of water vapor in the environment. Moisture is a common cause of decreased surface resistance and ion conduction in insulating materials; therefore, this characteristic significantly enhances the insulation reliability of the material in humid environments. Furthermore, during the mixing process, the amino groups at the polyamide chain ends react chemically with the remaining epoxy groups in the fluorinated epoxy prepolymer, forming strong chemical crosslinking points. This strong interfacial chemical bonding fundamentally solves the phase separation problem that easily occurs when epoxy resin and polyamide are simply physically blended, eliminating interfacial defects caused by poor compatibility. This modification not only improves the insulation capacity of the matrix itself but also creates a uniform, dense, continuous phase without weak interfaces, thereby improving the overall insulation performance of the material.

[0014] On the other hand, the present invention improves the insulation performance of the above-mentioned polymer material by adding BN@SiO2 insulating composite particle filler. For example... Figure 1This is a SEM image of the BN@SiO2 insulating composite particles prepared in this invention. Boron nitride is an excellent insulator; its two-dimensional sheet-like structure can construct a physical barrier in the polymer matrix, effectively extending the leakage current path and increasing the difficulty of breakdown. The outer SiO2 layer plays multiple roles: firstly, the silanol groups on its surface provide active sites for further surface modification, facilitating the grafting reaction of hexadecyltrimethoxysilane; secondly, SiO2 itself is a good insulator, and this dense shell, together with the BN core, constitutes a double insulating unit. Furthermore, the subsequent surface hydrophobication treatment using hexadecyltrimethoxysilane allows long alkyl chains to be chemically bonded to the SiO2 shell surface, forming hydrophobic molecular brushes. This imbues the filler particles themselves with hydrophobicity, creating a synergistic effect with the hydrophobic properties of the fluorinated resin matrix, jointly repelling moisture and preventing moisture accumulation at the filler-matrix interface to form conductive channels, thereby providing further insulation.

[0015] Preferably, in step S1, the amount of 2-(pentadecylfluorooctyl)methyl glycidyl ether added is 4 to 8 wt% of bisphenol A type epoxy resin.

[0016] Preferably, in step S1, the reaction temperature is 80-85°C and the reaction time is 2-4 hours.

[0017] Preferably, in step S2, the mass ratio of fluorinated modified epoxy resin prepolymer to polyamide particles is 10:6 to 8.

[0018] Preferably, in step S2, the reaction temperature is 260–270°C and the reaction time is 5–10 min.

[0019] Preferably, in step S3, the mass ratio of boron nitride nanosheets to tetraethyl orthosilicate is 10:1 to 2.

[0020] Preferably, in step S4, the mass ratio of BN@SiO2 core-shell powder to hexadecyltrimethoxysilane is 10:0.5-1.0.

[0021] Preferably, in step S5, the BN@SiO2 insulating composite particles undergo pre-modification treatment, including the following steps:

[0022] BN@SiO2 insulating composite particles were added to toluene and dispersed evenly by ultrasonic oscillation. Then, tridecafluorooctyltriethoxysilane was added, and the mixture was heated and stirred to react. After centrifugation, washing, and drying, the final product was obtained.

[0023] In the technical solution of this invention, the inventive team discovered through in-depth research that there are interfacial micro-defects between the fluorinated epoxy / polyamide composite resin matrix and the BN@SiO2 insulating composite particles. Specifically, the fluorinated epoxy / polyamide composite resin matrix has extremely low surface energy and exhibits strong fluorine-repellent properties, while the surface of the BN@SiO2 insulating composite particles treated with hexadecylsilane is an alkane chain, which is oleophilic. The difference in chemical properties between the two makes it difficult to achieve molecular-level tight wetting during composite formation, and nanoscale defects are easily generated at the interface. These micro-defects become electric field concentration points, which can cause charge accumulation, partial discharge, or even insulation breakdown under high voltage or high temperature operating environments, seriously restricting the further improvement of overall insulation performance and the full realization of synergistic effects. To further address this technical problem, this invention pretreats BN@SiO2 filler with tridecafluorooctyltriethoxysilane, thereby constructing an outward-oriented fluorocarbon chain bridging layer on the filler surface through chemical bonding. This fluorocarbon bridging layer exhibits excellent thermodynamic compatibility with the fluorinated resin matrix, significantly enhancing the wetting effect during melt blending and effectively eliminating interfacial micro-defects, thus greatly improving the breakdown voltage and insulation reliability of the composite material.

[0024] Preferably, the mass ratio of the BN@SiO2 insulating composite particles to tridecafluorooctyltriethoxysilane is 10:1 to 2.

[0025] An insulating material for the casing of a new energy battery is prepared by the above method.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. Epoxy resin is modified by 2-(pentadecylfluorooctyl)methyl glycidyl ether (introducing fluorine atoms to improve volume resistivity, dielectric strength and hydrophobicity), and polyamide is chemically crosslinked with fluorinated epoxy prepolymer to eliminate interface defects in physical blending and enhance the insulation performance of the material.

[0028] 2. Using BN@SiO2 composite particles as fillers, the BN sheet structure extends the leakage path, and the SiO2 layer forms double insulation. Furthermore, after hydrophobic modification, the particles work synergistically with the hydrophobicity of the fluorinated resin to block moisture and prevent the formation of conductive channels, thereby further improving the insulation performance.

[0029] 3. Pretreatment of BN@SiO2 filler with tridecafluorooctyltriethoxysilane is used to construct a fluorocarbon chain bridging layer, which improves its compatibility with the fluorinated resin matrix, eliminates microscopic defects at the interface, and significantly improves the breakdown voltage and insulation reliability of the composite material. Attached Figure Description

[0030] Figure 1 This is a SEM image of the BN@SiO2 insulating composite particles prepared according to the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0034] Step 1: Weigh 100g of bisphenol A type epoxy resin (E-51, epoxy value 0.51) into a three-necked flask, heat to 78℃ and start stirring (250 rpm) under continuous nitrogen protection. Slowly add a solution formed by dissolving 7g of 2-(pentadecylfluorooctyl)methyl glycidyl ether in 30mL of anhydrous butanone. After the addition is complete, add 0.5g of triphenylphosphine, then heat to 83℃ and continue stirring for 3h to obtain the fluorinated epoxy resin prepolymer.

[0035] Step 2: Put 100g of fluorinated epoxy resin prepolymer and 75g of polyamide 66 (PA66) granules into a mixer. Set the temperature to 265℃, the speed to 60r / min, and the mixing time to 8min. After the mixing is completed, take out the material and let it cool and solidify at room temperature. Then use a crusher to crush it into small pieces with a diameter of about 3-5mm to obtain the fluorinated epoxy / PA66 composite resin matrix.

[0036] Step 3: Weigh 20g of boron nitride nanosheets and add them to 400mL of anhydrous ethanol. Disperse the nanosheets evenly by ultrasonic vibration to obtain a suspension. Transfer the suspension to a three-necked round-bottom flask and place it in a 45℃ constant temperature water bath. Under mechanical stirring at 400r / min, slowly add a solution of 3.5g of tetraethyl orthosilicate dissolved in 50mL of anhydrous ethanol and 4mL of 25% ammonia catalyst. After the addition is complete, continue the reaction for 8h. After the reaction is complete, centrifuge the solid product using a high-speed centrifuge and wash it with anhydrous ethanol. Finally, dry the product in an 80℃ vacuum oven for 6h to obtain BN@SiO2 core-shell powder.

[0037] Step 4: Disperse 10g of BN@SiO2 core-shell powder in 200mL of toluene and ultrasonically vibrate to disperse it evenly. Then, add 0.9g of hexadecyltrimethoxysilane under mechanical stirring. Heat to 110℃ and stir for 4h. After the reaction is complete, collect the solid product by centrifugation and wash it three times with toluene. Finally, dry the product in an 80℃ vacuum oven for 6h to obtain surface-hydrophobic modified BN@SiO2 insulating composite particles.

[0038] 10g of surface-hydrophobic modified BN@SiO2 insulating composite particles were weighed and dispersed in 200mL of toluene. 1.8g of tridecafluorooctyltriethoxysilane was added to the system, and the mixture was refluxed and stirred at 80℃ for 5h. After the reaction was completed, the particles were centrifuged, washed with toluene, and dried under vacuum at 80℃ to obtain pretreated BN@SiO2 insulating composite particles.

[0039] Step 5: Weigh 150g of fluorinated epoxy / PA66 composite resin matrix, 15g of pretreated BN@SiO2 insulating composite particles, 0.3g of antioxidant 1010, and 0.75g of zinc stearate lubricant, and pour them into a high-speed mixer. Mix at 1000r / min for 5 minutes. Pour the premixed material into a co-rotating twin-screw extruder. Set the five temperatures from the feed port to the die head of the extruder to 250℃, 260℃, 270℃, 275℃, and 270℃, respectively, and set the screw speed to 300r / min. After melt extrusion and cooling in a water tank, the material is cut into uniform cylindrical particles of approximately 3mm in length by a pelletizer. Dry the resulting particles in a vacuum drying oven at 90℃ for 4 hours to obtain the insulating material for new energy battery casings.

[0040] Example 2

[0041] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0042] Step 1: Weigh 100g of bisphenol A type epoxy resin (E-51, epoxy value 0.51) and place it in a three-necked flask. Heat the flask to 78℃ and start stirring (250 rpm) under continuous nitrogen protection. Slowly add a solution of 5g of 2-(pentadecylfluorooctyl)methyl glycidyl ether dissolved in 30mL of anhydrous butanone. After the addition is complete, add 0.5g of triphenylphosphine. Then heat the flask to 83℃ and continue stirring for 3 hours to obtain the fluorinated epoxy resin prepolymer.

[0043] Step 2: Put 100g of fluorinated epoxy resin prepolymer and 65g of polyamide 66 (PA66) granules into a mixer. Set the temperature to 265℃, the speed to 60r / min, and the mixing time to 8min. After the mixing is completed, take out the material and let it cool and solidify at room temperature. Then use a crusher to crush it into small pieces with a diameter of about 3-5mm to obtain the fluorinated epoxy / PA66 composite resin matrix.

[0044] Step 3: Weigh 20g of boron nitride nanosheets and add them to 400mL of anhydrous ethanol. Disperse the nanosheets evenly by ultrasonic vibration to obtain a suspension. Transfer the suspension to a three-necked round-bottom flask and place it in a 45℃ constant temperature water bath. Under mechanical stirring at 400r / min, slowly add a solution of 2.5g of tetraethyl orthosilicate dissolved in 50mL of anhydrous ethanol and 4mL of 25% ammonia catalyst. After the addition is complete, continue the reaction for 8 hours. After the reaction is complete, centrifuge the solid product using a high-speed centrifuge and wash it with anhydrous ethanol. Finally, dry the product in an 80℃ vacuum oven for 6 hours to obtain BN@SiO2 core-shell powder.

[0045] Step 4: Disperse 10g of BN@SiO2 core-shell powder in 200mL of toluene and ultrasonically vibrate to disperse it evenly. Then, add 0.6g of hexadecyltrimethoxysilane under mechanical stirring. Heat to 110℃ and stir for 4h. After the reaction is complete, collect the solid product by centrifugation and wash it three times with toluene. Finally, dry the product in an 80℃ vacuum oven for 6h to obtain surface-hydrophobic modified BN@SiO2 insulating composite particles.

[0046] 10g of surface-hydrophobic modified BN@SiO2 insulating composite particles were weighed and dispersed in 200mL of toluene. 1.3g of tridecafluorooctyltriethoxysilane was added to the system, and the mixture was refluxed and stirred at 80℃ for 5h. After the reaction was completed, the particles were centrifuged, washed with toluene, and dried under vacuum at 80℃ to obtain pretreated BN@SiO2 insulating composite particles.

[0047] Step 5: Weigh 150g of fluorinated epoxy / PA66 composite resin matrix, 15g of pretreated BN@SiO2 insulating composite particles, 0.3g of antioxidant 1010, and 0.75g of zinc stearate lubricant, and pour them into a high-speed mixer. Mix at 1000r / min for 5 minutes. Pour the premixed material into a co-rotating twin-screw extruder. Set the five temperatures from the feed port to the die head of the extruder to 250℃, 260℃, 270℃, 275℃, and 270℃, respectively, and set the screw speed to 300r / min. After melt extrusion and cooling in a water tank, the material is cut into uniform cylindrical particles of approximately 3mm in length by a pelletizer. Dry the resulting particles in a vacuum drying oven at 90℃ for 4 hours to obtain the insulating material for new energy battery casings.

[0048] Example 3

[0049] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0050] Step 1: Weigh 100g of bisphenol A type epoxy resin (E-51, epoxy value 0.51) into a three-necked flask, heat to 78℃ and start stirring (250 rpm) under continuous nitrogen protection. Slowly add a solution formed by dissolving 6g of 2-(pentadecylfluorooctyl)methyl glycidyl ether in 30mL of anhydrous butanone. After the addition is complete, add 0.5g of triphenylphosphine, then heat to 83℃ and continue stirring for 3h to obtain the fluorinated epoxy resin prepolymer.

[0051] Step 2: Put 100g of fluorinated epoxy resin prepolymer and 70g of polyamide 66 (PA66) granules into a mixer. Set the temperature to 265℃, the speed to 60r / min, and the mixing time to 8min. After the mixing is completed, take out the material and let it cool and solidify at room temperature. Then use a crusher to crush it into small pieces with a diameter of about 3-5mm to obtain the fluorinated epoxy / PA66 composite resin matrix.

[0052] Step 3: Weigh 20g of boron nitride nanosheets and add them to 400mL of anhydrous ethanol. Disperse the nanosheets evenly by ultrasonic vibration to obtain a suspension. Transfer the suspension to a three-necked round-bottom flask and place it in a 45℃ constant temperature water bath. Under mechanical stirring at 400r / min, slowly add a solution of 3g of tetraethyl orthosilicate dissolved in 50mL of anhydrous ethanol and 4mL of 25% ammonia catalyst. After the addition is complete, continue the reaction for 8 hours. After the reaction is complete, centrifuge the solid product using a high-speed centrifuge and wash it with anhydrous ethanol. Finally, dry the product in an 80℃ vacuum oven for 6 hours to obtain BN@SiO2 core-shell powder.

[0053] Step 4: Disperse 10g of BN@SiO2 core-shell powder in 200mL of toluene and ultrasonically vibrate to disperse it evenly. Then, add 0.7g of hexadecyltrimethoxysilane under mechanical stirring. Heat to 110℃ and stir for 4h. After the reaction is complete, collect the solid product by centrifugation and wash it three times with toluene. Finally, dry the product in an 80℃ vacuum oven for 6h to obtain surface-hydrophobic modified BN@SiO2 insulating composite particles.

[0054] 10g of surface-hydrophobic modified BN@SiO2 insulating composite particles were weighed and dispersed in 200mL of toluene. 1.5g of tridecafluorooctyltriethoxysilane was added to the system, and the mixture was refluxed and stirred at 80℃ for 5h. After the reaction was completed, the particles were centrifuged, washed with toluene, and dried under vacuum at 80℃ to obtain pretreated BN@SiO2 insulating composite particles.

[0055] Step 5: Weigh 150g of fluorinated epoxy / PA66 composite resin matrix, 15g of pretreated BN@SiO2 insulating composite particles, 0.3g of antioxidant 1010, and 0.75g of zinc stearate lubricant, and pour them into a high-speed mixer. Mix at 1000r / min for 5 minutes. Pour the premixed material into a co-rotating twin-screw extruder. Set the five temperatures from the feed port to the die head of the extruder to 250℃, 260℃, 270℃, 275℃, and 270℃, respectively, and set the screw speed to 300r / min. After melt extrusion and cooling in a water tank, the material is cut into uniform cylindrical particles of approximately 3mm in length by a pelletizer. Dry the resulting particles in a vacuum drying oven at 90℃ for 4 hours to obtain the insulating material for new energy battery casings.

[0056] Example 4

[0057] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0058] Step 1: Weigh 100g of bisphenol A type epoxy resin (E-51, epoxy value 0.51) into a three-necked flask, heat to 78℃ and start stirring (250 rpm) under continuous nitrogen protection. Slowly add a solution formed by dissolving 8g of 2-(pentadecylfluorooctyl)methyl glycidyl ether in 30mL of anhydrous butanone. After the addition is complete, add 0.5g of triphenylphosphine, then heat to 85℃ and continue stirring for 4h to obtain the fluorinated epoxy resin prepolymer.

[0059] Step 2: Put 100g of fluorinated epoxy resin prepolymer and 80g of polyamide 66 (PA66) granules into a mixer. Set the temperature to 270℃, the speed to 60r / min, and the mixing time to 10min. After the mixing is completed, take out the material and let it cool and solidify at room temperature. Then use a crusher to crush it into small pieces with a diameter of about 3-5mm to obtain the fluorinated epoxy / PA66 composite resin matrix.

[0060] Step 3: Weigh 20g of boron nitride nanosheets and add them to 400mL of anhydrous ethanol. Disperse the nanosheets evenly by ultrasonic vibration to obtain a suspension. Transfer the suspension to a three-necked round-bottom flask and place it in a 45℃ constant temperature water bath. Under mechanical stirring at 400r / min, slowly add a solution of 4g of tetraethyl orthosilicate dissolved in 50mL of anhydrous ethanol and 4mL of 25% ammonia catalyst. After the addition is complete, continue the reaction for 8 hours. After the reaction is complete, centrifuge the solid product using a high-speed centrifuge and wash it with anhydrous ethanol. Finally, dry the product in an 80℃ vacuum oven for 6 hours to obtain BN@SiO2 core-shell powder.

[0061] Step 4: Disperse 10g of BN@SiO2 core-shell powder in 200mL of toluene and ultrasonically vibrate to disperse it evenly. Then, add 1.0g of hexadecyltrimethoxysilane under mechanical stirring. Heat to 110℃ and stir for 4h. After the reaction is complete, collect the solid product by centrifugation and wash it three times with toluene. Finally, dry the product in a vacuum oven at 80℃ for 6h to obtain surface-hydrophobic modified BN@SiO2 insulating composite particles.

[0062] 10g of surface-modified hydrophobic BN@SiO2 insulating composite particles were weighed and dispersed in 200mL of toluene. 2.0g of tridecafluorooctyltriethoxysilane was added to the system, and the mixture was refluxed and stirred at 80℃ for 5h. After the reaction was completed, the particles were centrifuged, washed with toluene, and dried under vacuum at 80℃ to obtain pretreated BN@SiO2 insulating composite particles.

[0063] Step 5: Weigh 150g of fluorinated epoxy / PA66 composite resin matrix, 15g of pretreated BN@SiO2 insulating composite particles, 0.3g of antioxidant 1010, and 0.75g of zinc stearate lubricant, and pour them into a high-speed mixer. Mix at 1000r / min for 5 minutes. Pour the premixed material into a co-rotating twin-screw extruder. Set the five temperatures from the feed port to the die head of the extruder to 250℃, 260℃, 270℃, 275℃, and 270℃, respectively, and set the screw speed to 300r / min. After melt extrusion and cooling in a water tank, the material is cut into uniform cylindrical particles of approximately 3mm in length by a pelletizer. Dry the resulting particles in a vacuum drying oven at 90℃ for 4 hours to obtain the insulating material for new energy battery casings.

[0064] Example 5

[0065] A method for preparing an insulating material for the casing of a new energy battery includes the following steps:

[0066] Step 1: Weigh 100g of bisphenol A type epoxy resin (E-51, epoxy value 0.51) and place it in a three-necked flask. Heat the flask to 78℃ and start stirring (250 rpm) under continuous nitrogen protection. Slowly add a solution of 4g of 2-(pentadecylfluorooctyl)methyl glycidyl ether dissolved in 30mL of anhydrous butanone. After the addition is complete, add 0.5g of triphenylphosphine. Then heat the flask to 80℃ and continue stirring for 2 hours to obtain the fluorinated epoxy resin prepolymer.

[0067] Step 2: Put 100g of fluorinated epoxy resin prepolymer and 60g of polyamide 66 (PA66) granules into a mixer. Set the temperature to 260℃, the speed to 60r / min, and the mixing time to 5min. After the mixing is completed, take out the material and let it cool and solidify at room temperature. Then use a crusher to crush it into small pieces with a diameter of about 3-5mm to obtain the fluorinated epoxy / PA66 composite resin matrix.

[0068] Step 3: Weigh 20g of boron nitride nanosheets and add them to 400mL of anhydrous ethanol. Disperse the nanosheets evenly by ultrasonic vibration to obtain a suspension. Transfer the suspension to a three-necked round-bottom flask and place it in a 45℃ constant temperature water bath. Under mechanical stirring at 400r / min, slowly add a solution of 2g of tetraethyl orthosilicate dissolved in 50mL of anhydrous ethanol and 4mL of 25% ammonia catalyst. After the addition is complete, continue the reaction for 8 hours. After the reaction is complete, centrifuge the solid product using a high-speed centrifuge and wash it with anhydrous ethanol. Finally, dry the product in an 80℃ vacuum oven for 6 hours to obtain BN@SiO2 core-shell powder.

[0069] Step 4: Disperse 10g of BN@SiO2 core-shell powder in 200mL of toluene and ultrasonically vibrate to disperse it evenly. Then, add 0.5g of hexadecyltrimethoxysilane under mechanical stirring. Heat to 110℃ and stir for 4h. After the reaction is complete, collect the solid product by centrifugation and wash it three times with toluene. Finally, dry the product in an 80℃ vacuum oven for 6h to obtain surface-hydrophobic modified BN@SiO2 insulating composite particles.

[0070] 10g of surface-hydrophobic modified BN@SiO2 insulating composite particles were weighed and dispersed in 200mL of toluene. 1.0g of tridecafluorooctyltriethoxysilane was added to the system, and the mixture was refluxed and stirred at 80℃ for 5h. After the reaction was completed, the particles were centrifuged, washed with toluene, and dried under vacuum at 80℃ to obtain pretreated BN@SiO2 insulating composite particles.

[0071] Step 5: Weigh 150g of fluorinated epoxy / PA66 composite resin matrix, 15g of pretreated BN@SiO2 insulating composite particles, 0.3g of antioxidant 1010, and 0.75g of zinc stearate lubricant, and pour them into a high-speed mixer. Mix at 1000r / min for 5 minutes. Pour the premixed material into a co-rotating twin-screw extruder. Set the five temperatures from the feed port to the die head of the extruder to 250℃, 260℃, 270℃, 275℃, and 270℃, respectively, and set the screw speed to 300r / min. After melt extrusion and cooling in a water tank, the material is cut into uniform cylindrical particles of approximately 3mm in length by a pelletizer. Dry the resulting particles in a vacuum drying oven at 90℃ for 4 hours to obtain the insulating material for new energy battery casings.

[0072] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that steps 1 and 2 are replaced by mixing 100g of bisphenol A type epoxy resin with 60g of polyamide 66 to obtain a mixture, and the fluorinated epoxy / PA66 composite resin matrix in step 5 is replaced by an equal mass of the mixture.

[0073] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that in step 5, the pretreated BN@SiO2 insulating composite particles are replaced with boron nitride nanosheets of equal mass.

[0074] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the BN@SiO2 insulating composite particles are not pretreated with tridecafluorooctyltriethoxysilane, and the pretreated BN@SiO2 insulating composite particles in step 5 are replaced with BN@SiO2 insulating composite particles of equal mass.

[0075] Performance testing:

[0076] 1. Volume resistivity test: According to GB / T 1410-2006 "Test methods for volume resistivity and surface resistivity of solid insulating materials", the insulating materials of each example and comparative example were made into circular samples with a diameter of 50 mm and a thickness of 2 mm. After being placed in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 h, a DC voltage of 500V was applied using a high resistance meter, and the volume resistivity value was read after stabilizing the voltage for 1 min. Three parallel samples were tested for each group of samples, and the average value was taken. The test results are shown in Table 1.

[0077] 2. Dielectric Strength Test: Following GB / T 1408.1-2016 "Electrical Strength Test Methods for Insulating Materials Part 1: Tests at Power Frequency", the material was processed into bubble-free specimens with a thickness of 1 mm and a diameter of 80 mm. An oil-immersed dielectric strength tester was used, applying a power frequency voltage at a step-up rate of 2 kV / s in transformer oil. The voltage value at which the specimen broke down was recorded. The dielectric strength was calculated based on the specimen thickness. Five parallel samples were tested in each group, and outliers were removed before taking the average value. The test results are shown in Table 1.

[0078] 3. Volume resistivity retention rate test in humid environments: The prepared volume resistivity test samples were aged in a constant temperature and humidity chamber at 40±2℃ and 95±3% relative humidity for 1000h. After removal, they were restored in a standard environment (23±2℃, 50±5%RH) for 2h. The volume resistivity after aging was measured according to the volume resistivity test method. The retention rate was calculated as "volume resistivity after aging / volume resistivity before aging × 100%". Three parallel samples were tested in each group, and the average value was taken. The test results are shown in Table 1.

[0079] 4. Glass transition temperature test: A differential scanning calorimeter (DSC) was used. A 10 mg sample of the pulverized material was heated from 30 °C to 200 °C at a rate of 10 °C / min under a nitrogen atmosphere (flow rate 50 mL / min). The temperature corresponding to the baseline inflection point in the DSC curve was recorded as Tg. Two parallel samples were tested in each group, and the average value was taken. The test results are shown in Table 1.

[0080] Table 1:

[0081]

[0082] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing an insulation material for a new energy battery case, characterized by, The method comprises the following steps: S1, heating bisphenol A type epoxy resin to melt, slowly adding 2-(pentadecafluoro octyl) methyl glycidyl ether solution in butanone under nitrogen protection and stirring, then adding triphenylphosphine catalyst, and heating to react to obtain fluorinated modified epoxy resin prepolymer; S2, reacting polyamide particles with the fluorinated modified epoxy resin prepolymer in a banbury mixer at 260-270℃, the mass ratio of the fluorinated modified epoxy resin prepolymer to the polyamide particles being 10:6-8, to obtain a fluorinated epoxy / polyamide composite resin matrix, which is cooled, broken and used; S3, dispersing boron nitride nanosheets in anhydrous ethanol, and obtaining a suspension through ultrasonic treatment; under constant temperature stirring, slowly adding anhydrous ethanol solution of tetraethyl orthosilicate and ammonia catalyst into the suspension at the same time, carrying out coating reaction of silicon dioxide, and after the reaction is completed, centrifuging, washing and drying to obtain BN@SiO2 core-shell powder; S4, dispersing the BN@SiO2 core-shell powder in toluene, adding hexadecyl trimethoxysilane, and carrying out reaction under reflux condition, and after the reaction is completed, centrifuging, washing and drying to obtain BN@SiO2 insulating composite particles with hydrophobic surface modification; S5, adding the BN@SiO2 insulating composite particles into toluene, ultrasonic oscillation and dispersion, then adding tridecafluorooctyl triethoxysilane, heating and stirring to react, and after centrifugal separation, washing and drying, modified BN@SiO2 insulating composite particles are obtained; Mixing fluorinated epoxy / polyamide composite resin matrix, modified BN@SiO2 insulating composite particles, antioxidant 1010 and zinc stearate lubricant, pre-mixing the mixed materials, putting the pre-mixed materials into a double screw extruder, melt extruding, cooling and pulling, pelletizing and drying, and the insulating material for new energy battery shell is obtained.

2. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, In the step S1, the addition amount of 2-(pentadecafluoro octyl) methyl glycidyl ether is 4-8wt% of bisphenol A type epoxy resin.

3. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, In the step S1, the reaction temperature is 80-85℃, and the reaction time is 2-4h.

4. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, In the step S2, the reaction time is 5-10min.

5. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, In the step S3, the mass ratio of boron nitride nanosheets to tetraethyl orthosilicate is 10:1-2.

6. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, In the step S4, the mass ratio of BN@SiO2 core-shell powder to hexadecyl trimethoxysilane is 10:0.5-1.

0.

7. The method for preparing an insulating material for a new energy battery casing according to claim 1, characterized in that, The mass ratio of the BN@SiO2 insulating composite particles to tridecafluorooctyl triethoxysilane is 10:1-2.

8. An insulating material for a new energy battery case, characterized by, Prepared by the method of any one of the above claims 1-7.

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