High-strength wear-resistant lithium battery thermal shrinkage sleeve film material and preparation method thereof

Abstract

The invention relates to the technical field of materials, in particular to a high-strength wear-resistant lithium battery heat-shrinkable sleeve film material and a preparation method thereof, and the high-strength wear-resistant lithium battery heat-shrinkable sleeve film material comprises an inner layer, a middle layer and an outer layer, the inner layer is an early-warning layer and comprises homo-polypropylene with a high melt index, master batches with an early-warning function and an antioxidant; composite molecules are formed between the core material fluorescence report unit and the fluorescence quenching unit of the early warning functional master batch through a silicon-oxygen-boron bond, so that pyrene chromophores and dinitrobenzene quenching groups are closely adjacent in space; in a normal state, the fluorescent probe shows a non-fluorescent state; when electrolyte leakage of the lithium battery occurs, fluorescence is recovered, and leakage early warning is realized; 2-methylimidazole catalyzes an epoxy group of the ethylene-glycidyl methacrylate copolymer to react with a maleic anhydride group, active sites of maleic anhydride are converted into an inert ester chain structure, and harmful side reactions between the active sites of maleic anhydride and the early warning layer are prevented.

Description

Technical Field

[0001] This invention relates to the field of materials technology, specifically to a high-strength, wear-resistant heat-shrinkable sleeve material for lithium batteries and its preparation method. Background Technology

[0002] Lithium-ion batteries, as a new generation of green high-energy chemical power sources, have been widely used in consumer electronics, electric vehicles, and energy storage systems. With the continuous improvement of energy density and increasingly stringent application scenarios, the safety issues of lithium-ion batteries are becoming increasingly prominent. Among these, electrolyte leakage is a major cause of internal short circuits, thermal runaway, and even fires and explosions. In the field of lithium-ion battery encapsulation materials, especially cylindrical lithium-ion batteries, polypropylene (PP) and polyester (PET / PETG) are commonly used basic resin materials for heat-shrinkable sleeves.

[0003] Polypropylene is favored for its excellent heat-sealing properties, good flexibility, and low cost. However, its poor tolerance to lithium battery electrolytes (usually containing lithium hexafluorophosphate) is a major concern. In the event of electrolyte leakage, the polypropylene layer will rapidly swell and corrode, leading to insulation failure and physical damage. This process occurs silently and can ultimately result in serious consequences such as short circuits. Polyester, on the other hand, has higher mechanical strength, excellent abrasion resistance, and superior resistance to electrolyte corrosion, making it the preferred choice for ensuring long-term reliability. However, its cost is higher. Summary of the Invention

[0004] (1) Technical problems to be solved

[0005] The purpose of this invention is to provide a high-strength, wear-resistant heat-shrinkable sleeve material for lithium batteries and its preparation method, which sacrifices the polypropylene layer to warn of electrolyte leakage and improves the safety of lithium batteries.

[0006] (2) Technical solution

[0007] To achieve the above objectives, on the one hand, the present invention provides a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, characterized in that it comprises an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 75-80 parts of high melt index homopolymer polypropylene, 3.0-4.0 parts of warning functional masterbatch, and 0.2-0.3 parts of antioxidant;

[0008] The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 8~12: 8~12:75~85:0.3~0.7; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0009] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 8-12 parts maleic anhydride-grafted polypropylene, 0.4-0.6 parts ethylene-glycidyl methacrylate copolymer, 0.02-0.03 parts 2-methylimidazole, and 0.1-0.2 parts antioxidant.

[0010] Furthermore, the outer layer is a wear-resistant layer, comprising the following components in parts by weight: 25-30 parts copolyester, 10-15 parts polyethylene terephthalate, 0.2-0.3 parts polysiloxane powder, and 0.1-0.2 parts UV stabilizer.

[0011] Furthermore, the antioxidants include antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; the ethylene-glycidyl methacrylate copolymer includes Lotader® AX8840.

[0012] Furthermore, the UV protectant includes UV-327.

[0013] Furthermore, the preparation method of the fluorescent reporter unit includes the following steps:

[0014] S11. In a three-necked round-bottom flask, 11-bromo-1-undecyl alcohol and anhydrous N,N-dimethylformamide were added and stirred to dissolve. After the system was purged with nitrogen three times, imidazole was added under an ice-water bath and nitrogen atmosphere. Anhydrous N,N-dimethylformamide solution of diisopropyl dichlorosilane was added dropwise. After the addition was complete, the ice bath was removed, and the reaction was stirred at room temperature. The mixture was poured into ice water and extracted three times with dichloromethane. The organic phases were combined and washed successively with saturated sodium bicarbonate solution, water, and saturated sodium chloride solution. The mixture was dried with anhydrous magnesium sulfate, filtered, and the filtrate was evaporated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography. The main fraction was collected and concentrated to obtain the first compound.

[0015] S12. In a round-bottom flask, add the first compound and anhydrous acetonitrile, dissolve them, and then add silver nitrate. Under nitrogen protection and in the dark, heat and reflux the reaction. After the reaction is complete, cool to room temperature, filter through a diatomaceous earth pad, wash the filter cake with acetonitrile, concentrate the filtrate to dryness under reduced pressure, and purify it by rapid silica gel column chromatography to obtain the second compound.

[0016] S13. In a round-bottom flask, add 1-pyrenic acid and anhydrous dichloromethane, shake well, add anhydrous N,N-dimethylformamide, and then add oxaloyl chloride dropwise. Stir the reaction at room temperature until clear, and then evaporate under reduced pressure to obtain a yellow solid. In another round-bottom flask, add the second compound, 4-dimethylaminopyridine, and anhydrous dichloromethane, dissolve to obtain a mixed solution. Under ice bath cooling and stirring, dissolve the yellow solid in dichloromethane and slowly add it dropwise to the mixed solution. After the addition is complete, remove the ice bath and react at room temperature overnight. After the reaction is complete, wash successively with dilute hydrochloric acid and saturated brine, dry with anhydrous sodium sulfate, filter, concentrate, and purify by silica gel column chromatography. Collect the yellow fluorescent fraction, concentrate it, and obtain a fluorescent reporter unit.

[0017] Furthermore, the preparation method of the fluorescence quenching unit includes the following steps:

[0018] S21. In a round-bottom flask, add 1,16-hexadecanediol and anhydrous acetonitrile, dissolve them, add potassium hydroxide, stir, then add 4-fluoro-1,2-dinitrobenzene, heat to reflux, cool, filter, concentrate by rotary evaporation, extract the residue with water and dichloromethane, dry the organic phase and concentrate, and purify by silica gel column chromatography to obtain the third compound.

[0019] S22. In a round-bottom flask, add the third compound and anhydrous dichloromethane. After dissolving, cool in an ice bath. While stirring, add a dichloromethane solution of phosphorus tribromide dropwise. After the addition is complete, allow the temperature to rise naturally to room temperature. Stir the reaction mixture and pour it into ice water. Stir vigorously and separate the liquids. Extract the aqueous phase with dichloromethane. Combine the organic phases and wash them successively with saturated sodium bicarbonate solution and water. Dry the mixture with anhydrous magnesium sulfate, filter, concentrate, and purify by silica gel column chromatography to obtain the fourth compound.

[0020] S23. In a Schlenk reaction tube, under a nitrogen atmosphere, compound IV, bis(pinacolyl)diboron and potassium acetate were added, followed by anhydrous 1,4-dioxane. After deoxygenation by bubbling with nitrogen, catalyst [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride was added. The mixture was heated and stirred vigorously. After cooling to room temperature, insoluble matter was removed by filtration through a diatomaceous earth mat. The filtrate was concentrated by rotary evaporation and purified by silica gel column chromatography to obtain the fluorescence quenching unit.

[0021] Furthermore, the preparation method of the early warning function masterbatch includes the following steps: a fluorescence reporter unit, a fluorescence quenching unit, high melt index homopolymer polypropylene, and an antioxidant are added to a high-speed heating mixer and mixed at 60-80°C for 5-10 minutes to obtain a premix; the premix is ​​then fed into a co-rotating twin-screw extruder and melted, sheared, mixed, and extruded at 170-185°C; the extruded strip is cooled in a 30-40°C warm water bath and cut into granules by a pelletizing knife; the granules are dried in a vacuum drying oven at 50°C for 4 hours and then sieved to obtain the early warning function masterbatch.

[0022] Based on the same inventive concept, in a second aspect, the present invention also provides a method for preparing a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, applicable to the preparation of the aforementioned high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, the preparation method comprising the following steps:

[0023] S31. Preparation of binder masterbatch: Maleic anhydride-grafted polypropylene, ethylene-glycidyl methacrylate copolymer, 2-methylimidazole and antioxidant are mixed evenly at high speed, and then melt-extruded, underwater pelletized and dried by a co-rotating twin-screw extruder to obtain binder masterbatch.

[0024] S32. Three-layer co-extrusion: Using a three-layer co-extrusion blown film unit, the inner layer components high melt index homopolymer polypropylene, early warning function masterbatch, and antioxidant are premixed and fed into the inner layer extruder of the co-extrusion machine; the binder masterbatch is fed into the middle layer extruder of the co-extrusion machine; the copolyester and polyethylene terephthalate are vacuum dried, mixed with polysiloxane powder and UV stabilizer, and fed into the outer layer extruder of the co-extrusion machine; the blown film bubble is rapidly cooled and shaped by the cold air blown out by the cooling air ring, corona treated, split, flattened, and rolled up to obtain a high-strength wear-resistant lithium battery heat shrink sleeve film material.

[0025] The core components of the masterbatch for early warning functionality are a fluorescent reporter unit and a fluorescent quencher unit. The 1-pyrene carboxylate group at one end of the fluorescent reporter unit molecule is a fluorescent chromophore with a large conjugated system, which generates a blue fluorescent signal when excited by external light. The 3,4-dinitrophenyl group at the end of the fluorescent quencher unit molecule is a fluorescent quencher group with an electron-withdrawing effect, which can receive and dissipate the energy generated by the excited pyrene chromophore through the fluorescence resonance energy transfer mechanism. In the preparation of the masterbatch, the diisopropylsilanol group of the fluorescent reporter unit and the borate group of the fluorescent quencher unit undergo dehydration condensation to form a silicon-oxygen-boron bond that is sensitive to fluoride ions, covalently linking the two units into a composite molecule, thereby making the pyrene chromophore and the dinitrophenyl quencher group spatially close to each other. Under normal conditions, the energy generated by the excitation of the pyrene chromophore in the composite molecule is transferred to the dinitrobenzene quencher group through the fluorescence resonance energy transfer mechanism and dissipated in the form of heat, resulting in the system fluorescence being turned off, macroscopically manifested as a non-fluorescent state. When the electrolyte of the lithium battery leaks, the lithium hexafluorophosphate in the electrolyte hydrolyzes to produce fluoride ions, which act as strong nucleophiles and attack the silicon-oxygen-boron bonds, causing them to break. This leads to the disconnection between the fluorescence reporter unit and the fluorescence quencher unit, and the pyrene chromophore and the dinitrobenzene quencher group undergo physical separation. The fluorescence resonance energy transfer process is disrupted, and the energy generated after the pyrene chromophore is excited cannot be dissipated, thus restoring its blue fluorescence. When a handheld long-wave ultraviolet lamp with a center wavelength of 365 nm is used to illuminate the leak point, a clear blue fluorescence will appear, thereby realizing a leak warning and improving the safety of lithium battery use.

[0026] Maleic anhydride-grafted polypropylene, being primarily polypropylene, exhibits a high degree of thermal expansion coefficient and processing performance matching the matrix material. This avoids internal stress or interface failure issues caused by material mismatch, making it a common and classic adhesive layer material. However, its highly reactive maleic anhydride groups readily act as electrophiles during high-temperature co-extrusion, attacking nucleophilic oxygen atoms in the silicon-oxygen-boron bond, thus causing the warning function to fail. Multiple epoxy groups on the ethylene-glycidyl methacrylate copolymer molecular chain are highly activated under the catalysis of 2-methylimidazole. The lone pair electrons on the tertiary amine nitrogen atom in the 2-methylimidazole molecule nucleophilically attack the epoxy ring, causing it to open and generate a zwitterionic intermediate. The alkoxy anion in this intermediate nucleophilically attacks the carbonyl carbon atom in the maleic anhydride group, opening the acid... The anhydride ring forms an ester bond with it; as 2-methylimidazole is continuously regenerated, it continuously drives the epoxy groups of the ethylene-glycidyl methacrylate copolymer to react with the maleic anhydride groups, consuming the active sites of maleic anhydride and converting them into an inert ester chain structure. The adhesive layer material is transformed from a highly reactive maleic anhydride-grafted polypropylene into a chemically inert modified polyolefin with blocked anhydride functional groups. This prevents harmful side reactions with silicon-oxygen-boron bonds during subsequent co-extrusion processing with the warning layer, ensuring the reliability of the intelligent warning function.

[0027] (3) Beneficial effects

[0028] Compared with the prior art, the beneficial effects of the present invention are:

[0029] 1. In this invention, the core material of the early warning function masterbatch, the fluorescent reporter unit and the fluorescent quencher unit, are connected by silicon-oxygen-boron bonds to form a composite molecule, resulting in the pyrene chromophore and the dinitrobenzene quencher group being spatially close. Under normal conditions, the energy generated by the excitation of the pyrene chromophore is transferred to the dinitrobenzene quencher group through the fluorescence resonance energy transfer mechanism and dissipated in the form of heat, resulting in a non-fluorescent state. When the electrolyte leaks in the lithium battery, the generated fluoride ions attack the silicon-oxygen-boron bonds, causing them to break, resulting in the disconnection between the two units. The pyrene chromophore and the dinitrobenzene quencher group then physically separate, disrupting the fluorescence resonance energy transfer process. The energy generated after the pyrene chromophore is excited cannot be dissipated, restoring blue fluorescence, thereby achieving leakage early warning and improving the safety of lithium battery use.

[0030] 2. In this invention, 2-methylimidazole catalyzes the reaction between the epoxy groups of the ethylene-glycidyl methacrylate copolymer and the maleic anhydride groups, converting the active sites of maleic anhydride into an inert ester chain structure. This prevents harmful side reactions with silicon-oxygen-boron bonds during subsequent co-extrusion processing with the warning layer, ensuring the reliability of the intelligent warning function. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process of a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0033] Example 1: This example discloses a high-strength wear-resistant lithium battery heat shrinkable sleeve material, including an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 78 parts high melt index homopolymer polypropylene, 4.0 parts warning functional masterbatch, and 0.25 parts antioxidant;

[0034] The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, a high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 10:10:80:0.5; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0035] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 10 parts maleic anhydride-grafted polypropylene, 0.5 parts ethylene-glycidyl methacrylate copolymer, 0.02 parts 2-methylimidazole, and 0.15 parts antioxidant.

[0036] The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 28 parts copolyester, 12 parts polyethylene terephthalate, 0.25 parts polysiloxane powder, and 0.15 parts UV stabilizer.

[0037] The antioxidants include antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; the ethylene-glycidyl methacrylate copolymer includes Lotader® AX8840.

[0038] The UV protectant includes UV-327.

[0039] The method for preparing the fluorescent reporter unit includes the following steps:

[0040] S11. In a dry 1000 mL three-necked round-bottom flask equipped with a magnetic stirrer, a constant-pressure dropping funnel, and a nitrogen inlet, add 53.0 g of 11-bromo-1-undecyl alcohol and 400 mL of anhydrous N,N-dimethylformamide. Stir to dissolve, and after the system is purged with nitrogen three times, add 30.6 g of imidazole in portions under an ice-water bath and nitrogen atmosphere. Slowly add 100 mL of anhydrous N,N-dimethylformamide solution containing 38.6 g of diisopropyl dichlorosilane using a constant-pressure dropping funnel, controlling the dropping rate to maintain the internal temperature below 30 °C. After the addition is complete, remove the ice bath and stir the reaction at room temperature for 12 h. Pour the reaction solution into 1600 mL of ice water and extract three times, each time using 400 mL of dichloromethane. Combine the organic phases and extract successively with 400 mL of saturated sodium bicarbonate solution, 400 mL of water, and 400 mL of... Wash with mL of saturated sodium chloride solution, dry with anhydrous magnesium sulfate, filter, and remove the solvent by rotary evaporation under reduced pressure at 40 °C to obtain the crude product. The crude product is purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 20:1, v / v), and the main fraction is collected and concentrated to obtain the first compound.

[0041] S12. In a dry 500 mL round-bottom flask, add 75.0 g of the first compound and 400 mL of anhydrous acetonitrile. After dissolving, add 42.4 g of silver nitrate. Under nitrogen protection and in the dark, heat to 80 °C and reflux for 8 h. After the reaction is complete, cool to room temperature and filter through a diatomaceous earth pad to remove the generated silver bromide precipitate. Wash the filter cake with a large amount of acetonitrile. Concentrate the filtrate to dryness under reduced pressure and purify by rapid silica gel column chromatography (eluent: dichloromethane / methanol = 15:1, v / v) to obtain the second compound.

[0042] S13. In a dry 250 mL round-bottom flask, add 4.84 g of 1-pyrenic acid and 60 mL of anhydrous dichloromethane, shake well, add one drop of anhydrous N,N-dimethylformamide, then slowly add 3.80 g of oxaloyl chloride, stir at room temperature for 3 h until clear, then remove excess oxaloyl chloride and solvent by rotary evaporation under reduced pressure to obtain a yellow solid; in another dry 250 mL round-bottom flask, add 7.18 g of the second compound, 0.24 g of 4-dimethylaminopyridine and 100 mL of anhydrous dichloromethane, dissolve to obtain a mixed solution; under ice bath cooling and stirring, dissolve the yellow solid in 20 mL of anhydrous dichloromethane. After adding mL of dichloromethane, slowly add it dropwise to the mixed solution. After the addition is complete, remove the ice bath and react overnight at room temperature. After the reaction is complete, wash successively with 100 mL of 1 mol / L dilute hydrochloric acid and saturated saline solution, dry with anhydrous sodium sulfate, filter, concentrate, and purify by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10:1 to 5:1, gradient elution). Collect the yellow fluorescent fraction, concentrate it, and obtain the fluorescent reporter unit.

[0043] The preparation method of the fluorescence quenching unit includes the following steps:

[0044] S21. In a 1000 mL round-bottom flask equipped with a condenser, 54.9 g of 1,16-hexadecanediol and 800 mL of anhydrous acetonitrile were added and dissolved. After dissolving, 33.6 g of potassium hydroxide was added and the mixture was stirred for 30 min. Then, 37.2 g of 4-fluoro-1,2-dinitrobenzene was added, and the mixture was heated to 80 °C and refluxed for 12 h. After cooling, the mixture was filtered, concentrated by rotary evaporation, and the residue was extracted with water and dichloromethane. The organic phase was dried and concentrated, and purified by silica gel column chromatography (petroleum ether / ethyl acetate = 5:1) to give the third compound.

[0045] S22. In a dry 500 mL round-bottom flask, add 42.0 g of the third compound and 200 mL of anhydrous dichloromethane. After dissolving, cool to 0 °C in an ice bath. While stirring, slowly add 50 mL of dichloromethane solution containing 10.1 g of phosphorus tribromide. After the addition is complete, allow the mixture to warm naturally to room temperature and stir for 4 h. Pour the mixture into 500 mL of ice water and stir vigorously. Separate the layers. Extract the aqueous phase with dichloromethane. Combine the organic phases and wash successively with saturated sodium bicarbonate solution and water. Dry the mixture with anhydrous magnesium sulfate, filter, concentrate, and purify by silica gel column chromatography (petroleum ether / ethyl acetate = 20:1) to obtain the fourth compound.

[0046] S23. In a dry 500 mL Schlenk reaction tube under a nitrogen atmosphere, 45.8 g of compound IV, 30.4 g of bis(pinacol)diboron and 29.4 g of potassium acetate were added, followed by 300 mL of anhydrous 1,4-dioxane. After bubbling with nitrogen to remove oxygen for 15 min, 1.5 g of catalyst [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride was added. The mixture was heated to 95 °C and stirred vigorously for 16 h. After cooling to room temperature, insoluble matter was removed by filtration through a diatomaceous earth mat. The filtrate was concentrated by rotary evaporation and purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 15:1) to obtain the fluorescence quenching unit.

[0047] The preparation method of the early warning function masterbatch includes the following steps: A fluorescent reporter unit, a fluorescent quenching unit, high melt index homopolymer polypropylene, and an antioxidant are added to a high-speed heating mixer and mixed at 60-80°C for 5-10 minutes to obtain a premix; the premix is ​​then fed into a co-rotating twin-screw extruder and melted, sheared, mixed, and extruded at 170-185°C; the extruded strip is cooled in a 30-40°C warm water bath and cut into granules by a pelletizing knife; the granules are dried in a vacuum drying oven at 50°C for 4 hours and then sieved to obtain the early warning function masterbatch.

[0048] The preparation method of the high-strength, wear-resistant lithium battery heat-shrinkable sleeve material includes the following steps:

[0049] S31. Preparation of binder masterbatch: Maleic anhydride-grafted polypropylene, ethylene-glycidyl methacrylate copolymer, 2-methylimidazole and antioxidant are mixed evenly at high speed, and then melt-extruded, underwater pelletized and dried by a co-rotating twin-screw extruder at 200~220°C to obtain binder masterbatch.

[0050] S32. Three-layer co-extrusion: Using a three-layer co-extrusion blown film unit, the inner layer components—high melt index homopolymer polypropylene, early warning masterbatch, and antioxidant—are premixed and fed into the inner layer extruder of the co-extrusion machine; the binder masterbatch is fed into the middle layer extruder of the co-extrusion machine; the copolyester and polyethylene terephthalate are vacuum dried at 150°C for 6 hours, mixed with polysiloxane powder and UV stabilizer, and then fed into the outer layer extruder of the co-extrusion machine; the co-extrusion die temperature is 190°C~200°C, and the blow-up ratio and draw ratio are controlled at 3.0~4.0. The blown film bubble is rapidly cooled and shaped by the cold air blown out by the cooling air ring, corona treated, slit, flattened, and wound up to obtain a high-strength, wear-resistant lithium battery heat-shrinkable sleeve film material. The preparation process is as follows: Figure 1 As shown.

[0051] Example 2: This example discloses a high-strength wear-resistant lithium battery heat shrinkable sleeve material, including an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 75 parts high melt index homopolymer polypropylene, 3.0 parts warning functional masterbatch, and 0.2 parts antioxidant;

[0052] The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, a high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 10:10:80:0.5; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0053] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 8 parts maleic anhydride-grafted polypropylene, 0.4 parts ethylene-glycidyl methacrylate copolymer, 0.02 parts 2-methylimidazole, and 0.1 parts antioxidant.

[0054] The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 25 parts copolyester, 10 parts polyethylene terephthalate, 0.2 parts polysiloxane powder, and 0.1 parts UV stabilizer.

[0055] The other components and preparation methods are the same as in Example 1.

[0056] Example 3: This example discloses a high-strength wear-resistant lithium battery heat shrinkable sleeve material, including an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 80 parts high melt index homopolymer polypropylene, 4.0 parts warning functional masterbatch, and 0.3 parts antioxidant;

[0057] The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, a high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 10:10:80:0.5; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0058] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 12 parts maleic anhydride-grafted polypropylene, 0.6 parts ethylene-glycidyl methacrylate copolymer, 0.03 parts 2-methylimidazole, and 0.2 parts antioxidant.

[0059] The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 30 parts copolyester, 15 parts polyethylene terephthalate, 0.3 parts polysiloxane powder, and 0.2 parts UV stabilizer.

[0060] The other components and preparation methods are the same as in Example 1.

[0061] Example 4: This example discloses a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, including an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 78 parts high melt index homopolymer polypropylene, 4.0 parts warning functional masterbatch, and 0.25 parts antioxidant;

[0062] The early warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 8:8:75:0.3; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0063] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 10 parts maleic anhydride-grafted polypropylene, 0.5 parts ethylene-glycidyl methacrylate copolymer, 0.02 parts 2-methylimidazole, and 0.15 parts antioxidant.

[0064] The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 28 parts copolyester, 12 parts polyethylene terephthalate, 0.25 parts polysiloxane powder, and 0.15 parts UV stabilizer.

[0065] The other components and preparation methods are the same as in Example 1.

[0066] Example 5: This example discloses a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, including an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, comprising the following components in parts by weight: 78 parts high melt index homopolymer polypropylene, 4.0 parts warning functional masterbatch, and 0.25 parts antioxidant;

[0067] The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, a high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 12:12:85:0.7; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks.

[0068] The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 10 parts maleic anhydride-grafted polypropylene, 0.5 parts ethylene-glycidyl methacrylate copolymer, 0.02 parts 2-methylimidazole, and 0.15 parts antioxidant.

[0069] The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 28 parts copolyester, 12 parts polyethylene terephthalate, 0.25 parts polysiloxane powder, and 0.15 parts UV stabilizer.

[0070] The other components and preparation methods are the same as in Example 1.

[0071] Comparative Example 1: Based on Example 1, but unlike Example 1, the fluorescent reporter unit in this comparative example does not introduce a Si-O- structure.

[0072] The method for preparing the fluorescent reporter unit includes the following steps:

[0073] S11. In a dry 500 mL round-bottom flask, add 75.0 g of 11-bromo-1-undecyl alcohol and 400 mL of anhydrous acetonitrile. After dissolving, add 42.4 g of silver nitrate. Under nitrogen protection and in the dark, heat to 80 °C and reflux for 8 h. After the reaction is complete, cool to room temperature and filter through a diatomaceous earth pad to remove the generated silver bromide precipitate. Wash the filter cake with a large amount of acetonitrile. Concentrate the filtrate to dryness under reduced pressure and purify by rapid silica gel column chromatography (eluent: dichloromethane / methanol = 15:1, v / v) to obtain the second compound.

[0074] S12. In a dry 250 mL round-bottom flask, add 4.84 g of 1-pyrene carboxylic acid and 60 mL of anhydrous dichloromethane, shake well, add one drop of anhydrous N,N-dimethylformamide, and then slowly add 3.80 g of oxaloyl chloride. Stir the reaction at room temperature for 3 h until clear, then remove excess oxaloyl chloride and solvent by rotary evaporation under reduced pressure to obtain a yellow solid; in another dry 250 mL round-bottom flask, add 7.18 g of the second compound, 0.24 g of 4-dimethylaminopyridine, and 100 mL of anhydrous dichloromethane, dissolve to obtain a mixed solution; under ice bath cooling and stirring, dissolve the yellow solid in 20 mL of anhydrous dichloromethane. After adding mL of dichloromethane, slowly add it dropwise to the mixed solution. After the addition is complete, remove the ice bath and react overnight at room temperature. After the reaction is complete, wash successively with 100 mL of 1 mol / L dilute hydrochloric acid and saturated saline solution, dry with anhydrous sodium sulfate, filter, concentrate, and purify by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 10:1 to 5:1, gradient elution). Collect the yellow fluorescent fraction, concentrate it, and obtain the fluorescent reporter unit.

[0075] The other components and preparation methods are the same as in Example 1.

[0076] Comparative Example 2: Based on Example 1, but unlike Example 1, the fluorescent reporter unit in this comparative example does not introduce the fluorescent group 1-pyrenecarboxylic acid.

[0077] The method for preparing the fluorescent reporter unit includes the following steps:

[0078] S11. In a dry 1000 mL three-necked round-bottom flask equipped with a magnetic stirrer, a constant-pressure dropping funnel, and a nitrogen inlet, add 53.0 g of 11-bromo-1-undecyl alcohol and 400 mL of anhydrous N,N-dimethylformamide. Stir to dissolve, and after the system is purged with nitrogen three times, add 30.6 g of imidazole in portions under an ice-water bath and nitrogen atmosphere. Slowly add 100 mL of anhydrous N,N-dimethylformamide solution containing 38.6 g of diisopropyl dichlorosilane using a constant-pressure dropping funnel, controlling the dropping rate to maintain the internal temperature below 30 °C. After the addition is complete, remove the ice bath and stir the reaction at room temperature for 12 h. Pour the reaction solution into 1600 mL of ice water and extract three times, each time using 400 mL of dichloromethane. Combine the organic phases and extract successively with 400 mL of saturated sodium bicarbonate solution, 400 mL of water, and 400 mL of... Wash with mL of saturated sodium chloride solution, dry with anhydrous magnesium sulfate, filter, and remove the solvent by rotary evaporation under reduced pressure at 40 °C to obtain the crude product. The crude product is purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 20:1, v / v), and the main fraction is collected and concentrated to obtain the fluorescent reporter unit.

[0079] The other components and preparation methods are the same as in Example 1.

[0080] Comparative Example 3: Based on Example 1, but unlike Example 1, the fluorescence quenching unit in this comparative example does not introduce the quenching group 3,4-dinitrophenyl.

[0081] The preparation method of the fluorescence quenching unit includes the following steps:

[0082] S21. In a dry 500 mL round-bottom flask, add 42.0 g of 1,16-hexadecanediol and 200 mL of anhydrous dichloromethane. After dissolving, cool to 0 °C in an ice bath. While stirring, slowly add 50 mL of dichloromethane solution containing 10.1 g of phosphorus tribromide. After the addition is complete, allow the mixture to warm naturally to room temperature and stir for 4 h. Pour the mixture into 500 mL of ice water and stir vigorously. Separate the layers. Extract the aqueous phase with dichloromethane. Combine the organic phases and wash successively with saturated sodium bicarbonate solution and water. Dry the mixture with anhydrous magnesium sulfate, filter, concentrate, and purify by silica gel column chromatography (petroleum ether / ethyl acetate = 20:1) to obtain the fourth compound.

[0083] S22. In a dry 500 mL Schlenk reaction tube, under a nitrogen atmosphere, 45.8 g of compound IV, 30.4 g of bis(pinacol)diboron and 29.4 g of potassium acetate were added, followed by 300 mL of anhydrous 1,4-dioxane. After bubbling with nitrogen to remove oxygen for 15 min, 1.5 g of catalyst [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride was added. The mixture was heated to 95 °C and stirred vigorously for 16 h. After cooling to room temperature, insoluble matter was removed by filtration through a diatomaceous earth mat. The filtrate was concentrated by rotary evaporation and purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 15:1) to obtain the fluorescence quenching unit.

[0084] The other components and preparation methods are the same as in Example 1.

[0085] Comparative Example 4: Based on Example 1, but unlike Example 1, the fluorescence quenching unit in this comparative example does not introduce pinacol borate.

[0086] The preparation method of the fluorescence quenching unit includes the following steps:

[0087] S21. In a 1000 mL round-bottom flask equipped with a condenser, add 54.9 g of 1,16-hexadecanediol and 800 mL of anhydrous acetonitrile. After dissolving, add 33.6 g of potassium hydroxide and stir for 30 min. Then add 37.2 g of 4-fluoro-1,2-dinitrobenzene and heat to 80 °C under reflux for 12 h. Cool, filter, concentrate by rotary evaporation, extract the residue with water and dichloromethane, dry the organic phase and concentrate, and purify by silica gel column chromatography (petroleum ether / ethyl acetate = 5:1) to obtain the fluorescence quenching unit.

[0088] The other components and preparation methods are the same as in Example 1.

[0089] Comparative Example 5: Based on Example 1, but unlike Example 1, this comparative example does not include a fluorescent reporter unit.

[0090] Comparative Example 6: Based on Example 1, but unlike Example 1, this comparative example does not include a fluorescence quenching unit.

[0091] Comparative Example 7: Based on Example 1, but unlike Example 1, this comparative example does not include a masterbatch with a warning function.

[0092] Comparative Example 8: Based on Example 1, except that this comparative example does not include ethylene-glycidyl methacrylate copolymer.

[0093] Comparative Example 9: Based on Example 1, except that this comparative example does not include 2-methylimidazole.

[0094] Comparative Example 10: Based on Example 1, except that this comparative example does not include ethylene-glycidyl methacrylate copolymer and 2-methylimidazole.

[0095] Test Example 1: Verification of Electrolyte Leakage Early Warning Function.

[0096] Samples: Heat shrinkable film samples obtained from Examples 1-5 and Comparative Examples 1-10 were cut to a size of 5cm × 5cm.

[0097] Simulated electrolyte: 1.0 mol / L lithium hexafluorophosphate (LiPF6) in ethylene carbonate (EC) / diethyl carbonate (DEC) (volume ratio 1:1).

[0098] Experimental Procedure: All coated samples were equilibrated in a desiccator at room temperature for 24 hours. In a dark room, all samples were irradiated with a 365 nm UV lamp, and their initial fluorescence state was observed and photographed. The initial fluorescence intensity (F0) of each sample surface was measured using a fluorescence spectrometer. The excitation wavelength was 345 nm, and the emission peak intensity at 396 nm was recorded. 10 μL of simulated electrolyte was carefully added to the center of each sample surface using a pipette. A stopwatch was started simultaneously to observe the fluorescence change at the drop point. The time required from the addition of the liquid to the appearance of a clear blue fluorescence visible to the naked eye was recorded as the "response time." At 1 minute and 5 minutes after addition, photographs were taken again under a UV lamp, and the fluorescence intensity (F) at the drop point was measured using a fluorescence spectrometer. Samples from Example 1 were selected, and 10 μL of deionized water and ethanol were added respectively. The presence of a fluorescence signal within 5 minutes was observed.

[0099] Data analysis: 1. Fluorescence changes; 2. Calculation of fluorescence intensity change rate: Change rate (%) = [(F - F0) / F0] × 100%; Results are shown in Table 1.

[0100] Table 1 Electrolyte Leakage Early Warning Function Detection

[0101] Fluorescence change Fluorescence intensity change rate Example 1 Strong blue fluorescence appeared at 30~40 seconds, and the signal was clear 3033.5~3055.7% Example 2 Strong blue fluorescence appeared at 45~55 seconds, and the signal was clear 3013.2~3027.1% Example 3 Strong blue fluorescence appeared at 32~43 seconds, and the signal was clear 3030.3~3051.5% Example 4 Strong blue fluorescence appeared at 40~52 seconds, and the signal was clear 3023.5~3042.4% Example 5 Strong blue fluorescence appeared at 31~40 seconds, and the signal was clear 3030.8~3053.6% Comparative Example 1 Strong blue fluorescence was always emitted, and there was no change before and after the addition of electrolyte 0.002~0.003% Comparative Example 2 No fluorescence signal was produced 0% Comparative Example 3 Strong blue fluorescence was always emitted, and there was no change before and after the addition of electrolyte 0.001~0.003% Comparative Example 4 Strong blue fluorescence was always emitted, and there was no change before and after the addition of electrolyte 0.002~0.004% Comparative Example 5 No fluorescence signal was produced 0% Comparative Example 6 Strong blue fluorescence was always emitted, and there was no change before and after the addition of electrolyte 0.001~0.002% Comparative Example 7 No fluorescence signal was produced 0% Comparative Example 8 The fluorescence signal was extremely weak, and the response was slow and dim 40.5~45.6% Comparative Example 9 The fluorescence signal was weak, and the response was slow 98.9~100.1% Comparative Example 10 No fluorescence signal was produced 0% Deionized water group No fluorescence signal was produced 0% Ethanol group No fluorescence signal was produced 0%

[0102] Based on the results in Table 1, compared with Comparative Examples 1 and 4, Example 1 shows that without the introduction of a Si-O- structure in the fluorescent reporter unit or the introduction of a pinacol boronic acid ester in the fluorescent quenching unit, a silicon-oxygen-boron bond cannot be formed, the fluorescence cannot be quenched, and blue fluorescence is always present. There is no change before and after the addition of electrolyte, and no warning function is provided. Compared with Comparative Examples 3 and 6, Example 1 shows that without a fluorescent quenching group or fluorescent quenching unit, blue fluorescence is always present, with no change before and after the addition of electrolyte, and no warning function is provided. Compared with Comparative Examples 2 and 5, Example 1 shows that without the presence of a fluorescent group or fluorescent reporter unit, no fluorescence signal is generated. Compared with Comparative Example 7, Example 1... It can be concluded that without a masterbatch with a warning function, the warning function cannot be performed; compared with Comparative Example 8, Example 1 shows that without ethylene-glycidyl methacrylate copolymer, the adhesive layer will undergo a side reaction with the warning layer, significantly affecting the warning function; compared with Comparative Example 9, Example 1 shows that without the catalytic effect of 2-methylimidazole, the ability of ethylene-glycidyl methacrylate copolymer to consume maleic anhydride active sites and convert them into inert ester chain structures is weakened, thus weakening the warning function; compared with Comparative Example 10, Example 1 shows that without ethylene-glycidyl methacrylate copolymer and 2-methylimidazole, the warning layer is affected by the adhesive layer, and the warning function is completely ineffective.

[0103] Test Example 2: The heat shrinkable film samples obtained in Examples 1-5 were subjected to basic performance tests; the test indicators and reference standards are as follows: tensile strength (refer to ASTM D882); elongation at break (refer to ASTM D882); heat shrinkage rate (120°C, 10min, refer to ASTM D2732); initial shrinkage temperature (ASTM D2732); the results are shown in Table 2; heat resistance (ASTM D648); dielectric strength (ASTM D149); volume resistivity (ASTM D257); abrasion resistance (ASTM D4060); the results are shown in Table 3.

[0104] Table 2 Basic Performance Testing of Heat Shrinkable Film

[0105] Tensile strength Elongation at break Heat shrinkage rate Initial shrinkage temperature Example 1 45.8±0.3 MPa 205.8±1.2% Radial: 70.5±0.5%, Axial: 10.3±0.4% 80.6±0.5°C Example 2 45.3±0.4 MPa 204.5±1.5% Radial: 69.7±0.4%, Axial: 10.1±0.3% 80.0±0.7°C Example 3 45.6±0.4 MPa 205.6±1.3% Radial: 70.5±0.5%, Axial: 10.2±0.3% 80.4±0.6°C Example 4 45.2±0.2 MPa 204.4±1.0% Radial: 70.0±0.3%, Axial: 10.2±0.2% 80.3±0.5°C Example 5 45.6±0.3 MPa 205.3±1.1% Radial: 70.4±0.5%, Axial: 10.3±0.3% 80.5±0.4°C

[0106] Table 3 Basic Performance Testing of Heat Shrinkable Film

[0107] Heat resistance Dielectric strength Volume resistivity Wear resistance Example 1 105.8±0.4°C 80.5±0.3 kV / mm ≥ 1 x 10 16 Ω·cm Weight loss 22.4±1.3 mg Example 2 105.0±0.6°C 79.7±0.5 kV / mm ≥ 1 x 10 16 Ω·cm Weight loss 24.0±1.0 mg Example 3 105.7±0.5°C 80.4±0.2 kV / mm ≥ 1 x 10 16 Ω·cm Weight loss 22.5±0.9 mg Example 4 105.1±0.4°C 80.2±0.4 kV / mm ≥ 1 x 10 16 Ω·cm Weight loss 23.2±1.2 mg Example 5 105.6±0.5°C 80.4±0.3 kV / mm ≥ 1 x 10 16 Ω·cm Weight loss 22.6±1.1 mg

[0108] Finally, it should be noted that 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 high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, characterized in that, It includes an inner layer, a middle layer, and an outer layer; the inner layer is a warning layer, which includes the following components in parts by weight: 75-80 parts high melt index homopolymer polypropylene, 3.0-4.0 parts warning functional masterbatch, and 0.2-0.3 parts antioxidant; The warning function masterbatch includes a fluorescence reporter unit, a fluorescence quenching unit, high melt index homopolymer polypropylene, and an antioxidant in a mass ratio of 8~12: 8~12:75~85:0.3~0.7; the fluorescence reporter unit and the fluorescence quenching unit form silicon-oxygen-boron bonds, which break when the electrolyte leaks. The intermediate layer is an adhesive layer, comprising the following components in parts by weight: 8-12 parts maleic anhydride-grafted polypropylene, 0.4-0.6 parts ethylene-glycidyl methacrylate copolymer, 0.02-0.03 parts 2-methylimidazole, and 0.1-0.2 parts antioxidant.

2. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 1, characterized in that, The outer layer is a wear-resistant layer, comprising the following components in parts by weight: 25-30 parts copolyester, 10-15 parts polyethylene terephthalate, 0.2-0.3 parts polysiloxane powder, and 0.1-0.2 parts UV stabilizer.

3. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 1, characterized in that, The antioxidants include antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1; the ethylene-glycidyl methacrylate copolymer includes Lotader® AX8840.

4. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 2, characterized in that, The UV protectant includes UV-327.

5. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 1, characterized in that, The method for preparing the fluorescent reporter unit includes the following steps: S11. In a three-necked round-bottom flask, 11-bromo-1-undecyl alcohol and anhydrous N,N-dimethylformamide were added and stirred to dissolve. After the system was purged with nitrogen three times, imidazole was added under an ice-water bath and nitrogen atmosphere. Anhydrous N,N-dimethylformamide solution of diisopropyl dichlorosilane was added dropwise. After the addition was complete, the ice bath was removed, and the reaction was stirred at room temperature. The mixture was poured into ice water and extracted three times with dichloromethane. The organic phases were combined and washed successively with saturated sodium bicarbonate solution, water, and saturated sodium chloride solution. The mixture was dried with anhydrous magnesium sulfate, filtered, and the filtrate was evaporated under reduced pressure to obtain the crude product. The crude product was purified by silica gel column chromatography. The main fraction was collected and concentrated to obtain the first compound. S12. In a round-bottom flask, add the first compound and anhydrous acetonitrile, dissolve them, and then add silver nitrate. Under nitrogen protection and in the dark, heat and reflux the reaction. After the reaction is complete, cool to room temperature, filter through a diatomaceous earth pad, wash the filter cake with acetonitrile, concentrate the filtrate to dryness under reduced pressure, and purify it by rapid silica gel column chromatography to obtain the second compound. S13. In a round-bottom flask, add 1-pyrenic acid and anhydrous dichloromethane, shake well, add anhydrous N,N-dimethylformamide, and then add oxaloyl chloride dropwise. Stir the reaction at room temperature until clear, and then evaporate under reduced pressure to obtain a yellow solid. In another round-bottom flask, add the second compound, 4-dimethylaminopyridine, and anhydrous dichloromethane, dissolve to obtain a mixed solution. Under ice bath cooling and stirring, dissolve the yellow solid in dichloromethane and slowly add it dropwise to the mixed solution. After the addition is complete, remove the ice bath and react at room temperature overnight. After the reaction is complete, wash successively with dilute hydrochloric acid and saturated brine, dry with anhydrous sodium sulfate, filter, concentrate, and purify by silica gel column chromatography. Collect the yellow fluorescent fraction, concentrate it, and obtain a fluorescent reporter unit.

6. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 1, characterized in that, The preparation method of the fluorescence quenching unit includes the following steps: S21. In a round-bottom flask, add 1,16-hexadecanediol and anhydrous acetonitrile, dissolve them, add potassium hydroxide, stir, then add 4-fluoro-1,2-dinitrobenzene, heat to reflux, cool, filter, concentrate by rotary evaporation, extract the residue with water and dichloromethane, dry the organic phase and concentrate, and purify by silica gel column chromatography to obtain the third compound. S22. In a round-bottom flask, add the third compound and anhydrous dichloromethane. After dissolving, cool in an ice bath. While stirring, add a dichloromethane solution of phosphorus tribromide dropwise. After the addition is complete, allow the temperature to rise naturally to room temperature. Stir the reaction mixture and pour it into ice water. Stir vigorously and separate the liquids. Extract the aqueous phase with dichloromethane. Combine the organic phases and wash them successively with saturated sodium bicarbonate solution and water. Dry the mixture with anhydrous magnesium sulfate, filter, concentrate, and purify by silica gel column chromatography to obtain the fourth compound. S23. In a Schlenk reaction tube, under a nitrogen atmosphere, compound IV, bis(pinacolyl)diboron and potassium acetate were added, followed by anhydrous 1,4-dioxane. After deoxygenation by bubbling with nitrogen, catalyst [1,1'-bis(diphenylphosphine)ferrocene]palladium(II) dichloride was added. The mixture was heated and stirred vigorously. After cooling to room temperature, insoluble matter was removed by filtration through a diatomaceous earth mat. The filtrate was concentrated by rotary evaporation and purified by silica gel column chromatography to obtain the fluorescence quenching unit.

7. The high-strength, wear-resistant lithium battery heat-shrinkable sleeve material according to claim 1, characterized in that, The preparation method of the early warning function masterbatch includes the following steps: A fluorescent reporter unit, a fluorescent quenching unit, high melt index homopolymer polypropylene, and an antioxidant are added to a high-speed heating mixer and mixed at 60-80°C for 5-10 minutes to obtain a premix; the premix is ​​then fed into a co-rotating twin-screw extruder and melted, sheared, mixed, and extruded at 170-185°C; the extruded strip is cooled in a 30-40°C warm water bath and cut into granules by a pelletizing knife; the granules are dried in a vacuum drying oven at 50°C for 4 hours and then sieved to obtain the early warning function masterbatch.

8. A method for preparing a high-strength, wear-resistant lithium battery heat-shrinkable sleeve material, applied to the preparation of the high-strength, wear-resistant lithium battery heat-shrinkable sleeve material as described in any one of claims 1 to 7, characterized in that, The preparation method includes the following steps: S31. Preparation of binder masterbatch: Maleic anhydride-grafted polypropylene, ethylene-glycidyl methacrylate copolymer, 2-methylimidazole and antioxidant are mixed evenly at high speed, and then melt-extruded, underwater pelletized and dried by a co-rotating twin-screw extruder to obtain binder masterbatch. S32. Three-layer co-extrusion: Using a three-layer co-extrusion blown film unit, the inner layer components high melt index homopolymer polypropylene, early warning function masterbatch, and antioxidant are premixed and fed into the inner layer extruder of the co-extrusion machine; the binder masterbatch is fed into the middle layer extruder of the co-extrusion machine; the copolyester and polyethylene terephthalate are vacuum dried, mixed with polysiloxane powder and UV stabilizer, and fed into the outer layer extruder of the co-extrusion machine; the blown film bubble is rapidly cooled and shaped by the cold air blown out by the cooling air ring, corona treated, split, flattened, and rolled up to obtain a high-strength wear-resistant lithium battery heat shrink sleeve film material.

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