Aluminum-plastic film and method for manufacturing the same

Abstract

The application relates to the field of packaging materials, and particularly discloses an aluminum-plastic film and a preparation method thereof. The aluminum-plastic film comprises a bonding layer for connecting an aluminum foil layer and a heat-sealing layer and for connecting the aluminum foil layer and an outer shell layer, the bonding layer is made of a hyperbranched modified bonding agent, and the hyperbranched modified bonding agent is made of raw materials including the following components in parts by weight: 25-35 parts of propylene monomer, 2-6 parts of a reactant one, 0.25-0.6 parts of a diimine nickel / palladium transition metal catalyst, and 1-3 parts of an auxiliary agent; the reactant one is composed of a compound containing both a carbon-carbon double bond and an epoxy group. The hyperbranched modified bonding agent prepared by the application can be in a molten state at 80 DEG C, the heat method compounding temperature of the aluminum-plastic film is significantly reduced, the possibility of inward curling of the aluminum-plastic film is reduced, the obtained bonding layer has good toughness, the possibility of rupture of the aluminum-plastic film in a processing and forming process is reduced, the deep-drawing forming performance and the short-circuit resistance of the aluminum-plastic film are improved, and the edge voltage of a lithium battery is stable.

Description

Technical Field

[0001] This application relates to the field of packaging materials technology, and more specifically, to aluminum-plastic films and their preparation methods. Background Technology

[0002] Aluminum-plastic film is a key material used in battery cell packaging technology. It is a composite of various plastics, aluminum foil, and adhesives, possessing high strength and high barrier properties, playing a crucial role in battery safety.

[0003] In related technologies, aluminum-plastic film production methods are mainly divided into dry lamination and thermal lamination. The thermal lamination process uses polypropylene porous foam as an adhesive, bonding the aluminum foil layer and polypropylene together. The aluminum-plastic film is synthesized under slow heating and pressing. However, this polypropylene porous foam requires high temperatures to melt and achieve its bonding effect, resulting in aluminum-plastic film with at least the following defects:

[0004] At high temperatures, the van der Waals forces of polypropylene porous foam are destroyed, and it becomes brittle after heating and curing. The aluminum-plastic film is prone to cracking during processing, resulting in poor deep drawing performance, poor short-circuit resistance, and unstable side voltage of lithium batteries. Summary of the Invention

[0005] To address the problem of unstable lithium battery side voltage caused by poor short-circuit resistance of aluminum-plastic film in the thermal composite process, this application provides an aluminum-plastic film and its preparation method.

[0006] Firstly, this application provides an aluminum-plastic film, employing the following technical solution:

[0007] The aluminum-plastic film includes an adhesive layer for connecting an aluminum foil layer to a heat-sealing layer and an adhesive layer for connecting the aluminum foil layer to an outer shell layer. The adhesive layer is made of a hyperbranched modified adhesive, which is made from raw materials comprising the following parts by weight:

[0008]

[0009] The reactant consists of a compound containing both carbon-carbon double bonds and epoxy groups.

[0010] By adopting the above technical solution, both the propylene monomer and reactant one contain carbon-carbon double bonds, which can form polymers through addition reactions. Since the diimine nickel / palladium transition metal catalyst contains metal active centers, these active centers easily migrate along the carbon chain, causing the carbon chain formed by the propylene monomer and reactant one to isomerize, thereby obtaining a hyperbranched modified adhesive with a hyperbranched structure.

[0011] Because reactant one contains polar groups such as epoxy groups, which are randomly distributed on the side groups of polyolefins; and because epoxy groups do not react with propylene monomers; therefore, the ends of the hyperbranched modified adhesive contain epoxy groups.

[0012] Hyperbranched modified adhesives have numerous side chains and low crystallinity. Compared with linear polypropylene, the glass transition temperature of hyperbranched modified adhesives is below 80℃, which is much lower than the melting temperature required for linear polypropylene. Other layers of aluminum-plastic film can be laminated at low temperatures, and the shrinkage difference between the layers is small, reducing the possibility of inward curling of aluminum-plastic film. Aluminum-plastic film has excellent anti-curling properties.

[0013] Furthermore, the hyperbranched modified adhesive has flexible alkyl segments and side chains, which have good plasticity and good toughness of the adhesive layer. This reduces the possibility of aluminum-plastic film cracking during processing and molding, improves the deep drawing performance and short-circuit resistance of aluminum-plastic film, and makes the side voltage of lithium battery stable.

[0014] Secondly, hyperbranched modified adhesives have many branching points, making it difficult for molecular chain segments to entangle. They also have lower viscosity. The air contained between the aluminum-plastic film layers floats and is discharged in the molten hyperbranched modified adhesive, reducing the generation of bubbles in the adhesive layer. This is beneficial to increasing the adhesion performance of the adhesive layer and improving the aluminum-plastic film's ability to prevent electrolyte swelling and the shedding of the inner surface layer.

[0015] Furthermore, hyperbranched modified adhesives contain epoxy groups, which can further consume oxygen in the interlayer air and increase the degree of crosslinking of the adhesive layer, thereby further improving the bonding performance of hyperbranched modified adhesives.

[0016] The selection of additives includes, but is not limited to, antioxidants. By selecting the right additives, the performance of hyperbranched modified adhesives can be maintained in a long-term and stable manner, thereby significantly extending the service life of aluminum-plastic films.

[0017] Optionally, the weight ratio of the propylene monomer to reactant one is 1:(0.1 to 0.2).

[0018] By adopting the above technical solution and adjusting the weight ratio of propylene monomer to reactant one, the epoxy content of the hyperbranched modified adhesive is made moderate. While improving the processing performance, deep drawing performance and anti-short circuit performance of the hyperbranched modified adhesive, the melt viscosity of the hyperbranched modified adhesive is controlled to make its flow rate moderate, so as to avoid the adhesive layer of the aluminum-plastic film being too thin and to ensure excellent interlayer bonding strength of each layer of the aluminum-plastic film.

[0019] Optionally, the weight ratio of the propylene monomer to the diimine nickel / palladium transition metal catalyst is (0.01 to 0.02).

[0020] By adopting the above technical solution and adjusting the weight ratio of propylene monomer to diimine nickel / palladium transition metal catalyst, it is beneficial to improve the length of the main chain alkyl segment of the hyperbranched modified adhesive, thereby further improving the toughness of the aluminum-plastic film and helping to improve the deep drawing performance and short-circuit resistance of the aluminum-plastic film.

[0021] Optionally, reactant one is glycidyl methacrylate and / or glycidyl acrylate. Preferably, reactant one is glycidyl acrylate.

[0022] By adopting the above technical solution, the composition of reactant one is optimized, so that the branching degree and viscosity of the obtained hyperbranched modified adhesive are moderate, avoiding excessive fluidity of the hyperbranched modified polymer, reducing the possibility of adhesive overflow, which is conducive to controlling the thickness of the adhesive layer and improving the processing performance of the hyperbranched modified adhesive.

[0023] Preferably, the diimine nickel / palladium transition metal catalyst is nickel bis-(2,6-diisopropylphenyl)butadiene diimide bromide and / or nickel bis-(phenyl)pentanediimide diimide bromide. More preferably, the diimine nickel / palladium transition metal catalyst is nickel bis-(2,6-diisopropylphenyl)butadiene diimide bromide and nickel bis-(phenyl)pentanediimide diimide bromide.

[0024] Optionally, the preparation method of the hyperbranched modified adhesive is as follows:

[0025] G1. Weigh out the following amounts of propylene monomer, reactant one, nickel / palladium diimide transition metal catalyst and auxiliaries as specified in the formula.

[0026] G2. Under a nitrogen atmosphere, preheat to the reaction temperature of 35-60℃, then mix the propylene monomer, reactant 1, and diimine nickel / palladium transition metal catalyst, keep the reaction at this temperature for 6-12 hours, then add the auxiliary agent, mix well, and purify to obtain the hyperbranched modified adhesive.

[0027] Preferably, the reaction temperature in step G2 is 45–50°C.

[0028] By adopting the above technical solution, the reaction temperature of the hyperbranched modified adhesive is adjusted, thereby adjusting the degree of branching of the hyperbranched modified adhesive and further improving the flowability and processing performance of the hyperbranched modified polymer.

[0029] Optionally, the adjuvant is an antioxidant and / or an anti-hydrolysis agent.

[0030] The antioxidants include, but are not limited to, 2,6-tri-butyl-4-methylphenol, bis(3,5-tri-butyl-4-hydroxyphenyl) sulfide, and pentaerythritol tetrakis[β-(3,5-tri-butyl-4-hydroxyphenyl)propionate]; the anti-hydrolysis agents include, but are not limited to, carbodiimide.

[0031] Preferably, the additive is a mixture of antioxidant and anti-hydrolysis agent in a weight ratio of 1:(1 to 1.5).

[0032] By adopting the above technical solution, antioxidants and anti-hydrolysis agents are compounded to achieve a synergistic effect in improving the durability of aluminum-plastic film. Antioxidants reduce the possibility of double bond breakage and aging of hyperbranched modified adhesives, but they can easily cause ring-opening of epoxy groups in hyperbranched modified adhesives. Carbodiimide can react with the ring-opened epoxy compounds to generate polyurea, which improves the interlayer adhesion strength and heat resistance on both sides of the aluminum foil layer.

[0033] Secondly, this application provides a method for preparing aluminum-plastic film, which adopts the following technical solution:

[0034] The preparation method of aluminum-plastic film includes the following steps:

[0035] Aluminum foil is passivated to obtain an aluminum foil layer;

[0036] The hyperbranched modified adhesive is placed between the outer shell film and the aluminum foil, heated to 80-100℃, and pressed and bonded for 5-20 seconds; then the hyperbranched modified adhesive is placed between the heat-sealing film and the aluminum foil, heated to 80-100℃, and pressed and bonded for 5-20 seconds to obtain the aluminum-plastic film.

[0037] The outer shell membrane material serves a protective function and has excellent heat resistance (temperature range of 160℃±15℃), abrasion resistance, puncture resistance, and bending resistance. Its materials include, but are not limited to, nylon.

[0038] The heat-sealable film material serves to improve electrolyte resistance, and its materials include, but are not limited to, polypropylene, polyethylene, ethylene-acrylic acid copolymer, polypropylene, or ion-crosslinked polymer resin;

[0039] By using hyperbranched modified adhesives instead of adhesives and polypropylene porous foaming resin, the reaction temperature of the aluminum-plastic film composite process can be kept low, the bonding time short, and the anti-curling properties of the aluminum foil, outer film material, and heat-sealing layer film material can be ensured. At the same time, the resulting adhesive layer has excellent adhesion and toughness, which can reduce the possibility of aluminum-plastic film cracking during processing and forming, improve the deep drawing performance and short-circuit resistance of aluminum-plastic film, and make the side voltage of lithium battery stable.

[0040] In summary, this application has the following beneficial effects:

[0041] 1. In this application, a hyperbranched modified adhesive is prepared using propylene monomer and a compound containing both carbon-carbon double bonds and epoxy groups. The hyperbranched modified adhesive has a hyperbranched structure and contains epoxy groups at the ends, and can replace polypropylene foaming resin to connect polypropylene layers and aluminum foil layers.

[0042] 2. The hyperbranched structure of the modified adhesive significantly lowers its melting point, allowing it to melt below 80°C. Other layers of the aluminum-plastic film can be laminated at low temperatures, resulting in small shrinkage differences between the layers and making it less prone to inward curling. The aluminum-plastic film exhibits excellent anti-curling properties.

[0043] 3. The epoxy groups and hyperbranched structure in the hyperbranched modified adhesive work together to enhance the bonding performance by consuming the air between the aluminum foil layer and the polypropylene layer through the epoxy groups. On the other hand, the low viscosity of the hyperbranched modified adhesive is conducive to the expulsion of interlayer air and reduces the possibility of air bubbles in the adhesive layer.

[0044] 4. When hyperbranched modified adhesives are used in combination with specific types of additives, the antioxidant properties of the hyperbranched modified adhesives can be improved, and the heat resistance of aluminum-plastic films can be enhanced, thereby significantly improving the durability of aluminum-plastic films. Detailed Implementation

[0045] The present application will be further described in detail below with reference to preparation examples and embodiments.

[0046] Example of preparation of nickel / palladium diimide transition metal catalyst

[0047] Preparation example a

[0048] Nickel bis-(2,6-diisopropylphenyl)butanediimide was prepared according to the following steps:

[0049] S1. 141.6 g of 2,6-diisopropylaniline and 17.2 g of butanedione were mixed in a weight ratio and dissolved in 400 mL of toluene. Then, 1 g of p-toluenesulfonic acid was added. The resulting solution was stirred and refluxed at 80 °C for 24 h. Then, it was refluxed at 120 °C for 3 days until the reactants were completely reacted. The resulting reaction solution was cooled to 20 °C and some of the toluene was evaporated under reduced pressure until a yellow solid appeared. Then, the evaporated reaction solution was diluted with 300 mL of anhydrous ethanol. At this time, a large amount of yellow solid precipitated out. The obtained yellow solid was collected by filtration and washed with ethanol to obtain pure α-diimine ligand.

[0050] S2. Under a nitrogen atmosphere, take 56.2 g of α-diimine ligand, 6.2 g of (DME)NiBr2, and 50 mL of dichloromethane. Stir the resulting mixture overnight at 20 °C, remove the solvent under reduced pressure to obtain a red solid, wash with 3 × 100 mL of anhydrous diethyl ether to obtain pure bis-(2,6-diisopropylphenyl)butadiene nickel bromide.

[0051] Preparation Example b

[0052] Nickel di-(phenyl)pentanediimide bromide was prepared according to the following steps:

[0053] S1. 74.4 g of aniline and 176.2 g of 2,3-pentanedione were mixed in a weight ratio and dissolved in 400 mL of toluene. Then, 1 g of p-toluenesulfonic acid was added. The resulting solution was stirred and refluxed at 80 °C for 24 h. Then, it was refluxed at 120 °C for 3 days until the reactants were completely reacted. The resulting reaction solution was cooled to 20 °C and some of the toluene was evaporated under reduced pressure until a solid appeared. Then, the evaporated reaction solution was diluted with 300 mL of anhydrous ethanol. At this time, a large amount of solid precipitated out. The obtained solid was collected by filtration and washed with ethanol to obtain pure α-diimine ligand.

[0054] S2. Under a nitrogen atmosphere, take 56.2 g of α-diimine ligand, 6.2 g of (DME)NiBr2, and 50 mL of dichloromethane. Stir the resulting mixture overnight at 20 °C, remove the solvent under reduced pressure, and obtain a solid. Wash with 3 × 100 mL of anhydrous diethyl ether to obtain pure di-(phenyl)pentanediimine nickel bromide.

[0055] Preparation example c

[0056] The bis-(2,6-diisopropylphenyl)butanediimide palladium chloride was prepared according to the following steps:

[0057] S1. 141.6 g of 2,6-diisopropylaniline and 17.2 g of butanedione were mixed in a weight ratio and dissolved in 400 mL of toluene. Then, 1 g of p-toluenesulfonic acid was added. The resulting solution was stirred and refluxed at 80 °C for 24 h. Then, it was refluxed at 120 °C for 3 days until the reactants were completely reacted. The resulting reaction solution was cooled to 20 °C and some of the toluene was evaporated under reduced pressure until a yellow solid appeared. Then, the evaporated reaction solution was diluted with 300 mL of anhydrous ethanol. At this time, a large amount of yellow solid precipitated out. The obtained yellow solid was collected by filtration and washed with ethanol to obtain pure α-diimine ligand.

[0058] S2. Under a nitrogen atmosphere, take 74.2 g of α-diimine ligand, 26.5 g of (COD) PdMeCl, and 300 mL of dichloromethane. Stir the resulting mixture at 20 °C for 3 days, remove the solvent under reduced pressure, concentrate, and then separate by column chromatography. Specifically, elute the unreacted diimine ligand onto silica gel with a 2:1 volume ratio of hexane to dichloromethane to obtain pure bis-(2,6-diisopropylphenyl)butadiene palladium chloride.

[0059] Preparation example of hyperbranched modified adhesive

[0060] Preparation Example 1

[0061] The hyperbranched modified adhesive was prepared according to the following method:

[0062] G1. Take 250g of propylene monomer, 20g of glycidyl methacrylate, 2.5g of bis-(2,6-diisopropylphenyl)butadiene palladium chloride, and 10g of antioxidant 1010;

[0063] G2. First, dry the reactor under vacuum at 90°C for at least 1 hour, then adjust the reactor to the required polymerization temperature of 35°C. Under a nitrogen atmosphere, add 38 mL of a mixed solution of dichloromethane, propylene monomer, and glycidyl methacrylate to the reactor. Then, inject 2 mL of a dichloromethane solution containing bis-(2,6-diisopropylphenyl)butadiene nickel bromide into the polymerization system using a syringe. After rapid stirring, pressurize the reactor and maintain it at a propylene pressure of 4 atm for 12 hours. Then, add antioxidant 1010 and stir. Vent the reactor, precipitate the copolymer with ethanol, and vacuum dry the polymer at 50°C for 12 hours to obtain the hyperbranched modified adhesive.

[0064] Preparation Example 2-16

[0065] The hyperbranched modified adhesive differs from the preparation example 1 in that the composition of the raw materials is different, as shown in Table 1 below.

[0066] Table 1. Raw material composition of hyperbranched modified adhesives

[0067]

[0068] Preparation Examples 17-19

[0069] The hyperbranched modified adhesive differs from that in Preparation Example 16 in that the reaction temperature and reaction time are different. The specific process parameters are as follows:

[0070] The required polymerization temperature for preparing the hyperbranched modified adhesive in Example 17 was 45°C, and the polymerization time was 8 hours.

[0071] The required polymerization temperature for preparing the hyperbranched modified adhesive in Example 18 was 50°C, and the polymerization time was 8 hours.

[0072] The required polymerization temperature for preparing the hyperbranched modified adhesive in Example 19 was 60°C, and the polymerization time was 6 hours.

[0073] Example

[0074] Example 1

[0075] An aluminum-plastic film has a structure comprising an outer shell layer, an adhesive layer, an aluminum foil layer, an adhesive layer, and a heat-sealing layer stacked sequentially.

[0076] It is prepared according to the following steps:

[0077] First, Ar2 was used as the working gas to clean the surface of the aluminum foil, and then passivation was performed to obtain an aluminum foil layer with a thickness of 40μm.

[0078] Nylon PA-66 was used as the outer shell layer membrane material, and the outer shell layer membrane material was stretched to a thickness of 15μm.

[0079] The hyperbranched modified adhesive prepared in Preparation Example 1 was placed between the outer shell film and the aluminum foil; the temperature was raised to the point where the hyperbranched modified adhesive was in a molten state, and the temperature was continued to rise until it reached 80°C. The mixture was then held at the temperature and extruded to bond the nylon PA-66 and the aluminum foil layer for 20 seconds.

[0080] Polypropylene (grade XCSJ) was used as the heat-sealing layer film material and stretched to a thickness of 55μm;

[0081] The hyperbranched modified adhesive prepared in Preparation Example 1 is then placed between the heat-sealing film and the aluminum foil; the temperature is raised until the hyperbranched modified adhesive is in a molten state, and the temperature is continued to rise until it reaches 80°C. The film is then held at the temperature and extruded to bond the polypropylene and aluminum foil layers together for 20 seconds to obtain an aluminum-plastic film.

[0082] The thickness of the adhesive layer formed by the hyperbranched modified adhesive was controlled to be 2 μm.

[0083] Example 2-19

[0084] The difference between the aluminum-plastic film and Example 1 lies in the material used for the adhesive layer, as shown in Table 2 below:

[0085] Table 2. Materials used in the adhesive layer

[0086] project Adhesive layer material project Adhesive layer material project Adhesive layer material Example 2 Preparation Example 2 Example 8 Preparation Example 8 Example 14 Preparation Example 14 Example 3 Preparation Example 3 Example 9 Preparation Example 9 Example 15 Preparation Example 15 Example 4 Preparation Example 4 Example 10 Preparation Example 10 Example 16 Preparation Example 16 Example 5 Preparation Example 5 Example 11 Preparation Example 11 Example 17 Preparation Example 17 Example 6 Preparation Example 6 Example 12 Preparation Example 12 Example 18 Preparation Example 18 Example 7 Preparation Example 7 Example 13 Preparation Example 13 Example 19 Preparation Example 19

[0087] Example 20

[0088] Aluminum-plastic film is prepared according to the following steps:

[0089] First, Ar2 was used as the working gas to clean the surface of the aluminum foil, and then passivation was performed to obtain an aluminum foil layer with a thickness of 40μm.

[0090] Nylon PA-66 was used as the outer shell layer membrane material, and the outer shell layer membrane material was stretched to a thickness of 25μm.

[0091] The hyperbranched modified adhesive prepared in Preparation Example 1 was placed between the outer shell film and the aluminum foil; the temperature was raised to the point where the hyperbranched modified adhesive was in a molten state, and the temperature was continued to rise until it reached 100°C. The mixture was then held at the temperature and extruded to bond the nylon PA-66 and the aluminum foil layer for 5 seconds.

[0092] Polypropylene (grade XCSJ) was used as the heat-sealing layer film material and stretched to a thickness of 40μm;

[0093] The hyperbranched modified adhesive prepared in Preparation Example 1 is then placed between the heat-sealing film and the aluminum foil; the temperature is raised until the hyperbranched modified adhesive is in a molten state, and the temperature is continued to rise until it reaches 100°C. The film is then held at the temperature and extruded to bond the polypropylene and aluminum foil layers together for 5 seconds to obtain an aluminum-plastic film.

[0094] Comparative Example

[0095] Comparative Example 1

[0096] The difference between the aluminum-plastic film and Example 1 is that it uses polypropylene porous foam material (grade: MPP25, density 36 kg / m³). 3 (Compressive strength 0.23 MPa) replaces the hyperbranched modified adhesive prepared in Preparation Example 1;

[0097] The thickness of the adhesive layer formed by the hyperbranched modified adhesive was controlled to be 2 μm.

[0098] Comparative Example 2

[0099] The aluminum-plastic film differs from that in Example 1 in that the adhesive layer uses an epoxy resin adhesive (brand name: DP405) instead of the hyperbranched modified adhesive prepared in Preparation Example 1.

[0100] The specific preparation steps are as follows:

[0101] First, Ar2 was used as the working gas to clean the surface of the aluminum foil, and then passivation was performed to obtain an aluminum foil layer with a thickness of 40μm.

[0102] Nylon PA-66 was used as the outer shell layer membrane material, and the outer shell layer membrane material was stretched to a thickness of 25μm.

[0103] Epoxy resin adhesive is applied to the outer shell membrane material, then bonded to aluminum foil, and heated to 100℃ for 5 seconds for heat curing.

[0104] Polypropylene (grade XCSJ) was used as the heat-sealing layer film material and stretched to a thickness of 40μm;

[0105] Next, place the epoxy resin adhesive on the heat-sealing film material, then bond it with the aluminum foil, heat it to 100℃ for 5 seconds to obtain the aluminum-plastic film;

[0106] The thickness of the adhesive layer formed by the epoxy resin adhesive is controlled to be 2 μm.

[0107] Performance testing

[0108] Inspection method: Visual inspection: Check the surface of the aluminum-plastic film sample for pits, scratches, and air bubbles between the composite layers. If there are no pits, scratches, or air bubbles, it is a qualified product. If there are pits, scratches, or air bubbles, it is a non-qualified product. Calculate the pass rate for a batch of samples. Pass rate = (Number of qualified products / Total number) × 100%.

[0109] Anti-curling performance test: The angle between the aluminum-plastic film and the horizontal plane is defined as 0 degrees. The test is to measure the angle between the edge of the sample after it is formed and the horizontal plane. The smaller the angle, the better the anti-curling performance.

[0110] Adhesion performance: Tested according to GB / T8808-1998 standard, the peel force between the aluminum foil layer and the heat seal layer is tested, unit: N / 15mm.

[0111] Electrolyte resistance: A sample 11 mm wide and 200 mm long was placed in the electrolyte and kept at a constant temperature of 85°C. The time it took for the peel force between the aluminum foil layer and the heat-sealing layer to fall below 6 N / 15 mm was recorded. (Standard electrolyte EC:DEC:DMC = 1:1:1, LiPF6 1 mol / L). A longer time indicates a longer service life.

[0112] Forming depth: Samples (200mm×110mm) were formed at different depths (97mm×55mm). Observe whether the samples have cracks, grooves, pitting, or delamination. Record the depth of the punching.

[0113] Side voltage stability performance: Packaging lithium battery components with aluminum-plastic film samples; testing the voltage between the positive electrode tab and the aluminum-plastic film; the lower the voltage, the less likely there is interlayer damage to the aluminum-plastic film, the better the short-circuit resistance, and the safer the lithium battery.

[0114] Test results

[0115] Table 3. Performance Tests of Aluminum-Plastic Film Samples

[0116]

[0117]

[0118] Table 4. Testing of forming depth and edge voltage stability of aluminum-plastic film samples

[0119] sample Ditch depth / mm Voltage / V sample Ditch depth / mm Voltage / V Example 1 9.15 0.77 Example 12 9.72 0.39 Example 2 9.16 0.76 Example 13 9.67 0.42 Example 3 9.28 0.68 Example 14 9.79 0.34 Example 4 9.37 0.62 Example 15 9.85 0.3 Example 5 9.00 0.87 Example 16 9.96 0.23 Example 6 9.42 0.59 Example 17 10.00 0.2 Example 7 9.21 0.73 Example 18 10.05 0.17 Example 8 9.49 0.54 Example 19 9.93 0.25 Example 9 9.43 0.58 Example 20 9.01 0.86 Example 10 9.60 0.47 Comparative Example 1 4.75 3.7 Example 11 9.61 0.46 Comparative Example 2 7.00 0.9

[0120] Combining Example 1 and Comparative Example 1 with Tables 3-4, it can be seen that Comparative Example 1, using conventional polypropylene porous foam material as an adhesive, showed a significantly lower pass rate in appearance inspection compared to Example 1, at only 63.3%. This demonstrates that the aluminum-plastic film prepared in this application has good processing performance and excellent appearance. Secondly, the adhesion strength between the aluminum foil layer and the heat-sealing layer of the aluminum-plastic film prepared in Comparative Example 1 was 6.0 N / 15 mm, and its electrolyte resistance time was only 48 h, indicating that conventional polypropylene porous foam material has poor adhesion performance, far inferior to the hyperbranched modified adhesive. Meanwhile, the hyperbranched modified adhesive exhibits excellent electrolyte resistance and a long service life. Furthermore, the pit depth of Comparative Example 1 was only 4.75 mm, yet the edge voltage already exceeded 1 V, indicating poor performance of the aluminum-plastic film, poor short-circuit resistance, and poor safety of the packaged lithium battery.

[0121] As can be seen from Example 1 and Comparative Example 2, and Tables 3-4, Comparative Example 2 uses conventional epoxy resin adhesive to bond the layers of aluminum-plastic film, but its bonding performance and electrolyte resistance are both poor, resulting in the aluminum-plastic film not being able to be used for a long time.

[0122] As can be seen from Examples 10-12 and Tables 3-4, the combined use of catalysts di-(2,6-diisopropylphenyl)butadiimide nickel bromide and di-(phenyl)pentadiimide nickel bromide has a significant impact on the hyperbranched modified adhesive, which can significantly improve the interlayer peel force between the aluminum foil layer and the heat-sealing layer of the aluminum-plastic film, the electrolyte resistance of the aluminum-plastic film, and the short-circuit resistance, thus having a synergistic effect.

[0123] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. An aluminum-plastic film, comprising an adhesive layer for connecting an aluminum foil layer and a heat-sealing layer, and an adhesive layer for connecting the aluminum foil layer and an outer shell layer, characterized in that: The adhesive layer is made of a hyperbranched modified adhesive, which is made of raw materials comprising the following parts by weight: 25-35 parts of propylene monomer; 2-6 parts of reactant one; 0.25-0.6 parts of diimine nickel / palladium transition metal catalyst; and 1-3 parts of additives. The reactant one is composed of a compound containing both carbon-carbon double bonds and epoxy groups, and the reactant one is glycidyl methacrylate and / or glycidyl acrylate.

2. The aluminum-plastic film according to claim 1, characterized in that: The weight ratio of the propylene monomer to reactant one is 1:(0.1 to 0.2).

3. The aluminum-plastic film according to claim 1, characterized in that: The weight ratio of the propylene monomer to the diimine nickel / palladium transition metal catalyst is 1:(0.01-0.02).

4. The aluminum-plastic film according to claim 1, characterized in that: The diimine nickel / palladium transition metal catalyst is bis-(2,6-diisopropylphenyl)butadiimine nickel bromide and / or bis-(phenyl)pentadiimine nickel bromide.

5. The aluminum-plastic film according to claim 1, characterized in that: The preparation method of the hyperbranched modified adhesive is as follows: G1, weigh the formulated amounts of propylene monomer, reactant one, nickel / palladium diimide transition metal catalyst and auxiliary agent; G2, under a nitrogen atmosphere, preheat to the reaction temperature of 35-60℃, then mix the propylene monomer, reactant one, and nickel / palladium diimide transition metal catalyst, keep the reaction at the temperature for 6-12 hours, then add the auxiliary agent, mix well, purify, and obtain the hyperbranched modified adhesive.

6. The aluminum-plastic film according to claim 5, characterized in that: The reaction temperature in step G2 is 45–50°C.

7. The aluminum-plastic film according to claim 1, characterized in that: The adjuvant is an antioxidant and / or an anti-hydrolysis agent.

8. The aluminum-plastic film according to claim 7, characterized in that: The additive is a mixture of antioxidant and anti-hydrolysis agent in a weight ratio of 1:(1 to 1.5).

9. The method for preparing the aluminum-plastic film according to any one of claims 1-8, characterized in that, The process includes the following steps: passivation treatment of aluminum foil to obtain an aluminum foil layer; placing a hyperbranched modified adhesive between the outer shell film and the aluminum foil, heating to 80-100℃, and pressing and bonding for 5-20 seconds; then placing the hyperbranched modified adhesive between the heat-sealing film and the aluminum foil, heating to 80-100℃, and pressing and bonding for 5-20 seconds to obtain an aluminum-plastic film.

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