Aluminum-plastic film with high flatness and preparation method thereof, and lithium ion battery

Abstract

The application belongs to the technical field of aluminum-plastic films, and particularly relates to an aluminum-plastic film with high flatness of punched shells, a preparation method thereof and a lithium ion battery, which comprises PET film, a first bonding layer, a high-temperature-resistant CPP layer, a second bonding layer, aluminum foil, a third bonding layer and CPP film which are sequentially arranged; the high-temperature-resistant CPP layer comprises the following components in mass fractions: 80-90 parts of homopolymer polypropylene resin, 5-10 parts of silicon-doped POE resin and 5-10 parts of aluminum nitride inorganic particles.

Description

Technical Field

[0001] This invention belongs to the field of aluminum-plastic film technology, specifically relating to an aluminum-plastic film with high flatness during punching, its preparation method, and lithium-ion batteries. Background Technology

[0002] Lithium-ion battery technology is maturing rapidly, and its applications in 3C electronic products, power batteries, and energy storage are increasing, leading to a greater demand for lithium battery packaging materials. Currently, there are three main packaging methods for lithium batteries: cylindrical, prismatic, and pouch. Cylindrical and prismatic packaging primarily uses aluminum and steel shells, while pouch packaging mainly uses aluminum-plastic film. Among these three methods, aluminum-plastic film pouches are gaining a larger market share due to their advantages in lightweight design and safety.

[0003] Aluminum-plastic composite film typically consists of an outer substrate layer (nylon film, polyester film), a middle aluminum foil layer, and an inner heat-sealing layer (polypropylene film). Depending on the manufacturing process, the punching performance and post-punching characteristics of aluminum-plastic composite film vary. Dry-process aluminum-plastic composite film has better punching performance, but the punched product is more prone to warping towards the substrate layer at the pre-reserved heat-sealing edge. This warping not only causes significant inconvenience for subsequent operations such as neat storage, trimming, and heat sealing, but the uneven heat-sealing edge also affects the heat transfer effect of the heat-sealed end, resulting in reduced production efficiency and heat-sealing quality.

[0004] Therefore, how to overcome the warping defect of dry-process aluminum-plastic film during punching to improve its flatness is a technical problem that urgently needs to be solved in this field.

[0005] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0006] This disclosure provides at least one aluminum-plastic film with high flatness in the casing, its preparation method, and a lithium-ion battery.

[0007] In a first aspect, embodiments of this disclosure provide an aluminum-plastic film with high flatness for punching shells, comprising: a PET film, a first adhesive layer, a high-temperature resistant CPP layer, a second adhesive layer, an aluminum foil, a third adhesive layer, and a CPP film stacked sequentially; wherein the high-temperature resistant CPP layer comprises the following components in parts by weight: 80-90 parts of homopolymer polypropylene resin, 5-10 parts of silica-doped POE resin, and 5-10 parts of aluminum nitride inorganic particles.

[0008] In one optional embodiment, the CPP film comprises the following components in parts by weight: 80-90 parts of ternary copolymer polypropylene resin, 5-10 parts of silica-doped POE resin, 2-8 parts of hyperbranched amide resin, and 1-5 parts of slip masterbatch.

[0009] In one alternative embodiment, the melt flow rate of the homopolymer polypropylene resin is 16-18 g / 10 min.

[0010] In one optional embodiment, the silica doping content in the silica-doped POE resin is 3-10%.

[0011] In one optional embodiment, the aluminum nitride inorganic particles have a particle size of 50-100 nm.

[0012] In one alternative embodiment, the melt flow rate of the ternary copolymer polypropylene resin is 6-8 g / 10 min.

[0013] In one optional embodiment, the thickness of the PET film is 10-15 μm; the thicknesses of the first adhesive layer, the second adhesive layer, and the third adhesive layer are 3-5 μm.

[0014] In one optional embodiment, the aluminum foil has a thickness of 35-45 μm, and after passivation treatment, the matte side of the aluminum foil is disposed on one side of the second adhesive layer, and the glossy side is disposed on one side of the third adhesive layer.

[0015] Secondly, this disclosure also provides a method for preparing a high-flatness aluminum-plastic film as described above, comprising the following steps: Step S1, coating both sides of an aluminum foil with an acid-resistant agent, passivating it to form an acid-resistant film, and allowing it to stand to obtain an aluminum foil with a matte and a glossy surface; Step S2, coating a PET film with polyurethane adhesive, heating it at high temperature to form a first adhesive layer, and then laminating it with a high-temperature resistant CPP layer; Step S3, coating a matte surface of the aluminum foil with polyurethane adhesive, heating it at high temperature to form a second adhesive layer, and then laminating it with the other side of the high-temperature resistant CPP layer; Step S4, coating a glossy surface of the aluminum foil with polyurethane adhesive, heating it at high temperature, and then laminating it with the corona-treated surface of the CPP film.

[0016] Thirdly, this disclosure also provides a lithium-ion battery that uses a soft-pack packaging, wherein the packaging material is the high-flatness aluminum-plastic film as described above.

[0017] The beneficial effects of this invention are that the high flatness aluminum-plastic film and its preparation method, and the lithium-ion battery, by setting a high-temperature resistant CPP layer containing homopolymer polypropylene resin, silica-doped POE resin and aluminum nitride inorganic particles, combine the characteristics of PET film and high-temperature resistant CPP film, balance the mechanical strength of the two, and thus overcome the warping defects of aluminum-plastic film. This allows the aluminum-plastic film to meet the requirements of deep drawing performance, puncture resistance and wear resistance while enhancing flatness, effectively ensuring the quality of heat sealing.

[0018] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0020] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the structure of an aluminum-plastic film with high flatness for stamping, provided in an embodiment of this disclosure.

[0022] In the picture:

[0023] 1. PET layer; 2. First adhesive layer; 3. High-temperature resistant CPP layer; 4. Second adhesive layer; 5. Aluminum foil; 6. Third adhesive layer; 7. CPP film. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0026] In this document, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. As used herein, expressions such as “at least one of…” modify the entire list of elements when following a list of elements, rather than individual elements in the list. For example, the expression “at least one of a, b, and c” should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0027] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] Please see Figure 1 ,like Figure 1 As shown, this disclosure provides an aluminum-plastic film with high flatness for punching shells, comprising: a PET film, a first adhesive layer, a high-temperature resistant CPP layer, a second adhesive layer, an aluminum foil, a third adhesive layer, and a CPP film stacked sequentially; wherein the high-temperature resistant CPP layer comprises the following components in parts by weight: 80-90 parts of homopolymer polypropylene resin, 5-10 parts of silica-doped POE resin, and 5-10 parts of aluminum nitride inorganic particles.

[0031] This disclosure also provides a method for preparing a high-flatness aluminum-plastic film as described above, comprising the following steps: Step S1, coating both sides of an aluminum foil with an acid-resistant agent, passivating it to form an acid-resistant film, and allowing it to stand to obtain an aluminum foil with a matte and a glossy surface; Step S2, coating a PET film with polyurethane adhesive, heating it at high temperature to form a first adhesive layer, and then laminating it with a high-temperature resistant CPP layer; Step S3, coating a matte surface of the aluminum foil with polyurethane adhesive, heating it at high temperature to form a second adhesive layer, and then laminating it with the other side of the high-temperature resistant CPP layer; Step S4, coating a glossy surface of the aluminum foil with polyurethane adhesive, heating it at high temperature, and then laminating it with the corona-treated surface of the CPP film.

[0032] This disclosure also provides a lithium-ion battery that uses a soft-pack packaging, wherein the packaging material is the high-flatness aluminum-plastic film as described above.

[0033] The performance of the aluminum-plastic film provided by this invention was tested according to the following method:

[0034] (1) Puncture performance

[0035] The puncture performance of the protective layer was tested using a Shimadzu AGS-X series electronic universal testing machine.

[0036] (2) Drawing depth

[0037] Use a shell punching machine to punch a pit. Start punching from 5.0mm and punch 10 samples consecutively. If there is no delamination, cracks, or pinholes when inspected under strong light, increase the pit by 0.2mm and continue punching 10 more samples until the shell breaks. Record the punching depth before the shell breaks, which is the limit punching depth.

[0038] (3) Heat sealability

[0039] Using a Japanese Tester Sangyo TP-701-B heat sealer, two 10cm*10cm aluminum-plastic films were aligned and heat-sealed at a heat-sealing temperature of 190℃, a pressure of 0.5 MPa, and a heat-sealing time of 3 seconds. After the samples cooled to room temperature, the heat seal strength was tested using a Shimadzu AGS-X series electronic universal testing machine.

[0040] (4) Screw flatness

[0041] Prepare a 130mm*220mm sample, punch a 5.5mm dent using a double-cavity mold, place it on a marble countertop for 1 hour, and use a steel ruler to measure the height of the four corners. Record the maximum value as the warping height of the punched shell.

[0042] Example 1

[0043] This invention provides an aluminum-plastic film.

[0044] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0045] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0046] 90 parts of homopolymer polypropylene resin V30G, 5 parts of silica-doped POE resin (silica accounting for 5%), and 5 parts of inorganic particles AlN were added in proportion, melt-filtered, and extruded through a T-die in three layers. The mixture was then cast at high speed and cooled to crystallize into a 15µm high-temperature resistant CPP film.

[0047] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on one side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0048] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15µm CPP at a lamination temperature of 80℃.

[0049] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the matte surface of the above-treated aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0050] After drying, the aluminum foil coated with adhesive is thermally bonded to the CPP surface of the previous composite structure at a temperature of 80°C.

[0051] 90 parts of ternary copolymer polypropylene resin TF400, 5 parts of silica-doped POE resin (silica accounts for 5%), 2 parts of hyperbranched amide resin, and 3 parts of slip masterbatch AB6018PP were added in proportion, melt-filtered, extruded through a T-die in three layers, cast at high speed, and cooled to crystallize into a 30μm CPP film.

[0052] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the aluminum foil. The third adhesive layer was dried at 80°C for 1 minute, and the thickness of the third adhesive layer was 3µm.

[0053] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0054] Example 2

[0055] The aluminum-plastic film provided in Example 1.

[0056] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0057] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0058] 80 parts of homopolymer polypropylene resin V30G, 10 parts of silica-doped POE resin (silica accounting for 5%), and 10 parts of inorganic particles AlN were added in proportion, melt-filtered, and extruded through a T-die in three layers. The mixture was then cast at high speed and cooled to crystallize into a 15μm high-temperature resistant CPP film.

[0059] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on one side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0060] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15µm CPP at a lamination temperature of 80℃.

[0061] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the matte surface of the above-treated aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0062] After drying, the aluminum foil coated with adhesive is thermally bonded to the CPP surface of the previous composite structure at a temperature of 80°C.

[0063] 90 parts of ternary copolymer polypropylene resin TF400, 5 parts of silica-doped POE resin (silica accounts for 5%), 2 parts of hyperbranched amide resin, and 3 parts of slip masterbatch AB6018PP were added in proportion, melt-filtered, extruded through a T-die in three layers, cast at high speed, and cooled to crystallize into a 30μm CPP film.

[0064] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the aluminum foil. The third adhesive layer was dried at 80°C for 1 minute, and the thickness of the third adhesive layer was 3µm.

[0065] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0066] Example 3

[0067] The aluminum-plastic film provided in Example 1.

[0068] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0069] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0070] 90 parts of homopolymer polypropylene resin V30G, 5 parts of silica-doped POE resin (silica accounting for 5%), and 5 parts of inorganic particles AlN were added in proportion, melt-filtered, and extruded through a T-die in three layers. The mixture was then cast at high speed and cooled to crystallize into a 15μm high-temperature resistant CPP film.

[0071] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on one side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0072] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15µm CPP at a lamination temperature of 80℃.

[0073] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the matte surface of the above-treated aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0074] After drying, the aluminum foil coated with adhesive is thermally bonded to the CPP surface of the previous composite structure at a temperature of 80°C.

[0075] 80 parts of ternary copolymer polypropylene resin TF400, 10 parts of silica-doped POE resin (silica accounting for 5%), 8 parts of hyperbranched amide resin, and 2 parts of slip masterbatch AB6018PP were added in proportion, melt-filtered, extruded through a T-die in three layers, cast at high speed, and cooled to crystallize into a 30μm CPP film.

[0076] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the aluminum foil. The third adhesive layer was dried at 80°C for 1 minute, and the thickness of the third adhesive layer was 3µm.

[0077] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0078] Example 4

[0079] The aluminum-plastic film provided in Example 1.

[0080] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0081] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0082] 80 parts of homopolymer polypropylene resin V30G, 10 parts of silica-doped POE resin (silica accounting for 5%), and 10 parts of inorganic particles AlN were added in proportion, melt-filtered, and extruded through a T-die in three layers. The mixture was then cast at high speed and cooled to crystallize into a 15μm high-temperature resistant CPP film.

[0083] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on one side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0084] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15µm CPP at a lamination temperature of 80℃.

[0085] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the matte surface of the above-treated aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0086] After drying, the aluminum foil coated with adhesive is thermally bonded to the CPP surface of the previous composite structure at a temperature of 80°C.

[0087] 80 parts of ternary copolymer polypropylene resin TF400, 10 parts of silica-doped POE resin (silica accounting for 5%), 8 parts of hyperbranched amide resin, and 2 parts of slip masterbatch AB6018PP were added in proportion, melt-filtered, extruded through a T-die in three layers, cast at high speed, and cooled to crystallize into a 30μm CPP film.

[0088] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the aluminum foil. The third adhesive layer was dried at 80°C for 1 minute, and the thickness of the third adhesive layer was 3µm.

[0089] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0090] Example 5

[0091] The aluminum-plastic film provided in Example 1.

[0092] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0093] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0094] 86 parts of homopolymer polypropylene resin V30G, 7 parts of silica-doped POE resin (silica accounting for 5%), and 7 parts of inorganic particles AlN were added in proportion, melt-filtered, and extruded through a T-die in three layers. The mixture was then cast at high speed and cooled to crystallize into a 15μm high-temperature resistant CPP film.

[0095] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on one side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0096] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15µm CPP at a lamination temperature of 80℃.

[0097] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the matte surface of the above-treated aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0098] After drying, the aluminum foil coated with adhesive is thermally bonded to the CPP surface of the previous composite structure at a temperature of 80°C.

[0099] 80 parts of ternary copolymer polypropylene resin TF400, 10 parts of silica-doped POE resin (silica accounting for 5%), 8 parts of hyperbranched amide resin, and 2 parts of slip masterbatch AB6018PP were added in proportion, melt-filtered, extruded through a T-die in three layers, cast at high speed, and cooled to crystallize into a 30μm CPP film.

[0100] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the aluminum foil. The third adhesive layer was dried at 80°C for 1 minute, and the thickness of the third adhesive layer was 3µm.

[0101] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0102] Comparative Example 1

[0103] A method for preparing aluminum-plastic film is provided.

[0104] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0105] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0106] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on the other side of the above-mentioned polyethylene terephthalate film. The first adhesive layer was dried at 90°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0107] After drying, the adhesive surface of the above-mentioned polyethylene terephthalate film coated with the adhesive layer is thermally laminated with 15u nylon at a lamination temperature of 80℃.

[0108] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was coated on the matte surface of the aluminum foil. The second adhesive layer was dried at 80°C for 1 minute, and the thickness of the second adhesive layer was 3µm.

[0109] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0110] The adhesive product model LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the above-mentioned composite aluminum foil-CPP. The third adhesive layer was dried at 80°C for 1 minute to form a third adhesive layer with a thickness of 3µm.

[0111] After drying, the aluminum foil coated with adhesive is thermally bonded to the nylon surface of the previous composite structure at a temperature of 80°C.

[0112] Comparative Example 2

[0113] A method for preparing aluminum-plastic film is provided.

[0114] Mix 60 parts of passivating agent NRC#300 (Nippon Paint (Shanghai) Surface Treatment Agent Co., Ltd.), 20 parts of ethanol and 20 parts of water.

[0115] The diluted passivation solution was applied to both sides of a 40µm aluminum foil and baked at 250°C for 3 minutes.

[0116] The adhesive product XH-60W provided by Guangdong Xinhui Chemical Co., Ltd. was prepared according to the recommended ratio, and then coated onto the matte surface of the aluminum foil. The first adhesive layer was dried at 80°C for 1 minute, and the thickness of the first adhesive layer was 3µm.

[0117] After drying, the aluminum foil coated with adhesive is thermally laminated with 30µm CPP at a temperature of 80°C.

[0118] The adhesive product LN-1212 provided by Chengdu Kecheng Fine Chemical Technology Co., Ltd. was prepared according to the recommended ratio. After preparation, it was applied to the glossy side of the above-mentioned composite aluminum foil-CPP. The second adhesive layer was dried at 80°C for 1 minute to form a second adhesive layer with a thickness of 3µm.

[0119] After drying, the aluminum foil coated with adhesive is thermally laminated with nylon at a temperature of 80°C.

[0120] Table 1. Performance test results of aluminum-plastic films provided in Examples 1-5 and Comparative Examples 1-3

[0121]

[0122]

[0123] Specifically, compared to Comparative Example 1, the embodiment provided by this invention replaces the nylon layer composited with PET with a high-temperature resistant CPP layer. There are strong hydrogen bonds between the nylon molecular chains, which can effectively transfer and disperse tensile forces, so it has good toughness and is not easily deformed. On the other hand, the high-temperature resistant CPP film with added nanoparticles can act as physical cross-linking points during the elastic stretching stage, limiting the excessive movement of molecular chains, thereby narrowing the elastic range. Therefore, it is easier to reach the yield point and thus undergo plastic deformation. Moreover, the material will also relax stress over time, making the aluminum-plastic film more flat overall.

[0124] Specifically, compared to Comparative Example 2, the embodiment provided by this invention adds an additional PET layer. In this embodiment, the nylon film is replaced with a high-temperature resistant CPP film. Under normal conditions, the puncture resistance of the nylon film is generally superior to that of the high-temperature resistant CPP film. The strong hydrogen bonds in the molecular structure of the nylon film give it high crystallinity and good mechanical properties at room temperature, effectively resisting punctures. In contrast, the intermolecular forces of the CPP film at room temperature are relatively weak, and its crystallinity is relatively low, so its puncture resistance at room temperature may be slightly worse. Therefore, by replacing the nylon layer with a high-temperature resistant CPP film, an additional PET film is added. The PET molecular chain consists of rigid benzene rings and flexible ethylene glycol segments. This structure gives the PET film a certain degree of toughness and strength. Higher crystallinity can improve the puncture resistance of the PET film. The crystalline regions can enhance the intermolecular forces, and when subjected to puncture force, the crystalline parts can effectively disperse the stress. Therefore, this embodiment adds a PET layer to compensate for the insufficient puncture resistance resulting from replacing the nylon layer.

[0125] In summary, this high-flatness aluminum-plastic film and its preparation method, along with the lithium-ion battery, combine the characteristics of PET film and high-temperature resistant CPP film by incorporating a high-temperature resistant CPP layer containing homopolymer polypropylene resin, silica-doped POE resin, and aluminum nitride inorganic particles. This balances the mechanical strength of both, overcoming the warping defects of aluminum-plastic film. The resulting aluminum-plastic film achieves improved flatness while meeting requirements for deep-drawing performance, puncture resistance, and abrasion resistance, effectively ensuring the quality of heat sealing.

[0126] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A high-flatness aluminum-plastic film for stamping, characterized in that, include: The PET film, first adhesive layer, high-temperature resistant CPP layer, second adhesive layer, aluminum foil, third adhesive layer and CPP film are stacked in sequence. in The high-temperature resistant CPP layer comprises the following components in parts by weight: 80-90 parts of homopolymer polypropylene resin, 5-10 parts of silica-doped POE resin and 5-10 parts of aluminum nitride inorganic particles; The CPP membrane comprises the following components in parts by weight: 80-90 parts of ternary copolymer polypropylene resin, 5-10 parts of silica-doped POE resin, 2-8 parts of hyperbranched amide resin and 1-5 parts of slip masterbatch. The silica doping content in the silica-doped POE resin in the high-temperature resistant CPP layer is 3-10%. The aluminum nitride inorganic particles have a particle size of 50-100 nm.

2. The aluminum-plastic film with high flatness as described in claim 1, characterized in that, The melt flow rate of the homopolymer polypropylene resin is 16-18 g / 10min.

3. The aluminum-plastic film with high flatness as described in claim 1, characterized in that, The melt flow rate of the ternary copolymer polypropylene resin is 6-8 g / 10min.

4. The aluminum-plastic film with high flatness as described in claim 1, characterized in that, The thickness of the PET film is 10-15 μm; The thickness of the first adhesive layer, the second adhesive layer and the third adhesive layer is 3-5 μm.

5. The aluminum-plastic film with high flatness as described in claim 1, characterized in that, The aluminum foil has a thickness of 35-45μm, and after passivation treatment, the matte side of the aluminum foil is set on one side of the second adhesive layer, and the glossy side is set on one side of the third adhesive layer.

6. A method for preparing a high-flatness aluminum-plastic film for punching as described in any one of claims 1-5, characterized in that, Includes the following steps: Step S1: Coat both sides of the aluminum foil with an acid-resistant agent, passivate to form an acid-resistant film, let stand, and obtain an aluminum foil with a matte and glossy surface; Step S2: Apply polyurethane adhesive to one side of the PET film, heat it at high temperature to form the first adhesive layer, and then laminate it with the high temperature resistant CPP layer. Step S3: Apply polyurethane adhesive to the matte surface of the aluminum foil, heat it at high temperature to form a second adhesive layer, and then laminate it to the other side of the high-temperature resistant CPP layer. Step S4: Apply polyurethane adhesive to the glossy side of the aluminum foil, heat it at high temperature, and then laminate it with the corona-treated side of the CPP film.

7. A lithium-ion battery, characterized in that, The product is packaged in a soft package, and the packaging material is the high flatness aluminum-plastic film as described in any one of claims 1-5.

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