A kind of high temperature resistant CPP for aluminum plastic film and its production method

Abstract

The present invention relates to the technical field of battery packaging materials, and in particular to a high-temperature resistant CPP for aluminum-plastic film and a production method thereof. The high-temperature resistant CPP for aluminum-plastic film provided by the present invention comprises a heat-sealing layer, a first adhesive layer, a core layer, a second adhesive layer and a composite layer arranged in sequence; polypropylene is used as the main component and is matched with a high-melting-point functional resin for multi-layer co-extrusion casting; through the design of the materials of each layer, a compatibilizer and an adhesive layer are added to form a high-temperature resistant CPP film by co-extrusion casting, which breaks through the temperature resistance of the original polypropylene pure material. When used in the situations of high-temperature heat sealing, long-term electrolyte immersion, high charging rate and high heat generation, it can maintain high heat sealing strength and heat peeling performance requirements, has excellent insulation and does not produce stress whitening, and is suitable for high-rate and high-heat applications such as power vehicle batteries; the production method provided by the present invention is produced through multi-layer co-extrusion casting, is simple to manufacture, low in cost, and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the technical field of battery packaging materials, in particular to a high-temperature resistant CPP for aluminum-plastic film and a production method thereof. Background Art

[0002] Aluminum-plastic film for lithium-ion battery flexible packaging is a composite flexible packaging material consisting of a base material (such as BOPA), aluminum foil, a sealing layer (such as CPP), and an adhesive. As a lithium battery packaging material, the film must possess excellent heat-sealing properties, insulation, mechanical strength, and ductility. It must also provide a barrier to moisture and oxygen, as well as high chemical stability against corrosive acids, alkalis, and salts within the battery. As the inner layer of the film, CPP's core requirements are to provide both sealing and insulation.

[0003] In the three-layer aluminum-plastic film structure, nylon has a melting point of around 220°C, while aluminum foil has a heat resistance of over 600°C. The heat-sealing layers and composite layer of CPP are made of binary or ternary random copolymer polypropylene, with a melting point of 125-145°C. The core layer is homopolymer polypropylene or block copolymer polypropylene, with a melting point of 155-165°C. CPP has the lowest heat resistance and is the weakest link in the three-layer structure, affecting the overall sealing performance of the film.

[0004] Soft-package battery failure primarily occurs at the seal, making the seal strength at this location a critical parameter during long-term use or storage. Experimental studies have shown that heat seal strength is significantly dependent on the heat seal temperature. Furthermore, compared to low-temperature heat seals, the seal strength of aluminum-plastic film heat-sealed at high temperatures remains higher in an electrolyte environment. Furthermore, when the aluminum-plastic film and metal electrode sheet are heat-sealed under pressure, if the CPP (carbonized plastic composite) as the inner layer of the film lacks a high-temperature insulating layer, the metal electrode is often pressed against the aluminum foil, causing a short circuit and rendering the battery useless. Finally, in the application of soft-package lithium batteries, particularly power batteries, the thermal peel strength of the aluminum foil and CPP at 120°C must be as high as possible to cope with high-rate and high-heat generation scenarios.

[0005] Currently, there are no effective solutions for improving the high-temperature resistance of CPP. For example, patent CN112918054A discloses adding 5-10 parts by mass of silicon nitride to the C layer of CPP to improve its heat resistance and alleviate the problem of deformation caused by high temperatures. For example, CN20872292U discloses adding a high-temperature insulating layer between the aluminum foil and the insulation layer. This layer can withstand temperatures of 200°C, preventing the risk of aluminum foil exposure and insulation protection failure, greatly improving the insulation and safety of the aluminum-plastic film. For example, CN116254069A discloses filling the adhesive layer between the heat-sealing layer and the aluminum foil with an insulating inorganic filler to prevent overmelting and foreign object penetration. None of the above existing technologies truly address improving high-temperature heat sealing and heat peeling performance.

[0006] In view of this, the present application aims to provide a high-temperature resistant CPP for aluminum-plastic film and a production method thereof, so as to better solve the above technical problems. Summary of the Invention

[0007] To solve the above problems, the present invention provides a high-temperature resistant CPP for aluminum-plastic film and a production method thereof. The CPP is mainly composed of polypropylene and is combined with a high-melting-point functional resin for multi-layer co-extrusion casting. By selecting and designing the melting point of polypropylene and the high-temperature resin of each layer material, and assisting with a compatibilizer and an adhesive layer, a high-temperature resistant CPP film is formed by co-extrusion casting. It breaks through the temperature resistance of the original polypropylene pure material. When used in the situations of high-temperature heat sealing, long-term electrolyte immersion, high charge rate and high heat generation, it can maintain high heat sealing strength and heat peeling performance requirements, excellent insulation and no stress whitening. In addition, the CPP is produced by multi-layer co-extrusion casting, which is simple to manufacture, low cost, and environmentally friendly.

[0008] The technical solution adopted in the present invention is:

[0009] A high-temperature resistant CPP for aluminum-plastic film, the CPP having a five-layer structure consisting of a heat-sealing layer, a first adhesive layer, a core layer, a second adhesive layer and a composite layer arranged in sequence;

[0010] The heat-sealing layer is made of a blend of ternary random copolymer polypropylene, homopolymer polypropylene (homo-PP) and open and smooth masterbatch;

[0011] Wherein, the core layer is made of a blend of block copolymer polypropylene (block-PP), thermoplastic polyester elastomer and maleic anhydride modified styrene elastomer;

[0012] Wherein, the composite layer is made of a blend of high melting point binary random copolymer polypropylene (rPP) and high melting point maleic anhydride modified polypropylene;

[0013] Wherein, the first adhesive layer and the second adhesive layer are respectively made of a single maleic anhydride modified polypropylene (MAH-g-PP) or a multi-component adhesive containing maleic anhydride modified polypropylene.

[0014] Furthermore, the total thickness of the CPP is set to 25um to 80um, wherein the layer ratio of the heat sealing layer, the first adhesive layer, the core layer, the second adhesive layer and the composite layer is set to 1:0.5:3:0.5:1 to 1:0.5:6:0.5:1.

[0015] Furthermore, the melting point of the ternary random copolymer polypropylene is greater than 128°C, the melt index is 3 to 10 g / 10 min (230°C / 2.16 kg), and the melt index is preferably 5 to 8 g / 10 min; the melting point of the selected homopolypropylene (homo-PP) is ≥165°C, and the melt index is 7 to 10 g / 10 min; the selected open and smooth masterbatch contains erucamide with a molecular weight of 9000 to 15000 and a content of 400 to 800 ppm. In the mixture, the high-melting-point ternary random PP is the main component, and the homopolypropylene (homo-PP) is used as a supplement to further improve the melting point of the blend, thereby improving the temperature resistance of the entire heat-sealing layer, adapting to heat sealing under higher temperature conditions, and moderately enhancing the heat-sealing strength as the heat-sealing temperature increases.

[0016] Furthermore, the homopolymer polypropylene (homo-PP) accounts for 5% to 25%, preferably 10% to 20%. If the proportion of homo-PP is further increased, the heat seal layer will become harder, and stress whitening and cracking will occur during deep punching; the smooth masterbatch accounts for 4% to 6%;

[0017] Furthermore, the block copolymer polypropylene (block-PP) has a melt index of 2 to 5 g / 10 min and a melting point of 160 to 167°C; the thermoplastic polyester elastomer is a block copolymer containing a polyester hard segment or a polyether hard segment, with a melt index of 5 to 15 g / 10 min (230°C / 2.16 kg), preferably 8 to 12 g / 10 min, a Shore hardness of ≤ 45D, and a melting point of ≥ 190°C. The higher melting point allows the core layer of the CPP to participate less in the heat sealing process during heat sealing, resulting in a high CPP retention rate and an effective insulation effect; the grafting rate of the maleic anhydride modified styrene elastomer is The styrene content is between 0.5% and 2%, the styrene content is between 65% and 85%, the melt index is between 5 and 15 g / 10 min (200°C / 2.16 kg), and the Shore hardness is between 40 and 80 A. Similarly, the mixture used in this layer is mainly composed of high-melting point block-PP supplemented by high-temperature resistant thermoplastic polyester elastomer, which greatly improves the temperature resistance of the core layer. The addition of maleic anhydride-modified styrene elastomer, on the one hand, acts as a compatibilizer to combine the other block-PP and thermoplastic polyester elastomer together, and on the other hand, acts as an elastomer to toughen the blend and avoid CPP stress whitening during deep punching of the aluminum-plastic film.

[0018] Furthermore, the thermoplastic polyester elastomer in the blend used in the CPP core layer accounts for 15% to 45%, preferably 25% to 35%. If the proportion is too low, the temperature resistance will not be significantly improved. If the proportion is too high, the blend will be difficult to process, and wavy lines will appear on the film surface, which cannot be improved by a compatibilizer. The maleic anhydride-modified styrene elastomer accounts for 10% to 20%.

[0019] Furthermore, the melting point range of the high melting point binary random copolymer polypropylene is 145°C to 155°C, and the melt index is 5 to 10 g / 10 min (230°C / 2.16 kg); the high melt index maleic anhydride modified polypropylene has a melt index of 80 to 200 g / 10 min (190°C / 2.16 kg), preferably 120 to 150 g / 10 min. Its own polarity and good fluidity play an activation role, thereby improving the thermal peeling performance of the composite layer.

[0020] Furthermore, the proportion of maleic anhydride-modified polypropylene in the blend is 20% to 70%, with a lower proportion being used when producing dry-process CPP and a higher proportion being used when producing hot-process CPP; if the proportion is too low, the thermal peelability will not be sufficiently improved, and if the proportion is too high, the film cannot be cast due to excessive fluidity.

[0021] Furthermore, the maleic anhydride-modified polypropylene has a grafting rate of 1% to 2%, a melting point ≥145°C, a melt index of 2 to 15 g / 10 min (230°C / 2.16 kg), and preferably 5 to 12 g / 10 min. The first adhesive layer and the second adhesive layer can be made of a single MAH-g-PP or a combination adhesive containing multiple components of MAH-g-PP. The two adhesive layers can be extruded by the same extruder or by two extruders in a distributed manner.

[0022] Based on the same inventive concept, the present application also provides a method for preparing the above-mentioned high-temperature resistant CPP for aluminum-plastic film, comprising the following preparation steps:

[0023] S1 according to the weight ratio of the raw materials were mixed to prepare the heat seal layer, the first adhesive layer, the core layer, the second adhesive layer and the composite layer;

[0024] S2. The raw materials of the heat-sealing layer, the first adhesive layer, the core layer, the second adhesive layer, and the composite layer are fed into the corresponding extruder of a five-layer co-extrusion casting machine. After setting the thickness ratio of the five layers and the extruder temperature, a film is formed by a co-extrusion casting process. The film is then corona treated using a corona machine to obtain a high-temperature resistant CPP for aluminum-plastic film.

[0025] The beneficial effects of the present invention are as follows:

[0026] 1. The present invention provides a high-temperature resistant CPP for aluminum-plastic film. The CPP has a five-layer structure consisting of a heat-sealing layer, a first adhesive layer, a core layer, a second adhesive layer, and a composite layer arranged in sequence. The CPP is mainly composed of polypropylene and a high-melting-point functional resin for multi-layer co-extrusion casting. By selecting and designing the melting point of polypropylene and the high-temperature resin in each layer, and supplemented by a compatibilizer and an adhesive layer, the high-temperature resistant CPP film is formed by co-extrusion casting. This surpasses the heat resistance of the original polypropylene pure material. When used in high-temperature heat sealing, long-term electrolyte immersion, high charge rate, and high heat generation situations, it can maintain high heat seal strength and heat peel performance requirements, has excellent insulation properties, and does not produce stress whitening. The high-temperature resistant CPP provided by the present invention has higher heat seal strength, sealing performance, heat peel performance, and insulation performance, and is suitable for high-rate and high-heat applications such as power vehicle batteries.

[0027] 2. The production method provided by the present invention is produced through multi-layer co-extrusion casting, which is simple to make, low in cost and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a schematic flow chart of the production method of the high temperature resistant CPP for aluminum plastic film of the present invention. DETAILED DESCRIPTION

[0029] To facilitate understanding of the present invention, the present invention will be described more fully below through examples, with preferred embodiments of the present invention provided below. However, the present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. Any other embodiments obtained by modifying or equivalently replacing the technical solution of the present invention without inventive results are within the scope of protection of the present invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0031] The numerical values ​​disclosed in the embodiments of the present invention are approximate values, not definite values. Where errors or experimental conditions permit, all values ​​within the error range may be included without being limited to the specific numerical values ​​disclosed in the embodiments of the present invention.

[0032] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0033] Example 1

[0034] The method for producing high-temperature resistant CPP for aluminum-plastic film provided in this embodiment comprises the following steps:

[0035] S1 according to the weight ratio of the raw materials were mixed to prepare the heat seal layer, the first adhesive layer, the core layer, the second adhesive layer and the composite layer;

[0036] Specifically, the heat seal layer is prepared using 80% low-melting-point ternary random copolymer polypropylene, 15% homopolymer polypropylene, and 5% slip masterbatch. The ternary random copolymer polypropylene (Lotte Chemical SFI-841) has a melting point of 130°C and a melt index of 5.5g / min; the homopolymer polypropylene (Borouge Chemical HD915CF) has a melting point of 167°C and a melt index of 8g / min.

[0037] Made of 55% block copolymer polypropylene (Formosa Plastics 3015S), 30% polyester elastomer (Chenguang Kexin The core layer is prepared by mixing 15% maleic anhydride-modified styrene elastomer (TPEE H2040) with a polyester elastomer melt index of 9 g / min, a hardness of 40D, and a melting point of 192°C; and a maleic anhydride-modified styrene elastomer (Kraton FG1901) with a grafting rate of 1.7%, a styrene content of 70%, a melt index of 5 g / min, and a Shore hardness of 75A.

[0038] The composite layer was prepared by using 65% high melting point binary random copolymer polypropylene and 35% high melt index maleic anhydride modified polypropylene, wherein the high melting point binary random copolymer polypropylene (Singapore TPC Company W331) has a melting point of 151°C and a melt index of 7g / min; the high melt index maleic anhydride modified polypropylene (Ruicheng Polymer P-800) has a grafting rate of 1% and a melt index of 100g / min;

[0039] The maleic anhydride-modified polypropylene (Mitsui Chemicals AT3177E) of the first and second adhesive layers has a grafting rate of 1%, a melting point of 149° C., and a melt index of 6.5 g / min.

[0040] S2. Blend the raw materials of the heat-sealing layer, core layer, composite layer and adhesive layer according to the above-mentioned required proportions according to the weight ratio, and put them into the corresponding extruder of the five-layer co-extrusion casting machine (layer structure is ADBDC). Set the thickness ratio of the three layers to 1:0.5:6:0.5:1, set the temperature of extruder B to 265°C, and set the temperature of other extruders to 235°C. Prepare an 80um CPP film through the co-extrusion casting process, and use a corona machine to treat the composite layer. The surface tension of the composite layer under the machine is ≥42dyn.

[0041] Example 2

[0042] The difference between this embodiment and embodiment 1 is that:

[0043] The core layer is prepared by using 65% block copolymerized polypropylene, 20% polyester elastomer and 15% maleic anhydride modified styrene elastomer.

[0044] Example 3

[0045] The difference between this embodiment and embodiment 1 is that:

[0046] The core layer is prepared by using 45% block copolymerized polypropylene, 40% polyester elastomer and 15% maleic anhydride modified styrene elastomer.

[0047] Example 4

[0048] The difference between this embodiment and embodiment 1 is that:

[0049] The composite layer is prepared by using 50% high melting point binary random copolymer polypropylene and 50% high melting index maleic anhydride modified polypropylene.

[0050] Example 5

[0051] The difference between this embodiment and embodiment 1 is that:

[0052] The composite layer is prepared by using 35% high melting point binary random copolymer polypropylene and 65% high melting index maleic anhydride modified polypropylene.

[0053] Comparative Example 1

[0054] In this comparative example, 90% of low melting point ternary random copolymer polypropylene and 5% of smooth masterbatch were used to prepare the heat seal layer, and the other layers were the same as those in Example 1.

[0055] Comparative Example 2

[0056] In this comparative example, 85% block copolymerized polypropylene and 15% ethylene propylene elastomer (commercially available) were used to prepare the core layer. The remaining layers were the same as those in Example 1.

[0057] Comparative Example 3

[0058] In this comparative example, pure binary random copolymer polypropylene (commercially available) was used to prepare the composite layer. The remaining layers were the same as those in Example 1.

[0059] Performance testing:

[0060] The CPP films in Examples 1 to 5 and Comparative Examples 1 to 3 were made into aluminum-plastic films (aluminum foil layer thickness 40 μm, nylon layer thickness 25 μm), and subjected to heat seal strength testing (including high temperature), CPP retention rate calculation, hot peel strength evaluation, and deep drawing performance testing.

[0061] The test method is as follows:

[0062] 1. Heat seal strength test: The test was conducted in accordance with 6.13.3 of TCIAPS0005-2018, with the heat seal temperature set at 180°C (normal) and 210°C (high), the heat seal pressure at 0.3 MPa, and the heat seal time at 3 seconds.

[0063] 2. Calculation of CPP retention rate: Calculate the change rate of two layers of CPP before and after heat sealing under double heat sealing conditions. Retention rate = CPP thickness after heat sealing / CPP thickness before heat sealing;

[0064] 3. Thermal peel strength test: The composite aluminum-plastic film sample is immersed in an electrolyte at 120°C for 24 hours (in a sealed container). After the sample is taken out, the composite peel strength of the CPP and aluminum foil layer is quickly tested using a tensile testing machine.

[0065] 4. Deep impact performance test: A deep impact tester is used to test the deep impact performance of the aluminum-plastic film and evaluate the deep impact resistance of the CPP film. The impact depth is 8mm, and stress whitening and cracking are observed. Five groups of samples are tested each time.

[0066] The test results are shown in the following table:

[0067]

[0068] From the test results in the above table, it can be seen that the aluminum-plastic film made of high-temperature resistant CPP produced in the embodiment of the present application has a high heat sealing strength compared with the conventional formula design, because the main raw material of the heat sealing layer of the high-temperature resistant CPP is a high melting point and a homopolymer PP with a higher melting point is added. The heat sealing strength is further improved at a higher heat sealing temperature, and the retention is excellent under the condition of immersion in electrolyte; and because the core layer is added with a high-temperature resistant polyester elastomer, the CPP retention rate is high after heat sealing, indicating that the CPP core layer participates in the heat sealing and the flow is reduced during heat sealing, which greatly enhances the heat resistance and insulation performance of the CPP; and the addition of high-melting-index maleic anhydride-modified polypropylene in the composite layer has higher polarity and fluidity, which enhances the high-temperature thermal peeling performance, and the deep punching performance is not inferior to that of conventional CPP, and the formed aluminum-plastic film is suitable for punching and forming.

[0069] In summary, the high-temperature resistant CPP for aluminum-plastic film provided by the present invention has a five-layer structure consisting of a heat-sealing layer, a first adhesive layer, a core layer, a second adhesive layer and a composite layer arranged in sequence; the CPP is mainly composed of polypropylene and a high-melting-point functional resin for multi-layer co-extrusion casting. By selecting and designing the melting point of polypropylene and the high-temperature resin of each layer material and the proportion, and supplemented by a compatibilizer and an adhesive layer, a high-temperature resistant CPP film is formed by co-extrusion casting, which breaks through the temperature resistance of the original polypropylene pure material. When used in the situations of high-temperature heat sealing, long-term electrolyte immersion, high charging rate and high heat generation, it can maintain high heat sealing strength and heat peeling performance requirements, excellent insulation and no stress whitening. The high-temperature resistant CPP provided by the present invention has higher heat sealing strength, sealing performance, heat peeling performance and insulation performance, and is suitable for high-rate and high-heat applications such as power vehicle batteries; and it is produced by multi-layer co-extrusion casting, which is simple to manufacture, low cost and environmentally friendly.

[0070] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high temperature resistant CPP for aluminum plastic film, characterized in that: The CPP is a five-layer structure consisting of a heat-sealing layer, a first adhesive layer, a core layer, a second adhesive layer and a composite layer arranged in sequence; The heat sealing layer is made of a blend of ternary random copolymer polypropylene, homopolymer polypropylene and open and smooth masterbatch; Wherein, the core layer is made of a blend of block copolymerized polypropylene, thermoplastic polyester elastomer and maleic anhydride modified styrene elastomer; Wherein, the composite layer is made of a blend of high melting point binary random copolymer polypropylene and high melting point maleic anhydride modified polypropylene; Wherein, the first adhesive layer and the second adhesive layer are respectively made of a single maleic anhydride modified polypropylene, or made of a multi-component adhesive containing maleic anhydride modified polypropylene; The melting point of the ternary random copolymer polypropylene is greater than 128°C; The melting point of the homopolypropylene is greater than 165°C; The block copolymer polypropylene has a melting point of 160-167°C; The melting point range of the high melting point binary random copolymer polypropylene is 145°C to 155°C; In the blend of the ternary random copolymer polypropylene, homopolymer polypropylene and open-mouthed smooth masterbatch, the weight proportion of homopolymer polypropylene is 5% to 25%, and the weight proportion of open-mouthed smooth masterbatch is 4% to 6%; In the blend of block copolymerized polypropylene, thermoplastic polyester elastomer and maleic anhydride modified styrene elastomer, the weight proportion of thermoplastic polyester elastomer is 15% to 45%, and the weight proportion of maleic anhydride modified styrene elastomer is 10% to 20%. In the blend of high melting point binary random copolymer polypropylene and high melt index maleic anhydride modified polypropylene, the weight proportion of high melt index maleic anhydride modified polypropylene is 20% to 70%; The high melt index maleic anhydride modified polypropylene has a melt index of 80-200 g / 10 min at 190° C. / 2.16 kg.

2. The high temperature resistant CPP for aluminum plastic film according to claim 1, characterized in that: The total thickness of the CPP is set to 25um~80um, wherein the thickness ratio of the heat sealing layer, the first adhesive layer, the core layer, the second adhesive layer and the composite layer is set to 1:0.5:3:0.5:1 to 1:0.5:6:0.5:

1.

3. The high temperature resistant CPP for aluminum plastic film according to claim 1, characterized in that: The melt index of the ternary random copolymer polypropylene at 230°C / 2.16 kg is 3-10 g / 10 min; the melt index of the homopolymer polypropylene is 7-10 g / 10 min; the open and smooth masterbatch contains erucamide with a molecular weight of 9,000-15,000 and a content of 400-800 ppm.

4. The high temperature resistant CPP for aluminum plastic film according to claim 1, characterized in that: The melt index of the block copolymer polypropylene is 2-5 g / 10min; the thermoplastic polyester elastomer is a block copolymer containing a polyester hard segment or a polyether hard segment, with a melt index of 5-15 g / 10min at 230°C / 2.16Kg, a Shore hardness of ≤45D, and a melting point of ≥190°C; the maleic anhydride-modified styrene elastomer has a grafting rate of 0.5%-2%, a styrene content of 65%-85%, a melt index of 5-15 g / 10min at 200°C / 2.16Kg, and a Shore hardness of 40-80A.

5. The high temperature resistant CPP for aluminum plastic film according to claim 1, characterized in that: The high melting point binary random copolymer polypropylene has a melt index of 5-10 g / 10 min at 230° C. / 2.16 kg.

6. The high temperature resistant CPP for aluminum plastic film according to claim 1, characterized in that: The maleic anhydride modified polypropylene of the first adhesive layer and the second adhesive layer has a grafting rate of 1% to 2%, a melting point of ≥145° C., and a melt index of 2 to 15 g / 10 min at 230° C. / 2.16 kg.

7. The method for preparing a high temperature resistant CPP for aluminum plastic film according to any one of claims 1 to 6, characterized in that: The method comprises the following preparation steps: S1 according to the weight ratio of the raw materials were mixed to prepare the heat seal layer, the first adhesive layer, the core layer, the second adhesive layer and the composite layer; S2. The raw materials of the heat-sealing layer, the first adhesive layer, the core layer, the second adhesive layer, and the composite layer are fed into the corresponding extruder of a five-layer co-extrusion casting machine. After setting the thickness ratio of the five layers and the extruder temperature, a film is formed by a co-extrusion casting process. The film is then corona treated using a corona machine to obtain a high-temperature resistant CPP for aluminum-plastic film.

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