High performance composite film for drone battery packaging

Abstract

This invention relates to the field of drone battery packaging materials technology, and discloses a high-performance composite film for drone battery packaging. Specifically, it involves: preparing an alkynylated PA6 / PET composite resin using an epoxy compatibilizer, PA6, PET, and 3-bromopropyne as raw materials; performing melt grafting modification on LLDPE with tetramethyltetravinylcyclotetrasiloxane, then oxidizing the alkenyl functional groups to epoxy functional groups, and reacting with sodium azide to obtain an azide-modified polyethylene resin; reacting this polyethylene resin with the alkynylated PA6 / PET composite resin via a click reaction to obtain a PA6 / PET / LLDPE composite resin, which is then blow-molded to obtain a PA6 / PET / LLDPE composite film. The PA6 / PET / LLDPE composite film prepared by this invention possesses excellent mechanical properties and can be used as the outer layer of an aluminum-plastic film to prepare a high-performance composite film for packaging drone batteries, effectively reducing the production cost of the aluminum-plastic film.

Description

Technical Field

[0001] This invention relates to the field of drone battery packaging materials technology, and more particularly to high-performance composite films for drone battery packaging. Background Technology

[0002] With the widespread application of drone technology in surveying, agriculture, logistics, security and consumer entertainment, the performance and safety requirements of its core energy unit - battery pack - are increasing. Drone batteries are usually high-energy-density lithium-ion or lithium polymer batteries, and their characteristics determine that they have extremely stringent requirements for packaging materials.

[0003] Currently, the most common battery packaging material on the market is aluminum-plastic film, which has the following structure: outer layer (polyethylene terephthalate or polyamide), adhesive layer (polyurethane or modified polyethylene acrylic adhesive), barrier layer (aluminum foil), adhesive layer (polyurethane or modified polyethylene acrylic adhesive), and inner layer (cast polypropylene or modified polyethylene). Because batteries are frequently subjected to vibration, impact, and potential puncture risks during takeoff, landing, flight, and transportation of drones, the outer layer needs to provide comprehensive physical protection for the battery to resist mechanical stress during transportation, loading, unloading, and use.

[0004] However, PET (polyethylene terephthalate) in the outer layer has poor toughness, and PA6 (polyamide 6) has high raw material costs. LLDPE (linear low-density polyethylene) not only has high toughness, but also has lower raw material costs. Therefore, LLDPE is used to replace part of PET and PA6 in the outer layer structure design to improve the toughness of aluminum-plastic film and reduce production costs.

[0005] Studies have found that LLDPE, PET and PA6 have poor compatibility and are prone to phase separation, making it difficult to achieve good interfacial bonding. This leads to a decrease in the tensile strength, puncture resistance and other properties of the composite film. Summary of the Invention

[0006] To improve the compatibility among LLDPE, PET, and PA6, this invention designs and synthesizes alkynylated PA6 / PET composite resin and azidolated polyethylene resin. Through an azido-alkynyl "click" reaction, azidolated polyethylene resin is covalently grafted onto the alkynylated PA6 / PET composite resin to obtain PA6 / PET / LLDPE composite resin. Furthermore, through blow molding, a PA6 / PET / LLDPE composite film with excellent mechanical properties is obtained. Moreover, by replacing part of PET and PA6, the production cost of aluminum-plastic film is reduced.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-performance composite film for drone battery packaging, the preparation method of the high-performance composite film includes the following steps:

[0009] Step 1: Under the action of an initiator, LLDPE resin is melt-grafted and modified using tetramethyltetravinylcyclotetrasiloxane, and the alkenyl functional groups in LLDPE resin are oxidized into epoxy functional groups. Finally, a ring-opening reaction is carried out with sodium azide to obtain azide polyethylene resin.

[0010] Step 2: Under the action of cuprous halide, the alkynyl functional groups in the alkynylated PA6 / PET composite resin undergo a click reaction with the azide groups in the azidolated polyethylene resin, and the LLDPE resin is covalently grafted onto the PA6 / PET composite resin. Finally, the PA6 / PET / LLDPE composite film is obtained by blow molding.

[0011] Step 3: Composite the PA6 / PET / LLDPE composite film with the adhesive layer, barrier layer and inner layer to obtain a high-performance composite film.

[0012] Preferably, the preparation method of the acetylated PA6 / PET composite resin includes the following steps:

[0013] In-situ compatibilization of PA6 resin and PET resin was carried out using epoxy compatibilizer, followed by chain extension reaction, to prepare hydroxyl-functionalized PA6 / PET composite masterbatch.

[0014] Under the action of an alkaline catalyst, hydroxyl-functionalized PA6 / PET composite masterbatch undergoes a substitution reaction with 3-bromopropyne to obtain alkynylated PA6 / PET composite resin.

[0015] Preferably, the mass ratio of PA6 resin to PET resin in the hydroxyl-functionalized PA6 / PET composite masterbatch is 8:1-3; the amount of epoxy compatibilizer is 5-10% of the total mass of PA6 resin and PET resin.

[0016] Preferably, the epoxy compatibilizer is one of ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether.

[0017] Preferably, the alkaline catalyst is one of potassium hydroxide and sodium hydroxide.

[0018] Preferably, the initiator is one of dicumyl peroxide and tert-butyl peroxide.

[0019] Preferably, the cuprous halide is one of cuprous bromide, cuprous chloride, and cuprous iodide.

[0020] Preferably, the process parameters of the extruder used in the blow molding process are as follows: the barrel temperature in three zones is 210-230℃, 240-260℃, and 240-260℃; the die head temperature is 230-250℃; and the screw speed is 25-35 r / min.

[0021] Preferably, the mass ratio of alkynylated PA6 / PET composite resin to azidolated polyethylene resin in the PA6 / PET / LLDPE composite film is 75-85:15-25.

[0022] Preferably, the thickness of the PA6 / PET / LLDPE composite film is 10-25 μm.

[0023] The beneficial effects of this invention are as follows:

[0024] Based on the ring-opening and substitution reaction mechanism of epoxy, an alkynylated PA6 / PET composite resin was prepared using epoxy compatibilizer, PA6 resin, PET resin and 3-bromopropyne as raw materials.

[0025] Under the action of an initiator, LLDPE resin is melt-grafted and modified using tetramethyltetravinylcyclotetrasiloxane to introduce alkenyl functional groups into LLDPE resin and oxidize the alkenyl functional groups into epoxy functional groups. Finally, it is reacted with sodium azide through an epoxy ring-opening azidation reaction to obtain azidated polyethylene resin.

[0026] Based on the azido-alkynyl "click" reaction mechanism, PA6 / PET / LLDPE composite resin was prepared by using alkynylated PA6 / PET composite resin and azido-modified polyethylene resin as raw materials under the action of cuprous halide. Then, PA6 / PET / LLDPE composite film was prepared by blow molding process.

[0027] Experimental results demonstrate that the PA6 / PET / LLDPE composite film prepared by this invention achieves a significant improvement in toughness, and the composite film does not show a significant decrease in tensile strength and puncture resistance.

[0028] PA6 / PET / LLDPE composite film is laminated with adhesive layer, barrier layer and inner layer to prepare high-performance composite film for packaging drone batteries, and effectively reduces the production cost of aluminum-plastic film. Detailed Implementation

[0029] Example 1:

[0030] The preparation of acetylated PA6 / PET composite resin includes the following steps:

[0031] Step S1: Preparation of hydroxyl-functionalized PA6 / PET composite masterbatch. The preparation mechanism is as follows: the epoxy group in 1,4-butanediol diglycidyl ether undergoes a ring-opening reaction with the polar functional groups in the end groups of PA6 resin and PET resin molecular chains to obtain hydroxyl-functionalized PA6 / PET composite masterbatch. The specific experimental steps are as follows: 80g of PA6 resin (model F136 / NA99001 / 4229D), 20g of PET resin (brand name 70G43L) and 0.8g of 1,4-butanediol diglycidyl ether are added to a high-speed mixer and mixed for 5min. Then, the mixture is placed in an extruder for melt extrusion granulation. The screw speed of the extruder is 200r / min, the temperature of zone 1 is 230℃, the temperature of zone 2 is 240℃, the temperature of zone 3 is 250℃, and the temperature of zone 4 is 260℃ to obtain hydroxyl-functionalized PA6 / PET composite masterbatch.

[0032] Step S2: Preparation of alkynylated PA6 / PET composite resin. The preparation mechanism is as follows: the hydroxyl groups in the hydroxyl-functionalized PA6 / PET composite masterbatch undergo a substitution reaction with the bromine functional groups in 3-bromopropyne to obtain the alkynylated PA6 / PET composite resin. The specific experimental steps are as follows: Under nitrogen protection, 20g of hydroxyl-functionalized PA6 / PET composite masterbatch and 2.81g of potassium hydroxide were added to 100mL of dimethyl sulfoxide and stirred in an ice bath for 2h. Then, 5.95g of 3-bromopropyne was added. After the addition was complete, the system temperature was raised to 80℃ and the reaction was allowed to proceed for 20h. After the reaction was completed, the mixture was filtered, washed, and dried at 60℃ for 10h to obtain the alkynylated PA6 / PET composite resin.

[0033] Example 2:

[0034] The preparation of azide-modified polyethylene resin includes the following steps:

[0035] Step SS1: Preparation of polyethylene resin containing alkenyl functional groups. The preparation mechanism is as follows: Under the action of dicumyl peroxide initiator, LLDPE resin is melt-grafted and modified with tetramethyltetravinylcyclotetrasiloxane to obtain polyethylene resin containing alkenyl functional groups, which includes the following raw materials in parts by weight: 100 parts LLDPE resin (model 7042); 8 parts tetramethyltetravinylcyclotetrasiloxane; 0.1 parts dicumyl peroxide;

[0036] The preparation method of polyethylene resin containing alkenyl functional groups is as follows: LLDPE resin, tetramethyltetravinylcyclotetrasiloxane and dicumyl peroxide are added to a high-speed mixer and mixed evenly. The mixed material is then placed in a twin-screw extruder for melt extrusion granulation. The screw speed of the twin-screw extruder is 150 r / min, and the temperatures of zones 1-4 are 130℃, 150℃, 170℃ and 180℃, respectively, to obtain polyethylene resin containing alkenyl functional groups.

[0037] Step SS2: Preparation of polyethylene resin containing epoxy groups. The preparation mechanism is as follows: under the action of glacial acetic acid and hydrogen peroxide, the alkenyl functional groups in the polyethylene resin containing alkenyl functional groups are oxidized to epoxy functional groups to obtain polyethylene resin containing epoxy groups. The specific experimental steps are as follows: 20g of polyethylene resin containing alkenyl functional groups is added to 100mL of toluene, the temperature is raised to 80℃, and stirred until dissolved. 20mL of glacial acetic acid and 1mL of concentrated sulfuric acid are added, and the system temperature is controlled at 70℃. 40mL of 50% hydrogen peroxide is added dropwise, and the reaction is carried out for 8h. After the reaction is completed, the temperature is lowered to room temperature. The reaction solution is washed successively with sodium carbonate solution and deionized water. The solvent is removed by rotary evaporation and dried in a vacuum drying oven at 50℃ for 10h to obtain polyethylene resin containing epoxy groups.

[0038] Step SS3: Preparation of azido-modified polyethylene resin. The preparation mechanism is as follows: using epoxy-containing polyethylene resin and sodium azide as raw materials, azido-modified polyethylene resin is obtained through an epoxy ring-opening azido reaction. The specific experimental steps are as follows: 20g of epoxy-containing polyethylene resin and 100mL of toluene are added to a 250mL round-bottom flask. The temperature is raised to 80℃ and stirred until dissolved. 20mL of deionized water containing 1.2g of sodium azide and 0.1g of ammonium chloride is added. The mixture is mechanically stirred until homogeneous and reacted at 50℃ for 48h. After the reaction is completed, the solvent is removed by rotary evaporation, washed, and vacuum dried at 50℃ for 10h to obtain azido-modified polyethylene resin.

[0039] Example 3:

[0040] PA6 / PET / LLDPE composite film I is prepared, comprising the following raw materials in parts by weight:

[0041] 80 parts of acetylated PA6 / PET composite resin;

[0042] 20 parts of azide-modified polyethylene resin;

[0043] 4.6 parts cuprous bromide;

[0044] 5.6 parts of N,N,N',N'',N''-pentamethyldivinyltriamine;

[0045] 60 parts of N,N-dimethylformamide;

[0046] The preparation method of PA6 / PET / LLDPE composite film I includes the following steps: adding alkynylated PA6 / PET composite resin and azidolated polyethylene resin to N,N-dimethylformamide, ultrasonically dispersing them evenly, adding cuprous bromide and N,N,N',N'',N''-pentamethyldivinyltriamine, mixing evenly, cycling the system through freezing-vacuuming-thawing three times, sealing under vacuum, reacting at 60°C for 2 hours, cooling to room temperature after the reaction, filtering, and vacuum drying to obtain PA6 / PET / LLDPE composite resin;

[0047] PA6 / PET / LLDPE composite resin was added to an extruder for blow molding. The extruder process parameters were as follows: barrel temperature in three zones: 220℃, 250℃, 250℃; die head temperature: 240℃; screw speed: 30r / min. A PA6 / PET / LLDPE composite film I with a thickness of 20μm was obtained.

[0048] Example 4:

[0049] PA6 / PET / LLDPE composite film II comprises the following raw materials in parts by weight: 85 parts alkynylated PA6 / PET composite resin; 15 parts azidolated polyethylene resin;

[0050] The only difference between the preparation process of PA6 / PET / LLDPE composite film II and PA6 / PET / LLDPE composite film I is that the raw material formulation of PA6 / PET / LLDPE composite film II is used instead of that of PA6 / PET / LLDPE composite film I.

[0051] Example 5:

[0052] PA6 / PET / LLDPE composite film III comprises the following raw materials in parts by weight: 75 parts alkynylated PA6 / PET composite resin; 25 parts azidolated polyethylene resin;

[0053] The only difference between the preparation process of PA6 / PET / LLDPE composite film III and that of PA6 / PET / LLDPE composite film I is that the raw material formulation of PA6 / PET / LLDPE composite film III is used instead of that of PA6 / PET / LLDPE composite film I.

[0054] Comparative example:

[0055] PA6 / PET composite film comprises the following raw materials in parts by weight: 50 parts PA6 resin (model F136 / NA99001 / 4229D) and 50 parts PET resin (grade 70G43L).

[0056] The only difference between the preparation process of PA6 / PET composite film and that of PA6 / PET / LLDPE composite film I is that the raw material formulation of PA6 / PET composite film is used instead of that of PA6 / PET / LLDPE composite film I.

[0057] Performance testing:

[0058] I. Tensile strength and elongation at break: The tensile strength and elongation at break of PA6 / PET / LLDPE composite film were tested according to GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets". The length of the PA6 / PET / LLDPE composite film sample was 200 mm and the width was 20 mm. The tensile speed was 200 mm / min.

[0059] II. Puncture resistance: The puncture resistance of PA6 / PET / LLDPE composite film was tested according to GB / T 37841-2019 "Test method for puncture resistance of plastic films and sheets". The size of the PA6 / PET / LLDPE composite film sample was 100mm×100mm, and the puncture speed was 50mm / min.

[0060] The test results are shown in Table 1 below;

[0061] Table 1 Performance test results of PA6 / PET / LLDPE composite film

[0062]

[0063] The experimental results in Table 1 show that:

[0064] The PA6 / PET / LLDPE composite film prepared by this invention achieves a significant improvement in toughness, while its mechanical properties (tensile strength and puncture resistance) do not decrease significantly.

Claims

1. A high-performance composite film for drone battery packaging, characterized in that, The method for preparing the high-performance composite film includes the following steps: Step 1: Under the action of an initiator, LLDPE resin is melt-grafted and modified using tetramethyltetravinylcyclotetrasiloxane, and the alkenyl functional groups in LLDPE resin are oxidized into epoxy functional groups. Finally, a ring-opening reaction is carried out with sodium azide to obtain azide polyethylene resin. Step 2: Under the action of cuprous halide, the alkynyl functional groups in the alkynylated PA6 / PET composite resin undergo a click reaction with the azide groups in the azidolated polyethylene resin, and the LLDPE resin is covalently grafted onto the PA6 / PET composite resin. Finally, the PA6 / PET / LLDPE composite film is obtained by blow molding. Step 3: Composite the PA6 / PET / LLDPE composite film with the adhesive layer, barrier layer and inner layer to obtain a high-performance composite film.

2. The high-performance composite film for drone battery packaging according to claim 1, characterized in that, The preparation method of the acetylated PA6 / PET composite resin includes the following steps: In-situ compatibilization of PA6 resin and PET resin was carried out using epoxy compatibilizer, followed by chain extension reaction, to prepare hydroxyl-functionalized PA6 / PET composite masterbatch. Under the action of an alkaline catalyst, hydroxyl-functionalized PA6 / PET composite masterbatch undergoes a substitution reaction with 3-bromopropyne to obtain alkynylated PA6 / PET composite resin.

3. The high-performance composite film for drone battery packaging according to claim 2, characterized in that, The mass ratio of PA6 resin to PET resin in the hydroxyl-functionalized PA6 / PET composite masterbatch is 8:1-3; the amount of epoxy compatibilizer is 5-10% of the total mass of PA6 resin and PET resin.

4. The high-performance composite film for drone battery packaging according to claim 2, characterized in that, The epoxy compatibilizer is one of ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and 1,4-butanediol diglycidyl ether.

5. The high-performance composite film for drone battery packaging according to claim 2, characterized in that, The alkaline catalyst is one of potassium hydroxide and sodium hydroxide.

6. The high-performance composite film for drone battery packaging according to claim 1, characterized in that, The initiator is one of dicumyl peroxide and tert-butyl peroxide.

7. The high-performance composite film for drone battery packaging according to claim 1, characterized in that, The cuprous halide is one of cuprous bromide, cuprous chloride, and cuprous iodide.

8. The high-performance composite film for drone battery packaging according to claim 1, characterized in that, The process parameters of the extruder used in the blow molding process are as follows: the temperature of the three zones of the barrel is 210-230℃, 240-260℃, and 240-260℃; the temperature of the die head is 230-250℃; and the screw speed is 25-35 r / min.

9. The high-performance composite film for drone battery packaging according to claim 1, characterized in that, The mass ratio of alkynylated PA6 / PET composite resin to azidolated polyethylene resin in the PA6 / PET / LLDPE composite film is 75-85:15-25.

10. The high-performance composite film for drone battery packaging according to any one of claims 1-9, characterized in that, The thickness of the PA6 / PET / LLDPE composite film is 10-25 μm.

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