High-barrier al-plastic film and preparation method thereof

Abstract

The application belongs to the technical field of battery packaging materials, and specifically provides a high-barrier aluminum plastic film and a preparation method thereof. The high-barrier aluminum plastic film comprises a nylon film layer, an outer adhesive layer, a modified aluminum foil layer, a modified inner adhesive layer and a modified heat-sealing layer which are stacked in sequence; the modified aluminum foil layer is prepared by coating an aluminum foil with polyvinyl alcohol, a silane coupling agent and nano-magnesium oxide; the modified inner adhesive layer is prepared by mixing modified chlorinated polypropylene and composite aerogel; and the modified heat-sealing layer is prepared by casting a film from polypropylene and self-repairing microcapsules. The high-barrier aluminum plastic film prepared by the application has the advantages of high barrier property and peel resistance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery packaging materials, and particularly relates to a high-barrier aluminum-plastic film and a preparation method thereof. BACKGROUND

[0002] As an important material for packaging soft-packaged lithium battery cells, the aluminum-plastic film is widely used in lithium battery product packaging due to its advantages of light weight, thin thickness, flexible design, and 360-degree arbitrary placement of the soft-packaged battery. However, the aluminum-plastic film as a packaging material needs to be in contact with electrolyte for a long time. Organic solvents such as ethylene carbonate and dimethyl carbonate in the electrolyte decompose under high pressure, high temperature or overcharging conditions to generate a large amount of gas, which causes the aluminum-plastic film to expand and rupture due to the inability to withstand excessive internal pressure. Meanwhile, LiPF6 in the electrolyte is prone to hydrolysis to produce HF, which corrodes the bonding interface of the heat-sealing layer / aluminum foil layer, destroys the bonding interface between the heat-sealing layer and the aluminum foil layer, and reduces the peeling force of the heat-sealing layer / aluminum foil layer, and even causes delamination of the heat-sealing layer and the aluminum foil layer.

[0003] To solve the above problems, the number of layers of the aluminum-plastic film is generally increased, a protective layer is coated on the aluminum foil layer, and the adhesive is modified to improve the barrier property of the aluminum-plastic film. For example, the patent application with the application publication number CN114665198A discloses a lithium-ion battery resistant to electrolyte, a preparation method thereof, and a lithium-ion battery. The electrolyte-resistant aluminum-plastic film includes a heat-resistant resin layer, an aluminum foil layer, a thermoplastic resin layer, and a neutralization reaction layer. The neutralization reaction layer is composed of an amine-based compound and a thermoplastic resin, is arranged inside the thermoplastic resin layer or on the surface of the thermoplastic resin layer away from the aluminum foil layer, and has a thickness of 10-40 microns. The prepared aluminum-plastic film has high-temperature electrolyte resistance.

[0004] In the above document, the neutralization reaction layer is arranged, and an amine-based compound is added to neutralize lithium hexafluorophosphate in the electrolyte under high-temperature conditions to generate hydrofluoric acid, thereby inhibiting the corrosion of the aluminum-plastic film by the hydrofluoric acid and improving the overall high-temperature electrolyte resistance of the aluminum-plastic film. However, the problem of expansion and rupture of the aluminum-plastic film due to gas generation caused by decomposition of the electrolyte under high pressure, high temperature or overcharging conditions has not been solved. SUMMARY

[0005] To further improve the barrier property of the aluminum-plastic film, the application provides a high-barrier aluminum-plastic film and a preparation method thereof.

[0006] The application first provides a high-barrier aluminum-plastic film, which includes a nylon film layer, an outer adhesive layer, a modified aluminum foil layer, a modified inner adhesive layer, and a modified heat-sealing layer arranged in sequence from the outside to the inside.

[0007] The modified aluminum foil layer is prepared by coating polyvinyl alcohol, silane coupling agent and nano-magnesium oxide on an aluminum foil.

[0008] The modified inner adhesive is prepared by mixing modified chlorinated polypropylene with composite aerogel;

[0009] The modified heat-sealing layer is prepared by casting film from polypropylene and self-repairing microcapsules.

[0010] Further, the preparation method of the modified aluminum foil layer comprises the following steps: A1, stirring polyvinyl alcohol and silane coupling agent at room temperature to obtain PVA-KH550 solution; A2, adding nano-magnesium oxide powder into the PVA-KH550 solution to uniformly disperse to obtain coating solution; A3, after alkaline washing and water washing of the aluminum foil, coating the coating solution on the surface of the aluminum foil, baking, cooling and rolling to obtain the modified aluminum foil layer.

[0011] Further, in the A3, the coating thickness of the coating solution on each side of the aluminum foil is 3-5 μm, and the baking temperature is 150-170℃.

[0012] Further, the preparation method of the modified inner adhesive comprises the following steps: B1, mixing chitosan solution, polyethyleneimine and cellulose nanofiber dispersion solution to obtain composite solution, crosslinking the composite solution with epichlorohydrin, and preparing composite aerogel through directional freezing and freeze-drying; B2, reacting maleic anhydride and initiator AIBN with chlorinated polypropylene to prepare modified chlorinated polypropylene; B3, mixing the composite aerogel with the modified chlorinated polypropylene solution to prepare the modified inner adhesive.

[0013] Further, in the B1, the addition amount of epichlorohydrin is 3-5 wt% of the composite solution.

[0014] Further, the preparation method of the modified heat-sealing layer comprises the following steps: C1, dissolving surfactant in ethanol, adding epoxy resin, and high-speed dispersing to form O / W emulsion; C2, adding water and ammonia water to the emulsion, stirring, and then adding silane coupling agent and tetraethyl orthosilicate in sequence to obtain SiO2 microcapsules through reaction; C3, reacting SiO2 microcapsules with p-xylylene formaldehyde to prepare self-repairing microcapsules; C4, mixing and melting polypropylene, amine curing agent and self-repairing microcapsules, and preparing the modified heat-sealing layer through casting film.

[0015] Further, in the C3, the addition amount of p-xylylene formaldehyde is 10-16 wt% of the SiO2 microcapsules.

[0016] Further, in the C4, the addition amount of self-repairing microcapsules is 8-12 wt% of the polypropylene.

[0017] Further, the application provides a preparation method of high-barrier aluminum plastic film, comprising the following steps: S1, modifying the matte surface of the aluminum foil layer by polyurethane adhesive and hot compounding with the nylon film layer; S2, modifying the inner adhesive layer by coating on the other side of the modified aluminum foil, hot pressing and compounding with the modified heat sealing layer, and curing to obtain the high-barrier aluminum plastic film.

[0018] Further, in the S1, the thickness of the modified aluminum foil layer is 40-50 mu m, and the thickness of the nylon film layer is 20-30 mu m; in the S2, the thickness of the modified heat sealing layer is 15-20 mu m.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] 1. The modified aluminum foil layer is coated with a dense composite coating layer on the surface of the aluminum foil by polyvinyl alcohol, KH550 and nano magnesium oxide, which can effectively block the penetration of oxygen and water vapor, and the nano magnesium oxide reacts with HF generated by the hydrolysis of electrolyte to form stable fluoride and form a passivation layer on the surface of the aluminum foil, avoiding the corrosion of HF to the aluminum foil and causing barrier failure.

[0021] 2. The modified inner adhesive layer is added with composite aerogel with amine groups on the surface, which can react with carbon dioxide generated by the decomposition of electrolyte or water penetration in the battery, eliminating part of the carbon dioxide and avoiding the accumulation of carbon dioxide to cause the aluminum plastic film to bulge and the interface to delaminate; at the same time, the amine groups of the composite aerogel and the aldehyde groups on the surface of the self-repairing microcapsule in the modified heat sealing layer can form a Schiff base dynamic covalent bond during the hot compounding process, which can buffer stress accumulation by breaking and recombining, improve the interfacial bonding force, and increase the interlayer peeling force.

[0022] 3. The self-repairing microcapsule wall material in the modified heat sealing layer is silica, and the core material is epoxy resin. When the wall material contacts HF, the microcapsule shell breaks to release the epoxy resin, which crosslinks with the curing agent D230 to realize self-repairing at the damaged part, thereby restoring the barrier performance of the heat sealing layer, and through layer-by-layer combination, the barrier performance of the aluminum plastic film is synergistically improved. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical scheme and beneficial technical effects of the application clearer, the application will be further described in detail below in combination with embodiments. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the application.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used in the description herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0025] In the case of using "comprise", "have" and "include" in the description herein, it is intended to cover the inclusive not exclusive inclusion, unless the explicit limiting term is used, such as "only", "consisting of" and the like, another component can also be added.

[0026] In the present application, the meaning of "at least one" is more than one, such as one, two and more than two. The meaning of "multiple" or "several" is at least two, such as two, three and the like. The meaning of "multiple layers" is at least two layers, such as two layers, three layers and the like, unless otherwise specifically limited. In the description of the present application, the meaning of "several" is at least one, such as one, two and the like, unless otherwise specifically limited.

[0027] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum value and the maximum value of the range, and every value between such minimum value and maximum value. Further, when the range refers to an integer, every integer between the minimum value and the maximum value of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein.

[0028] If not specifically stated, all steps of the present application can be carried out in sequence or randomly. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method also comprises step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc. Unless otherwise mentioned, the singular form of the term can include the plural form and cannot be understood as one in number.

[0029] The present application is further illustrated by the following examples, but not limited in scope by the examples.

[0030] When the embodiments give a numerical range, it should be understood that, unless otherwise stated in the present application, both ends of each numerical range and any one numerical between the two ends can be selected. Unless otherwise defined, all technical and scientific terms used in the present application have the same meaning as understood by those skilled in the art. Unless otherwise noted in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. All reagents or instruments, unless otherwise noted, are conventional products that can be obtained by commercial purchase. In addition to the specific methods, devices, materials used in the embodiments, any method, device and material of the prior art similar or equivalent to the methods, devices and materials described in the embodiments of the present application can also be used to implement the present application according to the mastery of the prior art by those skilled in the art and the description of the present application.

[0031] Embodiment 1

[0032] The preparation method of the modified aluminum foil layer in the present embodiment is as follows:

[0033] A1, 8g of polyvinyl alcohol was added to 100mL of water and heated and stirred, and after dissolution, it was cooled to room temperature; citric acid was added dropwise to the polyvinyl alcohol aqueous solution, the pH was adjusted to 6.5, 2g of KH550 was added, and stirring was carried out at room temperature for 2h to obtain a PVA-KH550 solution.

[0034] A2, 5g of nano-magnesium oxide powder was added to the PVA-KH550 solution, and magnetic stirring was carried out for 2h to obtain a coating solution.

[0035] A3, the aluminum foil was washed with an alkali by using a sodium hydroxide and sodium carbonate solution with a total concentration of 0.9mol / L, and was cleaned for 1min, and then was cleaned and dried with deionized water. The coating solution was coated on both sides of the aluminum foil by a micro-concave coating process, with a thickness of 3μm. After the aluminum foil was unwound, one side of the aluminum foil was coated by a roller in a liquid tank, and then was evenly scraped by a doctor blade. The aluminum foil was then guided to another roller in another liquid tank to coat the other side of the aluminum foil, and then was evenly scraped by a doctor blade. After that, the aluminum foil was baked in an oven at 150℃, and then was cooled and wound to obtain a modified aluminum foil layer.

[0036] The preparation method of the modified inner adhesive in the present embodiment is as follows:

[0037] B1, 2g of chitosan was dissolved in a 1% acetic acid solution (60℃), 2g of polyethyleneimine was mixed with 20mL of cellulose nanofiber dispersion (2wt%), and 3% of epoxy chloropropane was added. Crosslinking was carried out at 60℃ for 1h. After the mixture was degassed for 20min, it was injected into a mold, and was directionally frozen and solidified in a copper plate-liquid nitrogen bath. After that, it was freeze-dried at-55℃ for 48h to obtain a composite aerogel.

[0038] B2, 100 g of chlorinated polypropylene solution in ethanol was added into a three-necked flask, mixed with 5 g of maleic anhydride; nitrogen was blown to remove air, the condensate water was opened, the stirring was started (100 r / min), heated to 80°C, refluxed, 0.5 g of AIBN was added in total (2 equal amounts were added at intervals of 30 min), reacted for 5 h to obtain a modified chlorinated polypropylene solution.

[0039] B3, 0.5 g of composite aerogel was mixed with 25 mL of toluene, stirred uniformly at 25°C for 15 min, then rested for 10 min to obtain a composite aerogel dispersion; 30 g of modified chlorinated polypropylene solution was added into a flask, heated to 50°C, dissolved for 1.5 h, then the composite aerogel dispersion was added, and stirred uniformly at 25°C for 60 min, rested for 45 min to obtain a modified inner adhesive.

[0040] The preparation method of the modified heat-sealing layer in this embodiment is as follows:

[0041] C1, 91 mg of CTAB was dissolved in 50 mL of ethanol, 1 g of epoxy resin (bisphenol A) was added into the above solution, and a high-speed disperser was used for high-speed dispersion for 10 min to obtain an O / W emulsion;

[0042] C2, the emulsion was placed in a constant-temperature water bath, 3.5 mL of water and 5.5 mL of ammonia water were slowly added dropwise into the emulsion under stirring at 300 rpm, after stirring for 10 min, 265 µL of KH550 and 1.37 mL of tetraethyl orthosilicate were added, and the reaction was carried out for 6 h; after the reaction was completed, the supernatant was removed by centrifugation at 10000 rpm for 10 min, the precipitate was washed with ethanol and deionized water alternately for three times, and then vacuum dried to obtain SiO2 microcapsules.

[0043] C3, 2 g of SiO2 microcapsules were ultrasonically dispersed in 50 mL of ethanol, and 0.1 g of anhydrous sodium sulfate was added to obtain a SiO2 microcapsule dispersion; 211 mg of p-xylylene glycol was dissolved in 5 mL of anhydrous ethanol, and ultrasonication was performed for 10 min until complete dissolution; the p-xylylene glycol solution was slowly added dropwise into the SiO2 microcapsule dispersion while stirring (300 rpm), and 120 µL of glacial acetic acid was added to warm to 50°C; constant temperature stirring was carried out for 2 h; after the reaction was completed, the product was centrifuged (10000 rpm, 10 min), the supernatant was discarded, and the product was washed with anhydrous ethanol three times, and then vacuum dried at 50°C for 12 h to obtain self-repairing microcapsules.

[0044] C4, 10 g of polypropylene and 300 mg of curing agent D230 were melt-mixed, 0.8 g of self-repairing microcapsules was added into the melt, and then cast into a film on a casting machine to obtain a modified heat-sealing layer.

[0045] The preparation method of the high-barrier ALO film in this embodiment is as follows:

[0046] S1, the outer layer of the high-barrier ALO film is prepared by coating the outer layer of polyurethane adhesive on the matte surface of the modified aluminum foil with a thickness of 40 μm, and the thickness of the outer layer of adhesive is 4 μm. After drying, the outer layer of adhesive is formed, and then the modified aluminum foil is hot-combined with a nylon film with a thickness of 20 μm.

[0047] S2, the inner layer of the high-barrier ALO film is prepared by hot-combining the modified inner layer adhesive with the modified heat-sealing layer. The modified inner layer adhesive is coated on the other side of the modified aluminum foil, and the thickness is controlled to be 4 μm. After drying at 100 ℃ for 70 s, the obtained inner layer of adhesive is hot-pressed with the modified heat-sealing layer with a thickness of 18 μm at a temperature of 120 ℃ and a pressure of 0.4 MPa for 60 s, and then is aged in a 60 ℃ aging chamber for 120 h to obtain the high-barrier ALO film.

[0048] Embodiment 2

[0049] The preparation method of the modified aluminum foil layer in this embodiment is as follows:

[0050] A1, 8 g of polyvinyl alcohol is added to 100 mL of water and heated and stirred until dissolved, and then cooled to room temperature. Citric acid is added dropwise to the polyvinyl alcohol aqueous solution, the pH is adjusted to 6.5, 2 g of KH550 is added, and stirring is performed at room temperature for 2 h to obtain a PVA-KH550 solution.

[0051] A2, 5 g of nano-magnesium oxide powder is added to the PVA-KH550 solution, and magnetic stirring is performed for 2 h to uniformly disperse the coating solution.

[0052] A3, the aluminum foil is washed with an alkali by using a sodium hydroxide and sodium carbonate aqueous solution with a total concentration of 0.9 mol / L, and is cleaned for 1 min. Then, the aluminum foil is washed with deionized water and dried. The coating solution is coated on both sides of the aluminum foil by using a micro-concave coating process, and the thickness is 4 μm. After the aluminum foil is unwound, one side of the aluminum foil is coated by using a roller in a liquid tank, and then is uniformly scraped by using a scraper. The other side of the aluminum foil is coated by using a roller in another liquid tank, and then is uniformly scraped by using a scraper. After that, the aluminum foil is baked in an oven at 160 ℃, and then is cooled and wound to obtain the modified aluminum foil layer.

[0053] The preparation method of the modified inner layer adhesive in this embodiment is as follows:

[0054] B1, 2 g of chitosan is dissolved in a 1% acetic acid solution (60 ℃), 2 g of polyethyleneimine is mixed with 20 mL of cellulose nanofiber dispersion liquid (2 wt%), 4% epichlorohydrin is added, and crosslinking is performed at 60 ℃ for 1 h. After the mixture is degassed for 20 min, it is injected into a mold, and is directionally frozen and solidified by using a copper plate-liquid nitrogen bath. After that, the mixture is frozen and dried at-55 ℃ for 48 h to obtain a composite aerogel.

[0055] B2, 100 g of chlorinated polypropylene solution in ethanol was added into a three-necked flask, mixed with 5 g of maleic anhydride; nitrogen was blown to remove air, the condensate water was opened, the stirring was started (100 r / min), heated to 80°C, refluxed, 0.5 g of AIBN was added in total (2 equal amounts were added at intervals of 30 min), reacted for 5 h to obtain a modified chlorinated polypropylene solution.

[0056] B3, 0.5 g of composite aerogel was mixed with 25 mL of toluene, stirred uniformly at 25°C for 15 min, then rested for 10 min to obtain a composite aerogel dispersion; 30 g of modified chlorinated polypropylene solution was added into a flask, heated to 50°C, dissolved for 1.5 h, then the composite aerogel dispersion was added, and stirred uniformly at 25°C for 60 min, rested for 45 min to obtain a modified inner adhesive.

[0057] The preparation method of the modified heat-sealing layer in this embodiment is as follows:

[0058] C1, 182 mg of CTAB was dissolved in 50 mL of ethanol, 1 g of epoxy resin (bisphenol A) was added into the above solution, and a homogenizer was used for high-speed dispersion for 10 min to obtain an O / W emulsion;

[0059] C2, the emulsion was placed in a constant-temperature water bath, 3.5 mL of water and 5.5 mL of ammonia water were slowly added dropwise into the emulsion under stirring at 300 rpm, after stirring for 10 min, 265 μL of KH550 and 1.37 mL of tetraethyl orthosilicate were added, and the reaction was carried out for 6 h; after the reaction was completed, the supernatant was removed by centrifugation at 10,000 rpm for 10 min, the precipitate was washed with ethanol and deionized water alternately for three times, and then vacuum dried to obtain SiO2 microcapsules.

[0060] C3, 2 g of SiO2 microcapsules were ultrasonically dispersed in 50 mL of ethanol, and 0.1 g of anhydrous sodium sulfate was added to obtain a SiO2 microcapsule dispersion; 254 mg of p-xylylene glycol was dissolved in 5 mL of anhydrous ethanol, and ultrasonication was performed for 10 min until complete dissolution; the p-xylylene glycol solution was slowly added dropwise into the SiO2 microcapsule dispersion while stirring (300 rpm), and 120 μL of glacial acetic acid was added to warm to 50°C; constant temperature stirring was carried out for 2 h; after the reaction was completed, the product was centrifuged (10,000 rpm, 10 min), the supernatant was discarded, and the product was washed with anhydrous ethanol three times, and then vacuum dried at 50°C for 12 h to obtain self-repairing microcapsules.

[0061] C4, 10 g of polypropylene and 300 mg of curing agent D230 were melt-mixed, 1 g of self-repairing microcapsules was added into the melt, and then cast into a film on a casting machine to obtain a modified heat-sealing layer.

[0062] The preparation method of the high-barrier ALO film in this embodiment is as follows:

[0063] S1, the outer layer of the high-barrier ALO film is prepared by coating the outer layer of polyurethane adhesive on the matte surface of the modified aluminum foil with a thickness of 45 μm, and the thickness of the outer layer of adhesive is 4 μm. After drying, the outer layer of adhesive is formed, and then the modified aluminum foil is hot-combined with a nylon film with a thickness of 25 μm.

[0064] S2, the inner layer of the high-barrier ALO film is prepared by hot-combining the modified inner layer adhesive with the modified heat-sealing layer. The modified inner layer adhesive is coated on the other side of the modified aluminum foil, and the thickness is controlled to be 4 μm. After drying at 100 ℃ for 70 s, the obtained inner layer of adhesive is hot-pressed with the modified heat-sealing layer with a thickness of 15 μm at a temperature of 120 ℃ and a pressure of 0.4 MPa for 60 s, and then is aged in a 60 ℃ aging chamber for 120 h to obtain the high-barrier ALO film.

[0065] Example 3

[0066] The preparation method of the modified aluminum foil layer in this embodiment is as follows:

[0067] A1, 8 g of polyvinyl alcohol is added to 100 mL of water and heated and stirred until dissolved, and then cooled to room temperature. Citric acid is added dropwise to the polyvinyl alcohol aqueous solution, the pH is adjusted to 6.5, 2 g of KH550 is added, and stirring is performed at room temperature for 2 h to obtain a PVA-KH550 solution.

[0068] A2, 5 g of nano-magnesium oxide powder is added to the PVA-KH550 solution, and magnetic stirring is performed for 2 h to uniformly disperse the coating solution.

[0069] A3, the aluminum foil is washed with an alkali by using a sodium hydroxide and sodium carbonate aqueous solution with a total concentration of 0.9 mol / L, and is cleaned for 1 min. Then, the aluminum foil is washed with deionized water and dried. The coating solution is coated on both sides of the aluminum foil by using a micro-concave coating process, and the thickness is 5 μm. After the aluminum foil is unwound, one side of the aluminum foil is coated by using a roller in a liquid tank, and then is uniformly scraped by using a scraper. The other side of the aluminum foil is coated by using a roller in another liquid tank, and then is uniformly scraped by using a scraper. After that, the aluminum foil is baked in an oven at 170 ℃, and then is cooled and wound to obtain the modified aluminum foil layer.

[0070] The preparation method of the modified inner layer adhesive in this embodiment is as follows:

[0071] B1, 2 g of chitosan is dissolved in a 1% acetic acid solution (60 ℃), 2 g of polyethyleneimine is mixed with 20 mL of cellulose nanofiber dispersion liquid (2 wt%), 5% epoxy chloropropane is added, and crosslinking is performed at 60 ℃ for 1 h. After the mixture is degassed for 20 min, it is injected into a mold, and is directionally frozen and solidified by using a copper plate-liquid nitrogen bath. After that, the mixture is frozen and dried at-55 ℃ for 48 h to obtain a composite aerogel.

[0072] B2, 100 g of chlorinated polypropylene solution in ethanol was added into a three-necked flask, mixed with 5 g of maleic anhydride; nitrogen was blown to remove air, the condensate water was opened, the stirring was started (100 r / min), heated to 80°C, refluxed, 0.5 g of AIBN was added in total (2 equal amounts were added at intervals of 30 min), reacted for 5 h to obtain a modified chlorinated polypropylene solution.

[0073] B3, 0.5 g of composite aerogel was mixed with 25 mL of toluene, stirred uniformly at 25°C for 15 min, then rested for 10 min to obtain a composite aerogel dispersion; 30 g of modified chlorinated polypropylene solution was added into a flask, heated to 50°C, dissolved for 1.5 h, then the composite aerogel dispersion was added, and stirred uniformly at 25°C for 60 min, rested for 45 min to obtain a modified inner adhesive.

[0074] The preparation method of the modified heat-sealing layer in this example is as follows:

[0075] C1, 273 mg of CTAB was dissolved in 50 mL of ethanol, 1 g of epoxy resin (bisphenol A) was added into the above solution, and a high-speed disperser was used for 10 min to obtain an O / W emulsion;

[0076] C2, the emulsion was placed in a constant-temperature water bath, 3.5 mL of water and 5.5 mL of ammonia water were slowly added dropwise into the emulsion under stirring at 300 rpm, after stirring for 10 min, 265 μL of KH550 and 1.37 mL of tetraethyl orthosilicate were added, and the reaction was carried out for 6 h; after the reaction was completed, the supernatant was removed by centrifugation at 10000 rpm for 10 min, the precipitate was washed with ethanol and deionized water alternately for three times, and then vacuum dried to obtain SiO2 microcapsules.

[0077] C3, 2 g of SiO2 microcapsules were ultrasonically dispersed in 50 mL of ethanol, and 0.1 g of anhydrous sodium sulfate was added to obtain a SiO2 microcapsule dispersion; 317 mg of p-xylylene glycol was dissolved in 5 mL of anhydrous ethanol, and ultrasonication was performed for 10 min until complete dissolution; the p-xylylene glycol solution was slowly added dropwise into the SiO2 microcapsule dispersion while stirring (300 rpm), and 120 μL of glacial acetic acid was added to warm to 50°C; constant temperature stirring was carried out for 2 h; after the reaction was completed, the product was centrifuged (10000 rpm, 10 min), the supernatant was discarded, and the product was washed with anhydrous ethanol for three times, and then vacuum dried at 50°C for 12 h to obtain self-repairing microcapsules.

[0078] C4, 10 g of polypropylene and 300 mg of curing agent D230 were melt-mixed, 1.2 g of self-repairing microcapsules was added into the melt, and then cast into a film on a casting machine to obtain a modified heat-sealing layer.

[0079] The preparation method of the high-barrier ACF in the embodiment is as follows:

[0080] S1, the outer layer of the high-barrier ACF is prepared by coating the outer layer polyurethane adhesive on the matte surface of the modified aluminum foil with a thickness of 45 μm, and the thickness of the outer layer adhesive is 4 μm. After drying, the outer layer adhesive layer is formed, and then the high-barrier ACF is hot-composited with the nylon film with a thickness of 30 μm;

[0081] S2, the inner layer of the high-barrier ACF is prepared by hot-composing the modified inner layer adhesive and the modified heat-seal layer. The modified inner layer adhesive is coated on the other side of the modified aluminum foil, and the thickness is controlled to be 4 μm. After drying at 100 ℃ for 70 s, the obtained inner layer adhesive layer is hot-pressed with the modified heat-seal layer with a thickness of 15 μm at a temperature of 120 ℃ and a pressure of 0.4 MPa for 60 s, and then the high-barrier ACF is aged in a 60 ℃ aging chamber for 120 h.

[0082] Comparative Example 1

[0083] The preparation method of the modified inner layer adhesive in the comparative example is as follows:

[0084] B1, 2 g of chitosan is dissolved in 1% acetic acid solution (60 ℃), 2 g of polyethyleneimine is mixed with 20 mL of cellulose nanofiber dispersion solution (2 wt%), 4% of epoxy chloropropane is added, and crosslinking is carried out at 60 ℃ for 1 h. After the mixture is degassed for 20 min, it is injected into a mold, and directional freezing solidification is carried out in a copper plate-liquid nitrogen bath. After being frozen at-55 ℃ for 48 h, a composite aerogel is obtained.

[0085] B2, 100 g of a chlorinated polypropylene ethanol solution is added to a three-necked flask, and 5 g of maleic anhydride is uniformly mixed; nitrogen gas is blown to remove air, the condensate water is opened, the stirring is started (100 r / min), and heating is carried out to 80 ℃. After refluxing for 5 h, a total amount of 0.5 g of AIBN is added (in two equal amounts, with an interval of 30 min), and a modified chlorinated polypropylene solution is obtained.

[0086] B3, 0.5 g of the composite aerogel is mixed with 25 mL of toluene, and uniform stirring is carried out at 25 ℃ for 15 min, followed by standing for 10 min, to obtain a composite aerogel dispersion solution; 30 g of the modified chlorinated polypropylene solution is added to a flask, and 60 mL of cyclohexane is added. After being dissolved at 50 ℃ for 1.5 h, the composite aerogel dispersion solution is added, and uniform stirring is carried out at 25 ℃ for 60 min, followed by standing for 45 min, to obtain a modified inner layer adhesive.

[0087] The preparation method of the modified heat-seal layer in the comparative example is as follows:

[0088] C1, 182 mg of CTAB is dissolved in 50 mL of ethanol, 1 g of epoxy resin (bisphenol A) is added to the above solution, and high-speed dispersion is carried out using a homogenizer for 10 min to obtain an O / W emulsion;

[0089] C2, the emulsion was placed in a constant temperature water bath, 3.5 mL of water and 5.5 mL of ammonia were slowly added dropwise to the emulsion under stirring at 300 rpm, after stirring for 10 min, 265 μL of KH550 and 1.37 mL of tetraethyl orthosilicate were added, and the reaction was carried out for 6 h; after the reaction was completed, the supernatant was removed by centrifugation at 10,000 rpm for 10 min, the precipitate was washed with ethanol and deionized water alternately for three times, and then vacuum dried to obtain SiO2 microcapsules.

[0090] C3, 2 g of SiO2 microcapsules were ultrasonically dispersed in 50 mL of ethanol, and 0.1 g of anhydrous sodium sulfate was added to obtain a SiO2 microcapsule dispersion; 254 mg of terephthaldehyde was dissolved in 5 mL of anhydrous ethanol, and ultrasonication was performed for 10 min until complete dissolution; the terephthaldehyde solution was slowly added dropwise to the SiO2 microcapsule dispersion, stirring (300 rpm) was performed during the dropwise addition, and 120 μL of glacial acetic acid was added to warm to 50°C; constant temperature stirring was performed for 2 h, after the reaction was completed, the product was centrifuged (10,000 rpm, 10 min), the supernatant was discarded, and the product was washed with anhydrous ethanol three times, and then vacuum dried at 50°C for 12 h to obtain self-repairing microcapsules.

[0091] C4, 10 g of polypropylene and 300 mg of curing agent D230 were melt-mixed, 1 g of self-repairing microcapsules was added to the melt, and then cast into a film on a casting machine to obtain a modified heat-sealing layer.

[0092] The preparation method of the high-barrier aluminum-plastic film in the present comparative example is as follows:

[0093] S1, the outer layer of the high-barrier aluminum-plastic film was coated on the matte surface of an aluminum foil with a thickness of 45 μm with an outer layer polyurethane adhesive with a thickness of 4 μm, and after drying, an outer adhesive layer was formed, and then the outer adhesive layer was hot-combined with a nylon film with a thickness of 25 μm;

[0094] S2, the inner layer of the high-barrier aluminum-plastic film was a modified inner adhesive layer hot-combined with a modified heat-sealing layer, the modified inner adhesive layer was coated on the other side of the aluminum foil, and the thickness was controlled to be 4 μm, and the inner adhesive layer was dried at 100°C for 70 s to obtain an inner adhesive layer, and then the inner adhesive layer was hot-pressed with a modified heat-sealing layer with a thickness of 15 μm at a temperature of 120°C and a pressure of 0.4 MPa for 60 s, and then the high-barrier aluminum-plastic film was obtained by aging in a 60°C aging room for 120 h.

[0095] Comparative Example 2

[0096] The preparation method of the modified aluminum foil layer in the present comparative example is as follows:

[0097] A1. Add 8g of polyvinyl alcohol to 100mL of water, heat and stir until dissolved, then cool to room temperature; add citric acid dropwise to the polyvinyl alcohol aqueous solution to adjust the pH to 6.5, add 2g of KH550, and stir at room temperature for 2h to obtain a PVA-KH550 solution.

[0098] A2. Take 5g of nano magnesium oxide powder and add it to the PVA-KH550 solution. Stir magnetically for 2 hours to obtain a uniformly dispersed coating solution.

[0099] A3. Aluminum foil is alkaline washed with an aqueous solution of sodium hydroxide and sodium carbonate with a total concentration of 0.9 mol / L for 1 min, and then rinsed and dried with deionized water. The coating solution is then applied to the aluminum foil using a microgravure coating process to double-sided roll coating, with a thickness of 4 μm. After the aluminum foil is unwound by the unwinding machine, one side of the aluminum foil is coated on the roller in liquid tank one, and then evenly scraped with a scraper. The aluminum foil is then guided to the roller in liquid tank two to coat the other side, and then evenly scraped with a scraper. After baking in an oven at 160℃, it is cooled and wound up to obtain the modified aluminum foil layer.

[0100] The preparation method of the high-barrier aluminum-plastic film in this comparative example is as follows:

[0101] S1, the outer layer of the high-barrier aluminum-plastic film is coated with a 4μm thick polyurethane adhesive on the matte surface of a 45μm thick modified aluminum foil. After drying, it forms an outer adhesive layer, which is then thermally bonded to a 25μm thick nylon film.

[0102] S2, the inner layer of the high-barrier aluminum-plastic film is a thermal composite of an inner layer adhesive and a heat-sealing layer. The inner layer adhesive is coated on the other side of the modified aluminum foil, with a thickness of 4μm, and dried at 100℃ for 70s. The resulting inner layer adhesive is then hot-pressed with a 15μm thick heat-sealing layer at 120℃ and 0.4MPa pressure for 60s. Subsequently, it is cured in a 60℃ curing chamber for 120h to obtain the high-barrier aluminum-plastic film.

[0103] Performance testing

[0104] Mechanical property testing: In accordance with the requirements of 6.5 in T / CIAPS0005—2018 standard, the tensile strength and elongation at break of the high-barrier aluminum-plastic film were tested before and after 5 cycles of overcharging with lithium battery. Samples with a length greater than 150 mm and a width of (15±0.1) mm were cut and tested using a universal testing machine. The initial distance between the fixtures was (100±5) mm, and the film was stretched at a speed of (300±20) mm / min. The tensile strength and elongation at break were recorded.

[0105] Electrolyte resistance test: According to the requirements of 6.13.2 in T / CIAPS0005-2018 standard, the high barrier aluminum plastic film is cut into a sample of 15 mm x 100 mm, and the sample is placed in a container containing electrolyte, which completely immerses the sample. After sealing the container, it is placed in an oven at (85+2) ℃ for 24 h, and then cooled to room temperature. After wiping the sample clean, the appearance of the sample is immediately checked and the peeling force is tested at a speed of (100±10) mm / min using a universal material testing machine.

[0106] Barrier performance: According to GB / T 1037-2021 standard, the water vapor transmission rate of the high barrier aluminum plastic is tested.

[0107] Puncture resistance: According to GB / T 10004-2008 standard, the puncture strength of the high barrier aluminum plastic film is tested.

[0108] Table 1 Mechanical property test results of high barrier aluminum plastic films of Examples 1-3 and Comparative Examples 1-2

[0109]

[0110] Table 2 Performance test results of high barrier aluminum plastic films of Examples 1-3 and Comparative Examples 1-2

[0111]

[0112] Analyzing Examples 1-3 and Comparative Examples 1-2, combined with Tables 1-2, it can be seen that by coating a dense composite coating on the aluminum foil layer with polyvinyl alcohol, KH550, and nano magnesium oxide, adding composite aerogel to the modified inner adhesive, connecting the heat sealing layer through dynamic covalent bonds, and adding self-repairing microcapsules to the heat sealing layer, the high barrier aluminum plastic film has good barrier performance and mechanical properties. In Comparative Example 1, the aluminum foil was not modified by coating, which reduced the water and oxygen permeation barrier ability, resulting in a significant increase in the water vapor transmission rate of the high barrier aluminum plastic film in Comparative Example 1. In Comparative Example 2, composite aerogel and self-repairing microcapsules were not added to the inner adhesive and heat sealing layer, resulting in a lack of dynamic covalent connection between the inner adhesive layer and the heat sealing layer, the inner adhesive layer could not adsorb carbon dioxide gas, and the tensile strength and elongation at break of the high barrier aluminum plastic film in Comparative Example 2 were significantly reduced after overcharging cycle, and the electrolyte resistance peeling force was weakened.

[0113] Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features, any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A high barrier Al-PE film, characterized in that, It includes, from the outside to the inside, a nylon film layer, an outer adhesive layer, a modified aluminum foil layer, a modified inner adhesive layer, and a modified heat-sealing layer; The modified aluminum foil layer is prepared by coating aluminum foil with polyvinyl alcohol, silane coupling agent and nano magnesium oxide. The preparation method of the modified inner layer adhesive includes the following steps: B1, mixing chitosan solution, polyethyleneimine, and cellulose nanofiber dispersion to obtain a composite solution, crosslinking the composite solution with epichlorohydrin, and then directionally freezing and freeze-drying to obtain a composite aerogel; B2, reacting maleic anhydride and initiator AIBN with chlorinated polypropylene to obtain modified chlorinated polypropylene; B3, mixing the composite aerogel with the modified chlorinated polypropylene solution to obtain the modified inner layer adhesive. The preparation method of the modified heat-sealing layer includes the following steps: C1, dissolving a surfactant in ethanol, adding epoxy resin, and dispersing at high speed to form an O / W emulsion; C2, adding water and ammonia to the emulsion, stirring, and then adding a silane coupling agent and tetraethyl orthosilicate in sequence to react and obtain SiO2 microcapsules; C3, reacting the SiO2 microcapsules with terephthalaldehyde to obtain self-healing microcapsules; C4, mixing and melting polypropylene, amine curing agent, and self-healing microcapsules, and then casting to form a film to obtain the modified heat-sealing layer.

2. The high barrier A-LAB film according to claim 1, characterized in that, The method for preparing the modified aluminum foil layer includes the following steps: A1, stirring polyvinyl alcohol and silane coupling agent at room temperature to obtain a PVA-KH550 solution; A2, adding nano-magnesium oxide powder to the PVA-KH550 solution and dispersing it evenly to obtain a coating solution; A3, after washing the aluminum foil with alkali and water, coating the aluminum foil surface with the coating solution, baking, cooling and winding to obtain the coating solution.

3. The high barrier lamination film according to claim 2, wherein, In A3, the coating solution is applied to each side of the aluminum foil with a thickness of 3-5 μm, and the baking temperature is 150-170℃.

4. The high barrier lamination film according to claim 1, wherein, In B1, the amount of epichlorohydrin added is 3-5 wt% of the composite solution.

5. The high barrier lamination film according to claim 1, wherein, In C3, the amount of terephthalaldehyde added is 10-16 wt% of the SiO2 microcapsules.

6. The high barrier lamination film according to claim 1, wherein, In C4, the amount of self-healing microcapsules added is 8-12 wt% of polypropylene.

7. A process for the production of a high barrier lamination film as claimed in any one of claims 1 to 6, characterized in that, The process includes the following steps: S1, the matte surface of the modified aluminum foil layer is thermally bonded to the nylon film layer using a polyurethane adhesive; S2, the modified inner layer adhesive is applied to the other side of the modified aluminum foil, and then thermally bonded and cured with the modified heat-sealing layer to obtain a high-barrier aluminum-plastic film.

8. The method of claim 7, wherein the method further comprises the step of applying a primer layer to the inner surface of the aluminum foil before the step of applying the barrier layer. In S1, the thickness of the modified aluminum foil layer is 40-50 μm, and the thickness of the nylon film layer is 20-30 μm; in S2, the thickness of the modified heat-sealing layer is 15-20 μm.

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