High-barrier polyester packaging film and preparation method thereof

Abstract

The invention discloses a high-barrier polyester packaging film and a preparation method thereof, and relates to the technical field of packaging films. The plastic is prepared from the following components in parts by weight: 100 parts of polyethylene glycol terephthalate, 3-7 parts of maleic anhydride grafted polyethylene, 4-10 parts of ACR resin, 1-3 parts of polyethylene wax, 1-3 parts of calcium stearate, 0.1-1 part of sodium benzoate, 0.2-0.8 part of a silane coupling agent and 6-12 parts of modified nano cellulose. By introducing the modified nanocellulose and optimizing the component proportion, the comprehensive performance of the polyester packaging film is remarkably improved, and the prepared packaging film has excellent barrier property, mechanical property and processing adaptability, can meet the strict requirements of packaging materials, and is suitable for industrial production. And a high-performance and multifunctional novel material solution is provided for the packaging industry.

Description

Technical Field

[0001] The present invention relates to the technical field of packaging films, and in particular to a high-barrier polyester packaging film and a preparation method thereof. Background Art

[0002] With the rapid development of the modern packaging industry, polyester packaging films are widely used in the food, pharmaceutical, and chemical industries due to their excellent mechanical properties, chemical stability, and transparency. Polyethylene terephthalate (PET), the primary polyester packaging material, offers excellent tensile strength, chemical resistance, and thermal stability. However, its relatively poor barrier properties against gases and water vapor limit its application in high-end packaging.

[0003] At present, the main methods to improve the barrier properties of polyester packaging films include: (1) multi-layer composite structure design, which improves the overall barrier properties by compounding with high barrier materials such as EVOH and PVDC, but this method increases production costs and recycling difficulties; (2) surface coating technology, which coats the surface of the polyester film with a barrier coating, but the bonding strength between the coating and the substrate is poor and it is easy to fall off; (3) nanofiller modification, which constructs a maze effect by adding nanomaterials such as montmorillonite and graphene, but there are problems such as poor dispersion and poor compatibility.

[0004] In recent years, nanocellulose has attracted widespread attention due to its unique structural properties and environmental friendliness. Nanocellulose has a high aspect ratio, large specific surface area, and good mechanical properties, and can form an effective barrier network in a polymer matrix.

[0005] CN111761898A discloses a medical packaging film and a preparation method thereof, comprising an outer film layer, an inner film layer, and a phase change energy storage material encapsulated between the outer film layer and the inner film layer; the outer film layer comprises: 65-80 parts of polylactide, 3-9 parts of polybutylene succinate, 4-8 parts of nanocellulose, and 3-8 parts of polyethylene isophthalate; the inner film layer comprises: 65-80 parts of polylactic acid-glycolic acid copolymer, 8-12 parts of zinc chloride solution, 4-8 parts of nanocellulose, 4-8 parts of calcium propionate, and 0.5-5 parts of polyethylene terephthalate; the raw materials of each film layer of the invention are widely available and green and environmentally friendly. It is not only degradable, but also has excellent barrier properties, mechanical properties and high transparency, and can protect medical supplies.

[0006] However, the presence of a large number of hydroxyl groups on the surface of raw nanocellulose makes it highly hydrophilic and poorly compatible with the hydrophobic polyester matrix, resulting in weak interfacial bonding and difficulty in fully exerting its reinforcing and barrier properties. Furthermore, nanocellulose tends to agglomerate in the polyester matrix, affecting its uniform dispersion and performance.

[0007] Existing technologies for surface modification of nanocellulose primarily include silanization, esterification, and etherification. However, these methods often suffer from harsh reaction conditions, limited modification effects, and complex multi-step reactions. In particular, existing single modification methods struggle to meet the requirements for simultaneously improving hydrophobicity, compatibility, and flexibility.

[0008] Therefore, developing an efficient nanocellulose modification method to prepare polyester packaging film with excellent barrier properties and comprehensive performance is of great significance for promoting the advancement of packaging material technology. Summary of the Invention

[0009] In order to address the shortcomings of the existing technology, the purpose of the present invention is to provide a high-barrier polyester packaging film and a preparation method thereof. The present invention significantly improves the comprehensive performance of the polyester packaging film by introducing modified nanocellulose and optimizing the component ratio. The modified nanocellulose forms a dense nano-scale barrier network in the matrix, greatly improving the gas and water vapor barrier performance; the synergistic effect of the various components improves the mechanical strength, flexibility and thermal stability of the film, while optimizing the processing performance.

[0010] In order to achieve the above object, the present invention adopts the following technical solutions:

[0011] A high-barrier polyester packaging film is made from the following components, measured by weight: 100 parts of polyethylene terephthalate, 3-7 parts of maleic anhydride grafted polyethylene, 4-10 parts of ACR resin, 1-3 parts of polyethylene wax, 1-3 parts of calcium stearate, 0.1-1 part of sodium benzoate, 0.2-0.8 part of silane coupling agent, and 6-12 parts of modified nanocellulose.

[0012] Preferably, the silane coupling agent is one or more of silane coupling agents KH-550, KH-560, and KH-570.

[0013] Preferably, the modified nanocellulose is prepared by the following reaction steps:

[0014] (1) dispersing nanocellulose in deionized water, adjusting the pH of the system, slowly adding sodium periodate, reacting in the dark, centrifuging, washing, and drying the product to obtain aldehyded cellulose;

[0015] Sodium periodate oxidation of cellulose: A vicinal diol structure (-CHOH-CHOH-) exists at the C2 and C3 positions of the cellulose molecular chain. Sodium periodate, a strong oxidant, selectively cleaves the C-C bond between the vicinal diols through a cyclic intermediate, simultaneously oxidizing the two hydroxyl groups to form aldehyde groups. During the reaction, IO4- is reduced to IO3-. Each IO4- molecule consumed oxidizes one vicinal diol unit to generate two aldehyde groups, thereby introducing a large number of active aldehyde groups into the cellulose molecular chain, providing reaction sites for subsequent functionalization reactions.

[0016] Preferably, in step (1), the usage ratio of nanocellulose, deionized water, and sodium periodate is 10 g: 150-300 mL: 3-6 g.

[0017] Preferably, in step (1), the pH of the system is adjusted to 8-9 with sodium hydroxide solution; the reaction conditions are: stirring at 25-40° C. in the dark for 6-18 hours; and the product is washed with deionized water and ethanol 2-4 times in sequence.

[0018] (2) dispersing the aldehyde-modified cellulose in anhydrous ethanol, ultrasonically treating the cellulose, then adding dodecylamine and p-toluenesulfonic acid, and reacting the mixture under reflux in a nitrogen atmosphere. The product is cooled, filtered, washed, and dried to obtain an intermediate cellulose.

[0019] The reaction of aldehyde-modified cellulose with a dodecylamine Schiff base: Under the catalysis of p-toluenesulfonic acid, the amino nitrogen atom in the dodecylamine molecule uses its lone electron pair to nucleophilically attack the carbonyl carbon atom of the aldehyde group, forming an amino alcohol intermediate. Subsequently, under the catalysis of acid, the water molecule is removed to form a Schiff base structure containing a C=N double bond. This step not only introduces a long-chain alkyl group (dodecyl) onto the cellulose surface but also forms a reactive C=N double bond, paving the way for the next hydrosilylation reaction.

[0020] Preferably, in step (2), the usage ratio of aldehyded cellulose, anhydrous ethanol, dodecylamine and p-toluenesulfonic acid is 10 g: 150-300 mL: 6-12 g: 0.1-0.3 g.

[0021] Preferably, in step (2), ultrasonic treatment is performed for 30 to 60 minutes; the reflux reaction conditions are reflux reaction at 60 to 75° C. for 8 to 14 hours, and stirring is performed every 2 hours during the reaction; and the product is washed with ethanol and acetone 2 to 4 times in sequence.

[0022] (3) dispersing the intermediate fiber in xylene, then adding hydrogenated silicone oil and platinum catalyst, stirring and reacting under a nitrogen atmosphere, centrifuging, washing, and drying the product to obtain the modified nanocellulose.

[0023] Hydrosilylation of the intermediate cellulose with hydrogenated silicone oil: Under the action of a platinum catalyst (Karstedt catalyst), the Si-H bond in the hydrogenated silicone oil undergoes an addition reaction with the C=N double bond in the Schiff base structure. The reaction mechanism involves the platinum catalyst first coordinating and activating the Si-H bond, then inserting the C=N double bond of the Schiff base into the Pt-Si bond, and finally obtaining the addition product through reductive elimination. The reaction results in the elimination of the C=N double bond, forming a new C-N single bond and Si-C bond, successfully grafting the organosilicon group onto the cellulose surface, thereby significantly improving the hydrophobicity, flexibility, and thermal stability of cellulose.

[0024] Preferably, in step (3), the usage ratio of the intermediate fiber, xylene, hydrogenated silicone oil and platinum catalyst is 10 g: 150-300 mL: 5-10 mL: 0.1-0.4 mL; the platinum catalyst is 0.1-0.5 wt% of Karstedt catalyst.

[0025] Preferably, in step (3), the stirring reaction conditions are 80-110° C. for 4-10 h; and the product is washed with xylene and ethanol 2-4 times in sequence.

[0026] The present invention also claims protection for a method for preparing the high-barrier polyester packaging film, comprising the steps of: mixing the components, drying and removing water, putting them into a twin-screw extruder for melt extrusion, casting into a film, and cooling to obtain the high-barrier polyester packaging film.

[0027] Preferably, the product is dried at 130-150° C. for 4-6 hours to remove water; melt extrusion is performed at 270-290° C.; and the temperature of the casting roll is 105-135° C.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention provides a high-barrier polyester packaging film. Polyethylene terephthalate as a base resin provides good mechanical strength and basic barrier properties; maleic anhydride grafted polyethylene as a compatibilizer significantly improves the interfacial compatibility between modified nanocellulose and the PET matrix, avoiding phase separation; the addition of ACR resin effectively improves the impact resistance and toughness of the film, preventing brittle fracture; polyethylene wax and calcium stearate as lubricants and thermal stabilizers not only improve the processing performance of melt extrusion, but also improve the thermal stability of the film; the antibacterial function of sodium benzoate extends the service life of the packaging film; the silane coupling agent further enhances the interfacial bonding force between the modified nanocellulose and the PET matrix through chemical bonding, thereby achieving uniform dispersion and effective enhancement of the nanofiller.

[0030] 2. The present invention provides a method for preparing modified nanocellulose. The aldehyde groups introduced by sodium periodate oxidation in the first step not only provide active sites for subsequent reactions but also improve the dispersibility of cellulose by disrupting some hydrogen bond networks. The long dodecyl chains introduced by the Schiff base reaction in the second step increase the hydrophobicity of cellulose, effectively hindering the adsorption of water molecules on the cellulose surface and, in turn, the penetration and diffusion of water vapor in the polyester film, significantly improving the water vapor barrier performance of the polyester film. The long dodecyl chains also enhance the compatibility of the nanocellulose with the PET matrix, improving the mechanical properties of the composite film. The organosilicon groups introduced by the hydrosilylation reaction in the third step further enhance the hydrophobicity and effectively improve the water vapor barrier performance of the film. The flexible silicone segments significantly improve the film's tensile properties, low-temperature folding resistance, and flexibility. The high bond energy of the silicon-oxygen bonds enhances the film's moisture and heat resistance and thermal stability. After these three steps of modification, the nanocellulose has a dense structure and can form an effective nanoscale barrier network in the PET matrix, increasing the diffusion paths for gas and water vapor, significantly improving the gas barrier performance, mechanical strength, and durability of the packaging film. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0032] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from commercially purchased raw materials.

[0033] Nanocellulose was purchased from Zhejiang Jinjiahao Green Nanomaterials Co., Ltd.;

[0034] Karstedt catalyst was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0035] Polyethylene terephthalate was purchased from Dongguan Quanyou Plastic Raw Materials Co., Ltd., product number CR-8816;

[0036] Maleic anhydride grafted polyethylene was purchased from Shanghai Wanluji Plastic Technology Co., Ltd., model OE825;

[0037] ACR resin was purchased from Shandong Riko Chemical Co., Ltd.

[0038] A method for preparing a high-barrier polyester packaging film comprises the following steps:

[0039] (1) 10 g of nanocellulose is dispersed in 150-300 mL of deionized water, the pH of the system is adjusted to 8-9 with sodium hydroxide solution, 3-6 g of sodium periodate is slowly added, and the reaction is stirred at 25-40°C for 6-18 h in the dark. The product is centrifuged, washed with deionized water and ethanol for 2-4 times in sequence, and dried to obtain aldehyde-modified cellulose;

[0040] (2) 10 g of aldehyde-modified cellulose is dispersed in 150-300 mL of anhydrous ethanol, ultrasonic treatment is performed for 30-60 min, then 6-12 g of dodecylamine and 0.1-0.3 g of p-toluenesulfonic acid are added, and the reaction is refluxed at 60-75°C under nitrogen atmosphere for 8-14 h. The reaction is stirred every 2 h. The product is cooled, filtered, washed with ethanol and acetone for 2-4 times in sequence, and dried to obtain intermediate cellulose;

[0041] (3) 10 g of intermediate cellulose is dispersed in 150-300 mL of dimethylbenzene, then 5-10 mL of hydrogen silicone oil and 0.1-0.4 mL of 0.1-0.5 wt% Karstedt catalyst are added, and the reaction is stirred at 80-110°C under nitrogen atmosphere for 4-10 h. The product is centrifuged, washed with dimethylbenzene and ethanol for 2-4 times in sequence, and dried to obtain the modified nanocellulose;

[0042] (4) 100 parts of polyethylene terephthalate, 3-7 parts of maleic anhydride grafted polyethylene, 4-10 parts of ACR resin, 1-3 parts of polyethylene wax, 1-3 parts of calcium stearate, 0.1-1 part of sodium benzoate, 0.2-0.8 part of silane coupling agent, and 6-12 parts of modified nanocellulose are mixed, then dried at 130-150°C for 4-6 h to remove water, and then fed into a double-screw extruder to be melt-extruded at 270-290°C. The film is obtained by casting and cooling, and the casting roll temperature is 105-135°C.

[0043] The silane coupling agent is one or more of silane coupling agents KH-550, KH-560, and KH-570.

[0044] The application will be further described below through specific examples.

[0045] Example 1

[0046] A preparation method of a high-barrier polyester packaging film, comprising the following steps:

[0047] (1) 10 g of nanocellulose is dispersed in 200 mL of deionized water, the pH of the system is adjusted to 8.5 with sodium hydroxide solution, 6 g of sodium periodate is slowly added, and the reaction is stirred at 40°C for 6 h in the dark. The product is centrifuged, washed with deionized water and ethanol for 3 times in sequence, and dried to obtain aldehyde-modified cellulose;

[0048] (2) 10 g of the aldehyde group cellulose was dispersed in 200 mL of anhydrous ethanol, ultrasonic treatment for 45 min, then 12 g of dodecylamine and 0.3 g of p-toluenesulfonic acid were added, and the reaction was carried out at 75°C under nitrogen atmosphere for 8 h, and the product was cooled, filtered, washed with ethanol and acetone for 3 times, and dried to obtain the intermediate cellulose;

[0049] (3) 10 g of the intermediate cellulose was dispersed in 200 mL of xylene, then 10 mL of hydrogen-containing silicone oil and 0.4 mL of 0.3 wt% Karstedt catalyst were added, and the reaction was carried out at 110°C under nitrogen atmosphere for 4 h, and the product was centrifuged, washed with xylene and ethanol for 3 times, and dried to obtain the modified nanocellulose;

[0050] (4) 10000 g of polyethylene terephthalate, 700 g of maleic anhydride grafted polyethylene, 1000 g of ACR resin, 300 g of polyethylene wax, 300 g of calcium stearate, 100 g of sodium benzoate, 80 g of silane coupling agent KH-560, and 1200 g of the modified nanocellulose were mixed, then dried at 140°C for 5 h to remove water, and then melt-extruded in a double-screw extruder at 280°C to obtain the high-barrier polyester packaging film.

[0051] Example 2

[0052] A method for preparing a high-barrier polyester packaging film, comprising the following steps:

[0053] (1) 10 g of nanocellulose was dispersed in 200 mL of deionized water, and the pH of the system was adjusted to 8.5 with sodium hydroxide solution, and 5 g of sodium periodate was slowly added, and the reaction was carried out at 35°C under light shielding for 10 h, and the product was centrifuged, washed with deionized water and ethanol for 3 times, and dried to obtain the aldehyde group cellulose;

[0054] (2) 10 g of the aldehyde group cellulose was dispersed in 200 mL of anhydrous ethanol, ultrasonic treatment for 45 min, then 12 g of dodecylamine and 0.3 g of p-toluenesulfonic acid were added, and the reaction was carried out at 75°C under nitrogen atmosphere for 8 h, and the product was cooled, filtered, washed with ethanol and acetone for 3 times, and dried to obtain the intermediate cellulose;

[0055] (3) 10 g of the intermediate cellulose was dispersed in 200 mL of xylene, then 10 mL of hydrogen-containing silicone oil and 0.4 mL of 0.3 wt% Karstedt catalyst were added, and the reaction was carried out at 110°C under nitrogen atmosphere for 4 h, and the product was centrifuged, washed with xylene and ethanol for 3 times, and dried to obtain the modified nanocellulose;

[0056] (4) polyethylene terephthalate 10000 g, maleic anhydride grafted polyethylene 600 g, ACR resin 800 g, polyethylene wax 200 g, calcium stearate 200 g, sodium benzoate 70 g, silane coupling agent KH-560 60 g, modified nanocellulose 1000 g are mixed, then dried at 140°C for 5h to remove water, put into a twin-screw extruder, melt extruded at 280°C, cast into a film, the casting roller temperature is 120°C, and the cooling obtains the high-barrier polyester packaging film.

[0057] Example 3

[0058] A preparation method of a high-barrier polyester packaging film, comprising the following steps:

[0059] (1) 10 g of nanocellulose is dispersed into 200 mL of deionized water, the pH of the system is adjusted to 8.5 with sodium hydroxide solution, 4 g of sodium periodate is slowly added, and the reaction is stirred at 30°C for 14 h in the dark. The product is centrifuged and washed with deionized water and ethanol three times in turn, and dried to obtain aldehyde-modified cellulose;

[0060] (2) 10 g of aldehyde-modified cellulose is dispersed into 200 mL of anhydrous ethanol, ultrasonic treatment is performed for 45 min, then 8 g of dodecylamine and 0.2 g of p-toluenesulfonic acid are added, and the reaction is refluxed at 65°C under nitrogen atmosphere for 12 h. The reaction is stirred every 2 h. The product is cooled, filtered, washed with ethanol and acetone three times in turn, and dried to obtain an intermediate cellulose;

[0061] (3) 10 g of the intermediate cellulose is dispersed into 200 mL of dimethylbenzene, then 7 mL of hydrogen silicone oil and 0.2 mL of 0.3wt% Karstedt catalyst are added, and the reaction is stirred at 90°C under nitrogen atmosphere for 8 h. The product is centrifuged, washed with dimethylbenzene and ethanol three times in turn, and dried to obtain the modified nanocellulose;

[0062] (4) polyethylene terephthalate 10000 g, maleic anhydride grafted polyethylene 400 g, ACR resin 600 g, polyethylene wax 200 g, calcium stearate 200 g, sodium benzoate 40 g, silane coupling agent KH-560 40 g, modified nanocellulose 800 g are mixed, then dried at 140°C for 5h to remove water, put into a twin-screw extruder, melt extruded at 280°C, cast into a film, the casting roller temperature is 120°C, and the cooling obtains the high-barrier polyester packaging film.

[0063] Example 4

[0064] A preparation method of a high-barrier polyester packaging film, comprising the following steps:

[0065] (1) Disperse 10 g of nanocellulose in 200 mL of deionized water, adjust the pH of the system to 8.5 with sodium hydroxide solution, slowly add 3 g of sodium periodate, and stir the reaction at 25 °C in the dark for 18 h. The product is centrifuged, washed three times with deionized water and ethanol, and dried to obtain aldehyded cellulose.

[0066] (2) 10 g of aldehyded cellulose was dispersed in 200 mL of anhydrous ethanol and ultrasonically treated for 45 min. Then, 6 g of dodecylamine and 0.1 g of p-toluenesulfonic acid were added. The mixture was refluxed at 60°C under a nitrogen atmosphere for 14 h. During the reaction, the mixture was stirred every 2 h. The product was cooled and filtered. The product was washed three times with ethanol and acetone, and dried to obtain the intermediate cellulose.

[0067] (3) 10 g of the intermediate fiber was dispersed in 200 mL of xylene, and then 5 mL of hydrogenated silicone oil and 0.1 mL of 0.3 wt% Karstedt catalyst were added. The mixture was stirred at 80° C. under a nitrogen atmosphere for 10 h. The product was centrifuged, washed three times with xylene and ethanol, and dried to obtain the modified nanocellulose.

[0068] (4) 10000 g of polyethylene terephthalate, 300 g of maleic anhydride grafted polyethylene, 400 g of ACR resin, 100 g of polyethylene wax, 100 g of calcium stearate, 10 g of sodium benzoate, 20 g of silane coupling agent KH-560, and 600 g of modified nanocellulose were mixed, and then dried at 140° C. for 5 h to remove water. The mixture was put into a twin-screw extruder and melt-extruded at 280° C. to form a film. The casting roll temperature was 120° C. and the film was cooled to obtain the high barrier polyester packaging film.

[0069] Comparative Example 1

[0070] A method for preparing a high-barrier polyester packaging film comprises the following steps:

[0071] (1) Disperse 10 g of nanocellulose in 200 mL of deionized water, adjust the pH of the system to 8.5 with sodium hydroxide solution, slowly add 6 g of sodium periodate, and stir the reaction at 40 °C in the dark for 6 h. The product is centrifuged, washed three times with deionized water and ethanol, and dried to obtain aldehyded cellulose.

[0072] (2) 10 g of aldehyded cellulose was dispersed in 200 mL of anhydrous ethanol and ultrasonically treated for 45 min. Then, 12 g of dodecylamine and 0.3 g of p-toluenesulfonic acid were added and refluxed at 75 °C under a nitrogen atmosphere for 8 h. During the reaction, the mixture was stirred every 2 h. The product was cooled and filtered, and the product was washed three times with ethanol and acetone, and dried to obtain the intermediate cellulose.

[0073] (3) 10000 g of polyethylene terephthalate, 700 g of maleic anhydride grafted polyethylene, 1000 g of ACR resin, 300 g of polyethylene wax, 300 g of calcium stearate, 100 g of sodium benzoate, 80 g of silane coupling agent KH-560, 600 g of intermediate cellulose, and 600 mL of hydrogenated silicone oil were mixed, then dried at 140° C. for 5 h to remove water, put into a twin-screw extruder, melt-extruded at 280° C., cast into a film, the casting roll temperature was 120° C., and cooled to obtain the high barrier polyester packaging film.

[0074] Comparative Example 2

[0075] A method for preparing a high-barrier polyester packaging film comprises the following steps:

[0076] (1) Disperse 10 g of nanocellulose in 200 mL of deionized water, adjust the pH of the system to 8.5 with sodium hydroxide solution, slowly add 6 g of sodium periodate, and stir the reaction at 40 °C in the dark for 6 h. The product is centrifuged, washed three times with deionized water and ethanol, and dried to obtain aldehyded cellulose.

[0077] (2) 10000 g of polyethylene terephthalate, 700 g of maleic anhydride grafted polyethylene, 1000 g of ACR resin, 300 g of polyethylene wax, 300 g of calcium stearate, 100 g of sodium benzoate, 80 g of silane coupling agent KH-560, 600 g of formaldehyded cellulose, and 600 g of dodecylamine were mixed, and then dried at 140° C. for 5 h to remove water. The mixture was put into a twin-screw extruder and melt-extruded at 280° C. to form a film. The temperature of the casting roll was 120° C., and the film was cooled to obtain the high barrier polyester packaging film.

[0078] The polyester packaging films prepared in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to performance tests. The tensile strength and elongation at break of the packaging films were tested with reference to GB / T1040.3-2006 “Determination of tensile properties of plastics Part 3: Test conditions for films and sheets”; the oxygen permeability was tested with reference to GB / T19789-2021 “Oxygen permeability test for plastic films and sheets for packaging materials - Coulometer method”; the water vapor permeability was tested with reference to GB / T 1037-2021 “Determination of water vapor permeability of plastic films and sheets - Cup weight gain and weight loss method”; the contact angle of the sample surface was measured using an OCA20 contact angle meter from Dataphysics, Germany. The contact angle was measured at room temperature with a water droplet volume of 2.0 μL to detect the hydrophobicity; the specific data are shown in Table 1.

[0079] Table 1 High barrier polyester packaging film performance test results

[0080]

[0081] The above merely describes preferred specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art, according to the technical solution and inventive concept of the present application, makes equivalent replacement or change within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A high barrier polyester packaging film, characterized in that: The invention is prepared from the following components in parts by weight: 100 parts of polyethylene terephthalate, 3-7 parts of maleic anhydride grafted polyethylene, 4-10 parts of ACR resin, 1-3 parts of polyethylene wax, 1-3 parts of calcium stearate, 0.1-1 parts of sodium benzoate, 0.2-0.8 parts of silane coupling agent, and 6-12 parts of modified nanocellulose.

2. The high barrier polyester packaging film according to claim 1, characterized in that: The modified nanocellulose is prepared by the following reaction steps: (1) Dispersing the nanocellulose in deionized water, adjusting the pH of the system, slowly adding sodium periodate, reacting in the dark, centrifuging, washing, and drying the product to obtain aldehyded cellulose; (2) dispersing the aldehyde-modified cellulose in anhydrous ethanol, ultrasonically treating it, then adding dodecylamine and p-toluenesulfonic acid, and reflux reaction under nitrogen atmosphere. The product is cooled, filtered, washed, and dried to obtain the intermediate cellulose. (3) The intermediate fiber is dispersed in xylene, and then hydrogenated silicone oil and a platinum catalyst are added, and the reaction is stirred under a nitrogen atmosphere. The product is centrifuged, washed, and dried to obtain the modified nanocellulose.

3. The high barrier polyester packaging film according to claim 2, characterized in that: In step (1), the usage ratio of nanocellulose, deionized water, and sodium periodate is 10 g: 150-300 mL: 3-6 g.

4. The high barrier polyester packaging film according to claim 2, characterized in that: In step (1), the pH of the system is adjusted to 8-9 with sodium hydroxide solution; the reaction conditions are to stir and react in the dark at 25-40° C. for 6-18 hours; and the product is washed with deionized water and ethanol 2-4 times in sequence.

5. The high barrier polyester packaging film according to claim 2, characterized in that: In step (2), the ratio of aldehyded cellulose, anhydrous ethanol, dodecylamine and p-toluenesulfonic acid is 10 g: 150-300 mL: 6-12 g: 0.1-0.3 g.

6. The high barrier polyester packaging film according to claim 2, characterized in that: In step (2), ultrasonic treatment is performed for 30 to 60 minutes; the reflux reaction conditions are reflux reaction at 60 to 75° C. for 8 to 14 hours, and stirring is performed every 2 hours during the reaction; the product is washed with ethanol and acetone 2 to 4 times in sequence.

7. The high barrier polyester packaging film according to claim 2, characterized in that: In step (3), the ratio of the intermediate fiber, xylene, hydrogenated silicone oil, and platinum catalyst is 10 g: 150-300 mL: 5-10 mL: 0.1-0.4 mL; the platinum catalyst is 0.1-0.5 wt% of Karstedt catalyst.

8. The high barrier polyester packaging film according to claim 2, characterized in that: In step (3), the stirring reaction conditions are 80-110° C. for 4-10 h; the product is washed with xylene and ethanol 2-4 times in sequence.

9. A method for preparing the high barrier polyester packaging film according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: mixing the components, drying and removing water, putting the components into a twin-screw extruder for melt extrusion, casting into a film, and cooling to obtain the high-barrier polyester packaging film.

10. The preparation method according to claim 9, characterized in that Dry at 130-150°C for 4-6 hours to remove water; melt extrude at 270-290°C; the casting roll temperature is 105-135°C.

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