Composite aluminum foil packaging material and method for manufacturing the same

Abstract

The present application relates to the technical field of packaging materials, and particularly relates to a composite aluminum foil packaging material and a preparation method thereof, which comprises, from inside to outside, an aluminum foil layer, a primer layer, an antibacterial layer and a film restraining layer. The antibacterial layer contains multiple layers of antibacterial particles, which are modified by a silane coupling agent after taking zinc oxide as a core, and are coated with polymethyl methacrylate inner shells and chitosan outer shells in sequence, so as to realize efficient and persistent antibacterial property and improve the compatibility with the matrix. The film restraining layer is formed by a functional coating liquid, which contains a beta-cyclodextrin / cinnamaldehyde inclusion compound, chitosan and glycerol, so as to realize the controllable slow release of cinnamaldehyde and ensure long-acting antibacterial property. Through the synergistic effect of the layers, the material has excellent antibacterial property, good mechanical property, low water vapor permeability and high interlayer peeling strength, and is suitable for food and pet food packaging, and can effectively prolong the shelf life of products and improve the packaging safety and stability.

Description

Technical Field

[0001] This invention relates to the field of packaging materials technology, and in particular to a composite aluminum foil packaging material and its preparation method. Background Technology

[0002] Aluminum foil, due to its excellent barrier properties, heat resistance, and processing adaptability, has been widely used in packaging for food, pet food, pharmaceuticals, and daily chemicals. Existing composite aluminum foil packaging materials typically combine aluminum foil with substrates such as polyolefins and polyesters to achieve good mechanical strength and sealing. However, traditional composite aluminum foil packaging still has the following shortcomings: First, although the aluminum foil layer can block oxygen and moisture, it is easily affected by the external humid and hot environment during long-term storage, leading to a decline in the quality of the packaged product; second, the composite layer lacks effective antibacterial and microbial film inhibition functions, making it difficult to meet the high safety and long shelf-life requirements of food and pet food; third, some additives introduced to enhance functionality pose a potential migration risk, which is detrimental to food contact safety and makes it difficult to meet increasingly stringent regulatory requirements.

[0003] Chinese Patent Application No. CN202310117221.6 discloses a high-barrier packaging material and its preparation method. This packaging material comprises, sequentially, aluminum foil, a PE adhesive layer, a barrier layer, another PE adhesive layer, a substrate, and a PE film. The aluminum foil is bonded to a woven fabric via the adhesive layer. The barrier layer comprises the following raw materials in parts by weight: polyethylene: 100 parts; ethylene-vinyl alcohol copolymer: 20-30 parts; sheet-like nanomaterials: 10-20 parts; spherical alumina particles: 5-10 parts; dispersant modifier: 1-3 parts; acetylated chitosan nanofibers: 10-20 parts. However, this invention uses only acetylated chitosan nanofibers as the antibacterial component, which is prone to rapid degradation during storage and use, failing to achieve a long-term antibacterial effect. Chinese Patent Application No. CN202211264013.0 discloses a tearable packaging material, its preparation method, and a packaging container. The preparation method of this tearable packaging material includes: S10: coating an adhesive paste on the first surface of an aluminum foil layer and applying a sealing layer; S20: applying a first barrier layer on the second surface of the aluminum foil layer; S30: applying a second barrier layer on the first barrier layer, and hot-pressing the first barrier layer and the second barrier layer together at a hot-pressing temperature of 120℃-140℃ and a hot-pressing pressure of 0.4MPa-0.6MPa to prepare the tearable packaging material. When in use, the second barrier layer is peeled off from the first barrier layer to remove stains, bacteria, etc., adhering to the second barrier layer, effectively ensuring the cleanliness of the packaging material surface during use. However, this invention only adds nano-titanium dioxide and polyhexamethylene biguanide hydrochloride as antibacterial components in the sealing layer. These antibacterial components are rapidly depleted during moist heat sterilization or long-term storage, failing to achieve a long-lasting antibacterial effect. Furthermore, nano-titanium dioxide requires light to exert its antibacterial effect, and its antibacterial effect is significantly reduced in the dark or dark environment inside the packaging.

[0004] Therefore, how to further endow aluminum foil with long-lasting antibacterial and controlled release functions while maintaining its excellent barrier properties, and at the same time ensure its material safety and process feasibility, has become an urgent problem to be solved in current composite aluminum foil packaging technology. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a composite aluminum foil packaging material and its preparation method. Utilizing the synergistic effect of multilayer antibacterial particles and a functional coating liquid, a composite aluminum foil packaging material with highly efficient and long-lasting antibacterial properties is obtained. By modifying zinc oxide with a silane coupling agent and then coating it with polymethyl methacrylate and chitosan, core-shell structured antibacterial particles are obtained, achieving a dual antibacterial mechanism of ion release and physical barrier. By encapsulating cinnamaldehyde with β-cyclodextrin and combining it with chitosan and glycerol, a coating liquid with sustained-release function is obtained, forming an outer antibacterial barrier. By sequentially preparing a base coating layer, an antibacterial layer, and an anti-bacterial film layer on the aluminum foil surface, a packaging material with high antibacterial rate, excellent mechanical properties, strong water vapor barrier properties, and strong interlayer bonding is obtained.

[0006] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0007] A composite aluminum foil packaging material includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer;

[0008] The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid.

[0009] The method for preparing the antibacterial particles is as follows:

[0010] Step S1: First, disperse zinc oxide in a mixed solvent, sonicate for 5-10 min, then add silane coupling agent KH-560 solution, react at 40-50℃ for 50-60 min, and obtain core particles after post-processing.

[0011] Step S2: Add the core particles to deionized water, sonicate for 3-5 minutes, then add to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate, then add methyl methacrylate, and react for 4-5 hours under an inert atmosphere and at 65-75°C. After post-processing, the inner shell coated particles are obtained.

[0012] Step S3: Add the inner shell-coated particles to the chitosan-acetic acid aqueous solution, stir for 30-40 minutes, then adjust the pH to 5.4-5.6, and obtain multilayer antibacterial particles after post-treatment.

[0013] Further, in step S1, the mass ratio of anhydrous ethanol to deionized water in the mixed solvent is 95:5-10, the amount of zinc oxide added in the mixed solvent is 2-2.5 g / 100 mL, the mass ratio of zinc oxide to silane coupling agent KH-560 is 5:0.1-0.2, the solvent used for the silane coupling agent KH-560 solution is also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent is 0.01-0.02 g / 100 mL.

[0014] Further, in step S2, the amount of core particles added to the deionized water is 2-2.5 g / 100 mL, and the mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.01-0.02:0.02-0.03:4.5-5.5. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

[0015] Furthermore, in step S3, the amount of chitosan added to the acetic acid aqueous solution is 0.45-0.55 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.45-0.55:2.

[0016] The preparation method of the functional coating liquid is as follows:

[0017] Step a: Dissolve β-cyclodextrin in deionized water at 40-45℃, keep the temperature constant, then add cinnamaldehyde solution, stir for 50-60 min, then let stand for 50-60 min, and obtain cyclodextrin inclusion complex after post-processing;

[0018] Step b: Add the cyclodextrin inclusion complex to the chitosan acetic acid aqueous solution, sonicate for 2-3 minutes, then stir for 10-20 minutes, then add glycerol and stir for 5-10 minutes to obtain the functional coating solution.

[0019] Further, in step a, the amount of β-cyclodextrin added to the deionized water is 4.5-5 g / 100 mL, the mass ratio of β-cyclodextrin to cinnamaldehyde is 4.5-5:1, the solvent of the cinnamaldehyde solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:0.5-1, and the amount of cinnamaldehyde added to the solvent is 0.05-0.15 g / 100 mL.

[0020] Further, in step b, the amount of chitosan added to the acetic acid aqueous solution is 1-1.5 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 1-2:1-2:0.2.

[0021] The present invention also provides a method for preparing a composite aluminum foil packaging material, which is used to prepare the above-mentioned composite aluminum foil packaging material. The preparation method includes the following steps: sequentially preparing an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer.

[0022] The present invention has the following beneficial effects:

[0023] The preparation process of the antibacterial particles introduced in this invention involves the construction of a multi-layer composite structure, including a core particle, an inner shell coating layer, and a chitosan coating layer. This multi-layer structure design significantly improves the antibacterial performance. Specifically, zinc oxide, as the core material, enhances the dispersibility and stability of the particles through the introduction of a silane coupling agent; the subsequent methyl methacrylate coating layer further improves the water resistance and mechanical strength of the particles; and the final chitosan coating layer endows the particles with good biocompatibility and antibacterial activity. This multi-layer structure not only improves the stability of the antibacterial particles but also enhances their inhibitory ability against various pathogenic microorganisms, thereby achieving a highly efficient antibacterial effect in composite aluminum foil packaging materials. The functional coating solution first uses β-cyclodextrin and cinnamaldehyde as raw materials, forming a cyclodextrin inclusion complex through inclusion action, and then mixes it with chitosan and glycerol to form a functional coating solution. This coating solution not only has good film-forming properties but also enhances the stability and antibacterial properties of the coating layer through the inclusion action of cyclodextrin.

[0024] From an overall technical perspective, the synergistic effect of the design and manufacturing processes of each functional layer has led to a breakthrough in the comprehensive performance of the composite material. The aluminum foil substrate undergoes cleaning and corona treatment to ensure interface cleanliness and activation; the undercoat layer forms a strong bond with the aluminum foil layer through an epoxy-silane coupling system; the optimized dispersion of antibacterial particles in the antibacterial layer simultaneously provides reinforcement, toughening, and antibacterial functions; and the inhibitory film layer integrates multiple properties such as long-lasting antibacterial effect, high barrier properties, and strong interfacial bonding. This multi-layered structural design enables the composite aluminum foil packaging material to simultaneously possess excellent and durable antibacterial properties, good mechanical properties, extremely low water vapor permeability, and stable interlayer bonding strength. It overcomes the technical bottlenecks of traditional antibacterial packaging materials, such as easy loss of antibacterial agents, weak interfacial bonding, and limited functionality, providing an ideal solution for high-end food packaging. Attached Figure Description

[0025] Figure 1 Line graph showing the antibacterial rate of Escherichia coli;

[0026] Figure 2 This is a line graph showing the antibacterial rate of Staphylococcus aureus. Detailed Implementation

[0027] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0028] All raw materials used in the following examples are commercially available products. Zinc oxide, with a particle size of 50 nm and an effective ingredient content of 99%, was purchased from Fujian Ruisen New Materials Co., Ltd.; methyl methacrylate, with a density of 0.943 g / cm³. 3 Colorless, transparent liquid, purchased from Shandong Ruigang Chemical Co., Ltd.; chitosan, density 1 g / cm³ 3 The following products were purchased from Shandong Xindongneng Chemical Co., Ltd.: 1. Aluminum cleaning agent with 99% effective ingredient content and a melting point of 102.5℃; 2. Aluminum foil with 99.6% effective ingredient content, material 1060, and a thickness of 0.3mm; 3. E-44 epoxy resin with a viscosity of 13000-16000 mPa·s and an effective ingredient content ≥99%; 4. Food-grade defoamer GP330 with an acid value ≤0.5mgKOH / g and a hydroxyl value of 52~60mgKOH / g; 5. Ethylene-methyl acrylate copolymer (EMA) with a density of 0.940g / cm³. 3 The following materials were purchased: NA-11 (99% effective ingredient content), vitamin E powder (99% effective ingredient content), polyethylene wax (99% effective ingredient content), and acrylate leveling agent (BYK-333, 99% effective ingredient content, density 1.04 kg / m³). The nucleating agent was purchased from Dongguan Shangpin New Material Technology Co., Ltd.; the active ingredient was purchased from Wuhan Huaxiang Kejie Biotechnology Co., Ltd.; the antioxidant was purchased from Jiangsu Aofu Biotechnology Co., Ltd.; the active ingredient was purchased from Beijing Likang Weiye Technology Co., Ltd.; and the active ingredient was purchased from Beijing Likang Weiye Technology Co., Ltd. 3 Purchased from Guangzhou Wana Chemical Co., Ltd.; hydroxyethyl cellulose, viscosity 50000-100000 mPa·s, density 0.75 g / cm³. 3 It contains 99% active ingredients and was purchased from Jinan Kaichuang Chemical Co., Ltd.

[0029] Example 1

[0030] A composite aluminum foil packaging material includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer;

[0031] The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid.

[0032] The method for preparing the antibacterial particles is as follows:

[0033] Step S1: First, disperse zinc oxide in a mixed solvent and sonicate for 5 minutes at 300W and 40kHz. Then, add silane coupling agent KH-560 solution dropwise at a rate of 1 mL / min while stirring continuously at 1200 rpm. React at 40℃ for 60 minutes, allow to cool naturally to room temperature, centrifuge at 3000 rpm for 10 minutes, wash the precipitate twice with anhydrous ethanol, and then dry the precipitate in a vacuum drying oven at 65℃ for 12 hours. The particles were then cured in a muffle furnace at 115°C for 2 hours and naturally cooled to room temperature to obtain the core particles. The mass ratio of anhydrous ethanol to deionized water in the mixed solvent was 95:5, the amount of zinc oxide added in the mixed solvent was 2 g / 100 mL, and the mass ratio of zinc oxide to silane coupling agent KH-560 was 5:0.1. The solvent used for the silane coupling agent KH-560 solution was also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent was 0.01 g / 100 mL.

[0034] Step S2: Add the core particles to deionized water and sonicate for 3 minutes at a power of 300W and a frequency of 40kHz. Then add them to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate. Next, add methyl methacrylate dropwise at a rate of 1 mL / min while stirring at 800 rpm. React for 5 hours under a nitrogen atmosphere and at 65°C. After the reaction is complete, cool to room temperature and filter through a 200-mesh filter. Centrifuge the filtrate at 3000 rpm for 10 minutes. Then wash the precipitate twice with deionized water and dry it in a vacuum drying oven at 65°C for 12 hours to obtain the inner shell coated particles. The amount of core particles added to the deionized water is 2 g / 100 mL. The mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.01:0.02:4.5. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

[0035] Step S3: Add the inner shell coated particles to the chitosan-acetic acid aqueous solution, stir for 30 min, then adjust the pH to 5.4-5.6 with 0.1M NaOH solution, vacuum filter using a 0.45μm aqueous filter membrane, and vacuum dry the filter cake at 60℃ for 12 h. After drying, grind and pass through a 200-mesh sieve to obtain multilayer antibacterial particles. The amount of chitosan added in the 1% acetic acid aqueous solution is 0.45 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.45:2.

[0036] The preparation method of the functional coating liquid is as follows:

[0037] Step a: At 40℃, β-cyclodextrin was dissolved in deionized water, and the temperature was kept constant. Then, cinnamaldehyde solution was added dropwise at a rate of 2 mL / min, while stirring at 500 rpm. After the addition was complete, stirring was continued for 60 min. Then, the mixture was allowed to stand for 50 min, centrifuged at 3000 rpm for 10 min, and the precipitate was washed once with deionized water. The precipitate was then dried in a vacuum drying oven at 50℃ for 12 h to obtain the cyclodextrin inclusion complex. The amount of β-cyclodextrin added to the deionized water was 4.5 g / 100 mL, and the mass ratio of β-cyclodextrin to cinnamaldehyde was 4.5:1. The solvent of the cinnamaldehyde solution consisted of anhydrous ethanol and deionized water in a mass ratio of 9:0.5, and the amount of cinnamaldehyde added to the solvent was 0.05 g / 100 mL.

[0038] Step b: Add the cyclodextrin inclusion complex to the chitosan-acetic acid aqueous solution, sonicate for 2 min at a power of 400 W and a frequency of 40 kHz, then stir for 10 min, add glycerol, and stir for 5 min to obtain the functional coating solution. The amount of chitosan added in the 1% acetic acid aqueous solution is 1 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 1:1:0.2.

[0039] This invention also provides a method for preparing composite aluminum foil packaging materials, comprising the following steps:

[0040] (1) Aluminum foil layer: First, spray the aluminum foil with 2wt% neutral cleaning agent at 50℃ and 0.2MPa pressure for 30s, then rinse it twice with deionized water, and then dry it with hot air at 85℃ and wind speed of 2m / s for 15s.

[0041] (2) Base coating: First, dissolve epoxy resin in anhydrous ethanol, then add anhydrous ethanol solution of silane coupling agent KH-550, stir for 30 min, then add hexamethylenediamine and defoamer, stir at 300 rpm for 20 min, filter with a 400-mesh nylon filter, and use a micro-gravure coating machine to evenly coat the filtrate onto the surface of the aluminum foil layer at a coating speed of 15 m / min, a scraper pressure of 0.1 MPa, and a wet film thickness of 25 µm. Then bake at 60℃ for 10 min and cure with hot air at 120℃ for 20 min. The mass ratio of epoxy resin to anhydrous ethanol is 1:3, the mass ratio of silane coupling agent KH-550 to anhydrous ethanol in the anhydrous ethanol solution of silane coupling agent KH-550 is 0.1:1, and the mass ratio of epoxy resin, silane coupling agent KH-550, hexamethylenediamine, and defoamer is 10:0.5:1:0.1.

[0042] (3) Antibacterial layer: First, dissolve the ethylene-methyl acrylate copolymer in ethyl acetate at 60℃ and 800rpm, add nucleating agent, antioxidant and polyethylene wax, stir until completely dissolved, add antibacterial particles and first ultrasonically disperse for 5min at 300W and 40kHz, then stir at 1200rpm for 15min, filter with a 200-mesh filter, and then coat the filtrate evenly onto the base coating using a slot coater at a speed of 12m / min and a wet film thickness of 40µm. Then bake at 60℃ for 15min and cure at 85℃ for 30min. The amount of ethylene-methyl acrylate copolymer added in ethyl acetate is 30g / 100mL, and the mass ratio of ethylene-methyl acrylate copolymer, nucleating agent, antioxidant, polyethylene wax and antibacterial particles is 100:0.05:0.22:0.12:5.

[0043] (4) Antibacterial film layer: First, add 0.3wt% leveling agent and 0.5wt% hydroxyethyl cellulose to the functional coating solution, adjust the viscosity to 250±20mPa·s with NDJ-5S viscometer, filter with 400 mesh filter, and use a comma doctor blade coater to evenly coat the filtrate onto the antibacterial layer. The coating speed is 10m / min, the coating pressure is 0.08MPa, the wet film thickness is 20μm, and then dry with hot air at 60℃ for 10min and vacuum at 80℃ for 15min.

[0044] Example 2

[0045] A composite aluminum foil packaging material includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer;

[0046] The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid.

[0047] The method for preparing the antibacterial particles is as follows:

[0048] Step S1: First, disperse zinc oxide in a mixed solvent and sonicate for 10 min at 300 W and 40 kHz. Then, add silane coupling agent KH-560 solution dropwise at a rate of 1 mL / min while stirring continuously at 1200 rpm. React at 50°C for 50 min, allow to cool naturally to room temperature, centrifuge at 3000 rpm for 10 min, wash the precipitate twice with anhydrous ethanol, and then dry the precipitate in a vacuum drying oven at 65°C for 12 h. The particles were then cured in a muffle furnace at 115°C for 2 hours and allowed to cool naturally to room temperature to obtain the core particles. The mass ratio of anhydrous ethanol to deionized water in the mixed solvent was 95:10, the amount of zinc oxide added in the mixed solvent was 2.5 g / 100 mL, and the mass ratio of zinc oxide to silane coupling agent KH-560 was 5:0.2. The solvent used for the silane coupling agent KH-560 solution was also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent was 0.02 g / 100 mL.

[0049] Step S2: Add the core particles to deionized water and sonicate for 5 minutes at a power of 300W and a frequency of 40kHz. Then add them to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate. Add methyl methacrylate dropwise at a rate of 1 mL / min while stirring at 800 rpm. React for 4 hours under a nitrogen atmosphere and at 75°C. After the reaction is complete, cool to room temperature and filter through a 200-mesh filter. Centrifuge the filtrate at 3000 rpm for 10 minutes. Wash the precipitate twice with deionized water and dry it in a vacuum drying oven at 65°C for 12 hours to obtain the inner shell coated particles. The amount of core particles added to the deionized water is 2.5 g / 100 mL. The mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.02:0.03:5.5. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

[0050] Step S3: Add the inner shell coated particles to the chitosan-acetic acid aqueous solution and stir for 40 min. Then adjust the pH to 5.4-5.6 with 0.1 M NaOH solution. Vacuum filter using a 0.45 μm aqueous filter membrane. Dry the filter cake under vacuum at 60 °C for 12 h. After drying, grind and pass through a 200 mesh sieve to obtain multilayer antibacterial particles. The amount of chitosan added in the 1% acetic acid aqueous solution is 0.55 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.55:2.

[0051] The preparation method of the functional coating liquid is as follows:

[0052] Step a: At 45℃, β-cyclodextrin was dissolved in deionized water, and the temperature was kept constant. Then, cinnamaldehyde solution was added dropwise at a rate of 2 mL / min, while stirring at 500 rpm. After the addition was complete, stirring was continued for 50 min, and then the mixture was allowed to stand for 60 min. The mixture was then centrifuged at 3000 rpm for 10 min. The precipitate was washed once with deionized water and then dried in a vacuum drying oven at 50℃ for 12 h to obtain the cyclodextrin inclusion complex. The amount of β-cyclodextrin added to the deionized water was 5 g / 100 mL, the mass ratio of β-cyclodextrin to cinnamaldehyde was 5:1, and the solvent of the cinnamaldehyde solution was composed of anhydrous ethanol and deionized water in a mass ratio of 9:1. The amount of cinnamaldehyde added to the solvent was 0.15 g / 100 mL.

[0053] Step b: Add the cyclodextrin inclusion complex to the chitosan acetic acid aqueous solution, sonicate for 3 min at a power of 400 W and a frequency of 40 kHz, then stir for 20 min, add glycerol, and stir for 10 min to obtain the functional coating solution. The amount of chitosan added in the 1% acetic acid aqueous solution is 1.5 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 2:2:0.2.

[0054] The preparation method of the composite aluminum foil packaging material is the same as in Example 1.

[0055] Example 3

[0056] A composite aluminum foil packaging material includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer;

[0057] The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid.

[0058] The method for preparing the antibacterial particles is as follows:

[0059] Step S1: First, disperse zinc oxide in a mixed solvent and sonicate for 8 minutes at 300W and 40kHz. Then, add silane coupling agent KH-560 solution dropwise at a rate of 1 mL / min while stirring continuously at 1200 rpm. React at 45℃ for 55 minutes, allow to cool naturally to room temperature, centrifuge at 3000 rpm for 10 minutes, wash the precipitate twice with anhydrous ethanol, and then dry the precipitate in a vacuum drying oven at 65℃ for 12 hours. The core particles were obtained by curing in a muffle furnace at 115°C for 2 hours and then naturally cooling to room temperature. The mass ratio of anhydrous ethanol to deionized water in the mixed solvent was 95:7, the amount of zinc oxide added in the mixed solvent was 2.3 g / 100 mL, and the mass ratio of zinc oxide to silane coupling agent KH-560 was 5:0.15. The solvent used for the silane coupling agent KH-560 solution was also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent was 0.015 g / 100 mL.

[0060] Step S2: Add the core particles to deionized water and sonicate for 4 minutes at a power of 300W and a frequency of 40kHz. Then add them to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate. Next, add methyl methacrylate dropwise at a rate of 1 mL / min while stirring at 800 rpm. React for 4.5 hours under a nitrogen atmosphere and at 70°C. After the reaction is complete, cool to room temperature and filter through a 200-mesh filter. Centrifuge the filtrate at 3000 rpm for 10 minutes. Then wash the precipitate twice with deionized water and dry it in a vacuum drying oven at 65°C for 12 hours to obtain the inner shell coated particles. The amount of core particles added to the deionized water is 2.3 g / 100 mL. The mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.015:0.025:5. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

[0061] Step S3: Add the inner shell coated particles to the chitosan-acetic acid aqueous solution, stir for 35 min, then adjust the pH to 5.4-5.6 with 0.1M NaOH solution, vacuum filter using a 0.45μm aqueous filter membrane, and vacuum dry the filter cake at 60℃ for 12 h. After drying, grind and pass through a 200-mesh sieve to obtain multilayer antibacterial particles. The amount of chitosan added in the 1% acetic acid aqueous solution is 0.5 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.5:2.

[0062] The preparation method of the functional coating liquid is as follows:

[0063] Step a: At 43℃, β-cyclodextrin was dissolved in deionized water, and the temperature was kept constant. Then, cinnamaldehyde solution was added dropwise at a rate of 2 mL / min, while stirring at 500 rpm. After the addition was complete, stirring was continued for 55 min, and then the mixture was allowed to stand for 55 min. The mixture was then centrifuged at 3000 rpm for 10 min. The precipitate was washed once with deionized water and then dried in a vacuum drying oven at 50℃ for 12 h to obtain the cyclodextrin inclusion complex. The amount of β-cyclodextrin added to the deionized water was 4.8 g / 100 mL, and the mass ratio of β-cyclodextrin to cinnamaldehyde was 4.8:1. The solvent of the cinnamaldehyde solution consisted of anhydrous ethanol and deionized water in a mass ratio of 9:0.7, and the amount of cinnamaldehyde added to the solvent was 0.1 g / 100 mL.

[0064] Step b: Add the cyclodextrin inclusion complex to the chitosan acetic acid aqueous solution, sonicate for 2.5 min at a power of 400 W and a frequency of 40 kHz, then stir for 15 min, add glycerol, and stir for 7 min to obtain the functional coating solution. The amount of chitosan added in the 1% acetic acid aqueous solution is 1.3 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 1.5:1.5:0.2.

[0065] The preparation method of the composite aluminum foil packaging material is the same as in Example 1.

[0066] Comparative Example 1

[0067] A composite aluminum foil packaging material includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer;

[0068] The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid.

[0069] The method for preparing the antibacterial particles is as follows:

[0070] Step S1: First, disperse zinc oxide in a mixed solvent and sonicate for 8 minutes at 300W and 40kHz. Then, add silane coupling agent KH-560 solution dropwise at a rate of 1 mL / min while stirring continuously at 1200 rpm. React at 45℃ for 10 minutes, allow to cool naturally to room temperature, centrifuge at 3000 rpm for 10 minutes, wash the precipitate twice with anhydrous ethanol, and then dry the precipitate in a vacuum drying oven at 65℃ for 12 hours. The core particles were obtained by curing in a muffle furnace at 115°C for 2 hours and then naturally cooling to room temperature. The mass ratio of anhydrous ethanol to deionized water in the mixed solvent was 95:7, the amount of zinc oxide added in the mixed solvent was 2.3 g / 100 mL, and the mass ratio of zinc oxide to silane coupling agent KH-560 was 5:0.01. The solvent used for the silane coupling agent KH-560 solution was also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent was 0.015 g / 100 mL.

[0071] Step S2: Add the core particles to deionized water and sonicate for 4 minutes at a power of 300W and a frequency of 40kHz. Then add them to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate. Next, add methyl methacrylate dropwise at a rate of 1 mL / min while stirring at 800 rpm. React for 1 hour under a nitrogen atmosphere at room temperature. After the reaction, filter the solution through a 200-mesh filter and centrifuge the filtrate at 3000 rpm for 10 minutes. Then wash the precipitate twice with deionized water and dry the precipitate in a vacuum drying oven at 65℃ for 12 hours to obtain the inner shell coated particles. The amount of core particles added to the deionized water is 2.3 g / 100 mL, and the mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.015:0.01:1. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

[0072] Step S3: Add the inner shell coated particles to the chitosan-acetic acid aqueous solution, stir for 35 min, use a 0.45 μm aqueous filter membrane for vacuum filtration, dry the filter cake under vacuum at 60℃ for 12 h, grind after drying, and pass through a 200 mesh sieve to obtain multilayer antibacterial particles. The amount of chitosan added in the 1% acetic acid aqueous solution is 0.5 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.1:2.

[0073] The preparation method of the functional coating liquid is as follows:

[0074] Step a: At 43℃, β-cyclodextrin was dissolved in deionized water, and the temperature was kept constant. Then, cinnamaldehyde solution was added dropwise at a rate of 2 mL / min, while stirring continuously at 500 rpm. After the addition was complete, stirring was continued for 10 min. Then, the mixture was allowed to stand for 55 min, centrifuged at 3000 rpm for 10 min, and the precipitate was washed once with deionized water. The precipitate was then dried in a vacuum drying oven at 50℃ for 12 h to obtain the cyclodextrin inclusion complex. The amount of β-cyclodextrin added to the deionized water was 4.8 g / 100 mL, the mass ratio of β-cyclodextrin to cinnamaldehyde was 1:1, and the solvent of the cinnamaldehyde solution was composed of anhydrous ethanol and deionized water in a mass ratio of 9:0.7. The amount of cinnamaldehyde added to the solvent was 0.1 g / 100 mL.

[0075] Step b: Add the cyclodextrin inclusion complex to the chitosan acetic acid aqueous solution, sonicate for 2.5 min at a power of 400 W and a frequency of 40 kHz, then stir for 15 min, add glycerol, and stir for 7 min to obtain the functional coating solution. The amount of chitosan added in the 1% acetic acid aqueous solution is 1.3 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 1.5:1.5:0.1.

[0076] The preparation method of the composite aluminum foil packaging material is the same as in Example 1.

[0077] Comparative Example 2

[0078] In this comparative example, zinc oxide was used instead of antibacterial particles, and everything else was the same as in Example 1.

[0079] Comparative Example 3

[0080] In this comparative example, cinnamaldehyde solution was used instead of the functional coating liquid. The solvent of the cinnamaldehyde solution consisted of anhydrous ethanol and deionized water in a mass ratio of 9:0.7. The amount of cinnamaldehyde added to the solvent was 0.1 g / 100 mL. All other aspects were the same as in Example 1.

[0081] Comparative Example 4

[0082] In this comparative example, zinc oxide was used instead of antibacterial particles, and cinnamaldehyde solution was used instead of functional coating liquid. The solvent of cinnamaldehyde solution consisted of anhydrous ethanol and deionized water in a mass ratio of 9:0.7. The amount of cinnamaldehyde added to the solvent was 0.1 g / 100 mL. All other aspects were the same as in Example 1.

[0083] The composite aluminum foil packaging materials prepared in Examples 1-3 and Comparative Examples 1-4 were subjected to relevant performance tests. The antibacterial performance test was conducted according to the provisions of GB / T 31402-2023 "Determination of antibacterial activity of plastics and other non-porous materials". The tensile strength and elongation at break tests were conducted by preparing 10mm×100mm samples of composite aluminum foil packaging material and using a universal tensile testing machine at 25°C, a loading speed of 5mm / min, and an initial gauge length of 25mm. The water vapor transmission rate test was conducted according to the provisions of GB / T 26253-2010 "Determination of water vapor transmission rate of plastic films and sheets by infrared detector method", with test conditions of 38±0.5℃ and 90±2% humidity. The peel strength tests of aluminum foil-base coating, base coating-antibacterial layer, and antibacterial layer-inhibiting film layer were conducted according to the provisions of GB / T 8808-1988 "Peel test method for flexible composite plastic materials", with a sample size of 15mm×200mm and a test speed of 300mm / min.

[0084] Table 1 Performance Tests of Composite Aluminum Foil Packaging Materials

[0085]

[0086] As shown in Table 1 and Figure 1-2 As shown, the composite aluminum foil packaging materials prepared in Examples 1-3 are significantly superior to Comparative Example 1 in terms of antibacterial properties (against Escherichia coli and Staphylococcus aureus), mechanical properties (tensile strength and elongation at break), water vapor barrier properties, and interlayer peel strength (aluminum foil-base coating, base coating-antibacterial layer, antibacterial layer-inhibiting layer). This demonstrates that the comprehensive performance of the composite aluminum foil packaging materials prepared in the examples is superior to that of Comparative Example 1, thus indicating that the formulation of the composite aluminum foil packaging material proposed in this invention is optimal.

[0087] From Table 1 and Figure 1-2As can be seen, compared with the examples, the composite aluminum foil of Comparative Example 2 showed a significant decrease in antibacterial rate (Escherichia coli and Staphylococcus aureus), mechanical properties (tensile strength, elongation at break), water resistance (water vapor transmission rate), and interlayer peel strength, resulting in a worse overall performance. This is because it directly replaced the antibacterial particles with zinc oxide. The antibacterial particles have zinc oxide as the main core material, coated with a polymethyl methacrylate (PMMA) inner shell and a chitosan outer shell. Zinc oxide is a widely used antibacterial component; it can react with the cell membrane of microorganisms by releasing oxide ions or electrons, thereby destroying their cells. In terms of cell structure or function, zinc oxide can also generate reactive oxygen species, which can damage bacterial cell membranes and DNA, thereby inhibiting bacterial growth. The PMMA inner shell encapsulates ZnO, preventing the aggregation and rapid release of ZnO nanoparticles in the polymer matrix, achieving controlled and sustained release of zinc ions, thus extending the antibacterial efficacy. The chitosan molecules in the outer shell are positively charged, while the bacterial cell membrane is negatively charged. Through electrostatic adsorption, they firmly encapsulate the bacteria, causing cell membrane rupture and leakage of intracellular substances. These principles work together to significantly improve the antibacterial properties of the composite aluminum foil packaging material. In addition, the core particles provide rigid support, the PMMA inner shell improves the compatibility of the particles with the EMA matrix, and the chitosan outer shell increases hydrogen bonding with adjacent layers. Therefore, the introduction of core particles can enhance the mechanical properties of the composite aluminum foil packaging material. The antibacterial particles uniformly dispersed in the EMA matrix can effectively extend the diffusion path of water vapor molecules in the film. Their good dispersion in the antibacterial layer can also effectively avoid interface defects caused by agglomeration, ensuring the density and uniformity of the antibacterial layer itself, thus providing a good foundation for bonding with the base coating.

[0088] From Table 1 and Figure 1-2It can be seen that, compared with the examples, the composite aluminum foil of Comparative Example 3 showed a significant decrease in antibacterial rate (Escherichia coli and Staphylococcus aureus), mechanical properties (tensile strength and elongation at break), water resistance (water vapor transmission rate), and interlayer peel strength. This performance degradation is mainly due to the easy volatility and decomposition of cinnamaldehyde, which cannot form a stable and complete functional layer, resulting in a short antibacterial duration and weak interfacial adhesion. The reason is that cinnamaldehyde solution was used instead of functional coating liquid. The cyclodextrin inclusion complex, chitosan, glycerol and other components in the functional coating liquid can form a tight bond with the antibacterial layer and the base layer, enhancing the adhesion between the antibacterial layer and the base layer. In particular, the shell of the antibacterial particles is also chitosan. The chitosan molecular chains of the inhibition layer will penetrate and entangle with the chitosan molecular chains on the surface of the antibacterial particles. This makes a gradient transition and tough interface between the antibacterial layer and the inhibition layer, rather than a clear and fragile weak interface layer, thereby greatly improving the peel strength between the two. Hydrophobic cinnamaldehyde molecules are encapsulated within the lipophilic cavities of β-cyclodextrin, forming a molecular-level "reservoir." This inclusion complex significantly inhibits the volatility and oxidative degradation of cinnamaldehyde, preventing substantial loss during early processing and storage. When internal humidity increases or temperature changes, the inclusion complex dynamically releases cinnamaldehyde molecules. This controlled, sustained-release characteristic ensures the antibacterial active ingredient maintains its effectiveness throughout the shelf life, providing long-lasting antibacterial and antifungal protection and preventing spoilage. Furthermore, the released cinnamaldehyde synergistically interacts with zinc ions / chitosan in the antibacterial layer, attacking different targets on bacterial cell membranes, broadening the antibacterial spectrum and enhancing antibacterial efficiency. The β-cyclodextrin-cinnamaldehyde inclusion complex and chitosan form a dense hydrogen bond network, extending the diffusion path of water molecules / oxygen, thus reducing water vapor permeability. Hydroxyethyl cellulose, acting as a thickener, helps control the viscosity of the coating solution, ensuring film uniformity. Leveling agents can reduce defects such as orange peel and pinholes during the coating process and improve surface smoothness. Chitosan and glycerin in the functional coating solution, through synergistic effects with antibacterial particles, can not only enhance the mechanical strength and toughness of the material, but also impart a certain tensile strength to the composite aluminum foil packaging material, making it more resistant to external pressure or physical impact.

[0089] From Table 1 and Figure 1-2 It can be seen that, compared with the examples, the composite aluminum foil packaging material prepared in Comparative Example 4 has the worst performance data. This is because zinc oxide replaced the antibacterial particles, cinnamaldehyde solution replaced the functional coating liquid, the original "synergistic enhancement system" disappeared, the lack of multi-layer structure of antibacterial particles led to a double loss of antibacterial persistence and interfacial compatibility, and the destruction of the inclusion-film forming system of the functional coating liquid simultaneously weakened the barrier properties, mechanical properties and interlayer bonding force, ultimately reducing the antibacterial durability, surface stability and anti-pollution properties of the composite aluminum foil packaging material, and limiting the duration and stability of the antibacterial effect.

[0090] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A composite aluminum foil packaging material, characterized in that, It includes, from the inside out, an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer; The raw material for the antibacterial layer includes multiple layers of antibacterial particles; the raw material for the inhibitory film layer includes a functional coating liquid. The method for preparing the antibacterial particles is as follows: Step S1: First, disperse zinc oxide in a mixed solvent, sonicate for 5-10 min, then add silane coupling agent KH-560 solution, react at 40-50℃ for 50-60 min, and obtain core particles after post-processing. Step S2: Add the core particles to deionized water, sonicate for 3-5 minutes, then add to an aqueous solution containing sodium dodecyl sulfate and potassium persulfate, then add methyl methacrylate, and react for 4-5 hours under an inert atmosphere and at 65-75°C. After post-processing, the inner shell coated particles are obtained. Step S3: Add the inner shell coated particles to the chitosan acetic acid aqueous solution, stir for 30-40 minutes, then adjust the pH to 5.4-5.6, and obtain multilayer antibacterial particles after post-treatment; The preparation method of the functional coating liquid is as follows: Step a: Dissolve β-cyclodextrin in deionized water at 40-45℃, keep the temperature constant, then add cinnamaldehyde solution, stir for 50-60 min, then let stand for 50-60 min, and obtain cyclodextrin inclusion complex after post-processing; Step b: Add the cyclodextrin inclusion complex to the chitosan acetic acid aqueous solution, sonicate for 2-3 minutes, then stir for 10-20 minutes, then add glycerol and stir for 5-10 minutes to obtain the functional coating solution.

2. The composite aluminum foil packaging material according to claim 1, characterized in that, In step S1, the mass ratio of anhydrous ethanol to deionized water in the mixed solvent is 95:5-10, the amount of zinc oxide added in the mixed solvent is 2-2.5 g / 100 mL, the mass ratio of zinc oxide to silane coupling agent KH-560 is 5:0.1-0.2, the solvent used for the silane coupling agent KH-560 solution is also a mixed solvent, and the amount of silane coupling agent KH-560 added in the mixed solvent is 0.01-0.02 g / 100 mL.

3. The composite aluminum foil packaging material according to claim 1, characterized in that, In step S2, the amount of core particles added to the deionized water is 2-2.5 g / 100 mL, and the mass ratio of core particles, sodium dodecyl sulfate, potassium persulfate, and methyl methacrylate is 3:0.01-0.02:0.02-0.03:4.5-5.

5. The amount of sodium dodecyl sulfate in the aqueous solution containing sodium dodecyl sulfate and potassium persulfate is 0.45-0.55 g / 100 mL.

4. The composite aluminum foil packaging material according to claim 1, characterized in that, In step S3, the amount of chitosan added to the acetic acid aqueous solution is 0.45-0.55 g / 100 mL, and the mass ratio of chitosan to inner shell coated particles is 0.45-0.55:

2.

5. The composite aluminum foil packaging material according to claim 1, characterized in that, In step a, the amount of β-cyclodextrin added to the deionized water is 4.5-5 g / 100 mL, the mass ratio of β-cyclodextrin to cinnamaldehyde is 4.5-5:1, the solvent of the cinnamaldehyde solution is composed of anhydrous ethanol and deionized water in a mass ratio of 9:0.5-1, and the amount of cinnamaldehyde added to the solvent is 0.05-0.15 g / 100 mL.

6. The composite aluminum foil packaging material according to claim 1, characterized in that, In step b, the amount of chitosan added to the acetic acid aqueous solution is 1-1.5 g / 100 mL, and the mass ratio of cyclodextrin inclusion complex, chitosan, and glycerol is 1-2:1-2:0.

2.

7. A method for preparing a composite aluminum foil packaging material, characterized in that, The preparation method is used to prepare the composite aluminum foil packaging material as described in any one of claims 1-6. The preparation method includes the following steps: sequentially preparing an aluminum foil layer, a base coating layer, an antibacterial layer, and an anti-film layer.

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