A process for the preparation of a cheese stick packaging sheet

Abstract

The application relates to the technical field of cheese stick packaging material research and development, and discloses a preparation process of cheese stick packaging sheet material, which comprises the following steps: preparing an intermediate monomer; using a Schiff base reaction mechanism to prepare a ligand; through coordination, the ligand is combined with transition metal ions to prepare an antibacterial agent; the antibacterial agent is used for function modification of low-density polyethylene resin to prepare antibacterial polyethylene; the antibacterial polyethylene is used as raw material to generate an inner layer and an outer layer, ethylene-vinyl alcohol copolymer resin is used as raw material to generate an intermediate layer, and maleic anhydride grafted low-density polyethylene resin is used as raw material to generate a bonding layer; through multilayer co-extrusion and flow casting, the antibacterial sheet material is prepared. The application provides a process for preparing the antibacterial sheet material, and a cheese stick packaging sheet material with excellent antibacterial performance and meeting safety standards is prepared.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of cheese stick packaging material research and development, in particular to a preparation process of a cheese stick packaging sheet. BACKGROUND

[0002] As a common fermented dairy product, cheese sticks are favored by consumers due to their high calcium content, high nutrition and rich taste. The packaging materials commonly used for cheese sticks on the market include polyethylene materials, polypropylene materials, multi-layer composite materials and the like. Among them, the multi-layer composite material is widely used in the market due to its excellent barrier performance, good mechanical performance, strong compression resistance and the like, and has a good development prospect. However, the traditional multi-layer composite material is easy to become a carrier of microorganisms in the production, storage, circulation, transportation and use process, and pathogenic microorganisms can threaten the life and health of human beings and cause serious public environmental problems, which limits its actual use in the field of food packaging.

[0003] Adding an antibacterial agent is a main means to improve the antibacterial performance of food packaging materials, and only a small amount is often needed to achieve a broad-spectrum antibacterial effect. Patent No. CN116855006A discloses an antibacterial plastic packaging bag and a preparation method thereof. The plastic packaging bag is prepared by using polyethylene particles, vinyl cyanide, butadiene thermoplastic elastomer, antibacterial agent, slow-release agent and the like, which can effectively improve the overall antibacterial ability of the plastic packaging bag.

[0004] At present, the main antibacterial agents include natural antibacterial agents, organic antibacterial agents and inorganic antibacterial agents. Natural phenolic compounds are a family of compounds containing phenolic groups in their structures. Such compounds have strong antibacterial and antioxidant properties. Schiff bases have biological activities such as bacteriostasis, sterilization, antitumor and antiviral, and are often used as organic antibacterial agents. Inorganic antibacterial agents mainly include metal ion antibacterial agents such as silver zeolite, silver silica gel, silver activated carbon and silver hydroxyapatite-based antibacterial agents. SUMMARY

[0005] The application provides a preparation process of a cheese stick packaging sheet. The cheese stick packaging sheet prepared by the process has excellent antibacterial performance, good barrier performance and mechanical performance, and its sanitary performance meets the national standard requirements.

[0006] A preparation process of a cheese stick packaging sheet, comprising the following steps:

[0007] Step one: preparing an intermediate monomer;

[0008] Step two: preparing a ligand by using a Schiff base reaction mechanism;

[0009] Step three: preparing an antibacterial agent by complexing the ligand with a transition metal ion through coordination;

[0010] Step four: the low-density polyethylene resin is modified by the antibacterial agent to prepare an antibacterial polyethylene;

[0011] Step five: the antibacterial polyethylene is used as raw material to form an inner layer and an outer layer, the ethylene-vinyl alcohol copolymer resin is used as raw material to form a middle layer, the maleic anhydride grafted low-density polyethylene resin is used as raw material to form a bonding layer, and a multi-layer co-extrusion and flow casting process is used to prepare the antibacterial sheet.

[0012] Preferably, the preparation method of the intermediate monomer is as follows:

[0013] Step S1-1: the hydroxyl functional group of dihydroeugenol is subjected to a nucleophilic substitution reaction with the acyl chloride group of propionyl chloride by using propionyl chloride as an acylating agent and by using an organic base to catalyze the reaction, to generate an intermediate;

[0014] Step S1-2: the phenolic ester group of the intermediate is subjected to a rearrangement reaction by using a Fries rearrangement reaction mechanism and by using a Lewis acid to catalyze the reaction, to generate the intermediate monomer.

[0015] Preferably, the preparation method of the antibacterial sheet in step five is as follows:

[0016] Step S2-1: the antibacterial sheet is set to be a eleven-layer co-extruded film, and the film structure is as follows:

[0017] The first layer: the antibacterial polyethylene layer, 20-40 parts by weight;

[0018] The second layer: the maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0019] The third layer: the ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0020] The fourth layer: the maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0021] The fifth layer: the ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0022] The sixth layer: the ethylene-vinyl alcohol copolymer resin layer, 8-15 parts by weight;

[0023] The seventh layer: the ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0024] The eighth layer: the maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0025] The ninth layer: the ethylene-vinyl alcohol copolymer resin layer, 3-10 parts by weight;

[0026] The tenth layer: the maleic anhydride grafted low-density polyethylene resin layer, 2-5 parts by weight;

[0027] Eleventh layer: antibacterial polyethylene layer, 20-40 parts by weight;

[0028] Step S2-2: Put each raw material in step S2-1 into the hopper of the eleventh screw extruder of the eleven-layer co-extrusion film casting machine group, after mixing by stirring, the molten resin is converged at the die head through the flow divider, extruded through the die, cooled and wound to obtain an antibacterial sheet with a thickness of 80-120 μm.

[0029] Preferably, the preparation method of the antibacterial polyethylene is: 20-40 parts by weight of low-density polyethylene resin is dissolved in N,N-dimethylformamide, 0.5-3 parts by weight of antibacterial agent and 2-5 parts by weight of glycerol are added thereto in turn, and stirred and reacted at 40-60°C. After cooling, it is poured into a polytetrafluoroethylene mold and dried in an oven at 40-60°C, 60-80°C and 80-100°C in turn to obtain antibacterial polyethylene.

[0030] Preferably, the antibacterial agent is antibacterial agent I, and the preparation method of the antibacterial agent I is:

[0031] Step S3-1: using the Schiff base reaction mechanism, the amino functional group of 3-methylbenzylamine reacts with the carbonyl functional group of the intermediate monomer to generate ligand L1;

[0032] Step S3-2: the ligand L1 forms coordination with the transition metal ion to prepare the antibacterial agent I.

[0033] Preferably, the antibacterial agent is antibacterial agent II, and the preparation method of the antibacterial agent II is:

[0034] Step S4-1: using the Schiff base reaction mechanism, the amino functional group of 1,3-phenylenedimethylamine reacts with the carbonyl functional group of the intermediate monomer to generate ligand L2;

[0035] Step S4-2: the ligand L2 forms coordination with the transition metal ion to prepare the antibacterial agent II.

[0036] Preferably, the transition metal ion is selected from one or a combination of more than one of Ag + , Cu 2+ , Co 2+ , Mn 2+ , Zn 2+ .

[0037] The application of the antibacterial sheet prepared according to the above process in cheese stick packaging.

[0038] Beneficial effects:

[0039] The application designs and synthesizes a novel intermediate monomer, uses the intermediate monomer as raw material, synthesizes a ligand by using a Schiff base reaction, complexes the ligand with a transition metal ion, prepares an antibacterial agent, modifies polyolefin resin by using the antibacterial agent, and prepares antibacterial polyolefin resin; the antibacterial polyolefin resin is used as raw material to form an inner layer and an outer layer, and a multilayer co-extrusion and flow casting process is used to prepare antibacterial sheet;

[0040] It is found through experiments that the antibacterial sheet has antibacterial performance, and has relatively optimal barrier performance and mechanical properties, and the sanitary performance meets the requirements of national standards and can be used in cheese stick packaging. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The chemical reaction formula for synthesizing the intermediate;

[0042] Figure 2 The chemical structure formula of the intermediate monomer;

[0043] Figure 3 The chemical structure formula of the ligand L1;

[0044] Figure 4 The chemical structure formula of the ligand L2;

[0045] Figure 5 The columnar chart of the antibacterial performance experimental results of each sheet. DETAILED DESCRIPTION

[0046] Experimental example:

[0047] Experiment one: the ligand L1 is prepared, and the synthesis process is as follows:

[0048] (1) Synthesis of the intermediate: propionyl chloride is used as an acylating agent, the nucleophilic substitution reaction of the hydroxyl functional group of dihydroeugenol and the acyl chloride group of propionyl chloride is catalyzed by an organic base to generate the intermediate, and the chemical reaction formula is as shown in Figure 1

[0049] The organic base catalyst is selected to be triethylamine or pyridine; pyridine is selected in this experimental example;

[0050] The specific reaction steps of synthesizing the intermediate are as follows: 1.7 g of dihydroeugenol and 50 mL of ether are added to a round-bottom flask, stirred at room temperature for 30 min until completely dissolved, 0.8 g of pyridine is added, then 0.9 g of propionyl chloride is quickly added to the flask, stirred at room temperature for 60 min, filtered, washed with ether, concentrated, and dried to obtain the intermediate;

[0051] (2) Synthesis of the intermediate monomer: the Fries rearrangement reaction mechanism is used, the phenolic ester group of the intermediate is catalyzed by a Lewis acid to generate the intermediate monomer, and the chemical structure formula is as shown in​Figure 2 as shown;

[0052] wherein the Lewis acid catalyst is selected from one of aluminum trichloride, boron trifluoride, titanium tetrachloride, and tin tetrachloride; and the aluminum trichloride is used in the present experimental example;

[0053] The specific experimental steps for synthesizing the intermediate monomer are as follows: place a 100 mL round-bottom flask in an oil bath, heat to 60°C for 10 min, heat to 110°C for 5 min, add 2.2 g of the intermediate, stir for 10 min until completely melted, then add 2.0 g of anhydrous aluminum trichloride to the round-bottom flask in three portions (immediate heat release and generation of a large amount of hydrogen chloride gas), heat to 130°C and stir for 3 h, then cool to room temperature, pour 50 mL of 5% dilute hydrochloric acid solution into the flask, stand for 24 h, and filter, then wash with deionized water and recrystallize with ethanol to obtain the intermediate monomer;

[0054] (3) Synthesis of ligand L1: using the Schiff base reaction mechanism, a condensation reaction occurs between the amino functional group of 3-methylbenzylamine and the carbonyl functional group of the intermediate monomer to generate ligand L1, which has a chemical structural formula as shown in Figure 3 ;

[0055] The specific experimental steps for synthesizing the ligand L1 are as follows: add 2.3 g of the intermediate monomer and 50 mL of anhydrous ethanol to a round-bottom flask, under the action of mechanical stirring, heat to 40°C and stir for 20 min until completely dissolved, then cool to room temperature, and then slowly add a 3-methylbenzylamine solution (prepared from 1.2 g of 3-methylbenzylamine and 20 mL of anhydrous ethanol) to the flask at a rate of 1 drop per second using a disposable syringe, monitor using thin layer chromatography (developing agent: dichloromethane: petroleum ether = 1:2), stir at room temperature for 3 h, filter, recrystallize with anhydrous ethanol, and vacuum dry to obtain the ligand L1;

[0056] The proton nuclear magnetic resonance spectrum of the ligand L1 is characterized as follows: 1 H NMR (CDCI3, 400 MHz) δ: 0.93-0.96 (t, 3H), 1.16-1.19 (t, 3H), 1.60-1.68 (m, 2H), 2.33 (s, 3H), 2.58-2.61 (tt, 2H), 2.90-2.95 (m, 2H, -N=C(CH2)-), 3.88 (s, 3H), 4.75-4.76 (t, 2H, -(CH2)N=C-), 6.60-7.29 (m, 6H, Ar-H);

[0057] The ligand L1 is tested by using a Varion EL III type element analyzer, and the test results are as follows: the measured value of C element is 77.64% (theoretical value 77.50%), the measured value of H element is 8.39% (theoretical value 8.36%), and the measured value of N element is 4.25% (theoretical value 4.30%).

[0058] Experiment two: preparing ligand L2, the synthesis method is: using Schiff base reaction mechanism, through the condensation reaction of amino functional group of 1,3-phenyl dimethylamine and carbonyl functional group of intermediate monomer, ligand L2 is generated, the chemical structural formula is as shown in Figure 4 The synthesis steps and synthesis reaction conditions are referred to the synthesis experiment of ligand L1, and the difference between the synthesis experiment of ligand L1 and the synthesis experiment of ligand L2 is that 1.4g of 1,3-phenyl dimethylamine is used to replace 1.2g of 3-methyl benzylamine;

[0059] The nuclear magnetic resonance hydrogen spectrum of ligand L2 is characterized as: 1 H NMR (CDCl3, 400MHz) δ: 0.93-0.96 (t, 6H), 1.21-1.24 (t, 6H), 1.59-1.66 (m, 4H), 2.58-2.61 (tt, 4H), 2.90-2.94 (m, 4H, -N=C(CH2)-), 3.82 (s, 6H), 4.78-4.79 (t, 4H, -(CH2)N=C-), 6.59-7.30 (m, 8H, Ar-H);

[0060] The ligand L2 is tested by using a Varion EL III type element analyzer, and the test results are as follows: the measured value of C element is 75.07% (theoretical value 74.97%), the measured value of H element is 8.21% (theoretical value 8.14%), and the measured value of N element is 5.08% (theoretical value 5.14%). Example 1:

[0061] Preparation of antibacterial agent I: the coordination between N and O atoms in ligand L1 and transition metal ions is formed to prepare antibacterial agent I, and the specific experimental steps are as follows: 3.3g of ligand L1 and 50mL of anhydrous ethanol are added to a round-bottom flask, stirred at room temperature for 30min to completely dissolve, then a disposable syringe is used to slowly drop silver nitrate solution (prepared by 1.7g of silver nitrate and 20mL of anhydrous ethanol) into the flask at a speed of 1 drop per second, the temperature is increased to 50℃, and the reaction is stirred for 5h, then the solution is left to stand, filtered, and washed with ethanol to obtain antibacterial agent I.

[0062] Preparation of antibacterial agent II: the antibacterial agent II is prepared by forming coordination between N, O atoms in ligand L2 and transition metal ions, the preparation steps and reaction conditions are referred to the preparation experiment of antibacterial agent I, and the difference between the preparation experiment of antibacterial agent I and the preparation experiment of antibacterial agent II is that 5.5 g of ligand L2 is used to replace 3.3 g of ligand L1;

[0063] wherein the transition metal ion is selected from one or more than one combination of Ag + , Cu 2+ , Co 2+ , Mn 2+ , Zn 2+ ; and the embodiment selects Ag + . Example 2:

[0064] Preparation of antibacterial polyethylene I: 25 g of low-density polyethylene resin and 100 mL of N, N-dimethylformamide are added into a round-bottom flask, under the action of mechanical stirring, the temperature is raised to 50 ℃ and stirred for dissolution for 1 h, then 1 g of antibacterial agent I and 2.5 g of glycerol are sequentially added into the flask, and stirring reaction is maintained at 50 ℃ for 2 h, after cooling, the antibacterial polyethylene I is poured into a polytetrafluoroethylene mold, and is sequentially dried in ovens at 40 ℃, 60 ℃ and 80 ℃ for 12 h;

[0065] Preparation of antibacterial polyethylene II: the antibacterial agent II is used to replace the above antibacterial agent I, and the preparation steps and experimental conditions of the antibacterial polyethylene I are referred to, to prepare the antibacterial polyethylene II;

[0066] wherein the low-density polyethylene resin is purchased from China Sea Shell Petroleum Chemical Industry Co., Ltd., and has a specification of 2420H, Mn~180000 and MFR 2.0~2.5 g / 10 min. Example 3:

[0067] (1) Preparation of antibacterial sheet I, including the following steps:

[0068] Step one, the antibacterial sheet I is set to be a eleven-layer co-extrusion film, and the film structure is sequentially:

[0069] First layer: antibacterial polyethylene I layer, 30 parts by weight;

[0070] Second layer: maleic anhydride grafted low-density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0071] Third layer: ethylene-vinyl alcohol copolymer resin (EVOH) layer, 5 parts by weight;

[0072] Fourth layer: maleic anhydride grafted low-density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0073] Fifth layer: ethylene-vinyl alcohol copolymer resin (EVOH) layer, 5 parts by weight;

[0074] Sixth layer: ethylene-vinyl alcohol copolymer resin (EVOH) layer, 10 parts by weight;

[0075] Seventh layer: ethylene-vinyl alcohol copolymer resin (EVOH) layer, 5 parts by weight;

[0076] Eighth layer: maleic anhydride grafted low density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0077] Ninth layer: ethylene-vinyl alcohol copolymer resin (EVOH) layer, 5 parts by weight;

[0078] Tenth layer: maleic anhydride grafted low density polyethylene resin (PE-g-MAH) layer, 2.5 parts by weight;

[0079] Eleventh layer: antibacterial polyethylene I layer, 30 parts by weight;

[0080] Step two, each raw material in step one is respectively put into the hopper of the eleven screw extruders of the eleven-layer co-extrusion film casting machine group, after mixing by stirring, the molten resin is converged at the die head through the flow divider, extruded, cooled and wound through the die head, to obtain an antibacterial sheet I with a thickness of 100 μm;

[0081] The process parameter settings of the screw extruder corresponding to the antibacterial polyethylene I layer are: the temperatures of the first to third zones are 110℃, 140℃ and 160℃ respectively, the flow channel temperature is 150℃, and the rotation speed is 30r / min;

[0082] The process parameter settings of the screw extruder corresponding to the maleic anhydride grafted low density polyethylene resin (PE-g-MAH) layer are: the temperatures of the first to third zones are 115℃, 145℃ and 160℃ respectively, the flow channel temperature is 150℃, and the rotation speed is 15r / min;

[0083] The process parameter settings of the screw extruder corresponding to the ethylene-vinyl alcohol copolymer resin (EVOH) layer are: the temperatures of the first to third zones are 180℃, 200℃ and 210℃ respectively, the flow channel temperature is 205℃, and the rotation speed is 40r / min;

[0084] The maleic anhydride grafted low density polyethylene resin is purchased from Dongguan Tao Tao Plastic Raw Material Co., Ltd., with a specification of: 4288, Mn~130000, and a grafting rate of 4.5%; the ethylene-vinyl alcohol copolymer resin is purchased from Dongguan Kaisili Plastic Raw Material Co., Ltd., with a specification of: E105B, Mn~10000, and an ethylene content of 44%.

[0085] (2) Preparation of antibacterial sheet II: replace the antibacterial polyethylene I described above with antibacterial polyethylene II, refer to the preparation steps and experimental conditions of antibacterial sheet I, and antibacterial sheet II is prepared.

[0086] (3) Preparation of base sheet: refer to the preparation steps and experimental conditions of antibacterial sheet I, and the difference between the preparation experiment of antibacterial sheet I is that the antibacterial polyethylene I is replaced with low-density polyethylene resin, and the base sheet is prepared.

[0087] Performance test:

[0088] (1) MJ-250I type mold incubator is used for antibacterial performance test, and the specific test steps are as follows: the sample is cut into a circular sheet with a diameter of 6 mm, and is sterilized by ultraviolet lamp for 2h, then 100μL of bacterial solution (concentration is 1.0×10 6 CFU / mL) is coated on the culture medium, the sterile sample is pasted in the culture medium, and is placed in a 37℃ incubator for 24h, and the bacterial growth on the film surface and the diameter of the antibacterial ring are observed;

[0089] Among them, the bacterial solution is ATCC6538 type Staphylococcus aureus and ATCC25922 type Escherichia coli purchased from Shanghai Luwei Technology Co., Ltd.;

[0090] (2) The oxygen transmission rate performance test and water vapor transmission rate performance test of the sample are carried out according to GB / T 1038-2000 and GB / T 1037-2021 respectively, and the specific test steps are as follows: 30cm circular sample is placed in an environmental temperature of 25℃, and calcium chloride is used as a drying agent in a glass desiccator for 72h, then Y110 type oxygen transmission rate tester and W3 / 060 type water vapor transmission rate tester are used to test the barrier performance of the sample;

[0091] (3) Instron 5565 universal tensile testing machine is used to test the tensile strength of the sample, and the specific test steps are as follows: the sample of 150mm×20mm is fixed on the tensile testing machine, and the tensile test is carried out at a tensile rate of 5mm / min, and the longitudinal and transverse tensile strength of the sample is recorded, and the specific method is as follows:

[0092] Tensile strength (MPa) = tensile stress / (sample width × sample thickness);

[0093] (4) The health performance of the sample is tested according to GB / T 5009.60-2003 "Analysis method of polyethylene, polystyrene and polypropylene forming products for food packaging";

[0094] The experimental results are shown in Tables 1-3 below.

[0095] Table 1 antibacterial performance test results of each sheet

[0096]

[0097] Table 2 barrier properties and mechanical properties test results of each sheet

[0098]

[0099] Table 3 health performance test results of each sheet

[0100]

[0101] Note: The experimental results of physical and chemical indicators are based on GB / T 5009.58-2003 "Analysis method of polyethylene resin for food packaging hygiene standard";

[0102] According to the experimental data in Table 1 Figure 5 , through comprehensive analysis of the above experimental results, the following conclusions can be drawn:

[0103] (1) Compared with the base sheet without antibacterial functional modification, the antibacterial sheet prepared by the present application shows inhibitory effect on Staphylococcus aureus and Escherichia coli, and has antibacterial performance;

[0104] (2) The antibacterial sheet prepared by the present application also has slightly improved barrier properties and mechanical properties, and meets the national standard requirements for health, and can be used in cheese stick packaging.

Claims

1. A process for preparing a cheese stick packaging sheet, characterized in that, Includes the following steps: Step 1: Preparation of intermediate monomers, the specific preparation method is as follows: Using propionyl chloride as an acylation reagent, an intermediate was prepared by nucleophilic substitution reaction between the hydroxyl functional group of dihydroeugenol and the acyl chloride group of propionyl chloride catalyzed by an organic base. The chemical structural formula of dihydroeugenol is: ； The chemical structural formula of the intermediate is: ； Utilizing the Fries rearrangement mechanism, an intermediate monomer was prepared by rearranging the phenolic ester group of the intermediate via Lewis acid catalysis. Its chemical structural formula is as follows: ； Step 2: Prepare an antibacterial agent, wherein the antibacterial agent is antibacterial agent I or antibacterial agent II; The preparation method of antibacterial agent I is as follows: using the Schiff base reaction mechanism, the amino functional group of 3-methylbenzylamine undergoes a condensation reaction with the carbonyl functional group of the intermediate monomer to generate ligand L1; antibacterial agent I is prepared by the coordination of ligand L1 with transition metal ions. The chemical structural formula of ligand L1 is: ； The preparation method of antibacterial agent II is as follows: using the Schiff base reaction mechanism, the amino functional group of 1,3-phenylenediamine undergoes a condensation reaction with the carbonyl functional group of the intermediate monomer to generate ligand L2; antibacterial agent II is prepared by the coordination of ligand L2 with transition metal ions. The chemical structural formula of ligand L2 is: ； Step 3: Dissolve 20-40 parts by weight of low-density polyethylene resin in N,N-dimethylformamide, then add 0.5-3 parts by weight of antibacterial agent and 2-5 parts by weight of glycerol sequentially. Stir and react at 40-60°C, cool, and pour into a polytetrafluoroethylene mold. Dry in an oven at 40-60°C, 60-80°C, and 80-100°C sequentially to obtain antibacterial polyethylene. Step 4: Using antibacterial polyethylene as raw material to generate the inner and outer layers, ethylene-vinyl alcohol copolymer resin as raw material to generate the intermediate layer, and maleic anhydride-grafted low-density polyethylene resin as raw material to generate the adhesive layer, an antibacterial sheet is prepared by multi-layer co-extrusion and casting film formation process.

2. The preparation process of a cheese stick packaging sheet according to claim 1, characterized in that, The method for preparing the antibacterial sheet is as follows: Step S2-1: Set the antibacterial sheet to be an eleven-layer co-extruded film, the film structure of which is as follows: First layer: Antibacterial polyethylene layer, 20-40 parts by weight; Second layer: Maleic anhydride-grafted low-density polyethylene resin layer, 2-5 parts by weight; Third layer: 3-10 parts by weight of ethylene-vinyl alcohol copolymer resin layer; Fourth layer: Maleic anhydride-grafted low-density polyethylene resin layer, 2-5 parts by weight; Fifth layer: 3-10 parts by weight of ethylene-vinyl alcohol copolymer resin layer; Sixth layer: 8-15 parts by weight of ethylene-vinyl alcohol copolymer resin layer; Seventh layer: 3-10 parts by weight of ethylene-vinyl alcohol copolymer resin layer; Eighth layer: Maleic anhydride-grafted low-density polyethylene resin layer, 2-5 parts by weight; Ninth layer: 3-10 parts by weight of ethylene-vinyl alcohol copolymer resin layer; Tenth layer: Maleic anhydride-grafted low-density polyethylene resin layer, 2-5 parts by weight; Eleventh layer: Antibacterial polyethylene layer, 20-40 parts by weight; Step S2-2: The raw materials from step S2-1 are fed into the hoppers of the eleven screw extruders of the eleven-layer co-extrusion film casting machine. After mixing by stirring, the molten resin is collected at the die head by the distributor, cast and extruded through the die head, cooled and wound up to obtain an antibacterial sheet with a thickness of 80-120μm.

3. The preparation process of a cheese stick packaging sheet according to claim 1, characterized in that, The transition metal ion is Ag. + Cu 2+ Co 2+ Mn 2+ Zn 2+ One or more combinations of the above.

4. The application of the antibacterial sheet prepared by the process according to any one of claims 1-3 in cheese stick packaging.

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