High-barrier single-material sterile BIB packaging bag and preparation process

Abstract

The invention relates to the technical field of composite films for BIB packaging inner bags, and discloses a high-barrier single-material sterile BIB packaging bag and a preparation process thereof, the preparation process comprises the following steps: using vanillin, 3-bromopropene, gallic acid, diethylenetriamine and 1, 3-acetonedicarboxylic acid as raw materials to prepare a gallic acid type grafting monomer; the preparation method comprises the following steps: carrying out melt grafting modification treatment on LDPE (Low-Density Polyethylene) resin by using a gallic acid type grafting monomer, and compounding with graphene oxide through pi-pi accumulation action and hydrogen-bond interaction to prepare the graphene-polyethylene composite master batch with an antioxidant function; the preparation method comprises the following steps: preparing a polyethylene master batch, introducing the master batch into a seven-layer co-extruded film to prepare a polyethylene co-extruded film, and preparing the high-barrier single-material sterile BIB packaging bag by taking the co-extruded film as a raw material of an inner bag of the BIB packaging bag. The polyethylene co-extruded film prepared by the invention still shows excellent mechanical properties and barrier properties after being treated by a radiation sterilization technology, and can be used instead of an existing aluminized polyester bag.

Description

Technical Field

[0001] This invention relates to the field of composite film technology for inner bags of BIB packaging, and particularly to a high-barrier, single-material aseptic BIB packaging bag and its preparation process. Background Technology

[0002] BIB (Bag-in-Box) packaging is a new type of flexible packaging for liquids (such as edible oil, juice, and wine), mainly consisting of three parts: an inner bag, a valve on the inner bag, and an outer box. Currently, the inner bag of BIB packaging is composed of two layers of composite materials on one side, with the outer layer being a composite film (such as PET / AL / PE, NY / EVOH / PE, PET / VMPET / PE, etc.) and the inner layer being a single-layer PE film.

[0003] However, the outer composite film has problems such as difficulty in recycling, poor environmental performance, easy delamination, and high cost. On the other hand, the single-material composite film is environmentally friendly and easy to recycle, and has practical application value. Therefore, in the single-sided design of the inner bag of BIB packaging, a seven-layer co-extruded polyethylene film is used to replace the double-layer non-composite material (the outer layer is PET / VMPET / PE, and the inner layer is a single-layer PE film).

[0004] However, ordinary seven-layer co-extruded polyethylene film has poor barrier properties, making it difficult to meet the high barrier performance requirements of BIB packaging bags in practical use. Furthermore, BIB packaging bags require sterilization treatment using cobalt-60 gamma rays. To ensure the sterility of the packaging bags, the irradiation dose must be increased. However, excessive doses can cause cross-linking and chain breakage in the plastic material, affecting the physical and mechanical properties of the packaging bags. When gamma rays act on PE, the carbon-hydrogen bonds in the material break, forming highly reactive free radicals and hydrogen atoms. In the presence of oxygen, the oxygen in the PE matrix reacts with the free radicals to undergo oxidation, destroying the molecular chain structure of PE and leading to the degradation of the PE composite film.

[0005] Studies have found that nanosheet materials (graphene, hexagonal boron nitride, montmorillonite) can improve the barrier properties of plastic materials. Gallic acid is a common antioxidant that can inhibit the oxidation reaction of materials, thereby reducing radiation degradation damage. Summary of the Invention

[0006] Based on membrane design technology and formulation modification methods, this invention provides a polyethylene co-extruded film. After radiation sterilization, the barrier properties and tensile strength of the polyethylene co-extruded film are close to the performance requirements of existing aluminized polyester bags, and it can replace existing aluminized polyester bags.

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

[0008] A manufacturing process for a high-barrier, single-material aseptic BIB packaging bag includes the following steps:

[0009] Step 1: Synthesize gallic acid-type grafted monomers;

[0010] Step 2: Under the action of an initiator, gallic acid-type grafted monomers are used to melt-graft modified LDPE resin, and then it is compounded with graphene oxide through π-π stacking and hydrogen bonding to obtain graphene-polyethylene composite masterbatch with antioxidant function.

[0011] Step 3: Design the membrane structure, formulation and dosage of each layer of the seven-layer co-extruded film. Introduce the graphene-polyethylene composite masterbatch with antioxidant function into the seven-layer co-extruded film. Use the seven-layer co-extruded blow molding process to produce a polyethylene co-extruded film. Use this polyethylene co-extruded film as the raw material for the inner bag of the BIB packaging bag to produce a high-barrier single-material aseptic BIB packaging bag.

[0012] Preferably, the method for preparing the gallic acid-type grafted monomer is as follows:

[0013] Intermediate monomer 1 was prepared by a substitution reaction of 1 molar equivalent of vanillin with 1 molar equivalent of 3-bromopropene under the action of an alkaline catalyst.

[0014] Diethylenetriamine and triacetylgalloyl chloride undergo an acylation reaction in a molar ratio of 1:2 to prepare intermediate monomer 2.

[0015] Intermediate monomer 2, intermediate monomer 1, and 1,3-propanone dicarboxylic acid are reacted in a molar ratio of 1:1:1 to undergo the Mannich reaction, and then the acetyl group is removed to obtain gallic acid-type grafted monomers.

[0016] Preferably, the alkaline catalyst is either potassium carbonate or sodium carbonate.

[0017] Preferably, the membrane structure, formulation, and dosage of the seven-layer co-extruded membrane are as follows:

[0018] Outer layer: The formulation consists of 20-40 parts by weight of HDPE resin and 60-80 parts by weight of LLDPE resin, with a usage of 5-15 parts by weight;

[0019] Secondary outer layer: The formulation consists of 40-60 parts by weight of LLDPE resin and 40-60 parts by weight of LDPE resin, with a usage of 5-15 parts by weight;

[0020] Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 3-8 parts by weight;

[0021] Intermediate layer: The formulation consists of 50-70 parts by weight of LLDPE resin and 30-50 parts by weight of graphene-polyethylene composite masterbatch with antioxidant function, with a usage of 20-40 parts by weight.

[0022] Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 3-8 parts by weight;

[0023] Secondary inner layer: The formulation consists of 40-60 parts by weight of LLDPE resin and 40-60 parts by weight of LDPE resin, with a usage of 5-15 parts by weight;

[0024] Inner layer: The formula consists of 20-40 parts by weight of m-LLDPE resin, 20-40 parts by weight of LLDPE resin and 30-50 parts by weight of graphene-polyethylene composite masterbatch with antioxidant function, and the amount used is 20-40 parts by weight.

[0025] Preferably, the process parameters of the screw extruder corresponding to the intermediate layer are set as follows: zone 1 temperature is 125-135℃, zone 2 temperature is 150-170℃, zone 3 temperature is 170-180℃, flow channel temperature is 165-175℃, and screw speed is 35-45 r / min.

[0026] The process parameters of the screw extruder corresponding to the inner layer are set as follows: zone 1 temperature is 130-140℃, zone 2 temperature is 160-170℃, zone 3 temperature is 175-185℃, flow channel temperature is 170-180℃, and screw speed is 35-45 r / min.

[0027] Preferably, the thickness of the polyethylene co-extruded film is 50-200 μm.

[0028] Preferably, the formulation of the graphene-polyethylene composite masterbatch with antioxidant function is: 100 parts by weight of LDPE resin, 2-15 parts by weight of gallic acid graft monomer, 0.01-0.2 parts by weight of initiator and 3-8 parts by weight of graphene oxide.

[0029] Preferably, the initiator is one of tert-butyl peroxide or dicumyl peroxide.

[0030] Preferably, the diameter of the graphite oxide flakes is 50-200 nm.

[0031] The beneficial effects of this invention are as follows:

[0032] Intermediate monomer 1 was prepared by substitution reaction using bio-based vanillin and 3-bromopropene, which provides alkenyl functional groups; intermediate monomer 2 was prepared by acylation reaction using diethylenetriamine as bridging monomer and bio-based gallic acid as antioxidant functional monomer; and gallic acid-type grafted monomer was prepared by first undergoing Mannich reaction and then removing acetyl groups using intermediate monomer 2, intermediate monomer 1 and 1,3-propanone dicarboxylic acid as raw materials.

[0033] Under the action of an initiator, gallic acid-type grafted monomers are used to melt-graft modified LDPE resin, and then it is compounded with graphene oxide through π-π stacking and hydrogen bonding to obtain graphene-polyethylene composite masterbatch with antioxidant function.

[0034] Graphene-polyethylene composite masterbatch with antioxidant function is introduced into the inner and middle layers of a seven-layer co-extruded film, and a polyethylene co-extruded film is prepared by using a seven-layer co-extrusion blow molding process.

[0035] Experimental results showed that the polyethylene co-extruded film prepared by this invention still exhibited excellent mechanical and barrier properties after being treated with radiation sterilization technology, and could be used as a substitute for existing aluminized polyester bags. Detailed Implementation

[0036] Example 1:

[0037] The synthesis process of gallic acid-type grafted monomers is as follows:

[0038] Step 1: Based on the substitution reaction mechanism, the hydroxyl group in vanillin reacts with the bromine functional group in 3-bromopropene to generate intermediate monomer 1;

[0039] Step 2: Using gallic acid as a raw material, the phenolic hydroxyl group is first protected by acetylation with acetic anhydride, and then reacted with the acyl chloride agent SOCl2 to generate triacetylgalloyl chloride;

[0040] Based on the acylation reaction mechanism, the acyl chloride group in triacetylgallic chloride reacts with the primary amine group in diethylenetriamine to generate intermediate monomer 2;

[0041] Step 3: Using intermediate monomer 2, intermediate monomer 1 and 1,3-acetone dicarboxylic acid as raw materials, the Mannich reaction is carried out first, and then the acetyl group is removed to generate gallic acid-type grafted monomers.

[0042] The experimental procedure for gallic acid-type grafted monomers is as follows:

[0043] (1) Add 3g vanillin and 15mL acetone to a 100mL three-necked flask, stir to dissolve, then add 2.39g 3-bromopropene and 1.36g potassium carbonate, set the reaction temperature to 65℃, heat and stir under reflux for 24h, after the reaction is completed, evaporate the acetone solvent, add deionized water, extract with dichloromethane 3 times, then dry with anhydrous sodium sulfate and filter to obtain intermediate monomer 1;

[0044] The chemical structural formula of intermediate monomer 1 is:

[0045] ;

[0046] (2) Place 3g of gallic acid in a vacuum drying oven at 120℃ and dry for 4h to obtain anhydrous gallic acid;

[0047] 3g of anhydrous gallic acid, 6.7mL of acetic anhydride and 5.7mL of anhydrous pyridine were added to a 250mL round-bottom flask (ice bath), and the mixture was stirred in a water bath at 25℃ for 12h. Cold dilute sulfuric acid was added to precipitate crystals, which were then washed with water, filtered, and dried to obtain triacetyl gallic acid.

[0048] 3g of triacetylgallic acid was added to a 250mL round-bottom flask, followed by 10mL of dichloromethane solvent and 2mL of SOCl2. The mixture was stirred and refluxed at 30℃ for 4h. After the reaction was completed, the solvent was removed by rotary evaporation at 40℃ to obtain triacetylgallic chloride.

[0049] The chemical structural formula of triacetyl galloyl chloride is:

[0050] ;

[0051] 1 g of diethylenetriamine was added to a 250 mL round-bottom flask. 20 mL of distilled water was added and stirred to dissolve the amine at 25 °C. Then, under nitrogen atmosphere at 0 °C, 60 mL of anhydrous toluene solution containing 6.1 g of triacetyl galloyl chloride and 20% anhydrous potassium carbonate aqueous solution were added dropwise. The pH of the system was controlled at 9.5. After the addition was complete, the temperature of the system was raised to 25 °C and the reaction was allowed to proceed for 24 h. After the reaction was completed, the mixture was filtered, washed, and dried under vacuum at 50 °C for 6 h to obtain intermediate monomer 2.

[0052] The chemical structural formula of intermediate monomer 2 is as follows:

[0053] ;

[0054] (3) Add 5g of intermediate monomer 2 and 60mL of N,N-dimethylformamide to a 500mL three-necked flask, stir mechanically until homogeneous, add 1.46g of intermediate monomer 1 and 1.1g of 1,3-propanone dicarboxylic acid, raise the system temperature to 70℃, stir the reaction for 10h, after the reaction is completed, remove the solvent by vacuum distillation, filter, wash, and dry at 60℃ for 8h to obtain triacetyl gallic acid type grafted monomer;

[0055] 3g of triacetylgallic acid graft monomer was added to 100mL of sodium acetate solution and mixed. The acetyl groups were removed by hydrolysis at 70℃. During the hydrolysis process, 10% sodium hydroxide solution was added to adjust the pH of the system to 8. The mixture was filtered, washed, and dried in a vacuum drying oven at 60℃ for 10h to obtain the gallic acid graft monomer.

[0056] The chemical structural formula of the gallic acid-type graft monomer is:

[0057] ;

[0058] The 1H NMR characterization of the gallic acid-grafted monomer is as follows:

[0059] 1 H NMR (DMSO-d6, 400MHz) δ: 2.73-2.86 (m, 4H), 3.21-3.30 (m, 2H), 3.34-3.47 (m, 4H), 3.75-3.77 (d, 1H), 3.83 (s, 3H), 4.43-4.45 (d, 1H), 4.57-4.58 (d, 2 H), 5.29-5.41(dd, 2H), 6.01-6.10(m, 1H), 6.79-6.89(m, 3H), 6.99(s, 4H) , 8.36 (s, 2H), 8.41-8.43 (t, 2H), 8.76 (s, 4H), 12.29 (s, 1H), 12.54 (s, 1H).

[0060] Example 2:

[0061] (1) The graphene-polyethylene composite masterbatch a with antioxidant function includes the following raw materials in parts by weight:

[0062] 100 parts LDPE resin (brand name 2426K);

[0063] 8 gallic acid-type graft monomers;

[0064] 5 parts of graphene oxide (sheet diameter 80 nm);

[0065] 0.1 parts tert-butyl peroxide;

[0066] The preparation method of graphene-polyethylene composite masterbatch with antioxidant function is as follows: LDPE resin, gallic acid graft monomer and tert-butyl peroxide are added to a high-speed mixer and mixed evenly. The mixture is then transferred to a twin-screw extruder for melting, and graphene oxide is added for blending. Finally, the mixture is extruded and granulated to obtain graphene-polyethylene composite masterbatch a with antioxidant function.

[0067] The process parameters for the twin-screw extruder are as follows: zone 1 temperature is 110℃, zone 2 temperature is 125℃, zone 3 temperature is 135℃, zone 4 temperature is 135℃, and the screw speed is 40r / min.

[0068] (2) Prepare graphene-polyethylene composite masterbatch b with antioxidant function. The only difference between it and graphene-polyethylene composite masterbatch a with antioxidant function is that the amount of gallic acid grafted monomer is 2 parts by weight.

[0069] (3) Prepare graphene-polyethylene composite masterbatch c with antioxidant function. The only difference between it and graphene-polyethylene composite masterbatch a with antioxidant function is that the amount of gallic acid grafted monomer is 15 parts by weight.

[0070] Example 3:

[0071] The preparation of polyethylene co-extruded film A includes the following steps:

[0072] Step 1: Design the membrane structure of polyethylene co-extruded film A. The formulation and dosage of each membrane layer are as follows:

[0073] Outer layer: The formula consists of 30 parts by weight of HDPE resin and 70 parts by weight of LLDPE resin, and the amount used is 10 parts by weight;

[0074] Secondary outer layer: The formula consists of 50 parts by weight of LLDPE resin and 50 parts by weight of LDPE resin, and the amount used is 10 parts by weight;

[0075] Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 5 parts by weight;

[0076] Intermediate layer: The formulation consists of 60 parts by weight of LLDPE resin and 40 parts by weight of graphene-polyethylene composite masterbatch a with antioxidant function, with a usage of 30 parts by weight.

[0077] Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 5 parts by weight;

[0078] Secondary inner layer: The formula consists of 50 parts by weight of LLDPE resin and 50 parts by weight of LDPE resin, and the amount used is 10 parts by weight.

[0079] Inner layer: The formula consists of 30 parts by weight of m-LLDPE resin, 30 parts by weight of LLDPE resin and 40 parts by weight of graphene-polyethylene composite masterbatch a with antioxidant function, and the amount used is 30 parts by weight.

[0080] Step 2: The raw materials of each film layer in Step 1 are respectively fed into the hoppers of the seven screw extruders of the seven-layer co-extrusion film blow molding unit. After stirring and mixing, the molten resin is gathered at the die head through the distributor, extruded and blow-molded through the die head, cooled and wound up to prepare a polyethylene co-extruded film A with a thickness of 100μm.

[0081] The process parameters for the screw extruder corresponding to the outer layer are set as follows: zone 1 temperature is 140℃, zone 2 temperature is 170℃, zone 3 temperature is 185℃, flow channel temperature is 180℃, and screw speed is 30r / min.

[0082] The process parameters for the screw extruders corresponding to the outer and inner layers are set as follows: Zone 1 temperature is 120℃, Zone 2 temperature is 150℃, Zone 3 temperature is 170℃, runner temperature is 165℃, and screw speed is 30r / min.

[0083] The process parameters for the screw extruder corresponding to the adhesive layer are set as follows: Zone 1 temperature is 125℃, Zone 2 temperature is 150℃, Zone 3 temperature is 165℃, runner temperature is 160℃, and screw speed is 15r / min.

[0084] The process parameters for the screw extruder corresponding to the intermediate layer are set as follows: Zone 1 temperature is 130℃, Zone 2 temperature is 160℃, Zone 3 temperature is 175℃, runner temperature is 170℃, and screw speed is 40r / min.

[0085] The process parameters for the screw extruder corresponding to the inner layer are set as follows: Zone 1 temperature is 135℃, Zone 2 temperature is 165℃, Zone 3 temperature is 180℃, runner temperature is 175℃, and screw speed is 30r / min.

[0086] Among them, the grade of LDPE resin is 2426K; the grade of LLDPE resin is DFDA-7042; the grade of HDPE resin is LH608M; the grade of m-LLDPE resin is SP4020; and the grade of PE-g-MAH resin is 4288.

[0087] Example 4:

[0088] The polyethylene co-extruded film B is prepared, and its only difference from the polyethylene co-extruded film A is that graphene-polyethylene composite masterbatch b with antioxidant function is used instead of graphene-polyethylene composite masterbatch a with antioxidant function.

[0089] Example 5:

[0090] The polyethylene co-extruded film C is prepared, and its only difference from the polyethylene co-extruded film A is that graphene-polyethylene composite masterbatch c with antioxidant function is used instead of graphene-polyethylene composite masterbatch a with antioxidant function.

[0091] Performance testing:

[0092] The polyethylene co-extruded film prepared in this invention was cut into long strips with a length of 150 mm and a width of 20 mm. The samples were treated with a cobalt-60 gamma-ray radiation source with an irradiation dose of 70 kGy. After the irradiation was completed, the performance of the samples was tested.

[0093] I. Mechanical property testing: The longitudinal tensile strength of the sample was tested according to GB / T 1040.3-2006 "Test of tensile properties of plastics - Part 3: Test conditions for films and sheets" at a test speed of 200 mm / min.

[0094] II. Barrier Performance Test:

[0095] The oxygen barrier properties of the samples were tested according to GB / T 1038.1-2022 "Test methods for gas permeability of plastic films and sheets - Part 1: Differential pressure method", and the oxygen permeation of the samples was recorded.

[0096] The water resistance of the samples was tested according to GB / T 1037-2021 "Determination of Water Vapor Permeability of Plastic Films and Sheets - Cup Method for Weight Gain and Loss". The water vapor permeation of the samples was recorded. The test conditions were 23℃ and 90% relative humidity.

[0097] The test results are shown in Table 1 below;

[0098] Table 1 Performance test results of polyethylene co-extruded film

[0099] product Tensile strength (MPa) <![CDATA[Oxygen permeability [cm 3 / (m 2 ·24 h)]]]> <![CDATA[Water vapor transmission rate [g / (m 2 ·24 h)]]]> Polyethylene co-extruded film A 29.1 1.1 0.6 Polyethylene co-extruded film B 24.8 1.5 0.4 Polyethylene co-extruded film C 32.5 0.9 0.9

[0100] The following conclusions can be drawn from the experimental data in Table 1:

[0101] The polyethylene co-extruded film prepared using graphene-polyethylene composite masterbatch with antioxidant function as a functional modifier for the inner and middle layers of a seven-layer co-extruded polyethylene film still exhibits excellent mechanical and barrier properties after radiation sterilization treatment, approaching the performance requirements of existing aluminized polyester bags (tensile strength ≥30MPa, oxygen permeability ≤1cm). 3 / (m 2 •24h), water vapor transmission rate ≤0.5g / (m 2 ·24h).

Claims

1. A manufacturing process for a high-barrier, single-material aseptic BIB packaging bag, characterized in that, Includes the following steps: Step 1: Synthesize gallic acid-type grafted monomers, whose chemical structural formula is as follows: ； Step 2: Under the action of an initiator, gallic acid-type grafted monomers are used to melt-graft modified LDPE resin, and then it is compounded with graphene oxide through π-π stacking and hydrogen bonding to obtain graphene-polyethylene composite masterbatch with antioxidant function. Step 3: Design the membrane structure, formulation and dosage of each layer of the seven-layer co-extruded film. Introduce the graphene-polyethylene composite masterbatch with antioxidant function into the seven-layer co-extruded film. Use the seven-layer co-extruded blow molding process to produce a polyethylene co-extruded film. Use this polyethylene co-extruded film as the raw material for the inner bag of the BIB packaging bag to produce a high-barrier single-material aseptic BIB packaging bag.

2. The preparation process of a high-barrier, single-material aseptic BIB packaging bag according to claim 1, characterized in that, The preparation method of the gallic acid graft monomer is as follows: Intermediate monomer 1 was prepared by a substitution reaction of 1 molar equivalent of vanillin with 1 molar equivalent of 3-bromopropene under the action of an alkaline catalyst. Diethylenetriamine and triacetylgalloyl chloride undergo an acylation reaction in a molar ratio of 1:2 to prepare intermediate monomer 2. Intermediate monomer 2, intermediate monomer 1, and 1,3-propanone dicarboxylic acid are reacted in a molar ratio of 1:1:1 to undergo the Mannich reaction, and then the acetyl group is removed to obtain gallic acid-type grafted monomers.

3. The preparation process of a high-barrier, single-material aseptic BIB packaging bag according to claim 2, characterized in that, The alkaline catalyst is either potassium carbonate or sodium carbonate.

4. The preparation process of a high-barrier, single-material aseptic BIB packaging bag according to claim 1, characterized in that, The membrane structure, formulation, and dosage of the seven-layer co-extruded membrane are as follows: Outer layer: The formulation consists of 20-40 parts by weight of HDPE resin and 60-80 parts by weight of LLDPE resin, with a usage of 5-15 parts by weight; Secondary outer layer: The formulation consists of 40-60 parts by weight of LLDPE resin and 40-60 parts by weight of LDPE resin, with a usage of 5-15 parts by weight; Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 3-8 parts by weight; Intermediate layer: The formulation consists of 50-70 parts by weight of LLDPE resin and 30-50 parts by weight of graphene-polyethylene composite masterbatch with antioxidant function, with a usage of 20-40 parts by weight. Adhesive layer: The formulation is 100 parts by weight of PE-g-MAH resin, and the dosage is 3-8 parts by weight; Secondary inner layer: The formulation consists of 40-60 parts by weight of LLDPE resin and 40-60 parts by weight of LDPE resin, with a usage of 5-15 parts by weight; Inner layer: The formula consists of 20-40 parts by weight of m-LLDPE resin, 20-40 parts by weight of LLDPE resin and 30-50 parts by weight of graphene-polyethylene composite masterbatch with antioxidant function, and the amount used is 20-40 parts by weight.

5. The preparation process of a high-barrier, single-material aseptic BIB packaging bag according to claim 4, characterized in that, The process parameters of the screw extruder corresponding to the intermediate layer are set as follows: zone 1 temperature is 125-135℃, zone 2 temperature is 150-170℃, zone 3 temperature is 170-180℃, flow channel temperature is 165-175℃, and screw speed is 35-45r / min. The process parameters of the screw extruder corresponding to the inner layer are set as follows: zone 1 temperature is 130-140℃, zone 2 temperature is 160-170℃, zone 3 temperature is 175-185℃, flow channel temperature is 170-180℃, and screw speed is 35-45 r / min.

6. A high-barrier, single-material aseptic BIB packaging bag prepared according to any one of claims 1-5, characterized in that, The thickness of the polyethylene co-extruded film is 50-200 μm.

7. A high-barrier, single-material aseptic BIB packaging bag according to claim 6, characterized in that, The formulation of the graphene-polyethylene composite masterbatch with antioxidant function is as follows: 100 parts by weight of LDPE resin, 2-15 parts by weight of gallic acid graft monomer, 0.01-0.2 parts by weight of initiator and 3-8 parts by weight of graphene oxide.

8. The high-barrier, single-material aseptic BIB packaging bag according to claim 7, characterized in that, The initiator is one of tert-butyl peroxide or dicumyl peroxide.

9. A high-barrier, single-material aseptic BIB packaging bag according to claim 7, characterized in that, The diameter of the graphite oxide flakes is 50-200 nm.

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