High-barrier recyclable eleven-layer co-extrusion film for food packaging and preparation process

Abstract

The invention relates to the technical field of food packaging materials, and discloses a high-barrier recyclable eleven-layer co-extrusion film for food packaging and a preparation process thereof, and the preparation process comprises the following steps: preparing a compound which contains a hindered phenol group and a cinnamate group and has a compatible function; the preparation method comprises the following steps: compounding a compound which contains a hindered phenol group and a cinnamate group and has a compatible function with maleic anhydride grafted polyethylene resin PE-g-MAH to prepare a compatible component; the high-barrier recyclable eleven-layer co-extrusion film for food packaging is prepared by taking PA6, BVOH and PE as raw materials, improving the compatibility of BVOH and PE by utilizing compatible components, carrying out hydrolysis reaction on water-soluble BVOH to realize interlayer separation of PE and PA and adopting an eleven-layer co-extrusion blow molding film forming process. And the sanitary performance meets the national standard requirement, and the product is easy to recycle and conforms to the environment-friendly trend.

Description

Technical Field

[0001] The invention relates to the technical field of food packaging materials, in particular to a high-barrier recyclable eleven-layer co-extruded film for food packaging and a preparation process thereof. Background Art

[0002] Polyethylene (PE) is widely used in food packaging due to its light weight, good heat resistance, low price, cleanliness and hygiene. However, polyethylene is a non-polar polymer. Although it has good barrier properties to polar solvents such as water, it has high permeability to organic solvents and poor gas barrier properties. Therefore, its application range is limited. Nylon 6 (PA6) is a polar polymer. It has good barrier properties to non-polar solvents and gases, but poor barrier properties to polar solvents. In addition, the water absorption of nylon 6 also has a great influence on its structural stability and barrier properties.

[0003] BVOH produced by Mitsubishi Chemical Group is a water-soluble barrier material that, unlike conventional polyvinyl alcohol (PVOH), has excellent recyclability, helping to promote resource conservation throughout the packaging life cycle.

[0004] Therefore, PA6, BVOH and PE can be compounded to obtain a barrier material with the comprehensive properties of the three. However, due to the large differences in molecular polarity, chain structure and viscoelasticity ratio of PA6, BVOH and PE, they belong to a thermodynamically incompatible system. In order to obtain the desired morphology and excellent comprehensive properties of the final material, suitable compatibilizers must be introduced to improve the compatibility of the system. Summary of the invention

[0005] The present invention independently develops a compound with compatibility function containing hindered phenol groups and cinnamate groups, and compounding the compound with maleic anhydride grafted polyethylene resin to improve the compatibility of PA6, BVOH and PE. Based on this, a high-barrier recyclable eleven-layer co-extruded film for food packaging is provided. The film not only has very excellent barrier properties and can effectively block oxygen in meat, cheese, nuts and other food packaging, but also has hygienic properties that meet national standards. In addition, the water-soluble BVOH is hydrolyzed to separate PE and PA from each other, so the film is very easy to be recycled and meets the trend of environmental protection.

[0006] A preparation process of a high barrier recyclable eleven-layer co-extruded film for food packaging, comprising the following steps: Step 1: preparing a dialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group; Step 2: adding 60-90wt% of maleic anhydride grafted polyethylene resin PE-g-MAH and 10-40wt% of a dialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group into a high-speed mixer, mixing them evenly, and extruding and granulating them through a twin-screw extruder to prepare a compatible component; Step 3: Using PA6, BVOH and PE as raw materials, using compatible components to improve the compatibility of BVOH and PE, and using water-soluble BVOH to undergo hydrolysis reaction to achieve interlayer separation of PE and PA, and using eleven-layer co-extrusion blow molding film forming process to prepare a high barrier recyclable eleven-layer co-extrusion film for food packaging.

[0007] Preferably, the film structure of the eleven-layer co-extruded film and the raw material formula and dosage of each film layer are as follows: First layer: the raw material is low-density polyethylene resin LDPE, the dosage is 5-15 parts by weight; The second layer: the raw material is metallocene polyethylene resin m-LLDPE, the amount is 10-20 parts by weight; The third layer: the raw materials are compatible components, the amount is 3-10 parts by weight; The fourth layer: the raw material is BVOH, the dosage is 3-10 parts by weight; The fifth layer: the raw material is nylon resin PA6, the dosage is 5-15 parts by weight; The sixth layer: the raw material is BVOH, the dosage is 5-15 parts by weight; The seventh layer: the raw material is nylon resin PA6, the dosage is 5-15 parts by weight; The eighth layer: the raw material is BVOH, the dosage is 3-10 parts by weight; Ninth layer: the raw materials are compatible components, the amount is 3-10 parts by weight; The tenth layer: the raw material is metallocene polyethylene resin m-LLDPE, the amount is 10-20 parts by weight; The eleventh layer: the raw material is low-density polyethylene resin LDPE, and the amount used is 5-15 parts by weight.

[0008] Preferably, the preparation method of the dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is: based on the Mannich reaction mechanism, 3,5-di-tert-butyl-4-hydroxyacetophenone containing α-H is condensed with methyl 4-formylcinnamate and di-n-octylamine to generate a dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups.

[0009] Preferably, the preparation method of the trialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is: Firstly, n-octylamine is used as a nucleophilic reagent, and triethylamine is used to catalyze the nucleophilic substitution reaction between the amino functional group of 3.01-3.08 molar equivalents of n-octylamine and the chlorine functional group of 1 molar equivalent of cyanuric chloride to generate a tri(secondary amino) monomer; Then, based on the Mannich reaction mechanism, 3.01-3.08 molar equivalents of 3,5-di-tert-butyl-4-hydroxyacetophenone containing α-H, 3.01-3.08 molar equivalents of methyl 4-formylcinnamate and 1 molar equivalent of tri(secondary amino) monomer undergo condensation reaction to generate a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group.

[0010] Preferably, the preparation method of the eleven-layer co-extruded film is: the ingredients are prepared according to the formula of the eleven-layer co-extruded film, and the raw materials of each layer are respectively put into the hoppers of eleven screw extruders of the eleven-layer co-extruded film blow molding unit, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, the blow ratio is controlled at 2.5-2.9, and the film is cooled and wound to prepare the eleven-layer co-extruded film.

[0011] The thickness of the high barrier recyclable eleven-layer co-extruded film for food packaging prepared according to the above process is 50-200 μm.

[0012] Preferably, the oxygen permeability of the eleven-layer co-extruded film is less than 0.5 cm 3 / (m 2 •24h•0.1MPa), water vapor transmission rate <0.5g / (m 2 •24h).

[0013] Preferably, the longitudinal tensile strength of the eleven-layer co-extruded film is 40-45 MPa, the longitudinal tensile strength after 10 days of thermal oxidative aging is 30-40 MPa, and the longitudinal tensile strength after 10 days of photo-oxidative aging is 30-40 MPa.

[0014] Beneficial effects: The present invention designs and synthesizes a compound having a compatibility function containing a hindered phenol group and a cinnamate group, specifically: a dialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group and a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group; A dialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group is compounded with a maleic anhydride grafted polyethylene resin PE-g-MAH to obtain a compatible component for improving the compatibility of BVOH and PE. The compatible component is introduced into a composite system of PA6, BVOH and PE, and an eleven-layer co-extrusion blow molding film forming process is adopted to prepare a high-barrier recyclable eleven-layer co-extrusion film product for food packaging. The film product exhibits excellent barrier properties, aging resistance and mechanical properties, and its hygienic properties meet the requirements of national standards and can be used in food packaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the chemical structural formula of a dialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group; Figure 2 is the chemical structural formula of a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group; Figure 3 These are the performance test results of high barrier recyclable eleven-layer co-extruded film for food packaging. DETAILED DESCRIPTION Embodiment 1:

[0016] A high barrier recyclable eleven-layer co-extruded film for food packaging, the film structure and the raw material formula and dosage of each film layer are shown in Table 1; Table 1 Experimental formula of high barrier recyclable eleven-layer co-extruded film for food packaging

[0017] The formula of the compatible component is: 80wt% of maleic anhydride grafted polyethylene resin PE-g-MAH and 20wt% of alkyl chain compatible monomer containing hindered phenol group and cinnamate group; The alkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group is a dialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group; The preparation method of the dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is as follows: based on the Mannich reaction mechanism, α-H-containing 3,5-di-tert-butyl-4-hydroxyacetophenone is subjected to a condensation reaction with methyl 4-formylcinnamate and di-n-octylamine to generate a dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups, and its chemical structure is as follows Figure 1 As shown: The specific preparation steps of the dialkyl chain-type compatible monomer containing hindered phenol groups and cinnamate groups are as follows: under the protection of nitrogen, 2.5g of 3,5-di-tert-butyl-4-hydroxyacetophenone, 1.9g of methyl 4-formylcinnamate, 2.4g of di-n-octylamine and 60mL of anhydrous ethanol are added to a three-necked flask, 2 drops of concentrated hydrochloric acid are slowly added to the three-necked flask under mechanical stirring, the temperature is raised to 85°C and refluxed for reaction for 6h, the mixture is cooled to room temperature, the solvent is removed by rotary evaporation, and vacuum drying is performed to obtain the dialkyl chain-type compatible monomer containing hindered phenol groups and cinnamate groups; The nuclear magnetic resonance hydrogen spectrum of the dialkyl chain compatible monomer containing hindered phenol groups and cinnamate groups is characterized as follows: 1 HNMR (CDCl 3 ,400MHz) δ: 0.87-0.91(t, 6H), 1.20-1.31(m, 20H), 1.38(s, 18H), 1.53-1.60(m, 4H), 2.58-2.61(t, 4H ), 3.25-3.27(d, 2H), 3.73(s, 3H), 4.27-4.30(t, 1H), 6.33-6.50(dd, 2H), 7.27-7.51(m, 6H); The preparation method of the trialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is as follows: Firstly, n-octylamine is used as a nucleophilic reagent, and triethylamine is used to catalyze the nucleophilic substitution reaction between the amino functional group of 3.05 molar equivalents of n-octylamine and the chlorine functional group of 1 molar equivalent of cyanuric chloride to generate a tri(secondary amino) monomer; Then, based on the Mannich reaction mechanism, 3.03 molar equivalents of α-H-containing 3,5-di-tert-butyl-4-hydroxyacetophenone react with 3.03 molar equivalents of methyl 4-formylcinnamate and 1 molar equivalent of tri(secondary amine) monomer to generate a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group, and its chemical structure is as follows: Figure 2 As shown; The specific preparation steps of the trialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups are as follows: Add 1.8 g of cyanuric chloride and 30 mL of anhydrous N,N-dimethylformamide into a three-necked flask, stir at room temperature until all dissolved, then drop 5.0 mL of n-octylamine and 0.5 mL of triethylamine into the three-necked flask in sequence, heat to 40° C., stir and react for 6 h, filter, wash with deionized water and ethanol in sequence, and vacuum dry to obtain a tri(secondary amino) monomer; Under nitrogen protection, 7.5 g of 3,5-di-tert-butyl-4-hydroxyacetophenone, 5.7 g of methyl 4-formylcinnamate, 4.6 g of tri(secondary amino) monomer and 100 mL of anhydrous ethanol were added to a three-necked flask, and 5 drops of concentrated hydrochloric acid were slowly added to the three-necked flask under mechanical stirring. The temperature was raised to 85° C. and refluxed for 8 h. The mixture was cooled to room temperature, the solvent was removed by rotary evaporation, and vacuum dried to obtain a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group. The nuclear magnetic resonance hydrogen spectrum of the trialkyl chain compatible monomer containing hindered phenol groups and cinnamate groups is characterized as follows: 1 HNMR (CDCl 3 ,400MHz) δ: 0.87-0.91 (t, 9H), 1.23-1.32 (m, 30H), 1.41 (s, 54H), 1.68-1.76 (m, 6H), 3.36-3.38 (d, 6H) , 3.72 (s, 9H), 3.83-3.87 (t, 6H), 4.95-4.99 (t, 3H), 6.30-6.47 (dd, 6H), 7.30-7.53 (m, 18H). Embodiment 2:

[0018] A preparation process of a high barrier recyclable eleven-layer co-extruded film for food packaging includes the following specific steps: Step 1, preparing a compatible component: placing maleic anhydride grafted polyethylene resin PE-g-MAH and an alkyl chain compatible monomer containing a hindered phenol group and a cinnamate group in a vacuum drying oven at 80° C. and drying for 12 hours, then adding them into a high-speed mixer according to the formula of the compatible component and mixing them evenly, extruding and granulating them through a twin-screw extruder, and vacuum drying them at 80° C. for 6 hours to prepare a compatible component; Among them, the process parameters of the twin-screw extruder were set as follows: the temperatures of zones 1-6 were 165°C, 170°C, 175°C, 180°C, 180°C, and 185°C, respectively, and the rotation speed was 300r / min; Step 3, preparing an eleven-layer co-extruded film: according to the formula of the eleven-layer co-extruded film, the ingredients are prepared, and the raw materials of each layer are respectively put into the hoppers of the eleven screw extruders of the eleven-layer co-extruded film blow molding unit, and the molten resin is converged at the head of the die through the diverter, and is extruded and blown through the die head, and the blow-up ratio is controlled at 2.7, and the film is cooled and rolled to prepare an eleven-layer co-extruded film with a thickness of 100 μm; Among them, the process parameters of the screw extruder corresponding to the first, second, tenth and eleventh layers are set as follows: the temperature of zones 1-3 is 120°C, 150°C and 170°C respectively, the flow channel temperature is 165°C, and the speed is 30r / min; The process parameters of the screw extruder corresponding to the third and ninth layers are set as follows: the temperatures of zones 1-3 are 125°C, 150°C, and 165°C, respectively, the flow channel temperature is 160°C, and the speed is 15r / min; The process parameters of the screw extruder corresponding to the fifth and seventh layers were set as follows: the temperatures of zones 1-3 were 200°C, 230°C, and 270°C, respectively, the flow channel temperature was 260°C, and the rotation speed was 60r / min; The process parameters of the screw extruders corresponding to the fourth, sixth, and eighth layers were set as follows: the temperatures of zones 1-3 were 140°C, 170°C, and 195°C, respectively, the flow channel temperature was 190°C, and the rotation speed was 60r / min; When the alkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is a dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups, the prepared product is recorded as high barrier recyclable eleven-layer co-extruded film I for food packaging; When the alkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is a trialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups, the prepared product is recorded as high barrier recyclable eleven-layer co-extruded film II for food packaging. Embodiment 3:

[0019] Preparation of high barrier recyclable eleven-layer co-extruded film III for food packaging: The preparation process thereof differs from that of high barrier recyclable eleven-layer co-extruded film I for food packaging only in that the formula of the compatible components is: 60wt% maleic anhydride grafted polyethylene resin PE-g-MAH and 40wt% dialkyl chain-type compatible monomers containing hindered phenol groups and cinnamate groups. Embodiment 4:

[0020] Preparation of high barrier recyclable eleven-layer co-extruded film IV for food packaging: The preparation process thereof differs from that of high barrier recyclable eleven-layer co-extruded film I for food packaging only in that the formula of the compatible components is: 90wt% maleic anhydride grafted polyethylene resin PE-g-MAH and 10wt% dialkyl chain-type compatible monomers containing hindered phenol groups and cinnamate groups. Comparative Example 1:

[0021] Preparation of eleven-layer co-extruded film a: The preparation process thereof differs from the preparation process of high barrier recyclable eleven-layer co-extruded film I for food packaging only in that the formula of the compatible component is 100 wt % maleic anhydride grafted polyethylene resin PE-g-MAH. Comparative Example 2:

[0022] Preparation of eleven-layer co-extruded film b: The preparation process thereof differs from the preparation process of the high barrier recyclable eleven-layer co-extruded film I for food packaging only in that the formula of the compatible component is 100wt% maleic anhydride grafted polyethylene resin PE-g-MAH, and low-density polyethylene resin LDPE is used to replace nylon resin PA6 and BVOH. Performance Testing:

[0023] 1. Barrier performance test: (1) Oxygen barrier performance test: Use Y110 oxygen permeation tester to test the oxygen permeation rate of samples according to GB / T 1038-2000 "Plastic film and sheeting gas permeability test method pressure difference method" standard; (2) Use TC-03 water vapor transmission meter to test the water vapor transmission rate of samples according to GB / T 1037-2021 "Determination of Water Vapor Transmission Rate of Plastic Film and Sheeting - Cup Weight Gain and Weight Loss Method"; 2. Mechanical properties test: (1) Mechanical properties test: According to GB / T 1040.1-2018 "Determination of tensile properties of plastics", a 150 mm × 20 mm sample (sampled along the film blowing direction) was fixed on an Instron 5565 universal tensile testing machine and a tensile test was performed at a tensile rate of 5 mm / min; (2) Mechanical properties test after 10 days of thermal oxidative aging: First, a 150 mm × 20 mm sample (sampled along the film blowing direction) was placed in a forced ventilation thermal aging test chamber at 70 ° C for 10 days with an air change rate of 50 times / h. Then, in accordance with the GB / T1040.1-2018 "Determination of tensile properties of plastics" standard, the sample was fixed on an Instron 5565 universal tensile testing machine and a tensile test was performed at a tensile rate of 5 mm / min; (3) Mechanical properties test after 10 days of light-oxidation aging: First, a 150 mm × 20 mm sample (sampled along the film blowing direction) was placed in an accelerated light aging test box and treated under a UV lamp for 10 days. There were two UV lamps, both 36 W. The distance between the two lamps was 15 cm, and the distance between the sample and the lamp was 14 cm. Then, in accordance with the GB / T 1040.1-2018 "Determination of tensile properties of plastics" standard, the sample was fixed on an Instron 5565 universal tensile testing machine and a tensile test was performed at a tensile rate of 5 mm / min. 3. Hygienic performance test: The hygienic properties of the samples were tested in accordance with GB / T 5009.60-2003 "Analysis Method for Hygienic Standards of Polyethylene, Polystyrene and Polypropylene Molding Products for Food Packaging". The physical and chemical indicators of the experimental results were based on GB / T 5009.58-2003 "Analysis Method for Hygienic Standards of Polyethylene Resins for Food Packaging". The above experimental results are shown in Tables 2-4 and Figure 3 .

[0024] Table 2 Barrier performance test results of high barrier recyclable eleven-layer co-extruded film for food packaging

[0025] Table 3 Experimental results of mechanical properties of high barrier recyclable eleven-layer co-extruded film for food packaging

[0026] Table 4 Experimental results of hygienic properties of high barrier recyclable eleven-layer co-extruded film for food packaging

[0027] By comprehensively analyzing the above experimental results, the following conclusions can be drawn: Conclusion 1: The oxygen permeability of the eleven-layer co-extruded film prepared by the present invention is less than the oxygen permeability <0.5cm in GB / T 40266-2021 "General Rules for Quality of Oxide Barrier Transparent Plastic Composite Films and Bags for Food Packaging" 3 / (m 2 •24h•0.1MPa) technical requirements; The water vapor permeability of the eleven-layer co-extruded film prepared by the present invention is less than the water vapor permeability <0.5g / (m 2 • 24h) technical requirements; Accordingly, the eleven-layer co-extruded film prepared by the present invention exhibits excellent barrier properties; among them, the barrier properties of the eleven-layer co-extruded film II are the best; Conclusion 2: The eleven-layer co-extruded film prepared by the present invention also has very excellent aging resistance, and its sanitary performance meets the requirements of national standards, and can be used in food packaging.

Claims

1. A process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging, characterized in that: The following steps are involved: Step 1: preparing a dialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group; Step 2: adding 60-90wt% of maleic anhydride grafted polyethylene resin PE-g-MAH and 10-40wt% of a dialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group or a trialkyl chain type compatible monomer containing a hindered phenol group and a cinnamate group into a high-speed mixer, mixing them evenly, and extruding and granulating them through a twin-screw extruder to prepare a compatible component; Step 3: Using PA6, BVOH and PE as raw materials, using compatible components to improve the compatibility of BVOH and PE, and using water-soluble BVOH to undergo hydrolysis reaction to achieve interlayer separation of PE and PA, and using eleven-layer co-extrusion blow molding film forming process to prepare a high barrier recyclable eleven-layer co-extrusion film for food packaging.

2. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 1, characterized in that: The film structure of the eleven-layer co-extruded film and the raw material formula and dosage of each film layer are as follows: First layer: the raw material is low-density polyethylene resin LDPE, the dosage is 5-15 parts by weight; The second layer: the raw material is metallocene polyethylene resin m-LLDPE, the amount is 10-20 parts by weight; The third layer: the raw materials are compatible components, the amount is 3-10 parts by weight; The fourth layer: the raw material is BVOH, the dosage is 3-10 parts by weight; The fifth layer: the raw material is nylon resin PA6, the dosage is 5-15 parts by weight; The sixth layer: the raw material is BVOH, the dosage is 5-15 parts by weight; The seventh layer: the raw material is nylon resin PA6, the dosage is 5-15 parts by weight; The eighth layer: the raw material is BVOH, the dosage is 3-10 parts by weight; Ninth layer: the raw materials are compatible components, the amount is 3-10 parts by weight; The tenth layer: the raw material is metallocene polyethylene resin m-LLDPE, the amount is 10-20 parts by weight; The eleventh layer: the raw material is low-density polyethylene resin LDPE, and the amount used is 5-15 parts by weight.

3. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 1, characterized in that: The chemical structural formula of the dialkyl chain-type compatible monomer containing hindered phenol groups and cinnamate groups is: 。 4. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 3, characterized in that: The preparation method of the dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is as follows: based on the Mannich reaction mechanism, 3,5-di-tert-butyl-4-hydroxyacetophenone containing α-H is subjected to a condensation reaction with methyl 4-formylcinnamate and di-n-octylamine to generate a dialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups.

5. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 1, characterized in that: The chemical structural formula of the trialkyl chain-type compatible monomer containing hindered phenol groups and cinnamate groups is: 。 6. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 5, characterized in that: The preparation method of the trialkyl chain type compatible monomer containing hindered phenol groups and cinnamate groups is as follows: Firstly, n-octylamine is used as a nucleophilic reagent, and triethylamine is used to catalyze the nucleophilic substitution reaction between the amino functional group of 3.01-3.08 molar equivalents of n-octylamine and the chlorine functional group of 1 molar equivalent of cyanuric chloride to generate a tri(secondary amino) monomer; Then, based on the Mannich reaction mechanism, 3.01-3.08 molar equivalents of 3,5-di-tert-butyl-4-hydroxyacetophenone containing α-H, 3.01-3.08 molar equivalents of methyl 4-formylcinnamate and 1 molar equivalent of tri(secondary amino) monomer undergo condensation reaction to generate a trialkyl chain-type compatible monomer containing a hindered phenol group and a cinnamate group.

7. The process for preparing a high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 1, characterized in that: The preparation method of the eleven-layer co-extruded film is as follows: ingredients are prepared according to the formula of the eleven-layer co-extruded film, and the raw materials of each layer are respectively put into the hoppers of eleven screw extruders of the eleven-layer co-extruded film blow molding unit, the molten resin is converged at the head of the machine through a diverter, and is extruded and blow-molded through a die head, the blow-up ratio is controlled at 2.5-2.9, and the film is cooled and rolled up to prepare the eleven-layer co-extruded film.

8. A high barrier recyclable eleven-layer co-extruded film for food packaging prepared by the process according to any one of claims 1 to 7, characterized in that: The thickness of the eleven-layer co-extruded film is 50-200 μm.

9. The high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 8, characterized in that: The oxygen permeability of the eleven-layer co-extruded film is less than 0.5 cm 3 / (m 2 •24h•0.1MPa), water vapor transmission rate <0.5g / (m 2 •24h).

10. The high barrier recyclable eleven-layer co-extruded film for food packaging according to claim 8, characterized in that: The longitudinal tensile strength of the eleven-layer co-extruded film is 40-45 MPa, the longitudinal tensile strength after 10 days of thermal oxidation aging is 30-40 MPa, and the longitudinal tensile strength after 10 days of photo-oxidative aging is 30-40 MPa.

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