High-barrier polyethylene film and preparation method thereof

Abstract

The invention belongs to the technical field of film materials, and particularly relates to a high-barrier polyethylene film and a preparation method thereof. The material consists of a polyethylene-based film layer, a coating barrier layer and an aluminum-plated layer, wherein the polyethylene-based film layer is prepared by combining nine layers of co-extruded films with a micro-stretching process; the coating blocking layer is composed of a water-based acrylic acid coating layer and a water-based polyvinyl alcohol coating layer which are connected in sequence, the polyvinyl base film layer is coated with the water-based acrylic acid coating layer, and the aluminum plating layer is plated on the water-based polyvinyl alcohol coating layer in a vacuum mode. The high-barrier polyethylene film material is good in barrier effect and can be recycled.

Description

Technical Field

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

[0002] As people's requirements for the safety of food, medicine and other products continue to increase, and environmental awareness continues to strengthen, the market for high-barrier film packaging materials continues to grow. The moisture barrier and oxygen barrier properties of polyethylene films are usually used as indicators to evaluate the barrier properties of films.

[0003] Most of the existing high barrier films use VMPET, aluminum foil, PET, AL, EVOH, etc. as barrier materials to achieve the barrier purpose. The oxygen barrier (hereinafter referred to as OTR) of the prepared films exceeds 2000cm 3 / m 2 24h, moisture resistance (hereinafter referred to as WVTR) exceeds 6g / m 2 ·24 hours, the packaging contents are easily damaged by external forces during transportation and storage, and the food is easily oxidized or deteriorates due to moisture, which reduces the shelf life of the food. It cannot be used in the packaging of sensitive products such as medicines and chemicals. At the same time, the film is not made of a single material, which makes the recycling efficiency of the film low. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a high barrier polyethylene film and a preparation method thereof. The high barrier polyethylene film has good barrier effect and is recyclable.

[0005] In order to achieve one of the purposes of the present invention, the present invention adopts the following technical solutions:

[0006] A high barrier polyethylene film, the material consists of a polyethylene base film layer, a coating barrier layer, and an aluminum plating layer. The polyethylene base film layer is made of a nine-layer co-extruded film combined with a micro-stretching process; the coating barrier layer consists of a water-based acrylic coating layer and a water-based polyvinyl alcohol coating layer connected in sequence, the polyethylene base film layer is coated with a water-based acrylic coating layer, and the aluminum plating layer is vacuum-plated on the water-based polyvinyl alcohol coating layer.

[0007] Preferably, the nine-layer co-extruded film is respectively connected in sequence: A layer, B layer, C layer, D layer, E layer, F layer, G layer, H layer, and I layer, and the water-based acrylic coating layer is coated on the A layer; the raw materials and proportions of the A layer are the same as those of the I layer; the raw materials and proportions of the B layer, the raw materials and proportions of the C layer, the raw materials and proportions of the D layer, the raw materials and proportions of the E layer, the raw materials and proportions of the F layer, the raw materials and proportions of the G layer, and the raw materials and proportions of the H layer are the same.

[0008] Preferably, layer A and layer I are each composed of 74 parts by mass of a first metallocene polyethylene resin, 25 parts by mass of a second metallocene polyethylene resin and 1 part by mass of a processing aid; layer B, layer C, layer D, layer E, layer F, layer G and layer H are each composed of 89 parts by mass of a high-density polyethylene, 10 parts by mass of a high-pressure polyethylene and 1 part by mass of a processing aid.

[0009] Preferably, the first metallocene polyethylene resin is SP2520 produced by Mitsui Chemicals, with a density of 0.925 g / cm 3 The melt index is 2.0 g / 10 min. 190 ° C / 2.16 kg; the second metallocene polyethylene resin is 2005MC produced by ExxonMobil, with a density of 0.920 g / cm 3 The melt index is 0.5g / 10min.190℃ / 2.16kg; the brand of the processing aid is 100991-K produced by Anpaise Company, and the density is 0.940g / cm 3 The grade of high-density polyethylene is AT6900 or 5960G produced by Dow Chemical Company, with a density of 0.960-0.969 g / cm 3 The melt index is 1.2g / 10min.190℃ / 2.16kg; the grade of high-pressure polyethylene is 151BW produced by Exxon, and the density is 0.935g / cm 3 , the melt index is 3.5g / 10min.190℃ / 2.16kg.

[0010] Preferably, the thickness of the polyethylene-based film layer is 20um-60um; the thickness ratio of layer A, layer B, layer C, layer D, layer E, layer F, layer G, layer H, and layer I is 3:2:2:2:2:2:2:2:2:3.

[0011] Preferably, the aqueous polyvinyl alcohol coating layer is composed of 9-12 parts by mass of aqueous polyvinyl alcohol, 1.5-2.0 parts by mass of polyethyleneimine or 0.5-1.5 parts by mass of polyethylene water-based wax, and water; the brand of aqueous polyvinyl alcohol is PVA01 produced by Huangshan Xinli Ink Company.

[0012] Preferably, the water-based acrylic coating layer is made by diluting water-based acrylic acid and water in a mass ratio of 1:1. The brand of water-based acrylic acid is P2300 produced by Michelman Company, with a solid content of 33% and a coating dry glue amount of 0.5 g / m 2 -1.0g / m 2 When using, add deionized water for dilution, which can adjust the coating amount, improve the fluidity of the coating layer, and facilitate uniform coating.

[0013] In order to achieve the second object of the present invention, the present invention provides a method for preparing a high barrier polyethylene film, which specifically comprises the following steps:

[0014] S1. Preparation of polyethylene base film layer: nine layers of materials are respectively put into the barrel of a film blowing machine for melt co-extrusion, and the nine layers of materials are sequentially subjected to extrusion melting, bubble pulling, automatic side thickness, bubble stopping, primary traction, micro-stretching shaping, corona, secondary traction and winding to form a film bubble to obtain a nine-layer co-extruded polyethylene base film layer; wherein micro-stretching refers to a slight stretching of the base film layer, which can increase the surface tension of the base film layer, is conducive to the stability and improvement of the surface tension of the base film layer, avoids a large rebound of the base film layer, and has a higher flatness of the base film layer;

[0015] S2, the polyethylene base film layer prepared in step S1 is suspended and stored for 48 hours to allow the base film layer to be fully close to being fixed and the internal stress is eliminated, and then the aqueous acrylic coating liquid and the aqueous polyvinyl alcohol coating liquid (hereinafter referred to as the aqueous PVOH coating liquid) are uniformly coated on the polyethylene base film layer in a reverse kiss coating manner using a coating roller, and then dried and rolled to form a polyethylene film;

[0016] S3, vacuum evaporating aluminum oxide on the polyethylene film in step S2 to form a dense metal oxide layer to obtain a high barrier polyethylene film.

[0017] Preferably, in step S1, the melting section temperature of the film blowing machine is 40-80°C, the extrusion section temperature is 190-215°C, the die head temperature is 205°C, and the extrusion volume is 400-660kg / h; the blowing ratio of the bubble is 1:(1.2-2.5); the rotation time of the automatic side thickness is 35min-60min, to ensure that each point of the base film can be stably and automatically adjusted to ensure the uniformity of the thickness of the base film; the tension of the first traction is 150N; the ratio of micro-stretching and shaping is 1.02-1.10; the tension of the second traction is 80N, and the pressing force of the winding is 100N-200N, to ensure the normal operation of the base film layer.

[0018] The four-roll shaping stability includes a 75°C SD roller, an 85°C FD roller, a 90°C shaping roller AD, and a 50°C cooling roller CD to ensure the smooth running and shaping of the base film layer.

[0019] The coating liquid is applied by embossing process, in which the parameters of the anilox roller are 80LPI and the cell depth is 120um-160um, to ensure that the coating liquid can be spread evenly and the amount of wet glue of the coating liquid is high;

[0020] During the drying process, the five-stage oven drying temperature is designed with a gradient of 105℃ / 100℃ / 95℃ / 85℃ / 70℃, with a sufficiently large air intake of 5800m 3 / hour to ensure the drying of the aqueous polyvinyl alcohol coating liquid; the coating speed is 180 m / min, and the speed ratio of the reverse roller speed is 140%; the unwinding tension in step S2 is 10-16 kg, the winding tension during the coating process is 10-14 kg, and the winding pressing force is 22 kg-28 kg.

[0021] Preferably, in step 3, the alumina is aluminum wire with a diameter of 2.2 mm and a purity of 99.85%, provided by Runlida Company; the vacuum degree of vacuum aluminum plating is 10 -4 Under the conditions, two vacuum pump systems are used to maintain high vacuum for 20 minutes; a tungsten boat is used to heat alumina. The size of the tungsten boat is 130mm×40mm×9mm, and the power is 7KW-8KW to ensure sufficient melting and sublimation of alumina. At the same time, a special plasma generator is turned on to purify the surface of the base film layer. The power is 3KW-5KW; the temperature of the cooling roller is 0℃ to ensure sufficient cooling efficiency of the aluminum vapor. The tungsten boat is provided by Steck; the purity of oxygen is ≥99.995%, dust (φ≥0.5μm) ≤3.5 particles / L, and the impurity content is N 2 ≤10cm 3 / m 3 ,Ar≤5cm 3 / m 3 , H 2 O≤lcm 3 / m 3 , CO 2 ≤0.5cm 3 / m 3 ; The amount of pure oxygen entering is 500SCCM-800SCCM (SCCM Standard cubic centimeter per minute is a commonly used flow unit, which represents the number of cubic centimeters of oxygen flowing under standard conditions (pressure of 1atm, temperature of 0°C) per minute) to oxidize aluminum atoms during evaporation; the unwinding tension is set to 300N-500N, and the winding tension is set to 200N-300N.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1) The high barrier polyethylene film prepared by the present invention is a single material, which can effectively replace traditional barrier materials such as VMPET and aluminum foil, realize the recycling of single packaging material, and reduce carbon emissions. The high barrier polyethylene film OTR of the present invention is ≤0.6cm 3 / m 2 24h, WVTR≤1.0g / m 2·24H, compared with ordinary high barrier polyethylene film materials, the polyethylene film of the present invention has better barrier properties, is thinner and lighter, and has stronger processability. These characteristics can effectively save costs and are more environmentally friendly, while also meeting the application requirements of different fields. The present invention can be widely used in the fields of food, medicine, building insulation, electronic products, optical instruments, etc., greatly promoting the environmental friendliness of plastic composite packaging, that is, the goal of carbon reduction.

[0024] 2) The polyethylene-based film layer in the present invention is made of a nine-layer co-extruded film combined with a micro-stretching process; the nine-layer process has significant advantages in barrier properties, especially in high-barrier films, the barrier part occupies seven layers in the structure, which greatly improves the barrier effect of the film; with the advancement of polymers and processing technology, the percentage of the overall thickness of this part in the entire structure is constantly decreasing, but the same barrier properties are still maintained, which means that the nine-layer film can more effectively prevent the penetration of oxygen, moisture, etc. into the packaging contents, thereby extending the shelf life of the product; in terms of cost-effectiveness, compared with the seven-layer film, the nine-layer film can provide better mechanical, appearance and cost performance, and during the processing process, it can better control costs while maintaining product quality.

[0025] 3) The polyethylene film of the present invention has a higher tensile strength, which can effectively protect the safety of the package contents during transportation and storage, and reduce the risk of damage due to external forces; it has better barrier properties to oxygen and water vapor, which can effectively extend the shelf life of food and prevent food from deteriorating due to oxidation or moisture. At the same time, in the packaging of sensitive products such as medicines and chemicals, the high barrier property can also be effective to ensure the quality and safety of the products and prevent the influence of the external environment; the aluminum layer has stronger adhesion, which can improve its subsequent processing performance, and more effective bonding with the aluminum layer can further improve the barrier properties of the high-barrier PE.

[0026] 4) In the polyethylene-based film layer, both the A layer and the I layer use metallocene polyethylene resin with the brand name SP2520, the 2005MC metallocene polyethylene resin with the brand name and the processing aid with the brand name 100991-K. The particles of the first two types have high strength, good toughness and good impact resistance, which can reduce the risk of film breakage, and the 100991-K particles as a processing aid ensure smooth film feeding during the film blowing process; the B layer to the H layer are used as the core layer, and high-density polyethylene with the brand name AT6900 (or 5960G), high-pressure polyethylene with the brand name 151BW and the processing aid 100991-K are used. Among them, the high-density polyethylene has high wear resistance, impact resistance, toughness and chemical stability, which can greatly improve the physical properties and chemical stability of the film; in addition, the addition of high-pressure polyethylene can effectively improve the tensile strength of the film after longitudinal stretching, and has excellent stiffness and tension, which can keep the film flat and not curled after winding, and has good composite strength, which is beneficial to improve the peel strength and barrier properties of the film after composite with the low-temperature PE film.

[0027] 5) After the polyethylene high barrier film material of the present invention is coated with an oxygen barrier layer, it is then vacuum-plated with an aluminum oxide layer to form a dense metal oxide layer, which has excellent resistance to the penetration of water vapor, oxygen, etc., so that the film material can achieve the barrier performance of 5um-9um metal aluminum foil, and can become a substitute product for metal aluminum foil as a barrier material in composite packaging. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0029] Example 1

[0030] A high barrier polyethylene film, the proportion of the material is shown in Table 1 below:

[0031] Table 1

[0032]

[0033]

[0034] The water-based polyvinyl alcohol coating layer is composed of 9 parts by mass of water-based polyvinyl alcohol, 1.5 parts by mass of polyethyleneimine and 89.5 parts by mass of water. The water-based acrylic coating layer is made by diluting water-based acrylic acid and water in a mass ratio of 1:1. The brand of water-based acrylic acid is P2300 produced by Michelman Company, with a solid content of 33% and a coating dry adhesive amount of 0.9 g / m 2 ±0.2.

[0035] A method for preparing a high barrier polyethylene film comprises the following steps:

[0036] S1. Preparation of polyethylene-based film layer: The materials of each layer in Table 1 above are respectively put into the barrel of a film blowing machine for melt co-extrusion, and the film bubbles are formed to obtain nine-layer co-extruded polyethylene-based film layer through extrusion melting-bubble pulling-automatic side thickness-bubble stopping-traction-micro-stretching shaping-corona-second traction-winding, wherein the melting section temperature of the film blowing machine is 60° C., the extrusion section temperature is 205° C., the die head temperature is 195° C., and the extrusion rate is 506 kg / h;

[0037] Among them, the blowing ratio of the bubble is 1:1.9; the first traction tension is set to 150N, the second traction tension is 80N, and the winding pressure is 160N to ensure the normal operation of the base film; the automatic side thickness rotation time is 50min to ensure that each point of the base film can be stably and automatically adjusted to ensure the uniformity of the thickness of the base film; the micro-stretching ratio in the micro-stretching setting is 1.065, the four-roll setting is stable at SD roller 75℃, FD roller temperature 85℃, setting roller AD90℃, and cooling roller CD temperature 50℃ to ensure the smooth operation and setting of the base film;

[0038] S2, after the polyethylene-based film layer is suspended and stored for 48 hours, the aqueous acrylic coating liquid and the aqueous polyvinyl alcohol coating liquid are uniformly coated on the polyethylene-based film layer in a reverse kiss coating manner using a coating roller, and after drying and winding, a water-based acrylic coating layer and a water-based polyvinyl alcohol coating layer are sequentially formed on the polyethylene-based film layer to obtain a polyethylene film;

[0039] Among them, the specific parameters of the coating process are as follows:

[0040] Preparation of water-based polyvinyl alcohol coating liquid: heating deionized water to 90°C for 2 hours, then slowly adding water-based polyvinyl alcohol resin until it is completely emulsified, and adding polyethyleneimine to form a water-based PVOH coating liquid;

[0041] The coating is carried out by embossing process, the parameters of the anilox roller are 120LPI, and the cell depth is 150um, to ensure that the coating liquid can be spread evenly and the amount of wet glue of the coating liquid is high;

[0042] In the drying step, the five-stage oven drying temperature is designed with a gradient of 105 / 100 / 95 / 85 / 70, with a sufficiently large air intake of 5800m 3 / hour to ensure the drying of the water-based PVOH coating liquid;

[0043] The coating speed is 180 m / min, the reverse roller speed ratio is 140%, the unwinding tension is set to 12 kg, the winding tension is set to 12 kg, and the winding pressure is 26 kg;

[0044] After coating is completed and rolled up, it needs to be suspended in the air and left to stand for 24 hours to release the cohesive force of the coating.

[0045] S3, vacuum evaporating aluminum oxide on the polyethylene film in step S2 to form a dense metal oxide layer to obtain a high barrier polyethylene film 1.

[0046] Among them, the vacuum degree of vacuum aluminum plating is 10 -4 , using two sets of vacuum pump systems, evacuate for 20 minutes to form a high vacuum;

[0047] The power of the heated tungsten boat is designed to be 8KW to ensure sufficient melting and sublimation of the aluminum wire. At the same time, a special plasma generator is turned on to purify the surface of the film, and the power is set to 3KW;

[0048] The temperature of the cooling roller is set to 0°C to ensure sufficient cooling efficiency of the aluminum vapor; the amount of pure oxygen entering is set to 600 SCCM to oxidize the aluminum atoms during evaporation; the unwinding tension is set to 500N and the winding tension is set to 300N.

[0049] Example 2

[0050] A high barrier polyethylene film, the proportion of the material is shown in Table 2 below:

[0051] Table 2

[0052]

[0053] The water-based polyvinyl alcohol coating layer is composed of 11 parts by mass of water-based polyvinyl alcohol, 0.5 parts by mass of polyethylene water-based wax and 88.5 parts by mass of water. The water-based acrylic coating layer is made by diluting water-based acrylic acid and water in a mass ratio of 1:1. The brand of water-based acrylic acid is P2300 produced by Michelman Company, with a solid content of 33% and a coating dry glue amount of 0.6 g / m 2 ±0.2.

[0054] A method for preparing a high barrier polyethylene film comprises the following steps:

[0055] S1. Preparation of polyethylene-based film layer: The materials of each layer in Table 2 above are respectively put into the barrel of a film blowing machine for melt co-extrusion, and the film is subjected to extrusion melting-bubble pulling-automatic side thickness-bubble stopping-traction-micro-stretching shaping-corona-second traction-winding, wherein the melting section temperature of the film blowing machine is 55° C., the extrusion section temperature is 200° C., the die head temperature is 195° C., and the extrusion rate is 536 kg / h, to form a film bubble to obtain a nine-layer co-extruded polyethylene-based film layer;

[0056] Among them, the blowing ratio of the bubble is 1:2.2; the first traction tension is set to 120N, the second traction tension is 90N, and the winding pressure is 180N to ensure the normal operation of the base film; the automatic side thickness rotation time is 38min to ensure that each point of the base film can be stably and automatically adjusted to ensure the uniformity of the thickness of the base film; in the micro-stretching shaping, the micro-stretching ratio is 1.082, the four-roll shaping is stable at SD roller 70℃, FD roller temperature 80℃, shaping roller AD 85℃, and cooling roller CD temperature 40℃ to ensure the smooth operation and shaping of the base film;

[0057] S2, after the polyethylene-based film layer is suspended and stored for 48 hours, the aqueous acrylic coating liquid and the aqueous polyvinyl alcohol coating liquid are uniformly coated on the polyethylene-based film layer in a reverse kiss coating manner using a coating roller, and after drying and winding, a water-based acrylic coating layer and a water-based polyvinyl alcohol coating layer are sequentially formed on the polyethylene-based film layer to obtain a polyethylene film;

[0058] Among them, the specific parameters of the coating process are as follows:

[0059] Preparation of water-based polyvinyl alcohol coating liquid: heating deionized water to 90°C for 2 hours, then slowly adding water-based polyvinyl alcohol resin until it is completely emulsified, and adding polyethylene water-based wax to form a water-based PVOH coating liquid;

[0060] The coating is carried out by embossing process, the parameters of the anilox roller are 150LPI, and the cell depth is 120um, to ensure that the coating liquid can be spread evenly and the amount of wet glue of the coating liquid is high;

[0061] In the drying step, the five-stage oven drying temperature is designed with a gradient of 105 / 102 / 95 / 88 / 75, with a sufficiently large air intake of 4800m 3 / hour to ensure the drying of the water-based PVOH coating liquid;

[0062] The coating speed is 185 m / min, the reverse roller speed ratio is 140%, the unwinding tension is set to 13 kg, the winding tension is set to 13 kg, and the winding pressure is 25 kg;

[0063] After coating is completed and rolled up, it needs to be suspended in the air and left to stand for 24 hours to release the cohesive force of the coating.

[0064] S3, vacuum evaporating aluminum oxide on the polyethylene film in step S2 to form a dense metal oxide layer to obtain a high barrier polyethylene film 2.

[0065] Among them, vacuum aluminum plating is carried out at a vacuum degree of 10 -4 , using two sets of vacuum pump systems, evacuate for 20 minutes, and form a high vacuum;

[0066] The power of the heating tungsten boat is designed to be 8KW to ensure sufficient melting and sublimation of the aluminum wire. At the same time, a special plasma generator is turned on to purify the membrane surface, and the power is set to 4KW;

[0067] The cooling roller temperature is set at 0°C to ensure sufficient cooling efficiency of the aluminum vapor;

[0068] The amount of pure oxygen entering is set to 800 SCCM to oxidize the aluminum atoms during evaporation; the unwinding tension is set to 400N, and the winding tension is set to 300N.

[0069] The high barrier polyethylene film 1 and high barrier polyethylene film 2 prepared in Example 1-2 were tested for performance with a common HDPE film. The results are shown in Table 3 below:

[0070] Table 3

[0071]

[0072] in,

[0073] Tensile strength: measures the film toughness, tensile strength, composite film crack resistance and other requirements;

[0074] 10% tensile force: an indicator to measure the film's ability to resist deformation during processing;

[0075] Elongation at break %: represents film toughness, deformation resistance, etc.;

[0076] Friction coefficient: an indicator that affects the coating and aluminizing process and the smoothness of downstream use;

[0077] Barrier properties: Evaluation of the barrier capacity of polyethylene barrier films;

[0078] Right-angle tear: measures the tearability of packaging materials;

[0079] Aluminum oxide layer adhesion: an indicator to measure the peeling strength of subsequent composite processing.

[0080] As can be seen from Table 3, the polyethylene film prepared by the present invention has good tensile properties, can better resist external forces, protect the items in the package from damage, and at the same time improve the overall durability and reliability of the package; the excellent barrier ability to external factors such as gas and moisture can effectively prevent the penetration of substances such as oxygen and water vapor that affect the contents of the package, thereby extending the shelf life and safety of items such as food and medicine, and reducing the risk of deterioration; in the subsequent composite processing, the higher adhesion of the aluminum layer makes the coating and the substrate tightly combined, not easy to fall off or delaminate, thereby improving the integrity and durability of the composite film, and further improving the stability and reliability of the composite film in the subsequent processing and use process, which is fully in line with the development prospects of the industry.

[0081] The present invention can replace the use of PET, AL, and EVOH as barrier materials in plastic composite flexible packaging materials, solve the problem of poor barrier properties of polyolefin film materials in the industry, and fill the gap in high-barrier film materials for single polyolefin composite packaging. The high-barrier polyethylene film of the present invention can be widely used in aseptic packaging and single flexible packaging composite materials to replace common barrier materials such as VMPET and aluminum foil, realize the recycling of a single packaging material, and greatly promote the environmental friendliness and carbon reduction goals of plastic composite packaging.

Claims

1. A high barrier polyethylene film, characterized in that: The material consists of a polyethylene-based film layer, a coating barrier layer, and an aluminum-plated layer. The polyethylene-based film layer is made of a nine-layer co-extruded film combined with a micro-stretching process; the coating barrier layer consists of a water-based acrylic coating layer and a water-based polyvinyl alcohol coating layer connected in sequence, the polyethylene-based film layer is coated with a water-based acrylic coating layer, and the aluminum-plated layer is vacuum-plated on the water-based polyvinyl alcohol coating layer.

2. A high barrier polyethylene film according to claim 1, characterized in that: The nine-layer co-extruded film comprises an A layer, a B layer, a C layer, a D layer, an E layer, a F layer, a G layer, a H layer and an I layer which are connected in sequence, and the water-based acrylic coating layer is coated on the A layer; the raw materials and proportions of the A layer are the same as those of the I layer; the raw materials and proportions of the B layer, the C layer, the D layer, the E layer, the F layer, the G layer and the H layer are the same.

3. A high barrier polyethylene film according to claim 2, characterized in that: The A layer and the I layer are each composed of 74 parts by mass of a first metallocene polyethylene resin, 25 parts by mass of a second metallocene polyethylene resin and 1 part by mass of a processing aid; the B layer, the C layer, the D layer, the E layer, the F layer, the G layer and the H layer are each composed of 89 parts by mass of a high-density polyethylene, 10 parts by mass of a high-pressure polyethylene and 1 part by mass of a processing aid.

4. A high barrier polyethylene film according to claim 3, characterized in that: The brand of the first metallocene polyethylene resin is SP2520 produced by Mitsui Chemicals; the brand of the second metallocene polyethylene resin is 2005MC produced by ExxonMobil; the brand of the processing aid is 100991-K produced by Ansense; the brand of the high-density polyethylene is one of AT6900 or 5960G produced by Dow Chemical Company; the brand of the high-pressure polyethylene is 151BW produced by Exxon.

5. The high barrier polyethylene film according to claim 2, characterized in that: The thickness of the polyethylene-based film layer is 20um-60um; the thickness ratio of the A layer, the B layer, the C layer, the D layer, the E layer, the F layer, the G layer, the H layer, and the I layer is 3:2:2:2:2:2:2:2:2:

3.

6. The high barrier polyethylene film according to claim 1, characterized in that: The water-based polyvinyl alcohol coating layer is composed of 9-12 parts by mass of water-based polyvinyl alcohol, 1.5-2.0 parts by mass of polyethylene imine or 0.5-1.5 parts by mass of polyethylene water-based wax, and water; the brand of the water-based polyvinyl alcohol is PVA01 produced by Huangshan Xinli Ink Company.

7. The high barrier polyethylene film according to claim 1, characterized in that: The water-based acrylic coating layer is prepared by diluting water-based acrylic acid and water in a mass ratio of 1:

1. The brand of the water-based acrylic acid is P2300 produced by Michelman.

8. A method for preparing a high barrier polyethylene film according to any one of claims 1 to 7, characterized in that: The steps include: S1. Preparation of polyethylene-based film layer: nine layers of materials are respectively put into the barrel of a film blowing machine for melt co-extrusion, and the process includes extrusion melting, bubble pulling, automatic side thickness, bubble stopping, primary traction, micro-stretching and shaping, corona, secondary traction and winding to form a film bubble to obtain a nine-layer co-extruded polyethylene-based film layer; S2, the polyethylene-based film layer prepared in step S1 is suspended and stored for 48 hours, and then the aqueous acrylic coating liquid and the aqueous polyvinyl alcohol coating liquid are uniformly coated on the polyethylene-based film layer in a reverse kiss coating manner using a coating roller, and then dried and rolled to form a polyethylene film; S3, vacuum evaporating aluminum oxide on the polyethylene film in step S2 to obtain a high barrier polyethylene film.

9. The method for preparing a high barrier polyethylene film according to claim 8, characterized in that: In step S1, the melting section temperature of the film blowing machine is 40-80°C, the extrusion section temperature is 190-215°C, the die head temperature is 205°C, and the extrusion volume is 400-660kg / h; the blowing ratio of the bubble is 1:(1.2-2.5); the rotation time of the automatic side thickness is 35min-60min; the tension of the first traction is 150N; the ratio of the micro-stretching setting is 1.02-1.10; the tension of the second traction is 80N, and the pressing force of the winding is 100N-200N.

10. The method for preparing a high barrier polyethylene film according to claim 8, characterized in that: In step 3, the alumina is aluminum wire with a diameter of 2.2 mm and a purity of 99.85%.

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