A high barrier coating film for food packaging and preparation method thereof

Abstract

The present application discloses a high-barrier coating for food packaging and a preparation method thereof, and relates to the field of food packaging materials. The high-barrier coating comprises an MDOPE film, a modified PVA coating and an aluminum oxide barrier layer arranged in sequence. Before depositing the aluminum oxide barrier layer on the surface of the modified PVA coating, the modified PVA coating is first subjected to corona or plasma treatment; wherein the raw materials for preparing the modified PVA coating include water-soluble polyvinyl alcohol, modified graphene oxide and a diluent, and the weight ratio of the water-soluble polyvinyl alcohol, the modified graphene oxide and the diluent is (8.2-9.6): (1-1.5): 100, and the modified graphene oxide is obtained by modifying the graphene oxide with a modifier including a water-soluble monoepoxy-terminated polyether and an aminosilane coupling agent. The coating of the present application has excellent oxygen and water vapor barrier properties, can be applied to the field of food packaging, and effectively prolong the storage time of food.

Description

Technical Field

[0001] The present application relates to the field of food packaging materials, and in particular to a high-barrier coating for food packaging and a preparation method thereof. Background Art

[0002] Food packaging materials play a vital role in ensuring food quality and safety. As consumers' requirements for food safety and freshness continue to increase, traditional food packaging materials can no longer meet market demand. Especially in terms of barrier properties, traditional materials often cannot meet high barrier requirements, which in turn affects the shelf life of food. Therefore, the development of food packaging materials with high barrier properties has become one of the urgent issues to be solved in the industry. The development of this field is of great significance to improving food preservation quality and extending food shelf life.

[0003] In the related art, in order to improve the barrier properties of food packaging materials, a barrier coating is usually applied to the surface of the film, and a common coating is polyvinyl alcohol (PVA). PVA is widely used in coatings of packaging materials due to its excellent gas barrier properties in low humidity environments. However, PVA coatings have strong water absorption and are easily soluble in water, so their barrier properties are significantly reduced in humid environments.

[0004] To solve this problem, the inventors tried to add fillers with good barrier properties, such as graphene oxide, to the PVA coating. The addition of graphene oxide can enhance the barrier properties of the coating material, especially in preventing water vapor penetration. Although the addition of graphene oxide can effectively improve the barrier properties, since graphene oxide is prone to agglomeration, there is a problem of poor dispersibility in the PVA coating, which is not conducive to effectively improving the overall barrier properties of the PVA coating. Summary of the invention

[0005] In order to overcome the problem that the poor dispersibility of graphene oxide in the PVA coating affects the overall barrier properties of the PVA coating, the present application provides a high-barrier coating for food packaging and a preparation method thereof.

[0006] In the first aspect, the high barrier coating film for food packaging provided in the present application adopts the following technical solution:

[0007] A high-barrier coating for food packaging comprises an MDOPE film, a modified PVA coating and an aluminum oxide barrier layer which are arranged in sequence. Before depositing the aluminum oxide barrier layer on the surface of the modified PVA coating, the modified PVA coating is first subjected to corona or plasma treatment. The raw materials for preparing the modified PVA coating comprise water-soluble polyvinyl alcohol, modified graphene oxide and a diluent, the weight ratio of the water-soluble polyvinyl alcohol, the modified graphene oxide and the diluent is (8.2-9.6):(1-1.5):100, and the modified graphene oxide is obtained by modifying graphene oxide with a modifier comprising a water-soluble monoepoxy-terminated polyether and an aminosilane coupling agent.

[0008] The present application adds a specific amount of a modifier including a water-soluble monoepoxy-terminated polyether and an aminosilane coupling agent to water-soluble polyvinyl alcohol to modify graphene oxide to obtain modified graphene oxide, wherein the modified graphene oxide has good dispersibility in water-soluble polyvinyl alcohol, which is conducive to obtaining a modified PVA coating with good barrier performance consistency and improving the barrier performance of the coating in a humid environment. In addition, the present application also adds a layer of aluminum oxide barrier layer on the surface of the modified PVA coating to prevent the modified PVA coating from directly contacting the air, which is conducive to further improving the water vapor barrier ability of the coating. Furthermore, considering the interlayer bonding strength between the aluminum oxide barrier layer and the modified PVA coating, the present application first performs corona or plasma treatment on the modified PVA coating before depositing the aluminum oxide barrier layer on the surface of the modified PVA coating to further improve the water vapor barrier ability of the coating, so that the coating can be applied to the field of food packaging and effectively extend the storage time of food.

[0009] In some specific embodiments, the preparation method of the modified graphene oxide includes the following steps: dissolving an aminosilane coupling agent in water, then adding graphene oxide, heating to 40-45°C for reaction, then adding a water-soluble monoepoxy-terminated polyether, stirring evenly, heating to 100-105°C for reaction, then centrifuging and drying to obtain modified graphene oxide.

[0010] In the present application, the graphene oxide is first modified by using an aminosilane coupling agent, and after the aminosilane coupling agent is grafted on the graphene oxide, a water-soluble monoepoxy-terminated polyether is then added, and the epoxy group on the water-soluble monoepoxy-terminated polyether reacts with the amino group of the aminosilane coupling agent on the graphene oxide to graft a polyether segment on the graphene oxide, wherein the introduction of the silane segment and the polyether segment increases the steric hindrance of the graphene oxide, increases the distance between the graphene oxide particles, and reduces the interaction force, so that the modified graphene oxide is not easy to agglomerate in the PVA coating and can be evenly dispersed.

[0011] In some specific embodiments, the weight ratio of the aminosilane coupling agent, water, graphene oxide, and water-soluble monoepoxy-terminated polyether is (4.2-5.5):100:(1-1.2):(9.4-10.6).

[0012] In some specific embodiments, in the modified graphene oxide, the modifier further comprises alkenyl benzoic acid, and the water-soluble monoepoxy-terminated polyether is a monoepoxy-terminated polyether containing an unsaturated double bond.

[0013] In the process of preparing modified graphene oxide in the present application, alkenyl benzoic acid can also be added. At the same time, the water-soluble monoepoxy-terminated polyether uses a monoepoxy-terminated polyether containing an unsaturated double bond, such as a water-soluble allyl epoxy-terminated polyether. By copolymerizing alkenyl benzoic acid with the monoepoxy-terminated polyether containing an unsaturated double bond, modified graphene oxide with good dispersibility in water-soluble polyvinyl alcohol can be obtained, and the high temperature resistance of the modified PVA coating is improved, thereby improving the barrier stability of the coating in a high temperature cooking environment.

[0014] In some specific embodiments, the preparation method of the modified graphene oxide comprises the following steps: dissolving an aminosilane coupling agent in water, then adding graphene oxide, heating to 40-45°C for reaction, then adding a water-soluble monoepoxy-terminated polyether, stirring evenly, heating to 100-105°C for reaction, then adding alkenyl benzoic acid and persulfate, heating to 70-80°C for reaction, and finally centrifuging and drying to obtain modified graphene oxide.

[0015] The preparation of modified graphene oxide in the present application can be further preferably as follows: firstly, graphene oxide is modified by aminosilane coupling agent, after which the aminosilane coupling agent is grafted onto the graphene oxide, a monoepoxy-terminated polyether containing unsaturated double bonds is then added, and polyether segments are grafted onto the graphene oxide through the reaction of the epoxy group on the monoepoxy-terminated polyether containing unsaturated double bonds with the amino group of the aminosilane coupling agent on the graphene oxide, and finally, alkenyl benzoic acid and the monoepoxy-terminated polyether containing unsaturated double bonds are copolymerized to further increase the steric hindrance of the graphene oxide. At the same time, the high temperature resistance of the modified PVA coating can also be improved, thereby improving the barrier stability of the coating in a high temperature environment.

[0016] In some specific embodiments, the weight ratio of the aminosilane coupling agent, water, graphene oxide, water-soluble monoepoxy-terminated polyether, alkenyl benzoic acid and persulfate is (4.2-5.5):100:(1-1.2):(9.4-10.6):(1-1.2):(0.1-0.2).

[0017] In some specific embodiments, the water-soluble polyvinyl alcohol is polyvinyl alcohol 200 or polyvinyl alcohol 400, and the diluent is water.

[0018] In the second aspect, the present application provides a method for preparing a high barrier coating for food packaging, which adopts the following technical solution:

[0019] A method for preparing a high barrier coating for food packaging comprises the following steps:

[0020] S1, uniformly coating a layer of modified PVA coating on the surface of the MDOPE film;

[0021] S2, performing corona treatment or plasma treatment on the surface of the modified PVA coating to obtain a corona surface or a plasma surface;

[0022] S3, vacuum evaporating an aluminum oxide barrier layer on the corona surface or plasma surface of the modified PVA coating.

[0023] In some specific embodiments, in step S2, the power of the corona treatment is 1.2-1.6 kw, and the power of the plasma treatment is 0.8-1.2 kw.

[0024] Power control of corona treatment or plasma treatment can effectively improve the activity of the surface of the modified PVA coating, thereby enhancing the adhesion of the subsequent aluminum oxide barrier layer on its surface and significantly improving the barrier performance of the coating.

[0025] In some specific embodiments, in step S3, the wire feeding speed of the aluminum wire is 270-290 mm / min, and the oxygen delivery speed is 6900-8000 sccm.

[0026] The control of the wire feeding speed of the aluminum wire and the oxygen delivery speed can make the aluminum oxide barrier layer have good uniformity and high density, further improving the barrier performance of the coating.

[0027] In summary, this application at least includes the following beneficial technical effects:

[0028] (1) The present application adds a specific amount of a modifier including a water-soluble monoepoxy-terminated polyether and an aminosilane coupling agent to water-soluble polyvinyl alcohol to modify graphene oxide to obtain modified graphene oxide, wherein the modified graphene oxide has good dispersibility in water-soluble polyvinyl alcohol, which is conducive to obtaining a modified PVA coating with good barrier performance consistency and improving the barrier performance of the coating in a humid environment. In addition, the present application also adds a layer of aluminum oxide barrier layer on the surface of the modified PVA coating to prevent the modified PVA coating from directly contacting the air, which is conducive to further improving the water vapor barrier ability of the coating. Furthermore, considering the interlayer bonding strength between the aluminum oxide barrier layer and the modified PVA coating, the present application first performs corona or plasma treatment on the modified PVA coating before depositing the aluminum oxide barrier layer on the surface of the modified PVA coating to further improve the water vapor barrier ability of the coating, so that the coating can be applied to the field of food packaging and effectively extend the storage time of food.

[0029] (2) In the process of preparing the modified graphene oxide of the present application, alkenyl benzoic acid can also be added. At the same time, the water-soluble monoepoxy-terminated polyether uses a monoepoxy-terminated polyether containing an unsaturated double bond, such as a water-soluble allyl epoxy-terminated polyether. By copolymerizing alkenyl benzoic acid with the monoepoxy-terminated polyether containing an unsaturated double bond, a modified graphene oxide with good dispersibility in water-soluble polyvinyl alcohol can be obtained, and at the same time, the high temperature resistance of the modified PVA coating is improved, thereby improving the barrier stability of the coating in a high temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a schematic structural diagram of a high barrier coating for food packaging according to an embodiment of the present application.

[0031] Description of reference numerals:

[0032] 1. MDOPE film; 2. Modified PVA coating; 3. Alumina barrier layer. DETAILED DESCRIPTION

[0033] The present application is further described below in conjunction with specific experiments.

[0034] Preparation Example

[0035] [Preparation Example 1-1]

[0036] A modified graphene oxide comprises the following raw materials:

[0037] Aminosilane coupling agent: 4.2 kg. In this embodiment, the aminosilane coupling agent is specifically aminosilane coupling agent KH550; Graphene oxide: 1 kg. In this embodiment, the graphene oxide is graphene oxide with a product number of xyh001 from Xinyuhong;

[0038] Water-soluble monoepoxy-terminated polyether: 9.4 kg. In this embodiment, the water-soluble monoepoxy-terminated polyether adopts Cologne's active allyl epoxy-terminated polyether KL-91B;

[0039] Water: 100kg.

[0040] In this preparation example, the preparation method of modified graphene oxide includes the following steps:

[0041] The aminosilane coupling agent was dissolved in water, and then graphene oxide was added, the temperature was raised to 40°C for reaction for 1 hour, and then a water-soluble monoepoxy-terminated polyether was added, and after stirring evenly, the temperature was raised to 100°C for reaction for 2 hours, followed by centrifugal separation and drying to obtain modified graphene oxide.

[0042] [Preparation Example 1-2]

[0043] A modified graphene oxide comprises the following raw materials:

[0044] Aminosilane coupling agent: 5.5 kg. In this embodiment, the aminosilane coupling agent is specifically aminosilane coupling agent KH550; Graphene oxide: 1.2 kg. In this embodiment, the graphene oxide is graphene oxide with the product number xyh001 of Xinyuhong; Water-soluble monoepoxy-terminated polyether: 10.6 kg. In this embodiment, the water-soluble monoepoxy-terminated polyether is Cologne's active allyl epoxy-terminated polyether KL-91B;

[0045] Water: 100kg.

[0046] In this preparation example, the preparation method of modified graphene oxide includes the following steps:

[0047] The aminosilane coupling agent was dissolved in water, and then graphene oxide was added, the temperature was raised to 45°C for reaction for 1 hour, and then a water-soluble monoepoxy-terminated polyether was added, and after stirring evenly, the temperature was raised to 105°C for reaction for 2 hours, followed by centrifugal separation and drying to obtain modified graphene oxide.

[0048] [Preparation Example 1-3]

[0049] A modified graphene oxide, which differs from [Preparation Example 1-1] in that 1 kg of p-vinylbenzoic acid and 0.1 kg of potassium persulfate are also added.

[0050] In this preparation example, the preparation method of modified graphene oxide includes the following steps:

[0051] The aminosilane coupling agent was dissolved in water, and then graphene oxide was added, the temperature was raised to 40°C for reaction for 1 hour, and then a water-soluble monoepoxy-terminated polyether was added, stirred evenly, and the temperature was raised to 100°C for reaction for 2 hours, followed by addition of p-vinylbenzoic acid and potassium persulfate, the temperature was raised to 75°C for reaction for 2 hours, and finally centrifuged and dried to obtain modified graphene oxide.

[0052] [Preparation Example 1-4]

[0053] A modified graphene oxide, which differs from [Preparation Example 1-3] in that p-vinylbenzoic acid is replaced by an equal amount of acrylic acid.

[0054] [Preparation Example 1-5]

[0055] A modified graphene oxide, which differs from [Preparation Example 1-1] in that an equal amount of aminosilane coupling agent is used instead of a water-soluble monoepoxy-terminated polyether.

[0056] [Preparation Example 1-6]

[0057] A modified graphene oxide, which differs from [Preparation Example 1-1] in that the aminosilane coupling agent is replaced by an equal amount of a water-soluble monoepoxy-terminated polyether.

[0058] [Preparation Example 2-1]

[0059] A modified PVA coating material comprises the following raw materials:

[0060] Water-soluble polyvinyl alcohol: 9.6 kg, specifically polyvinyl alcohol 200;

[0061] Modified graphene oxide: 1 kg, specifically modified graphene oxide prepared in [Preparation Example 1-1];

[0062] Diluent: 100 kg. In this preparation example, the diluent is specifically water.

[0063] The preparation method of the modified PVA coating material comprises the following steps:

[0064] Adding the modified graphene oxide to 20 kg of diluent, stirring at a stirring speed of 800 r / min for 1 h, to obtain a modified graphene oxide dispersion;

[0065] Add water-soluble polyvinyl alcohol to 80 kg of diluent, and stir at a stirring speed of 200 r / min for 30 min to obtain a polyvinyl alcohol dispersion;

[0066] The modified graphene oxide dispersion was mixed with the polyvinyl alcohol dispersion, and stirred at a stirring speed of 300 r / min for 30 min to obtain a modified PVA coating material.

[0067] [Preparation Example 2-2]

[0068] A modified PVA coating material comprises the following raw materials:

[0069] Water-soluble polyvinyl alcohol: 8.2 kg, specifically polyvinyl alcohol 200;

[0070] Modified graphene oxide: 1.5 kg, specifically modified graphene oxide prepared in [Preparation Example 1-2];

[0071] Diluent: 100 kg. In this preparation example, the diluent is specifically water.

[0072] The preparation method of the modified PVA coating material comprises the following steps:

[0073] Adding the modified graphene oxide to 20 kg of diluent, stirring at a stirring speed of 800 r / min for 1 h, to obtain a modified graphene oxide dispersion;

[0074] Add water-soluble polyvinyl alcohol to 80 kg of diluent, and stir at a stirring speed of 200 r / min for 30 min to obtain a polyvinyl alcohol dispersion;

[0075] The modified graphene oxide dispersion was mixed with the polyvinyl alcohol dispersion, and stirred at a stirring speed of 300 r / min for 30 min to obtain a modified PVA coating material.

[0076] [Preparation Example 2-3]

[0077] A modified PVA coating material, which is different from [Preparation Example 2-1] in that the modified graphene oxide adopts the modified graphene oxide prepared in [Preparation Example 1-3].

[0078] [Preparation Example 2-4]

[0079] A modified PVA coating material, which is different from [Preparation Example 2-1] in that the modified graphene oxide adopts the modified graphene oxide prepared in [Preparation Example 1-4].

[0080] [Preparation Example 2-5]

[0081] A modified PVA coating material, which is different from [Preparation Example 2-1] in that the modified graphene oxide adopts the modified graphene oxide prepared in [Preparation Example 1-5].

[0082] [Preparation Example 2-6]

[0083] A modified PVA coating material, which is different from [Preparation Example 2-1] in that the modified graphene oxide adopts the modified graphene oxide prepared in [Preparation Example 1-6].

[0084] Example

[0085] [Example 1]

[0086] A high barrier coating for food packaging, reference Figure 1 , comprising an MDOPE film 1, a modified PVA coating 2 and an aluminum oxide barrier layer 3 arranged in sequence.

[0087] In this embodiment, the method for preparing the high barrier coating includes the following steps:

[0088] S1. A layer of modified PVA coating material prepared in [Preparation Example 2-1] is uniformly coated on the surface of MDOPE film 1, and after drying, a modified PVA coating 2 is obtained; the thickness of the modified PVA coating 2 is controlled to be 2 μm;

[0089] S2, performing corona treatment on the surface of the modified PVA coating 2, the corona power is 1.4kw, and obtaining a corona surface;

[0090] S3. Vacuum evaporate an aluminum oxide barrier layer 3 on the corona surface of the modified PVA coating 2. During the evaporation, the wire feeding speed of the aluminum wire is controlled to be 280 mm / min, the oxygen delivery speed is controlled to be 7500 sccm, and the thickness of the aluminum oxide barrier layer 3 is controlled to be 100A to obtain a high barrier coating.

[0091] [Example 2]

[0092] A high barrier coating for food packaging, which differs from [Example 1] in that: in step S1, a modified PVA coating material obtained in [Preparation Example 2-2] is applied.

[0093] [Example 3]

[0094] A high barrier coating for food packaging, which differs from [Example 1] in that: in step S1, a modified PVA coating material obtained in [Preparation Example 2-3] is applied.

[0095] [Example 4]

[0096] A high barrier coating for food packaging, which differs from [Example 1] in that: in step S1, a modified PVA coating material obtained in [Preparation Example 2-4] is applied.

[0097] Comparative Example

[0098] [Comparative Example 1]

[0099] A coating, which differs from [Example 1] in that step S2 is omitted.

[0100] [Comparative Example 2]

[0101] A coating, which differs from [Example 3] in that step S2 is omitted.

[0102] [Comparative Example 3]

[0103] A coating, which differs from [Example 1] in that: in step S1, the modified PVA coating material obtained in [Preparation Example 2-5] is applied.

[0104] [Comparative Example 4]

[0105] A coating, which differs from [Example 1] in that: in step S1, the modified PVA coating material obtained in [Preparation Example 2-6] is applied.

[0106] Performance testing

[0107] 1. Oxygen permeability test: The oxygen permeability of the coatings in each embodiment and comparative example was tested according to ASTM D 3985, wherein the smaller the oxygen permeability, the better the oxygen barrier performance. The oxidation permeability of this application is ≤0.5cc / ㎡.day to meet the requirements.

[0108] 2. Water vapor transmission rate test: The water vapor transmission rate of the coatings in each embodiment and comparative example was tested according to ASTM F 1249, wherein the smaller the water vapor transmission rate, the better the water vapor barrier performance. The water vapor transmission rate of this application is ≤0.5g / ㎡.day to meet the requirements.

[0109] 3. The coated films in the embodiments and comparative examples were heat-sealed into small bags of 200 mm × 120 mm, filled with water to two-thirds of the bag volume, vented and sealed, and placed in an autoclave and boiled for 15 minutes. The temperatures of the autoclave were 121°C and 135°C, respectively. After 15 minutes, the bags were cooled to room temperature and taken out to check whether there was obvious deformation or abnormal delamination between the layers.

[0110] Table 1

[0111]

[0112] The difference between Comparative Example 1 and Example 1 is that the step of corona treatment of the modified PVA coating is omitted in Comparative Example 1. Combined with the test results in Table 1, it can be seen that the barrier performance of the coating film in Comparative Example 1 for oxygen and water vapor is significantly reduced. It can be seen that corona treatment of the modified PVA coating can effectively improve the barrier performance of the coating film.

[0113] The difference between Comparative Example 2 and Example 3 is that the step of corona treatment of the modified PVA coating is omitted in Comparative Example 2. Combined with the test results in Table 1, it can be seen that the barrier performance of the coating film in Comparative Example 2 for oxygen and water vapor is reduced, and the coating film is easily delaminated after high-temperature cooking. It can be seen that corona treatment of the modified PVA coating can not only improve the barrier performance of the coating film, but also help improve the cooking resistance of the modified PVA coating in Example 3.

[0114] The difference between Comparative Examples 3-4 and Example 3 is that the modified graphene oxide in Comparative Example 3 is a modified graphene oxide obtained by modifying graphene oxide with an aminosilane coupling agent alone, and the modified graphene oxide in Comparative Example 4 is a modified graphene oxide obtained by modifying graphene oxide with a water-soluble monoepoxy-terminated polyether alone. Combined with the test results in Table 1, it can be seen that the barrier properties of the coatings in Comparative Examples 3 and 4 are reduced in terms of oxygen and water vapor, among which the barrier properties of the coating in Comparative Example 4 are more significantly reduced. It can be seen that the modified graphene oxide in the modified PVA coating, which is obtained by modifying graphene oxide with an aminosilane coupling agent and a water-soluble monoepoxy-terminated polyether, is more conducive to improving the barrier properties of the modified PVA coating.

[0115] The difference between Example 3 and Example 1 is that p-vinylbenzoic acid is also added to the modified graphene oxide in Example 3. Combined with the test results in Table 1, it can be seen that the barrier performance of the coating in Example 3 against oxygen and water vapor is further improved, and the coating in Example 3 is not easy to delaminate after high-temperature cooking. It can be seen that the modified graphene oxide in the modified PVA coating is obtained by modifying the graphene oxide with aminosilane coupling agent, water-soluble monoepoxy-terminated polyether containing unsaturated double bonds, and alkenylbenzoic acid, which can improve the barrier performance of the coating while improving the high-temperature cooking resistance of the coating.

[0116] The difference between Example 4 and Example 3 is that the modified graphene oxide in Example 4 is obtained by modifying graphene oxide with aminosilane coupling agent, water-soluble monoepoxy-terminated polyether containing unsaturated double bonds and acrylic acid. Combined with the test results in Table 1, it can be seen that after using acrylic acid instead of p-vinylbenzoic acid, the coating is prone to stratification after high-temperature cooking. It can be seen that the modified graphene oxide in the modified coating is preferably the modified graphene oxide obtained by modifying graphene oxide with aminosilane coupling agent, water-soluble monoepoxy-terminated polyether containing unsaturated double bonds and alkenylbenzoic acid, which can improve the barrier performance of the coating while improving the high-temperature cooking resistance of the coating.

[0117] This specific implementation manner is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the specific implementation manner as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A high barrier coating for food packaging, characterized in that: The invention comprises an MDOPE film (1), a modified PVA coating (2) and an aluminum oxide barrier layer (3) which are arranged in sequence. Before depositing the aluminum oxide barrier layer (3) on the surface of the modified PVA coating (2), the modified PVA coating (2) is first subjected to a corona or plasma treatment. The raw materials for preparing the modified PVA coating (2) comprise water-soluble polyvinyl alcohol, modified graphene oxide and a diluent. The weight ratio of the water-soluble polyvinyl alcohol, modified graphene oxide and the diluent is (8.2-9.6):(1-1.5):

100. The modified graphene oxide is first modified by an aminosilane coupling agent, and then the aminosilane coupling agent is grafted onto the graphene oxide. Then, the amino group of the aminosilane coupling agent on the graphene oxide reacts with the epoxy group on the monoepoxy-terminated polyether containing an unsaturated double bond, and then a polyether segment and an unsaturated double bond are introduced into the graphene oxide. Finally, the graphene oxide is obtained by copolymerizing alkenyl benzoic acid with the unsaturated double bond grafted onto the graphene oxide.

2. The high barrier coating film for food packaging according to claim 1, characterized in that: The preparation method of the modified graphene oxide comprises the following steps: The aminosilane coupling agent is dissolved in water, and then graphene oxide is added, the temperature is raised to 40-45°C for reaction, and then a water-soluble monoepoxy-terminated polyether is added, stirred evenly, and the temperature is raised to 100-105°C for reaction, followed by adding alkenyl benzoic acid and persulfate, and the temperature is raised to 70-80°C for reaction, and finally centrifuged and dried to obtain modified graphene oxide.

3. The high barrier coating film for food packaging according to claim 2, characterized in that: The weight ratio of the aminosilane coupling agent, water, graphene oxide, water-soluble monoepoxy-terminated polyether, alkenyl benzoic acid and persulfate is (4.2-5.5):100:(1-1.2):(9.4-10.6):(1-1.2):(0.1-0.2).

4. A high barrier coating film for food packaging according to any one of claims 1 to 3, characterized in that: The water-soluble polyvinyl alcohol is polyvinyl alcohol 200 or polyvinyl alcohol 400, and the diluent is water.

5. A method for preparing a high barrier coating for food packaging, based on the high barrier coating for food packaging according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, uniformly coating a layer of modified PVA coating (2) on the surface of the MDOPE film (1); S2, performing corona treatment or plasma treatment on the surface of the modified PVA coating (2) to obtain a corona surface or a plasma surface; S3, vacuum evaporating an aluminum oxide barrier layer (3) on the corona surface or plasma surface of the modified PVA coating (2).

6. The method for preparing a high barrier coating film for food packaging according to claim 5, characterized in that: In step S2, the power of the corona treatment is 1.2-1.6 kw, and the power of the plasma treatment is 0.8-1.2 kw.

7. The method for preparing a high barrier coating film for food packaging according to claim 5, characterized in that: In step S3, the wire feeding speed of the aluminum wire is 270-290 mm / min, and the oxygen delivery speed is 6900-8000 sccm.

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