Single material high barrier liquid retort pouch

Abstract

The present application belongs to the technical field of polymer materials, and particularly relates to a single-material high-barrier liquid cooking packaging bag. In view of the problem that the high-temperature-resistant cooking packaging in the prior art is usually composed of multiple substrates and is inconvenient to classify and recycle, the present application provides a single-material high-barrier liquid cooking packaging bag made of a high-barrier film. The high-barrier film comprises, from outside to inside, an outer layer, a high-barrier functional layer, a bonding layer, a structure reinforcing layer and an inner layer. The outer layer, the high-barrier functional layer, the bonding layer, the structure reinforcing layer and the inner layer all contain polypropylene material. The present application provides a high-barrier film with a five-layer structure comprising, from outside to inside, an outer layer, a high-barrier functional layer, a bonding layer, a structure reinforcing layer and an inner layer. The main component of each layer is polypropylene, so that high barrier is achieved while facilitating the subsequent classification and recycling steps.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, and in particular relates to a single-material high-barrier liquid retort packaging bag. Background Technology

[0002] High-temperature retort packaging is a common packaging method for foods such as meat and soy products. It typically uses vacuum packaging and undergoes high-temperature sterilization, allowing for storage at room temperature. Foods packaged in retort packaging are convenient to carry, ready to eat after opening, hygienic, and retain their flavor well, making them popular with consumers. However, current high-temperature retort packaging technologies are usually composed of multiple composite materials. After use, these bags made of various materials are difficult to sort and recycle, easily leading to resource waste and environmental pollution.

[0003] To address this issue, people have conducted exploratory research in long-term production and daily life practices. For example, a Chinese invention patent application [Application No.: 202510580158.9] discloses a high-barrier, high-temperature resistant retort packaging film based on a single recyclable PP material. The product structure of this invention patent application consists of the following layers arranged sequentially: PP layer / PP-g-MAH layer / functional layer / PP-g-MAH layer / MPP layer; PP layer: the raw material formula is 100wt% polypropylene resin, and the dosage is 20-35 parts by weight; PP-g-MAH layer: the raw material formula is 100wt%... Maleic anhydride grafted polypropylene resin, with a dosage of 3-10 parts by weight; MPP layer: raw material formulation of 100wt% metallocene polypropylene resin, with a dosage of 20-35 parts by weight; functional layer: raw material formulation of 100wt% high-barrier polypropylene-based composite material with high temperature resistance and puncture resistance, with a dosage of 20-35 parts by weight; the high-barrier polypropylene-based composite material with high temperature resistance and puncture resistance is obtained by first compounding alkenylated phenyl double-cage cage-type polysilsesquioxane with graphene oxide through π-π stacking and hydrogen bonding, and then loading it onto polypropylene resin through free radical coupling reaction and molecular chain intercalation.

[0004] Although this patent application provides a high-barrier, high-temperature retort packaging film made of a single polypropylene material, its barrier ability is still relatively limited and needs further improvement. Summary of the Invention

[0005] The purpose of this invention is to address the above-mentioned problems by providing a single-material high-barrier liquid retort packaging bag.

[0006] To achieve the above objectives, the present invention adopts the following technical solutions: A single-material high-barrier liquid retort packaging bag, the packaging bag being made of a high-barrier film, the high-barrier film comprising, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer, wherein the outer layer, the high-barrier functional layer, the adhesive layer, the structural reinforcement layer, and the inner layer all contain polypropylene material.

[0007] In the above-mentioned single-material high-barrier liquid retort packaging bag, the outer layer is made of biaxially oriented polypropylene material with a thickness of 20-30 μm.

[0008] In the above-mentioned single-material high-barrier liquid retort packaging bag, the high-barrier functional layer comprises 60-90 parts by weight of isotactic polypropylene, 0.05-0.2 parts by weight of modified graphene nanosheets, 2-20 parts by weight of polyethylene terephthalate, and 1-10 parts by weight of maleic anhydride-grafted polypropylene.

[0009] In the aforementioned single-material high-barrier liquid retort packaging bag, the modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion. Then, perform ultrasonic treatment for 30-60 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotary cold plasma reactor, evacuate and dry at 80-100℃ for 30-60 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 5-10 min. During the activation process, the pressure is maintained at 20-50 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor. Perform plasma modification for 45-90 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

[0010] In the above-mentioned single-material high-barrier liquid retort packaging bag, the volume ratio of propylene monomer to ethylene monomer is 9-3:1.

[0011] In the above-mentioned single-material high-barrier liquid retort packaging bag, the thickness of the high-barrier functional layer is 10-20μm.

[0012] In the above-mentioned single-material high-barrier liquid retort packaging bag, the adhesive layer is maleic anhydride-grafted polypropylene, and the thickness of the adhesive layer is 5-8 μm.

[0013] In the above-mentioned single-material high-barrier liquid retort packaging bag, the grafting rate of the maleic anhydride-grafted polypropylene is 0.9%-1.1%.

[0014] In the above-mentioned single-material high-barrier liquid retort packaging bag, the structural reinforcement layer comprises 80-100 parts by weight of block copolymer polypropylene and 13-17 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 20-30 μm.

[0015] In the aforementioned single-material high-barrier liquid retort packaging bag, the inner layer comprises 90-100 parts by weight of ternary random copolymer polypropylene, 4-6 parts by weight of hydrogenated styrene-butadiene block copolymer, 0.8-1.2 parts by weight of erucamide, 0.1-0.3 parts by weight of calcium stearate, and 0.8-1.2 parts by weight of nano-silica, and the thickness of the inner layer is 20-50 μm.

[0016] Compared with existing technologies, the advantages of this invention are: 1. This invention provides a high-barrier membrane with a five-layer structure comprising an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer, from the outside to the inside. The main component of each layer is polypropylene, thus achieving high barrier properties while facilitating subsequent sorting and recycling steps.

[0017] 2. The present invention modifies graphene nanosheets with plasma, which can form an interface layer on the surface of graphene nanosheets, improve the compatibility between graphene nanosheets and polypropylene materials, and enable them to have a better dispersion state in the high barrier functional layer, effectively forming a "maze" structure in the high barrier functional layer, thereby improving the barrier properties.

[0018] 3. This invention uses a specific ratio of propylene monomer and ethylene monomer to plasma modify graphene nanosheets. Introducing a small amount of ethylene monomer can make the formed interface layer have better flexibility while ensuring compatibility with polypropylene materials, better buffering stress, and reducing the possibility of brittle fracture of graphene nanosheets during processing. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to specific embodiments.

[0020] Example 1

[0021] This embodiment provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0022] The outer layer is made of biaxially oriented polypropylene and has a thickness of 20 μm.

[0023] The high-barrier functional layer comprises 60 parts by weight of isotactic polypropylene, 0.2 parts by weight of modified graphene nanosheets, 20 parts by weight of polyethylene terephthalate, and 10 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 0.9%. The thickness of the high-barrier functional layer is 10 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion. Then, perform ultrasonic treatment for 30 minutes. After solid-liquid separation, the pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 80°C for 30 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 5 min. During the activation process, the pressure is maintained at 20 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor at a volume ratio of 3:1. Perform plasma modification for 90 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

[0024] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 5 μm and a grafting rate of 0.9%.

[0025] The structural reinforcement layer comprises 80 parts by weight of block copolymer polypropylene and 17 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 20 μm.

[0026] The inner layer comprises 90 parts by weight of ternary random copolymer polypropylene, 6 parts of hydrogenated styrene-butadiene block copolymer, 1.2 parts of erucamide, 0.3 parts of calcium stearate, and 1.2 parts of nano-silica, with a thickness of 20 μm.

[0027] Example 2

[0028] This embodiment provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0029] The outer layer is made of biaxially oriented polypropylene and has a thickness of 30 μm.

[0030] The high-barrier functional layer comprises 90 parts by weight of isotactic polypropylene, 0.05 parts by weight of modified graphene nanosheets, 2 parts by weight of polyethylene terephthalate, and 1 part by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.1%. The thickness of the high-barrier functional layer is 20 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion. Then, perform ultrasonic treatment for 60 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 100°C for 60 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 10 min. During the activation process, the pressure is maintained at 50 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor at a volume ratio of 9:1. Perform plasma modification for 90 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

[0031] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 8 μm and a grafting rate of 1.1%.

[0032] The structural reinforcement layer comprises 100 parts by weight of block copolymer polypropylene and 13 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 30 μm.

[0033] The inner layer comprises 100 parts by weight of ternary random copolymer polypropylene, 4 parts of hydrogenated styrene-butadiene block copolymer, 0.8 parts of erucamide, 0.1 parts of calcium stearate, and 0.8 parts of nano-silica, with a thickness of 50 μm.

[0034] Example 3

[0035] This embodiment provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0036] The outer layer is made of biaxially oriented polypropylene and has a thickness of 24 μm.

[0037] The high-barrier functional layer comprises 75 parts by weight of isotactic polypropylene, 0.1 parts by weight of modified graphene nanosheets, 10 parts by weight of polyethylene terephthalate, and 5 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.0%. The thickness of the high-barrier functional layer is 12 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion, then perform ultrasonic treatment for 45 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 90°C for 40 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 8 min. During the activation process, the pressure is maintained at 30 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor at a volume ratio of 7:1. Perform plasma modification for 60 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

[0038] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 6 μm and a grafting rate of 1.0%.

[0039] The structural reinforcement layer comprises 90 parts by weight of block copolymer polypropylene and 14 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 23 μm.

[0040] The inner layer comprises 95 parts by weight of ternary random copolymer polypropylene, 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 1.0 part by weight of erucamide, 0.2 parts by weight of calcium stearate, and 1.0 part by weight of nano-silica, and the thickness of the inner layer is 25 μm.

[0041] Comparative Example 1 This comparative example provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0042] The outer layer is made of biaxially oriented polypropylene and has a thickness of 24 μm.

[0043] The high-barrier functional layer comprises 75 parts by weight of isotactic polypropylene, 0.1 parts by weight of graphene nanosheets, 10 parts by weight of polyethylene terephthalate, and 5 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.0%. The thickness of the high-barrier functional layer is 12 μm.

[0044] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 6 μm and a grafting rate of 1.0%.

[0045] The structural reinforcement layer comprises 90 parts by weight of block copolymer polypropylene and 14 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 23 μm.

[0046] The inner layer comprises 95 parts by weight of ternary random copolymer polypropylene, 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 1.0 part by weight of erucamide, 0.2 parts by weight of calcium stearate, and 1.0 part by weight of nano-silica, and the thickness of the inner layer is 25 μm.

[0047] Comparative Example 2 This comparative example provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0048] The outer layer is made of biaxially oriented polypropylene and has a thickness of 24 μm.

[0049] The high-barrier functional layer comprises 75 parts by weight of isotactic polypropylene, 0.1 parts by weight of modified graphene nanosheets, 10 parts by weight of polyethylene terephthalate, and 5 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.0%. The thickness of the high-barrier functional layer is 12 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion, then perform ultrasonic treatment for 45 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 90°C for 40 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 8 min. During the activation process, the pressure is maintained at 30 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer into the reactor for plasma modification for 60 min. During the modification process, the pressure is maintained at 20 Pa to obtain modified graphene nanosheets.

[0050] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 6 μm and a grafting rate of 1.0%.

[0051] The structural reinforcement layer comprises 90 parts by weight of block copolymer polypropylene and 14 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 23 μm.

[0052] The inner layer comprises 95 parts by weight of ternary random copolymer polypropylene, 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 1.0 part by weight of erucamide, 0.2 parts by weight of calcium stearate, and 1.0 part by weight of nano-silica, and the thickness of the inner layer is 25 μm.

[0053] Comparative Example 3 This comparative example provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0054] The outer layer is made of biaxially oriented polypropylene and has a thickness of 24 μm.

[0055] The high-barrier functional layer comprises 75 parts by weight of isotactic polypropylene, 0.1 parts by weight of modified graphene nanosheets, 10 parts by weight of polyethylene terephthalate, and 5 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.0%. The thickness of the high-barrier functional layer is 12 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion, then perform ultrasonic treatment for 45 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 90°C for 40 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 8 min. During the activation process, the pressure is maintained at 30 Pa. After activation, close the argon gas inlet valve and introduce ethylene monomer into the reactor. Perform plasma modification for 60 min, maintaining the pressure at 20 Pa during the modification process to obtain modified graphene nanosheets.

[0056] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 6 μm and a grafting rate of 1.0%.

[0057] The structural reinforcement layer comprises 90 parts by weight of block copolymer polypropylene and 14 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 23 μm.

[0058] The inner layer comprises 95 parts by weight of ternary random copolymer polypropylene, 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 1.0 part by weight of erucamide, 0.2 parts by weight of calcium stearate, and 1.0 part by weight of nano-silica, and the thickness of the inner layer is 25 μm.

[0059] Comparative Example 4 This comparative example provides a single-material high-barrier liquid retort packaging bag, which is made of a high-barrier film. The high-barrier film includes, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer.

[0060] The outer layer is made of biaxially oriented polypropylene and has a thickness of 24 μm.

[0061] The high-barrier functional layer comprises 75 parts by weight of isotactic polypropylene, 0.1 parts by weight of modified graphene nanosheets, 10 parts by weight of polyethylene terephthalate, and 5 parts by weight of maleic anhydride-grafted polypropylene. The grafting rate of the maleic anhydride-grafted polypropylene is 1.0%. The thickness of the high-barrier functional layer is 12 μm. The modified graphene nanosheets are prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion, then perform ultrasonic treatment for 45 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotating cold plasma reactor, evacuate and dry at 90°C for 40 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 8 min. During the activation process, the pressure is maintained at 30 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor at a volume ratio of 1:1. Perform plasma modification for 60 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

[0062] The adhesive layer is maleic anhydride-grafted polypropylene with a thickness of 6 μm and a grafting rate of 1.0%.

[0063] The structural reinforcement layer comprises 90 parts by weight of block copolymer polypropylene and 14 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 23 μm.

[0064] The inner layer comprises 95 parts by weight of ternary random copolymer polypropylene, 5 parts by weight of hydrogenated styrene-butadiene block copolymer, 1.0 part by weight of erucamide, 0.2 parts by weight of calcium stearate, and 1.0 part by weight of nano-silica, and the thickness of the inner layer is 25 μm.

[0065] Application Example 1 Using the high-barrier membrane components and structures described in Examples 3 and Comparative Examples 1-4, high-barrier membranes 1-5 were prepared through the same co-extrusion process. The oxygen permeation of high-barrier membranes 1-5 was measured using the measurement method described in GB / T 1038.1-2022 "Test Methods for Gas Permeability of Plastic Films and Sheets Part 1: Differential Pressure Method". The water vapor permeation of high-barrier membranes 1-5 was measured using the measurement method described in GB / T 1037-2021 "Determination of Water Vapor Permeability of Plastic Films and Sheets - Cup Weight Gain and Loss Method". The results are shown in the table below:

[0066] Results Analysis: The results above show that the high-barrier membrane 1 provided by the present invention has lower oxygen permeability and water vapor permeability than high-barrier membranes 2-5, that is, it has better barrier properties and achieves the expected purpose of the present invention.

[0067] The specific embodiments described herein are merely illustrative of the spirit of the invention. Those skilled in the art to which this invention pertains may make various modifications or additions to the described specific embodiments or use similar methods to substitute them, without departing from the spirit of the invention or exceeding the scope defined by the appended claims.

Claims

1. A single-material high-barrier liquid retort packaging bag, wherein the packaging bag is made of a high-barrier film, characterized in that: The high-barrier membrane comprises, from the outside to the inside, an outer layer, a high-barrier functional layer, an adhesive layer, a structural reinforcement layer, and an inner layer, all of which contain polypropylene material.

2. The single-material high-barrier liquid retort packaging bag as described in claim 1, characterized in that: The outer layer is made of biaxially oriented polypropylene material and has a thickness of 20-30 μm.

3. The single-material high-barrier liquid retort packaging bag as described in claim 1, characterized in that: The high-barrier functional layer comprises 60-90 parts by weight of isotactic polypropylene, 0.05-0.2 parts by weight of modified graphene nanosheets, 2-20 parts by weight of polyethylene terephthalate, and 1-10 parts by weight of maleic anhydride-grafted polypropylene.

4. The single-material high-barrier liquid retort packaging bag as described in claim 3, characterized in that: The modified graphene nanosheets were prepared by the following method: Step 1: Place the graphene nanosheets in a container and add more than 10 times the volume of anhydrous ethanol for dispersion. Then, perform ultrasonic treatment for 30-60 minutes. After solid-liquid separation, pretreated graphene nanosheets are obtained. Step 2: Transfer the pretreated graphene nanoparticles obtained in Step 1 to a rotary cold plasma reactor, evacuate and dry at 80-100℃ for 30-60 min, then introduce argon gas and start the radio frequency power supply for plasma activation for 5-10 min. During the activation process, the pressure is maintained at 20-50 Pa. After activation, close the argon gas inlet valve and introduce propylene monomer and ethylene monomer into the reactor. Perform plasma modification for 45-90 min, maintaining the pressure at 20 Pa during the modification process, to obtain modified graphene nanosheets.

5. The single-material high-barrier liquid retort packaging bag as described in claim 4, characterized in that: The volume ratio of propylene monomer to ethylene monomer is 9-3:

1.

6. The single-material high-barrier liquid retort packaging bag as described in claim 3, characterized in that: The thickness of the high-barrier functional layer is 10-20 μm.

7. The single-material high-barrier liquid retort packaging bag as described in claim 1, characterized in that: The adhesive layer is maleic anhydride-grafted polypropylene, and the thickness of the adhesive layer is 5-8 μm.

8. A single-material high-barrier liquid retort pouch as described in claim 3 or 7, characterized in that: The grafting rate of the maleic anhydride-grafted polypropylene is 0.9%-1.1%.

9. The single-material high-barrier liquid retort packaging bag as described in claim 1, characterized in that: The structural reinforcement layer comprises 80-100 parts by weight of block copolymer polypropylene and 13-17 parts by weight of hydrogenated styrene-butadiene block copolymer, and the thickness of the structural reinforcement layer is 20-30 μm.

10. The single-material high-barrier liquid retort packaging bag as described in claim 1, characterized in that: The inner layer comprises 90-100 parts by weight of ternary random copolymer polypropylene, 4-6 parts by weight of hydrogenated styrene-butadiene block copolymer, 0.8-1.2 parts by weight of erucamide, 0.1-0.3 parts by weight of calcium stearate, and 0.8-1.2 parts by weight of nano-silica, and the thickness of the inner layer is 20-50 μm.

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