A biodegradable, high-strength, high-barrier membrane

Abstract

This invention relates to a biodegradable, high-strength, high-barrier membrane, which is composed of a double-layer composite, comprising a bottom layer of P3H4B-PBAT membrane and an upper layer of hydrophobic modified cellulose membrane. The upper surface of the bottom P3H4B-PBAT membrane is plasma-treated and then coated with a silica membrane layer by vacuum sputtering. The lower surface of the hydrophobic modified cellulose membrane layer is silanized. The surface-modified P3H4B-PBAT membrane and the hydrophobic modified cellulose membrane layer are then composited by hot pressing. The composite membrane exhibits excellent mechanical properties and good oxygen and carbon dioxide barrier properties, and can be applied to packaging for food, pharmaceuticals, and other products.

Description

Technical Field

[0001] This invention relates to a method for preparing a membrane, and more particularly to a biodegradable membrane material with high strength, toughness, and high gas barrier properties. Background Technology

[0002] In packaging, especially in the field of packaging films, plastic materials are still widely used. PE, PP, and PET films remain the mainstream packaging films. These petroleum-based plastics have excellent processability and good mechanical properties; some materials, such as PET, also possess superior barrier properties. Despite their superior performance, their non-degradable nature has brought a series of environmental problems. Finding packaging materials that also possess excellent properties and are fully biodegradable remains a focus of research.

[0003] In the food and pharmaceutical packaging industry, the requirements for membrane materials are very high. While ensuring mechanical properties, they also need to possess special functionalities. For example, to preserve quality, the membrane needs good oxygen barrier properties, and for packaging that directly contacts food, it is best to also have a certain degree of antibacterial properties. However, achieving all these characteristics while ensuring biodegradability is very difficult. For instance, membrane materials made directly from biodegradable materials often cannot achieve good barrier properties due to their structural characteristics. For example, polylactic acid (PLA) membranes, PLA / PBAT membranes, and PVA membranes, due to their inherent structural limitations, cannot achieve the required oxygen permeability and carbon dioxide barrier properties. While much research has focused on the barrier properties of biodegradable membrane materials—such as increasing the crystallinity of polylactic acid (PLA) by adding nucleating agents to improve its gas barrier properties; extending the gas passage path by incorporating nanoparticles like nano-montmorillonite into PLA and polycaprolactone; and adding barrier-resistant resins like EVOH to biopolyesters—these approaches have proven challenging. Adding nanoparticles alone cannot achieve truly high gas barrier properties, while adding high-barrier polymers contradicts the fundamental goal of full biodegradability. Clearly, only the development of truly fully biodegradable materials that simultaneously meet the requirements of both strength and barrier properties has real practical significance and industrial potential.

[0004] To address the above issues, this patent aims to develop a fully degradable membrane material with good gas barrier properties. By using a special multilayer composite method to coordinate the functions of different functional layers, the overall performance can be balanced. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of biodegradable materials in terms of barrier properties and poor mechanical properties, and to develop membrane materials with good mechanical properties and gas barrier properties.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A biodegradable, high-strength, high-barrier membrane is composed of a double-layer membrane, comprising a bottom layer of P3H4B (polyhydroxyalkanoate)-PBAT (butylene adipate-butylene terephthalate copolymer) membrane and an upper layer of hydrophobically modified cellulose membrane. The bottom P3H4B-PBAT membrane is formed by melt extrusion casting, while the upper hydrophobically modified cellulose membrane is formed by solution casting. The upper surface of the P3H4B-PBAT membrane is covered with a silica layer by vacuum sputtering, and the lower surface of the hydrophobically modified cellulose membrane is silanized. The treated double-layer membrane is then composited by hot pressing.

[0008] Furthermore, the thickness of the P3H4B-PBAT membrane is between 0.15-0.35 mm, the thickness of the silicon oxide layer is between 0.05-0.08 mm, and the thickness of the hydrophobic modified cellulose membrane layer is between 0.08-0.16 mm.

[0009] Furthermore, the P3H4B-PBAT membrane is formed by melt extrusion of P3H4B and PBAT as the main raw materials, with the addition of biomass compatibilizer, biomass plasticizer, and antioxidant; wherein the mass ratio of P3H4B (poly(3-hydroxybutyric acid-co-4-hydroxybutyrate)) to PBAT is between 80:20 and 50:50; the amount of biomass compatibilizer and biomass plasticizer is between 2% and 4% of the main material mass, and the amount of antioxidant is between 0.5% and 1.2% of the main material mass.

[0010] Furthermore, the molecular structural formula of P34HB is as follows: ;

[0011] Where n = 100-150, m = 200-280.

[0012] Furthermore, the molecular weight of the PBAT is between 20,000 and 60,000.

[0013] Furthermore, the biomass compatibilizer is a biopolyester graft, including one of polylactic acid grafted with maleic anhydride, polycaprolactone grafted with maleic anhydride, and polylactic acid grafted with β-hydroxyethyl acrylate; the molecular weight of the biopolyester used is between 20,000 and 50,000, preferably between 20,000 and 35,000.

[0014] Furthermore, the biomass plasticizer is tributyl citrate, triethyl citrate, epoxidized soybean oil bioplasticizer, and commercial SOY-CIZER. TM BP series of bio-based plasticizers.

[0015] Furthermore, the process conditions for melt extrusion film formation are as follows: the main material and auxiliary material are mixed evenly in a high-speed mixer, and then fed into a twin-screw extruder for casting, and the mixture is heated at 180-220°C.o Melt extrusion casting under C conditions.

[0016] Furthermore, the hydrophobically modified cellulose membrane is made primarily of long-chain hydrophobically modified hydroxyethyl cellulose, with the addition of defoamers, leveling agents, plasticizers, and other additives, dissolved in a solvent and then cast into a film.

[0017] Furthermore, the solvent used needs to be selected based on the modification and solubility of the raw materials.

[0018] Furthermore, the long-chain hydrophobic modified hydroxyethyl cellulose is obtained by using hydroxyethyl cellulose as a starting material and haloalkanes as modifiers, through the etherification and substitution of hydroxyl groups to obtain modified hydroxyethyl cellulose with a long-chain structure. The length and content of the hydrophobic chain can be controlled by changing the type of haloalkanes, such as bromododecane and bromooctadecane, and the amount used.

[0019] Furthermore, the long-chain hydrophobically modified hydroxyethyl cellulose contains a long-chain component, the mass of which is calculated based on the mass of hydroxyethyl cellulose, and is between 10-20%.

[0020] Furthermore, the plasticizer of the hydrophobically modified cellulose membrane is preferably an epoxy fatty acid ester or an epoxy soybean oil.

[0021] Furthermore, the silanization modification process of the lower surface of the hydrophobic modified cellulose membrane is as follows: a silane coupling agent is dissolved in ethanol to form a solution with a mass fraction of 3-6%, the solution is uniformly sprayed onto the membrane surface, and the modified membrane is obtained after drying; the silane coupling agent can be one of KH540, KH550, KH560, KH792, Si-563, and A-171 coupling agents, which can effectively ensure the bonding between the hydrophobic modified cellulose membrane and the silicon oxide membrane.

[0022] Furthermore, the basic mechanical properties of the P3H4B-PBAT membrane are as follows: tensile strength and elongation at break are between 30.6-52.4 MPa and 89.2-152.6%, respectively, and tear strength is between 126.2 N and 198.4 N; the basic mechanical properties of the hydrophobically modified cellulose membrane are as follows: tensile strength and elongation at break are between 22.5-38.2 MPa and 58.5-124.3%, respectively, and tear strength is between 54.5 N and 92.1 N.

[0023] Furthermore, the composite of the P3H4B-PBAT membrane layer and the hydrophobically modified cellulose membrane layer is achieved by setting one or more temperature groups to 60-85°C. o The two rollers between C are hot-pressed for 1-2 minutes at a pressure between 0.5-2 MPa to achieve a tight bond between the two layers.

[0024] Furthermore, the beneficial effects of the present invention are as follows: it adopts a fully degradable double-layer structure, wherein the bottom P3H4B-PBAT membrane ensures good basic mechanical strength and tensile properties, the attached silica layer provides sufficient gas barrier properties, and the outer hydrophobic modified cellulose membrane layer not only plays a role in further synergistically enhancing tensile, tear and other mechanical properties, but also helps to improve gas barrier properties and provide surface hydrophobicity. The special treatment between the two layers will also greatly enhance the bonding between the modified cellulose membrane layer and the silica membrane layer, thereby synergistically improving performance.

[0025] Furthermore, the membrane of the present invention is tested in the following manner:

[0026] The tensile strength and elongation at break of the membrane were tested according to GB / T 1040.3-2006 standard;

[0027] The tear strength of the membrane was tested according to GB / T 16578.3-2008 standard;

[0028] The impact strength of the membrane was tested according to GB / T 9639.1-2008 standard;

[0029] The puncture resistance of the membrane was tested according to GB / T 37841-2019 standard;

[0030] The oxygen barrier properties of the membrane were tested according to GB / T 18454-2019 standard;

[0031] The carbon dioxide barrier properties of the membrane were tested according to GB / T 1038.1-2022 standard. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the multilayer structure of the membrane prepared in Example 1. Detailed Implementation

[0033] Exemplary embodiments of the present invention will be described in detail below. However, these embodiments are for illustrative purposes only, and the present invention is not limited thereto.

[0034] Example 1

[0035] like Figure 1 As shown, a biodegradable, high-strength, high-barrier membrane is composed of a double-layer membrane, including a bottom P3H4B-PBAT membrane layer 1-1 and an outer hydrophobic modified cellulose membrane layer 2-1. The upper surface of the bottom P3H4B-PBAT membrane layer 1-1 is plasma-treated and then covered with a silicon oxide layer 1-2 by vacuum sputtering. The lower surface of the hydrophobic modified cellulose membrane layer 2-1 is silanized and covered with a silane-modified layer 2-2. The composite between the two layers is then achieved by hot pressing.

[0036] The thickness of the P3H4B-PBAT membrane is 0.26 mm, the thickness of the silica layer is 0.06 mm, and the thickness of the hydrophobically modified cellulose membrane is 0.1 mm.

[0037] The P3H4B-PBAT membrane is formed by melt extrusion of P3H4B and PBAT as the main raw materials, with the addition of polylactic acid grafted maleic anhydride, tributyl citrate, and antioxidant 1020. The mass ratio of P3H4B to PBAT is 70:30. The amounts of polylactic acid grafted maleic anhydride and tributyl citrate are 3.5% and 2.5% of the main material mass, respectively, and the amount of antioxidant 1020 is 0.7% of the main material mass.

[0038] The molecular structure of P34HB is as follows:

[0039] ;

[0040] Where n=120, m=250.

[0041] The molecular weight of the PBAT is 35,000.

[0042] The molecular weight of the polylactic acid grafted with maleic anhydride is 32,000.

[0043] The melt extrusion film forming process conditions are as follows: the main material and auxiliary material are mixed evenly in a high-speed mixer, and then fed into a twin-screw extruder for casting, at 190-220 °C. o Melt extrusion casting film under C conditions.

[0044] The hydrophobic modified cellulose membrane is obtained by solvent casting using octadecane-modified hydroxyethyl cellulose as raw material, with the addition of 0.5% by mass of defoamer, 0.5% by mass of leveling agent, and 1.5% by mass of epoxidized soybean oil, and DMSO as solvent.

[0045] The long-chain hydrophobically modified hydroxyethyl cellulose has a long carbon chain content of 14% based on the mass of hydroxyethyl cellulose.

[0046] The silanization modification of the lower surface of the hydrophobic modified cellulose membrane is achieved by dissolving Si-563 coupling agent in ethanol to form a 5% mass fraction solution, uniformly spraying the solution onto the membrane surface, and drying to obtain the modified membrane.

[0047] The composite of the bottom P3H4B-PBAT membrane layer and the outer hydrophobic modified cellulose membrane layer is achieved through two sets of temperature settings of 60°C and 60°C respectively. o C, 70 o The rollers of C achieve a tight bond between the two layers by pressing each group of rollers for 1.5 minutes at a pressure of 1 MPa.

[0048] The properties of the prepared membrane material are shown in Table 1.

[0049] Example 2

[0050] A biodegradable, high-strength, high-barrier membrane is composed of a double-layer membrane, including a bottom P3H4B-PBAT membrane layer and an outer hydrophobic modified cellulose membrane layer. The upper surface of the bottom P3H4B-PBAT membrane layer is plasma-treated and then covered with a silicon oxide layer by vacuum sputtering. The lower surface of the hydrophobic modified cellulose membrane layer is silanized and covered with a silane-modified layer. The composite between the two layers is then achieved by hot pressing.

[0051] The thickness of the P3H4B-PBAT membrane is 0.18 mm, the thickness of the silica layer is 0.08 mm, and the thickness of the hydrophobically modified cellulose membrane is 0.14 mm.

[0052] The P3H4B-PBAT membrane is formed by melt extrusion of P3H4B and PBAT as the main raw materials, with the addition of polycaprolactone-grafted maleic anhydride, triethyl citrate, and antioxidant 1020. The mass ratio of P3H4B to PBAT is 75:25. The amounts of polylactic acid-grafted maleic anhydride and tributyl citrate are 3% and 2.8% of the main material mass, respectively, and the amount of antioxidant 1020 is 1% of the main material mass.

[0053] The molecular structure of P34HB is as follows:

[0054] ;

[0055] Where n=150, m=260.

[0056] The molecular weight of the PBAT is 42,000.

[0057] The molecular weight of the polylactic acid grafted with maleic anhydride is 38,000.

[0058] The melt extrusion film forming process conditions are as follows: the main material and auxiliary material are mixed evenly in a high-speed mixer, and then fed into a twin-screw extruder for casting, at 190-220 °C. o Melt extrusion casting film under C conditions.

[0059] The hydrophobically modified cellulose membrane is obtained by solvent casting using dodecane hydrophobically modified hydroxyethyl cellulose as raw material, with the addition of 0.8% by mass of defoamer, 0.8% by mass of leveling agent, and 2.2% by mass of epoxidized soybean oil, and DMSO as solvent.

[0060] The long-chain hydrophobically modified hydroxyethyl cellulose has a long carbon chain content of 16% based on the mass of hydroxyethyl cellulose.

[0061] The silanization modification of the lower surface of the hydrophobic modified cellulose membrane is achieved by dissolving KH792 coupling agent in ethanol to form a 4% mass fraction solution, uniformly spraying the solution onto the membrane surface, and drying to obtain the modified membrane.

[0062] The composite of the bottom P3H4B-PBAT membrane layer and the outer hydrophobic modified cellulose membrane layer is achieved through two sets of temperature settings at 65°C and 65°C respectively. o C, 75 o The rollers of C, with each set of rollers pressing for 2 minutes and at a pressure of 1.2 MPa, achieve a tight bond between the two layers.

[0063] The properties of the prepared membrane material are shown in Table 1.

[0064] Example 3

[0065] A biodegradable, high-strength, high-barrier membrane is composed of a double-layer membrane, including a bottom P3H4B-PBAT membrane layer and an outer hydrophobic modified cellulose membrane layer. The upper surface of the bottom P3H4B-PBAT membrane layer is plasma-treated and then covered with a silicon oxide layer by vacuum sputtering. The lower surface of the hydrophobic modified cellulose membrane layer is silanized and covered with a silane-modified layer. The composite between the two layers is then achieved by hot pressing.

[0066] The thickness of the P3H4B-PBAT membrane is 0.33 mm, the thickness of the silica layer is 0.07 mm, and the thickness of the hydrophobically modified cellulose membrane layer is 0.15 mm.

[0067] The P3H4B-PBAT membrane is made primarily of P3H4B and PBAT, with the addition of polycaprolactone-grafted maleic anhydride and SOY-CIZER. TM The BP series bio-based plasticizer and antioxidant 1020 are compounded and melt-extruded into a film; the mass ratio of P3H4B and PBAT is 75:25; the amount of polylactic acid grafted maleic anhydride and tributyl citrate is 3% and 2.8% of the main material mass, respectively, and the amount of antioxidant T501 is 1% of the main material mass.

[0068] The molecular structure of P34HB is as follows:

[0069] ;

[0070] Where n=110, m=270.

[0071] The molecular weight of the PBAT is 48,000.

[0072] The molecular weight of the polycaprolactone-grafted maleic anhydride is 38,000.

[0073] The melt extrusion film forming process conditions are as follows: the main material and auxiliary material are mixed evenly in a high-speed mixer, and then fed into a twin-screw extruder for casting, at 190-220 °C. o Melt extrusion casting film under C conditions.

[0074] The main raw material of the hydrophobic modified cellulose membrane is octadecane hydrophobically modified hydroxyethyl cellulose, with 0.6% by mass of defoamer, 0.6% by mass of leveling agent, and 2.6% by mass of epoxy fatty acid methyl ester added, and ethyl acetate is used as solvent to obtain the membrane by solvent casting.

[0075] The long-chain hydrophobically modified hydroxyethyl cellulose has a long carbon chain content of 18% based on the mass of hydroxyethyl cellulose.

[0076] The silanization modification of the lower surface of the hydrophobic modified cellulose membrane is achieved by dissolving KH550 coupling agent in ethanol to form a 5% mass fraction solution, uniformly spraying the solution onto the membrane surface, and drying to obtain the modified membrane.

[0077] The composite of the bottom P3H4B-PBAT membrane layer and the outer hydrophobic modified cellulose membrane layer is achieved through two sets of temperature settings at 65°C and 65°C respectively. o C, 75 o The rollers of C achieve a tight bond between the two layers by pressing each group of rollers for 1.5 minutes at a pressure of 1.5 MPa.

[0078] The properties of the prepared membrane material are shown in Table 1.

[0079] Example 4

[0080] A biodegradable, high-strength, high-barrier membrane is composed of a double-layer membrane, including a bottom P3H4B-PBAT membrane layer and an outer hydrophobic modified cellulose membrane layer. The upper surface of the bottom P3H4B-PBAT membrane layer is plasma-treated and then covered with a silicon oxide layer by vacuum sputtering. The lower surface of the hydrophobic modified cellulose membrane layer is silanized and covered with a silane-modified layer. The composite between the two layers is then achieved by hot pressing.

[0081] The thickness of the P3H4B-PBAT membrane is 0.16 mm, the thickness of the silica layer is 0.07 mm, and the thickness of the hydrophobically modified cellulose membrane is 0.09 mm.

[0082] The P3H4B-PBAT membrane is made primarily of P3H4B and PBAT, with the addition of polycaprolactone-grafted maleic anhydride and SOY-CIZER. TMThe BP series bio-based plasticizer and antioxidant 1020 are compounded and melt-extruded into a film; the mass ratio of P3H4B and PBAT is 75:25; the amounts of polylactic acid grafted β-hydroxyethyl acrylate and epoxidized soybean oil are 3% and 2.8% of the main material mass, respectively, and the amount of antioxidant T501 is 1% of the main material mass.

[0083] The molecular structure of P34HB is as follows:

[0084] ;

[0085] Where n=140, m=210.

[0086] The molecular weight of the PBAT is 48,000.

[0087] The molecular weight of the polycaprolactone-grafted maleic anhydride is 28,000.

[0088] The melt extrusion film forming process conditions are as follows: the main material and auxiliary material are mixed evenly in a high-speed mixer, and then fed into a twin-screw extruder for casting, at 190-220 °C. o Melt extrusion casting under C conditions.

[0089] The hydrophobically modified cellulose membrane is obtained by solvent casting using dodecane hydrophobically modified hydroxyethyl cellulose as raw material, with the addition of 0.6% of defoamer, 0.6% of leveling agent, and 2.2% of epoxidized soybean oil by mass, and DMSO as solvent.

[0090] The long-chain hydrophobically modified hydroxyethyl cellulose has a long carbon chain content of 14% based on the mass of hydroxyethyl cellulose.

[0091] The silanization modification of the lower surface of the hydrophobic modified cellulose membrane is achieved by dissolving KH540 in ethanol to form a 4.5% mass fraction solution, uniformly spraying the solution onto the membrane surface, and drying to obtain the modified membrane.

[0092] The composite of the bottom P3H4B-PBAT membrane layer and the outer hydrophobic modified cellulose membrane layer is achieved through two sets of temperature settings of 60°C and 60°C respectively. o C, 80 o The rollers of type C achieve a tight bond between the two layers by pressing each set of rollers for 1.5 minutes.

[0093] The properties of the prepared membrane material are shown in Table 1.

[0094] Comparative Example 1

[0095] Compared to the comparative example and Example 1, there was no upper hydrophobic modified cellulose membrane layer, but the other formulations and processes were completely identical.

[0096] The properties of the prepared membranes are shown in Table 1:

[0097] As shown in Table 1, when the hydrophobic modified cellulose membrane layer on the surface is removed, its tensile strength, elongation at break and tear strength all decrease slightly. This is because the lower P3H4B-PBAT membrane no longer has synergy and some force dispersion. At the same time, the gas barrier properties also decrease slightly, indicating that the upper hydrophobic modified cellulose membrane layer also plays a certain role in gas barrier synergy.

[0098] Comparative Example 2

[0099] Compared with the comparative example and Example 2, no silicon oxide layer was formed on the surface of the P3H4B-PBAT film, but the other formulations and processes were completely the same.

[0100] The properties of the prepared membranes are shown in Table 1:

[0101] As shown in Table 1, the mechanical properties of the membrane decrease slightly without the intermediate silicon oxide layer, while the gas barrier properties decrease significantly. This indicates that the silicon oxide layer still plays a major barrier role in the membrane.

[0102] Comparative Example 3

[0103] Compared with the comparative example and Example 1, the P3H4B-PBAT membrane layer was changed to a PLA membrane layer, while the other formulations and processes were completely the same.

[0104] The PLA film layer is made by melt extrusion of PLA as the main material, with the addition of plasticizer, toughening agent and nucleating agent. The basic mechanical properties of the film alone are: tensile strength and elongation at break of 36.7MPa and 24.6%, respectively, and transverse and longitudinal tear strength of 104.6N and 67.9N, respectively.

[0105] The properties of the prepared membranes are shown in Table 1:

[0106] As shown in Table 1, the overall membrane's toughness and tear strength decreased significantly, and its barrier properties also decreased to some extent. This indicates that the performance of the base membrane has a significant impact on the overall membrane and also affects the overall gas barrier effect.

[0107] Comparative Example 4

[0108] Compared with the comparative example and Example 1, the hydrophobic modified cellulose membrane layer was changed to a cellulose acetate membrane layer, while the other formulations and processes were completely the same.

[0109] The cellulose acetate membrane is formed by dissolving the cellulose acetate in ethanol solvent containing 60% water and then casting it into a film. The thickness of the membrane is 0.08 mm. The basic mechanical properties of the membrane alone are: tensile strength and elongation at break of 21.6 MPa and 57.4%, respectively, and transverse and longitudinal tear strengths of 27.6 N and 22.4 N, respectively.

[0110] The properties of the prepared membranes are shown in Table 1:

[0111] As shown in Table 1, the overall strength, toughness, and tear strength of the membrane all decreased to some extent, and the barrier properties also decreased to some extent, indicating that the upper membrane also played a synergistic role in the overall performance and barrier properties of the membrane.

[0112] Table 1. Performance of membrane materials prepared in the examples and comparative examples

[0113] Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Tensile strength (MPa) 46.4 42.9 56.5 55.9 37.6 39.7 35.8 42.3 Elongation at break (%) 104.5 88.1 128.9 132.8 114.5 83.8 25.8 83.4 Tear strength (longitudinal) / (transverse) (MPa) 204.6 / 182.4 173.9 / 142.8 231.7 / 187.6 142.6 / 93.8 134.4 / 131.7 201.3 / 171.5 109.3 / 87.6 165.5 / 127.4 Puncture resistance (N) 13.5 11.7 16.8 14.3 11.4 10.8 12.4 13.7 <![CDATA[O2 transmission rate cm 3 / (m 3 ·24hr·MPa)]]> 82.3 42.1 56.7 76.5 104.6 672.9 173.8 127.6 <![CDATA[CO2 transmission rate cm 3 / (m 3 ·24hr·MPa)]]> 93.7 35.4 51.2 69.8 133.5 629.3 196.9 169.5

Claims

1. A biodegradable, high-strength, high-barrier membrane, composed of a bilayer membrane composite, comprising a bottom P3H4B-PBAT membrane layer and an upper hydrophobically modified cellulose membrane layer; wherein, The bottom P3H4B-PBAT film layer is formed by melt extrusion. After film formation, the upper surface is treated with plasma and covered with a silica film layer by vacuum sputtering. The upper hydrophobic modified cellulose film layer is formed by solution casting. After film formation, the lower surface is silanized and modified. The treated double-layer film is composited by hot pressing. The thickness of the P3H4B-PBAT film layer is between 0.15-0.35 mm, the thickness of the silica film layer is between 0.05-0.08 mm, and the thickness of the hydrophobic modified cellulose film layer is between 0.08-0.16 mm. Its characteristics also include: The basic mechanical properties of the P3H4B-PBAT membrane are: tensile strength between 30.6-52.4 MPa, elongation at break between 89.2-152.6%, and tear strength between 126.2 N-198.4 N; the basic mechanical properties of the hydrophobically modified cellulose membrane are: tensile strength between 22.5-38.2 MPa, elongation at break between 58.5-124.3%, and tear strength between 54.5 N-92. The temperature is between 1N; the P3H4B-PBAT membrane layer and the hydrophobic modified cellulose membrane layer are composited by hot pressing with one or more sets of dual rollers with temperatures set between 60-85℃ for 1-2 minutes and pressure between 0.5-2MPa to achieve a tight bond between the two layers; the hydrophobic modified cellulose membrane layer is made of long-chain hydrophobic modified hydroxyethyl cellulose as the main raw material, with the addition of a small amount of defoamer, leveling agent and plasticizer, dissolved in a solvent and then cast into a film by solution casting.

2. The biodegradable, high-strength, high-barrier membrane as described in claim 1, characterized in that, The P3H4B-PBAT membrane is formed by melt extrusion of P3H4B and PBAT as the main raw materials, with the addition of biomass compatibilizer, biomass plasticizer and antioxidant; wherein the mass ratio of P3H4B and PBAT is between 80:20 and 50:50; the amount of biomass compatibilizer and biomass plasticizer is between 2% and 4% of the mass of the main raw materials, and the amount of antioxidant is between 0.5% and 1.2% of the mass of the main raw materials.

3. The biodegradable, high-strength, high-barrier membrane as described in claim 2, characterized in that, The biomass compatibilizer is one of polylactic acid grafted with maleic anhydride, polycaprolactone grafted with maleic anhydride, or polylactic acid grafted with β-hydroxyethyl acrylate.

4. The biodegradable, high-strength, high-barrier membrane as described in claim 2, characterized in that, The biomass plasticizer is tributyl citrate, triethyl citrate, or epoxidized soybean oil bioplasticizer.

5. The biodegradable, high-strength, high-barrier membrane as described in claim 1, characterized in that, The silanization modification process of the lower surface of the hydrophobic modified cellulose membrane is as follows: a silane coupling agent is dissolved in ethanol to form a solution with a mass fraction of 3-6%, the solution is sprayed evenly onto the surface of the hydrophobic modified cellulose membrane, and the modified membrane is obtained after natural drying. The silane coupling agent is one of KH540, KH550, KH560, KH792, Si-563, and A-171.

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