High-performance composite film and preparation method thereof

Abstract

The invention belongs to the technical field of polymer composite materials, and particularly relates to a high-performance composite film and a preparation method thereof.The high-performance composite film comprises a barrier enhancement layer, an outermost layer, a first bonding layer, a base material layer, a second bonding layer and an inner layer, and the barrier enhancement layer is formed by inorganic oxide formed on the outer surface of the outermost layer through vacuum evaporation; the outermost layer is composed of polyamide and inorganic nanometer temperature-resistant filler dispersed in the polyamide, the outermost layer is bonded with the base material layer through the first bonding layer, and through combination of the outermost layer, the first bonding layer, the base material layer, the second bonding layer and the inner layer, a five-layer composite membrane structure which is firm in interlayer combination, reasonable in structure and easy to industrially produce is provided. The preparation process is simplified through the integrated co-extrusion molding and on-line evaporation technology; the composite film is ensured to still have excellent high-temperature steaming resistance and high oxygen and water vapor barrier property while simplification is carried out.

Description

Technical Field

[0001] This invention belongs to the field of polymer composite materials technology, and particularly relates to a high-performance composite membrane and its preparation method. Background Technology

[0002] Multilayer composite films are widely used in the packaging industry because they can integrate multiple functions. In particular, packaging that requires high-temperature sterilization (such as retorting at temperatures above 121°C) requires composite films to have both excellent long-term barrier properties (against oxygen and water vapor) and dimensional stability and mechanical strength at high temperatures.

[0003] In existing technologies, as described in patent CN120503490B, performance requirements are met by designing a complex structure with up to seven or more layers, including a heat-resistant layer, a barrier layer, an aluminum-plated layer, and a heat-sealing layer. While this solution offers excellent performance, it suffers from significant drawbacks such as complex structure, cumbersome manufacturing process, and high cost.

[0004] Therefore, there is an urgent need in this field for a composite membrane solution that can simplify the structure, reduce costs, and be suitable for continuous and efficient production while maintaining excellent high temperature resistance and high barrier properties. Summary of the Invention

[0005] The purpose of this invention is to provide a high-performance composite membrane and its preparation method to solve the above-mentioned technical problems.

[0006] To achieve the above objectives, the specific technical solution of the present invention for a high-performance composite membrane and its preparation method is as follows: A high-performance composite membrane includes: a barrier reinforcement layer, an outermost layer, a first adhesive layer, a substrate layer, a second adhesive layer, and an inner layer. The barrier reinforcement layer is an inorganic oxide layer deposited on the outer surface of the outermost layer by vacuum evaporation. The barrier reinforcement layer is an outer surface coating of the outermost layer. The outermost layer is composed of polyamide and inorganic nano-heat-resistant fillers dispersed therein. The outermost layer is bonded to the substrate layer via the first adhesive layer, which is composed of a first maleic anhydride-grafted polyolefin adhesive resin. The substrate layer and the inner heat-sealing layer are bonded via the second adhesive layer, which is composed of a second maleic anhydride-grafted polyolefin adhesive resin. The inner layer is composed of metallocene polyethylene and is a heat-sealing layer.

[0007] Furthermore, the barrier reinforcement layer formed by inorganic oxide is made of silicon oxide or aluminum oxide, and its thickness is 30-50 nm.

[0008] Furthermore, the barrier reinforcement layer is made of titanium oxide.

[0009] Furthermore, the barrier reinforcement layer is made of metal nitride, preferably silicon nitride.

[0010] Furthermore, in the outermost layer, the inorganic nano-temperature-resistant filler is alumina, which accounts for 8%-20% of the total mass of the outermost layer material, preferably 10%-15%.

[0011] Furthermore, the inorganic nano-temperature resistant filler is silicon dioxide or boron nitride.

[0012] Furthermore, the inorganic nano-temperature resistant filler is a spherical or sheet-like inorganic nanoparticle with a particle size in the range of 10nm-100nm.

[0013] Furthermore, the mass of the alumina accounts for 10%-15% of the total mass of the outermost layer material.

[0014] Furthermore, the polyamide is PA6 or a copolymer PA.

[0015] Furthermore, the substrate layer is made of polyethylene or polypropylene.

[0016] Furthermore, the first adhesive layer and the second adhesive layer are independently selected from maleic anhydride-grafted polyethylene or maleic anhydride-grafted polypropylene.

[0017] Furthermore, the high-barrier, retortable composite film is used in the packaging of food requiring high-temperature retort; utilizing the high-temperature resistance, high oxygen barrier properties, and high water vapor barrier properties of the composite film, it is used to package contents that need to be sterilized at 121°C or above, including food, pharmaceuticals, or medical devices.

[0018] Furthermore, a method for preparing a high-performance composite membrane includes the following steps: Step S1: Five-layer co-extrusion molding S1.1 The dried outermost functional masterbatch, first adhesive layer resin (PE-g-MAH), base layer resin (HDPE), second adhesive layer resin (PE-g-MAH) and inner layer resin (mPE) are precisely metered and fed into the five independent extruders of the five-layer co-extrusion casting equipment. S1.2 Set the temperature of each extruder: Outermost extruder: 240-250℃ First adhesive layer extruder: 190-200℃; Substrate layer extruder: 200-210℃; Second adhesive layer extruder: 190-200℃; Inner extruder: 180-190℃; S1.3 The molten material passes through a multi-channel distributor and is combined with the die head, then extruded in one step to form a five-layer composite preform. The structure of the composite preform from bottom to top (from the side in contact with the cooling roller to the air side) is as follows: outermost layer; first adhesive layer; substrate layer; second adhesive layer; inner layer. The S1.4 preform is cooled and shaped by cooling rollers; Step S2: Online Corona Treatment S2.1 Guide the co-extruded preform through the corona treatment device; S2.2 The outermost surface is subjected to corona treatment. The total power of the corona treatment needs to be adjusted according to the actual film width and linear velocity in production. The surface energy of the outermost layer after treatment should not be less than 50mN / m. Step S3: Online vapor deposition S3.1 The corona-treated film preform is immediately guided into the vacuum evaporation chamber, and the film preform enters the vacuum evaporation chamber in a flat state; S3.2 Evacuate the vacuum chamber to a vacuum level ≤ 5.0 × 10⁻⁶. -3 Pa; S3.3 The substrate temperature of the film preform is controlled within the range of -10℃ to -20℃ by a cooling system; S3.4 The electron beam evaporation source is activated to bombard and heat the silicon dioxide target. The deposition rate is controlled at 1.0-2.0 nm / s; S3.5 uses a film thickness monitoring system to stop evaporation when the thickness of the deposited silicon oxide (SiOx) layer reaches 40nm (which can be set in the range of 30-50nm); S3.6 The inorganic oxide barrier reinforcement layer is completely formed on the outermost surface of the five-layer composite membrane preform; Step S4: Post-processing and winding S4.1 Further cool the vapor-deposited composite film to room temperature; S4.2 The quality of the membrane material is monitored using testing equipment such as online thickness gauges; S4.3 Finally, the qualified product is rolled up and packaged to obtain the high-performance composite film.

[0019] Furthermore, prior to the online evaporation step, the outermost surface of the five-layer composite film preform is subjected to corona treatment to ensure that the surface energy of the outermost layer is not less than 50 mN / m. In the online evaporation step, the deposition rate of silicon oxide is controlled at 1.0-2.0 nm / s.

[0020] 15. The preparation method according to claim 13, characterized in that the raw material ratio for preparing the outermost functional masterbatch is: polyamide (PA6): 80-92 parts by mass; inorganic nano-heat resistant filler (alumina, Al2O3): 8-20 parts by mass; dispersing agent (titanium ester coupling agent, such as NDZ-201): 1-3 parts by mass; The preparation process of the outermost functional masterbatch: S51 Pretreatment: Alumina nanoparticles were dried in a forced-air dryer at 105℃ for 4 hours to remove adsorbed moisture; S52. High-speed mixing: The metered dry PA6 resin, alumina filler, and titanate coupling agent are added together into a high-speed mixer; S53. Surface treatment and initial mixing: Mix at 600-80℃ and 600-800 rpm for 5-8 minutes to ensure the coupling agent is evenly coated on the filler surface and initially mixed with PA6 resin; S54. Melt Blending and Granulation: The mixed material is fed into a co-rotating twin-screw extruder. The temperatures of each section of the extruder, from the feeding section to the die head, are set to 220℃, 235℃, 245℃, 250℃, and 245℃ respectively. The screw speed is 300 rpm. After melt extrusion, water cooling, and pelletizing, the outermost functional masterbatch is obtained. S55. Post-treatment: Dry the masterbatch at 80℃ for 6 hours and set aside for later use.

[0021] The advantages of this invention are: This invention provides a five-layer composite membrane structure that features strong interlayer bonding, a rational structure, and ease of industrial production through a combination of an outermost layer, a first adhesive layer, a substrate layer, a second adhesive layer, and an inner layer; 2. This invention simplifies the preparation process through integrated co-extrusion molding and online vapor deposition technology; 3. This invention simplifies the process while ensuring that the composite membrane still possesses excellent high-temperature cooking resistance and high barrier properties against oxygen and water vapor. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall structure of the present invention; The markings in the diagram are as follows: 1. Outermost layer, 2. First adhesive layer, 3. Substrate layer, 4. Second adhesive layer, 5. Inner layer, 6. Barrier reinforcement layer. Detailed Implementation

[0023] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0025] Example 1 A method for preparing a high-performance composite membrane, wherein the preparation process of the outermost functional masterbatch is as follows: S51 Pretreatment: Alumina nanoparticles were dried in a forced-air dryer at 105℃ for 4 hours to remove adsorbed moisture; S52. High-speed mixing: The metered dry PA6 resin, alumina filler, and titanate coupling agent are added together into a high-speed mixer; S53. Surface treatment and initial mixing: Mix at 600-80℃ and 600-800 rpm for 5-8 minutes to ensure the coupling agent is evenly coated on the filler surface and initially mixed with PA6 resin; S54. Melt Blending and Granulation: The mixed material is fed into a co-rotating twin-screw extruder. The temperatures of each section of the extruder, from the feeding section to the die head, are set to 220℃, 235℃, 245℃, 250℃, and 245℃ respectively. The screw speed is 300 rpm. After melt extrusion, water cooling, and pelletizing, the outermost functional masterbatch is obtained. S55. Post-treatment: Dry the masterbatch at 80℃ for 6 hours and set aside for later use.

[0026] Preferably, the preparation of the outermost layer, first adhesive layer, substrate layer, second adhesive layer, and inner layer materials of the composite film is as follows: Preferably, the raw material ratio for preparing the outermost functional masterbatch is as follows: polyamide (PA6): 80-92 parts by weight; inorganic nano heat-resistant filler (alumina, Al2O3): 8-20 parts by weight; dispersing agent (titanium ester coupling agent, such as NDZ-201): 1-3 parts by weight. Preferably, the preparation of the raw materials for the first and second adhesive layers is as follows: the raw materials for the first and second adhesive layers are maleic anhydride-grafted polyethylene (PE-g-MAH) or maleic anhydride-grafted polypropylene (PP-g-MAH) as adhesive resins, wherein the maleic anhydride grafting rate is preferably 0.8%-1.5%; the adhesive resin is dried at 80°C for 3 hours to prevent bubbles from being generated during processing due to moisture.

[0027] Preferably, the substrate layer raw material is prepared as follows: the substrate layer raw material is high-density polyethylene (HDPE) or polypropylene (PP) resin; before use, the substrate resin is dried at 80°C for 3 hours.

[0028] Preferably, the preparation of the inner heat-sealing layer material is as follows: the inner heat-sealing layer material is metallocene polyethylene (mPE) as the heat-sealing material; an appropriate amount of slip agent (such as erucamide) or anti-blocking agent may be added according to the needs of the inner heat-sealing layer material; the mPE resin is dried at 50°C for 4 hours.

[0029] Preferably, the target material of the barrier reinforcement layer is a high-purity (≥99.99%) silicon dioxide (SiO2) target or an aluminum (Al) target.

[0030] Preferably, when the barrier reinforcement layer is a silicon target, the process gas for the silicon target is high-purity oxygen.

[0031] Example 2 Preparation of the outermost layer, first adhesive layer, substrate layer, second adhesive layer and inner layer materials of the composite film obtained by Example 1; like Figure 1 As shown, a high-performance composite membrane includes: a barrier reinforcement layer, an outermost layer, a first adhesive layer, a substrate layer, a second adhesive layer, and an inner layer. The barrier reinforcement layer is an inorganic oxide layer deposited on the outer surface of the outermost layer by vacuum evaporation. The barrier reinforcement layer is an outer surface coating of the outermost layer. The outermost layer is composed of polyamide and inorganic nano-heat-resistant fillers dispersed therein. The outermost layer is bonded to the substrate layer through the first adhesive layer, which is composed of a first maleic anhydride-grafted polyolefin adhesive resin. The substrate layer and the inner heat-sealing layer are bonded through the second adhesive layer, which is composed of a second maleic anhydride-grafted polyolefin adhesive resin. The inner layer is composed of metallocene polyethylene and is a heat-sealing layer.

[0032] The barrier reinforcement layer formed by inorganic oxide is made of silicon oxide or aluminum oxide, and its thickness is 30-50 nm.

[0033] The barrier reinforcement layer is made of titanium oxide.

[0034] The barrier reinforcement layer is made of metal nitride, preferably silicon nitride.

[0035] In the outermost layer, the inorganic nano-temperature resistant filler is alumina, which accounts for 8%-20% of the total mass of the outermost layer material, preferably 10%-15%.

[0036] The inorganic nano-temperature resistant filler is silicon dioxide or boron nitride.

[0037] The inorganic nano-temperature resistant filler is a spherical or sheet-like inorganic nanoparticle with a particle size in the range of 10nm-100nm.

[0038] The mass of the alumina accounts for 10%-15% of the total mass of the outermost layer material.

[0039] The polyamide is PA6 or a copolymer PA.

[0040] The substrate layer is made of polyethylene or polypropylene.

[0041] The first adhesive layer and the second adhesive layer are independently selected from maleic anhydride-grafted polyethylene or maleic anhydride-grafted polypropylene.

[0042] The high-barrier, retortable composite film is used in the packaging of food subjected to high-temperature retort processes. Utilizing the high-temperature resistance, high oxygen barrier properties, and high water vapor barrier properties of the composite film, it is used to package contents requiring sterilization at 121°C or higher, including food, pharmaceuticals, or medical devices.

[0043] Example 3 Preparation of the outermost layer, first adhesive layer, substrate layer, second adhesive layer and inner layer materials of the composite film obtained by Example 1; A method for preparing a high-performance composite membrane includes the following steps: Step S1: Five-layer co-extrusion molding; S1.1 The dried outermost functional masterbatch, first adhesive layer resin (PE-g-MAH), base layer resin (HDPE), second adhesive layer resin (PE-g-MAH) and inner layer resin (mPE) are precisely metered and fed into the five independent extruders of the five-layer co-extrusion casting equipment. S1.2 Set the temperature of each extruder: Outermost extruder: 240-250℃ First adhesive layer extruder: 190-200℃; Substrate layer extruder: 200-210℃; Second adhesive layer extruder: 190-200℃; Inner extruder: 180-190℃; S1.3 The molten material passes through a multi-channel distributor and is combined with the die head, then extruded in one step to form a five-layer composite preform. The structure of the composite preform from bottom to top (from the side in contact with the cooling roller to the air side) is as follows: outermost layer; first adhesive layer; substrate layer; second adhesive layer; inner layer. The S1.4 preform is cooled and shaped by cooling rollers; Step S2: Online corona treatment; S2.1 Guide the co-extruded preform through the corona treatment device; S2.2 The outermost surface is subjected to corona treatment. The total power of the corona treatment needs to be adjusted according to the actual film width and linear velocity in production. The surface energy of the outermost layer after treatment should not be less than 50 mN / m. This step aims to improve the adhesion between the outermost surface and the subsequent vapor-deposited layer. Step S3: Online vapor deposition (formation of the barrier reinforcement layer); S3.1 The corona-treated film preform is immediately guided into the vacuum evaporation chamber, and the film preform enters the vacuum evaporation chamber in a flat state; S3.2 Evacuate the vacuum chamber to a vacuum level ≤ 5.0 × 10⁻⁶. -3 Pa; S3.3 The substrate temperature of the film preform is controlled within the range of -10℃ to -20℃ by a cooling system; S3.4 The electron beam evaporation source is activated to bombard and heat the silicon dioxide target. The deposition rate is controlled at 1.0-2.0 nm / s; S3.5 uses a film thickness monitoring system to stop evaporation when the thickness of the deposited silicon oxide (SiOx) layer reaches 40nm (which can be set in the range of 30-50nm); S3.6 The inorganic oxide barrier reinforcement layer is completely formed on the outermost surface of the five-layer composite membrane preform; Step S4: Post-processing and winding; S4.1 Further cool the vapor-deposited composite film to room temperature; S4.2 The quality of the membrane material is monitored using testing equipment such as online thickness gauges; S4.3 Finally, the qualified product is rolled up and packaged to obtain the high-performance composite film.

[0044] Preferably, before the online vapor deposition step, the outermost surface of the five-layer composite film preform is subjected to corona treatment so that the surface energy of the outermost layer is not less than 50mN / m.

[0045] Preferably, in the online vapor deposition step, the deposition rate of silicon oxide is controlled at 1.0-2.0 nm / s.

[0046] Preferably, the substrate temperature of the film preform is in the range of -10°C to -20°C, which not only provides a stable low-temperature substrate for the deposition of the inorganic barrier layer and promotes the formation of a dense and continuous coating, but also effectively inhibits the thermal deformation of the substrate and enhances the adhesion between the coating and the substrate. Too low a temperature (e.g., <-30°C) may lead to excessive energy consumption and brittle film material; too high a temperature (e.g., >0°C) will not effectively inhibit molecular motion and stress generation.

[0047] Preferably, the total power of the corona treatment = energy density × treatment area; Preferably, the processing area = film width × linear velocity × time (i.e., effective electrode working time). Example 4 Preferably, the composite membrane structure comprises, from the outside to the inside: a barrier reinforcement layer (40nm SiOx); an outermost layer (PA6+8% Al2O3, 10μm); a first adhesive layer (PE-g-MAH, 5μm); a substrate layer (HDPE, 25μm); a second adhesive layer (PE-g-MAH, 5μm); and an inner layer (mPE, 30μm). The total thickness is approximately 75μm.

[0048] Preferably, the preparation of each layer of materials and the preparation of the composite membrane are as follows: Preferred preparation of the outermost functional masterbatch: Raw material ratio: Polyamide PA6: 92 parts by mass; Alumina (Al2O3): 8 parts by mass; Titanate coupling agent (NDZ-201): 2 parts by mass.

[0049] Preferably, the preparation process is as follows: After drying alumina at 105°C for 4 hours, it is added to a high-speed mixer along with PA6 resin and coupling agent, and mixed at 70°C and 700 rpm for 6 minutes. Subsequently, it is melt-blended, extruded, water-cooled, pelletized, and dried using a twin-screw extruder at 230°C to obtain the outermost functional masterbatch.

[0050] Preferred five-layer co-extrusion molding: raw materials and feed amount for each layer (based on the production of 100kg composite film preform): Outermost functional masterbatch: 10 kg; First adhesive layer resin (PE-g-MAH): 5 kg; Substrate layer resin (HDPE): 25 kg; Second adhesive layer resin (PE-g-MAH): 5 kg; Inner layer resin (metallocene polyethylene mPE): 30 kg; Preferably, the co-extrusion process involves drying each of the above-mentioned raw materials separately and feeding them into the five extruders of a five-layer co-extrusion casting equipment. The outermost layer temperature is set to 240°C, the first and second adhesive layers to 195°C, the substrate layer to 205°C, and the inner layer temperature to 185°C. The five-layer composite preform is obtained through a single co-extrusion process using a die.

[0051] Preferably, in-line evaporation: the outermost layer of the film preform is corona treated (surface energy 52 mN / m), followed by deposition under a vacuum of 3.0 × 10⁻⁶ mN / m. -3 A 40 nm thick silicon oxide barrier reinforcement layer was deposited at a deposition rate of 1.5 nm / s under Pa and substrate temperature of -15 °C.

[0052] Preferably, the post-processing steps are cooling, inspection, and winding to obtain the finished product.

[0053] Example 5 Preferably, the composite membrane structure comprises, from the outside to the inside: a barrier reinforcement layer (40nm SiOx); an outermost layer (PA6 + 15% Al2O3, 12μm); a first adhesive layer (PE-g-MAH, 5μm); a substrate layer (HDPE, 25μm); a second adhesive layer (PE-g-MAH, 5μm); and an inner layer (mPE, 30μm). The total thickness is approximately 77μm.

[0054] Preferably, the preparation of each layer of materials and the preparation of the composite membrane are as follows: Preferred preparation of the outermost functional masterbatch: raw material ratio: PA6: 85 parts by mass; alumina: 15 parts by mass; NDZ-201: 2.5 parts by mass.

[0055] Preferably, the preparation process is the same as in Example 4.

[0056] Preferred five-layer co-extrusion molding: raw materials and feed amount for each layer (based on the production of 100kg composite film preform): Outermost functional masterbatch: 12 kg First adhesive layer resin (PE-g-MAH): 5 kg Substrate layer resin (HDPE): 25 kg Second adhesive layer resin (PE-g-MAH): 5 kg Inner layer resin (mPE): 30 kg Preferably, the co-extrusion process is the same as in Example 4.

[0057] Preferably, the online vapor deposition and post-treatment are the same as in Example 4.

[0058] Comparative Example 1 (without adhesive layer) Structure and fabrication: An attempt was made to fabricate a four-layer structure: a barrier reinforcement layer (40nm SiOx); an outermost layer (PA6 + 15% Al2O3, 12μm); a substrate layer (HDPE, 40μm); and an inner layer (mPE, 30μm).

[0059] Preparation process: The preparation of the outermost masterbatch is the same as in Example 2; four-layer co-extrusion is used, with the following material inputs for each layer: 12 kg of outermost masterbatch, 40 kg of base layer resin, and 30 kg of inner layer resin. The adhesive layer is omitted. The subsequent vapor deposition process is the same as in Example 4.

[0060] Results: The interface was unstable during co-extrusion, and defects appeared between the layers after film formation. The interlayer adhesion was <1 N; within 15 mm, it was extremely easy to peel off. This proves that a strong composite cannot be achieved without an adhesive layer.

[0061] Comparative Example 2 (without nanofillers) Structure and preparation: The structure is basically the same as in Example 2, but the outermost layer is only PA6 (without aluminum oxide) with a thickness of 12 μm.

[0062] Preparation process: The outermost layer uses 12 kg of pure PA6 resin. The first adhesive layer weighs 5 kg, the substrate layer weighs 25 kg, the second adhesive layer weighs 5 kg, and the inner layer weighs 30 kg. Co-extrusion and subsequent processes are the same as in Example 2.

[0063] Results: A composite membrane was successfully prepared and used to compare the effects of nanofillers.

[0064] Comparative Example 3 (without vapor deposition layer) Preparation process: The five-layer co-extrusion steps and material input are the same as in Example 5. After co-extrusion, the online vapor deposition step is omitted, and post-processing and winding are carried out directly.

[0065] Results: A five-layer co-extruded film without vapor deposition was successfully prepared and used to compare the role of the barrier reinforcement layer.

[0066] Comparative Example 4 (simulating the closest existing technology) Structure and preparation: A seven-layer composite membrane was prepared according to Example 1 of CN120503490B.

[0067] Preparation process: The process is carried out according to the multi-step independent co-extrusion, coating and dry compounding process described herein.

[0068] Result: A composite membrane was successfully prepared and used as a performance comparison benchmark.

[0069] The composite films obtained from the examples and comparative examples were tested, and the results are shown in Table 1.

[0070] Tensile strength was tested according to GB / T1040.3-2006. The tensile strength of the composite film and the tensile strength after steaming at 121℃ for 40 minutes were tested respectively. Oxygen permeability was tested at 23°C and 0% relative humidity. Water vapor transmission rate was tested at 28℃ and 90% relative humidity. Table 1: Performance Test Results

[0071] Among them, the sample of Comparative Example 2 showed local blistering after the cooking test, indicating that its interlayer adhesion was not stable under high temperature and high humidity. As can be seen from Table 1: Comparative Example 1 demonstrates that without the "first adhesive layer and second adhesive layer", a strong interlayer bond cannot be achieved; Comparative Example 3 demonstrates that the barrier performance is completely lost without the "barrier reinforcement layer"; The comparison between Comparative Example 3 and Example 5 demonstrates that the "barrier enhancement layer" and its thickness range (30-50nm) are key to achieving high barrier properties. The comparison between Comparative Example 2 and Examples 4 and 5 demonstrates that, within the range of 8%-20% and preferably within the range of 10%-15%, the addition of alumina can significantly improve the boiling resistance and barrier properties of the composite film. The simplified five-layer co-extrusion + online vapor deposition structure of Examples 4 and 5 achieves or exceeds the core performance (barrier properties and boiling resistance) of the seven-layer complex structure of Comparative Example 4. At the same time, the process is greatly simplified and more environmentally friendly. This proves that the high-performance composite film of the present invention provides excellent performance while also having the characteristics of simplified structure and high production efficiency.

[0072] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A high performance composite membrane characterized in that, Comprising: a barrier enhancement layer, an outermost layer, a first adhesive layer, a substrate layer, a second adhesive layer and an inner layer, the barrier enhancement layer is an inorganic oxide layer deposited on the outer surface of the outermost layer by vacuum evaporation, the barrier enhancement layer is the outer surface coating of the outermost layer, the outermost layer is composed of polyamide and inorganic nano-temperature-resistant filler dispersed therein, the outermost layer is bonded to the substrate layer through the first adhesive layer, the first adhesive layer is composed of a first maleic anhydride grafted polyolefin adhesive resin, the substrate layer is bonded to the inner layer through the second adhesive layer, the second adhesive layer is composed of a second maleic anhydride grafted polyolefin adhesive resin, the inner layer is composed of metallocene polyethylene, and the inner layer is a heat-seal layer.

2. The high performance composite film of claim 1, wherein, The material of the barrier enhancement layer formed by the inorganic oxide is silicon oxide or aluminum oxide, and the thickness is 30-50 nm.

3. The high performance composite film of claim 1, wherein, In the outermost layer, the inorganic nano-temperature-resistant filler is aluminum oxide, and the mass accounts for 8%-20% of the total mass of the outermost layer material, preferably 10%-15%.

4. The high-barrier retortable composite film according to claim 1 or 2, characterized in that, The inorganic nano-temperature-resistant filler is silicon dioxide or boron nitride.

5. The high performance composite film of claim 1, wherein, The material of the substrate layer is polyethylene or polypropylene.

6. The high performance composite film of claim 1, wherein, The first adhesive layer and the second adhesive layer are independently selected from maleic anhydride grafted polyethylene or maleic anhydride grafted polypropylene.

7. Use of the high-barrier retort-resistant composite film according to any one of claims 1-7 in packaging of high-temperature retort food products; characterized in that, The composite film is used for packaging contents that need to be sterilized at a temperature of 121°C or above, including food, medicine or medical devices, by taking advantage of its high temperature resistance, high oxygen barrier property and high water vapor barrier property.

8. A method for producing a high performance composite membrane as claimed in any one of claims 1 to 7, characterized by, Comprising the following steps: Step S1: five-layer co-extrusion molding S1.1 accurately measure and feed the dried outermost layer functional master batch, first adhesive layer resin (PE-g-MAH), substrate layer resin (HDPE), second adhesive layer resin (PE-g-MAH) and inner layer resin (mPE) into five independent extruders of a five-layer co-extrusion casting equipment respectively; S1.2 set the temperature of each extruder: Outermost layer extruder: 240-250°C First adhesive layer extruder: 190-200°C; Substrate layer extruder: 200-210°C; Second adhesive layer extruder: 190-200°C; Inner layer extruder: 180-190°C; S1.3 the molten material passes through a multi-channel distributor and a die, converges in the die, and is extruded in one step to obtain a five-layer composite film blank; the structure of the composite film blank from bottom to top (from the side of the chill roller to the air side) is as follows: outermost layer; first adhesive layer; substrate layer; second adhesive layer; inner layer; S1.4 the film blank is cooled and shaped by a cooling roller; Step S2: online corona treatment S2.1 guide the co-extruded film blank through a corona treatment device; S2.2 corona treat the outer surface of the outermost layer, the total power of the corona treatment needs to be adjusted according to the actual production film width and line speed, and the surface energy of the treated outermost layer should be not less than 50 mN / m; Step S3: online evaporation S3.1 immediately guide the corona-treated film blank into a vacuum evaporation chamber, and the film blank enters the vacuum evaporation chamber in a flat state; S3.2 The vacuum chamber is evacuated to a vacuum of < 5.0 x 10 -3 Pa; S3.3 control the substrate temperature of the film blank in the range of -10°C to -20°C through a cooling system; S3.4 Start the electron beam evaporation source to bombard and heat the silicon dioxide target. Control the deposition rate at 1.0-2.0 nm / s; S3.5 When the thickness of the deposited silicon oxide (SiOx) layer reaches 40 nm (which can be set in the range of 30-50 nm), stop the evaporation by the film thickness monitoring system; S3.6 The inorganic oxide barrier enhancement layer is completely formed on the outermost surface of the five-layer composite film embryo; Step S4: Post-processing and winding S4.1 Further cool the evaporated composite film to room temperature; S4.2 Monitor the quality of the film material by online thickness gauge and other detection equipment; S4.3 Finally, wind and package the qualified products, and obtain the high-performance composite film.

9. The preparation method according to claim 8, characterized in that, Before the online evaporation step, perform corona treatment on the outermost surface of the five-layer composite film embryo to make the outermost surface energy not less than 50 mN / m. In the online evaporation step, the deposition rate of silicon oxide is controlled at 1.0-2.0 nm / s.

10. The method of claim 8, wherein, The raw material ratio of the outermost functional masterbatch: polyamide (PA6): 80-92 parts by mass; inorganic nano-temperature-resistant filler (aluminum oxide, Al2O3): 8-20 parts by mass; Dispersion aid (titanate coupling agent, such as NDZ-201): 1-3 parts by mass; The preparation process of the outermost functional masterbatch: S51 Pretreatment: Dry the aluminum oxide nano-powder at 105°C for 4 hours by blowing to remove adsorbed moisture; S52. High-speed mixing: Put the metered dry PA6 resin, aluminum oxide filler and titanate coupling agent into a high-speed mixer together; S53. Surface treatment and preliminary mixing: Mix at 60-80°C at a speed of 600-800 rpm for 5-8 minutes to make the coupling agent uniformly wrap the surface of the filler and preliminarily mix with the PA6 resin; S54. Melt blending and granulation: Put the mixed material into a co-rotating twin-screw extruder. Set the temperature of each section of the extruder from the feeding section to the die head at 220°C, 235°C, 245°C, 250°C, 245°C. The screw speed is 300 rpm. After melt extrusion, water cooling and granulation, the outermost functional masterbatch is obtained; S55. Post-processing: Dry the masterbatch at 80°C for 6 hours for standby use.

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