High-barrier biaxially oriented polyamide film and method for producing the same

Abstract

The application discloses a high-barrier bidirectional-stretching polyamide film and a preparation method thereof, the film is composed of a three-layer structure, and the three layers are A, B and C from top to bottom. The A layer and the C layer are each composed of 10wt%-20wt% of polyamide 6, 66wt%-83.5wt% of polyamide MXD6, 6wt%-15wt% of high-barrier MXD6 master batch and 0.5wt%-3wt% of anti-sticking master batch; the B layer comprises 10wt%-20wt% of MXD6, 70wt%-85wt% of PA6 and 2wt%-8wt% of high-barrier polyamide 6 master batch. The film prepared by the method has the advantages of easiness in production and industrialization, good mechanical properties, high barrier performance, great improvement in the sensitivity of polyamide 6 to water vapor and improved barrier performance under high-humidity conditions.

Description

Technical Field

[0001] This invention relates to a high-barrier biaxially oriented polyamide film and its preparation method. Background Technology

[0002] Bis-axially oriented polyamide 6 (BOPA6) film is the third largest polymer film packaging material after biaxially oriented polypropylene (BOPP) and biaxially oriented polyethylene terephthalate (BOPET). It has a wider operating temperature range (-60~150℃), better gas barrier properties, and excellent puncture resistance, abrasion resistance, and solvent resistance, making it widely used in food and pharmaceutical packaging. With the rapid development of new energy and microelectronics industries, especially in the food, pharmaceutical, electronic component, and military supplies sectors, higher demands are being placed on the barrier properties of packaging materials for freshness and quality preservation. Although BOPA6 film has relatively good barrier properties, it is still insufficient to meet the packaging requirements of electronic components.

[0003] To improve the barrier properties of BOPA6 films, many methods such as multilayer composites, blending, copolymerization, coating, layer-by-layer self-assembly, vacuum evaporation, and nanocomposites have been rapidly developed. Currently, the mainstream products in the high-barrier film market include polyvinyl alcohol (PVA) coated high-barrier films, PVDC high-barrier films, EVOH high-barrier films, nylon high-barrier films, and inorganic oxide coated films. In addition, poly(m-phenylene adipamide) (MXD6) films and silicon oxide vapor-deposited films have also gained widespread market attention in recent years. Among the many methods, combining multilayer composites and nanocomposites can leverage the advantages of both methods to improve the barrier properties of the film. Multilayer composites refer to combining two or more films with different barrier properties through a specific process. In this way, penetrating molecules must pass through several layers of membranes to reach the inside of the packaging, effectively extending the penetration path and thus improving the barrier properties. Nanocomposites are nanomaterials prepared using impermeable sheet-like nanoparticles with a large aspect ratio through intercalation composites, in-situ polymerization, or sol-gel methods. The addition of sheet-like nanoparticles not only reduces the volume fraction of the polymer matrix in the system, thereby decreasing the solubility of permeating molecules, but also extends the permeation path of these molecules, reducing their diffusion rate and improving barrier properties. Combining multilayer composites and nanocomposites can achieve a synergistic effect, resulting in superior barrier performance. Currently, layered nanofillers such as montmorillonite (MMT) and layered double hydroxides (LDHs) have become a research hotspot due to their unique structure and excellent properties. Therefore, using MXD6 as a surface layer in a multilayer composite with PA6, and introducing MMT into MXD6, will significantly improve the barrier properties of the membrane material. Summary of the Invention

[0004] In view of the deficiencies of the prior art, one object of the present invention is to provide a supramolecular ionic polymer exfoliated nano-montmorillonite.

[0005] To solve the above problems, the technical solution of the present invention is: a high-barrier biaxially oriented polyamide film, which is composed of three co-extruded biaxially oriented polyamide films, namely A, B and C, from top to bottom;

[0006] Both layers A and C consist of 10wt%~20wt% PA6, 66wt%~83.5XD6, 6wt%~15 high-barrier MXD6 masterbatch, and 0.5wt%~3wt% anti-sticking masterbatch;

[0007] Layer B consists of 10wt%~20wt% MXD6, 70wt%~85wt% PA6, and 2wt%~8wt% high-barrier PA6 masterbatch.

[0008] Furthermore, the thickness of the high-barrier biaxially oriented polyamide film is 12~25μm, the thickness of layer A and layer C is 2~4μm, and at least one side of layer A and layer C is subjected to corona treatment.

[0009] Furthermore, the anti-sticking masterbatch is a modified polyamide masterbatch containing an opening agent, a slip agent, and a dispersant.

[0010] Furthermore, the high-barrier MXD6 masterbatch is MXD6 modified with inorganic layered nanoparticles; the high-barrier PA6 masterbatch is PA6 modified with inorganic layered nanoparticles.

[0011] Furthermore, the inorganic layered nanoparticles are a composite of supramolecular ionic polymer-exfoliated nano-montmorillonite and supramolecular ionic polymer-exfoliated layered double hydroxides.

[0012] Furthermore, the supramolecular ionic polymer exfoliated nano-montmorillonite is an exfoliated MMT composed of supramolecular ionic polymers containing melamine cations, polyfunctional imidazole cations and heteropolyacid anions between the layers.

[0013] Furthermore, the supramolecular ionic polymer exfoliated layered double hydroxide is an exfoliated LDH composed of supramolecular ionic polymers containing sulfonic acid anions, diimidazole cations, and heteropolyacid anions between the layers.

[0014] Furthermore, the weight ratio of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide is 4 / 1 to 1 / 2, and the total content of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide in the high-barrier PA6 masterbatch is 20wt% to 30wt%.

[0015] Furthermore, the weight ratio of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide is 4 / 1 to 1 / 2, and the total content of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide in the high-barrier MXD6 masterbatch is 30wt% to 40wt%.

[0016] The present invention also provides a method for preparing the above-mentioned high-barrier biaxially oriented polyamide film, characterized by comprising the following steps:

[0017] (1) Preparation of high-barrier MXD6 masterbatch:

[0018] The supramolecular ionomer exfoliated nano-montmorillonite, supramolecular ionomer exfoliated layered double hydroxide, MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material.

[0019] The coarse material is crushed and mixed evenly with the coupling agent. The mixture is then melt-extruded and granulated using a twin-screw extruder to obtain the masterbatch product. The extruder temperature is set to 250~290ºC and the extruder speed is 300r / min~500r / min. After dehumidification and drying, the product is ready for use.

[0020] (2) Preparation of high-barrier PA6 masterbatch:

[0021] The supramolecular ionomer exfoliated nano-montmorillonite, supramolecular ionomer exfoliated layered double hydroxide, PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material.

[0022] The coarse material is crushed and mixed evenly with the coupling agent. The mixture is then melt-extruded and granulated using a twin-screw extruder to obtain the masterbatch product. The extruder temperature is set to 240~280ºC and the extruder speed is 300r / min~500r / min. After dehumidification and drying, the product is ready for use.

[0023] (3) Mix the components in layers A, B, and C according to the proportions and disperse them evenly using a high-speed mixer;

[0024] (4) The above-mentioned uniformly mixed layers are melted and co-extruded through three extruders, so that the melt is cast through a T-die to a quench roll with a surface temperature of 20~35 ºC for rapid cooling.

[0025] (5) The above-mentioned castings are conditioned in a water bath at 30~75 ºC for 10 minutes. After conditioning, the surface of the castings is dried with an air knife to remove residual moisture. Then, they are stretched synchronously or in stages at a temperature of 130~190 ºC and a stretching ratio of 2.5~3.5.

[0026] (6) The film obtained above is heat-set and at least one of the A layer and C layer is corona treated. Then it is wound up and slit to obtain the film, wherein the film thickness is 12~25μm and the thickness of the A layer and C layer is 2~4μm.

[0027] The beneficial effects of this invention are:

[0028] 1. High-barrier films are prepared by combining organic / inorganic composites and MXD6 / PA6 composites to achieve high gas barrier performance;

[0029] 2: Introducing supramolecular ionic polymers into the interlayer of the nanolayer structure is beneficial to the dispersion of the layers in the polyamide matrix. When these polymers are combined with polyamide materials with barrier properties to form a thin film, the solubility coefficient of gas molecules in the film can be effectively reduced, and a "tortuous path" can be formed to extend the gas permeation path, hindering the diffusion of gas in the matrix, thereby significantly improving the gas barrier performance of the polyamide film.

[0030] 3: Both the surface and bottom layers are barrier layers based on MXD6, which can significantly improve PA6's sensitivity to moisture and enhance its barrier performance under high humidity conditions.

[0031] 4. This invention is easy to produce and industrialize, and can significantly improve the barrier properties of membrane materials. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of the high-barrier biaxially oriented polyamide film of the present invention.

[0033] In the diagram, A is the barrier layer, B is the core layer, and C is the barrier layer. Detailed Implementation

[0034] The present invention will be further described in detail below with reference to the embodiments:

[0035] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment; layers A and C are composed of PA6, MXD6, high-barrier MXD6 masterbatch, and anti-sticking masterbatch; layer B is composed of MXD6, PA6, and high-barrier PA6 masterbatch.

[0036] The anti-sticking masterbatch is a modified polyamide masterbatch containing an opening agent, a slip agent, and a dispersant.

[0037] The high-barrier MXD6 masterbatch is MXD6 modified with inorganic layered nanoparticles; the high-barrier PA6 masterbatch is PA6 modified with inorganic layered nanoparticles.

[0038] The inorganic layered nanoparticles are a composite of supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT) and supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH).

[0039] Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT) is an exfoliated MMT composed of supramolecular ionic polymers containing melamine cations, polyfunctional imidazole cations and heteropolyacid anions between its layers.

[0040] Supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH) is an exfoliated type of LDH composed of supramolecular ionic polymers containing sulfonic acid anions, diimidazole cations and heteropolyacid anions between the layers.

[0041] The weight ratio of supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT) to supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH) is 4 / 1 to 1 / 2, and the total content of supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT) and supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH) in the high-barrier PA6 masterbatch is 20wt% to 30wt%.

[0042] The total content of supramolecular ionomer exfoliated nano-montmorillonite (C-MMT) and supramolecular ionomer exfoliated layered double hydroxide (C-LDH) in the high-barrier MXD6 masterbatch is 30wt%~40wt%.

[0043] Example 1

[0044] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 10wt% PA6, 83.5wt% MXD6, 6wt% high-barrier MXD6 masterbatch, and 0.5wt% anti-sticking masterbatch. Layer B is composed of 10wt% MXD6, 85wt% PA6, and 5wt% high-barrier PA6 masterbatch.

[0045] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 250ºC and the extruder speed is 300 r / min. After dehumidification and drying, it is ready for use.

[0046] Preparation of high-barrier PA6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, and then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 240ºC and the extruder speed is 300 rpm. After dehumidification and drying, it is ready for use.

[0047] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 20ºC for rapid cooling. The cast sheets are then conditioned in a 30ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a temperature of 130ºC and a stretching ratio of 2.5. The resulting film is then heat-set, and layer A is corona-treated. Finally, it is wound up and slit to obtain the film, which has a thickness of 12μm, with layers A and C each having a thickness of 2μm.

[0048] Example 2

[0049] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 12wt% PA6, 79wt% MXD6, 8wt% high-barrier MXD6 masterbatch, and 1wt% anti-sticking masterbatch. Layer B is composed of 12wt% MXD6, 80wt% PA6, and 8wt% high-barrier PA6 masterbatch.

[0050] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 255ºC and the extruder speed is 350 r / min. After dehumidification and drying, it is ready for use.

[0051] Preparation of high-barrier PA6 masterbatch: Supramolecular ionomer exfoliated nano-montmorillonite (C-MMT), supramolecular ionomer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, and then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 245ºC and the extruder speed is 350r / min. After dehumidification and drying, it is ready for use.

[0052] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 22ºC for rapid cooling. The cast sheets are then conditioned in a 40ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 140ºC and a stretching ratio of 3. The resulting film is then heat-set, and layer C is corona-treated. Finally, the film is wound and slit to obtain the film, which has a thickness of 15μm, with layers A and C each having a thickness of 2μm.

[0053] Example 3

[0054] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 14wt% PA6, 74wt% MXD6, 10wt% high-barrier MXD6 masterbatch, and 2wt% anti-sticking masterbatch. Layer B is composed of 14wt% MXD6, 80wt% PA6, and 6wt% high-barrier PA6 masterbatch.

[0055] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 260ºC and the extruder speed is 375 r / min. After dehumidification and drying, it is ready for use.

[0056] Preparation of high-barrier PA6 masterbatch: Supramolecular ionomer exfoliated nano-montmorillonite (C-MMT), supramolecular ionomer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 250ºC and the extruder speed is 375r / min. After dehumidification and drying, it is ready for use.

[0057] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die to a quench roll at a surface temperature of 24ºC for rapid cooling. The cast sheets are then conditioned in a 50ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 150ºC and a stretching ratio of 3.5. The resulting film is then heat-set, and layer A is corona-treated. Finally, it is wound and slit to obtain the film, which has a thickness of 12μm, with layers A and C each having a thickness of 2μm.

[0058] Example 4

[0059] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 15wt% PA6, 70wt% MXD6, 12wt% high-barrier MXD6 masterbatch, and 3wt% anti-sticking masterbatch. Layer B is composed of 16wt% MXD6, 80wt% PA6, and 6wt% high-barrier PA6 masterbatch.

[0060] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 265ºC and the extruder speed is 400 r / min. After dehumidification and drying, it is ready for use.

[0061] Preparation of high-barrier PA6 masterbatch: Supramolecular ionomer exfoliated nano-montmorillonite (C-MMT), supramolecular ionomer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 255ºC and the extruder speed is 400 r / min. After dehumidification and drying, it is ready for use.

[0062] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 25ºC for rapid cooling. The cast sheets are then conditioned in a 60ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 160ºC and a stretching ratio of 4. The resulting film is then heat-set, and layer A is corona-treated. Finally, it is wound up and slit to obtain the film, which has a thickness of 15μm, with layers A and C each having a thickness of 2μm.

[0063] Example 5

[0064] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 16wt% PA6, 68wt% MXD6, 14wt% high-barrier MXD6 masterbatch, and 2wt% anti-sticking masterbatch. Layer B is composed of 18wt% MXD6, 80wt% PA6, and 2wt% high-barrier PA6 masterbatch.

[0065] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 270ºC and the extruder speed is 425 r / min. After dehumidification and drying, it is ready for use.

[0066] Preparation of high-barrier PA6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, and then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 260ºC and the extruder speed is 425r / min. After dehumidification and drying, it is ready for use.

[0067] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 26ºC for rapid cooling. The cast sheets are then conditioned in a 70ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 180ºC and a stretching ratio of 3.5. The resulting film is then heat-set, and layer C is corona-treated. Finally, the film is wound and slit to obtain the film with a thickness of 25μm, and the thicknesses of layers A and C are both 4μm.

[0068] Example 6

[0069] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 18wt% PA6, 66wt% MXD6, 15wt% high-barrier MXD6 masterbatch, and 1wt% anti-sticking masterbatch. Layer B is composed of 20wt% MXD6, 72wt% PA6, and 8wt% high-barrier PA6 masterbatch.

[0070] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is pulverized and mixed evenly with coupling agent, then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 280ºC and the extruder speed is 450 r / min. After dehumidification and drying, it is ready for use.

[0071] Preparation of high-barrier PA6 masterbatch: Supramolecular ionomer exfoliated nano-montmorillonite (C-MMT), supramolecular ionomer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 270ºC and the extruder speed is 450 r / min. After dehumidification and drying, it is ready for use.

[0072] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 28ºC for rapid cooling. The cast sheets are then conditioned in a 75ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 190ºC and a stretching ratio of 3. The resulting film is then heat-set, and layer A is corona-treated. Finally, the film is wound and slit to obtain the film, which has a thickness of 25μm, with layers A and C each having a thickness of 4μm.

[0073] Example 7

[0074] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 20wt% PA6, 67.5wt% MXD6, 12wt% high-barrier MXD6 masterbatch, and 0.5wt% anti-sticking masterbatch. Layer B is composed of 12wt% MXD6, 84wt% PA6, and 4wt% high-barrier PA6 masterbatch.

[0075] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 285ºC and the extruder speed is 475r / min. After dehumidification and drying, it is ready for use.

[0076] Preparation of high-barrier PA6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, and then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 275ºC and the extruder speed is 475r / min. After dehumidification and drying, it is ready for use.

[0077] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 30ºC for rapid cooling. The cast sheets are then conditioned in a 60ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 140ºC and a stretching ratio of 2.5. The resulting film is then heat-set, and layer C is corona-treated. Finally, the film is wound and slit to obtain the film, which has a thickness of 20μm, with layers A and C each having a thickness of 3μm.

[0078] Example 8

[0079] The high-barrier biaxially oriented polyamide film consists of layers A, B, and C from top to bottom, with one side of layer A undergoing unwinding corona treatment. Layers A and C are composed of 10wt% PA6, 81wt% MXD6, 8wt% high-barrier MXD6 masterbatch, and 1wt% anti-sticking masterbatch. Layer B is composed of 10wt% MXD6, 82wt% PA6, and 8wt% high-barrier PA6 masterbatch.

[0080] Preparation of high-barrier MXD6 masterbatch: Supramolecular ionic polymer exfoliated nano-montmorillonite (C-MMT), supramolecular ionic polymer exfoliated layered double hydroxide (C-LDH), MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is then pulverized and mixed evenly with coupling agent, melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 290ºC and the extruder speed is 500 r / min. After dehumidification and drying, it is ready for use.

[0081] Preparation of high-barrier PA6 masterbatch: Supramolecular ionomer exfoliated nano-montmorillonite (C-MMT), supramolecular ionomer exfoliated layered double hydroxide (C-LDH), PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material; the coarse material is crushed and mixed evenly with coupling agent, and then melt-extruded and granulated through a twin-screw extruder to obtain the finished masterbatch. The extruder temperature is set at 280ºC and the extruder speed is 500 r / min. After dehumidification and drying, it is ready for use.

[0082] The components of layers A, B, and C are mixed in proportion and dispersed evenly using a high-speed mixer. The uniformly mixed layers are then melted and co-extruded using three extruders, allowing the melt to flow through a T-die onto a quench roll at a surface temperature of 35ºC for rapid cooling. The cast sheets are then conditioned in a 50ºC water bath for 10 minutes. After conditioning, the surface of the cast sheets is dried with an air knife to remove residual moisture, and then stretched synchronously or in stages at a stretching temperature of 130ºC and a stretching ratio of 2.5. The resulting film is then heat-set, and layer C is corona-treated. Finally, the film is wound and slit to obtain the film, which has a thickness of 20μm, with layers A and C each having a thickness of 3μm.

[0083] The high-barrier biaxially oriented polyamide films prepared in the above embodiments were tested, and the properties are shown in the table below:

[0084] Table 1. Performance Comparison of Various Embodiments

[0085] <![CDATA[Water vapor transmission rate (g∙m -2 ∙d -1 , 40 °C, 60 wt% relative humidity)]]> <![CDATA[Oxygen transmission rate (cm 3 ∙m -2 ∙d -1 , 23°C, 60 wt% relative humidity)]]> Example 1 1.20 0.82 Example 2 1.12 0.76 Example 3 1.40 1.01 Example 4 1.01 0.68 Example 5 0.95 0.40 Example 6 0.70 0.04 Example 7 0.99 0.65 Example 8 1.03 0.69

Claims

1. A high-barrier biaxially oriented polyamide film, characterized in that: It consists of three co-extruded biaxially oriented polyamide films, A, B, and C, arranged from top to bottom. Both layers A and C consist of 10wt%~20wt% PA6, 66wt%~83.5XD6, 6wt%~15 high-barrier MXD6 masterbatch, and 0.5wt%~3wt% anti-sticking masterbatch; Layer B consists of 10wt%~20wt% MXD6, 70wt%~85wt% PA6, and 2wt%~8wt% high-barrier PA6 masterbatch; The high-barrier MXD6 masterbatch is MXD6 modified with inorganic layered nanoparticles; the high-barrier PA6 masterbatch is PA6 modified with inorganic layered nanoparticles. The inorganic layered nanoparticles are a composite of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxides. The supramolecular ionic polymer exfoliated nano-montmorillonite is an exfoliated MMT composed of supramolecular ionic polymers containing melamine cations, polyfunctional imidazole cations and heteropolyacid anions between the layers. The supramolecular ionic polymer exfoliated layered double hydroxide is an exfoliated type of LDH composed of supramolecular ionic polymers containing sulfonic acid anions, diimidazole cations and heteropolyacid anions between the layers.

2. The high-barrier biaxially oriented polyamide film according to claim 1, characterized in that: The high-barrier biaxially oriented polyamide film has a thickness of 12~25μm, with the A layer and C layer each having a thickness of 2~4μm, and at least one side of the A and C layers undergoing corona treatment.

3. The high-barrier biaxially oriented polyamide film according to claim 1, characterized in that: The anti-sticking masterbatch is a modified polyamide masterbatch containing an opening agent, a slip agent, and a dispersant.

4. The high-barrier biaxially oriented polyamide film according to claim 1, characterized in that: The weight ratio of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide is 4 / 1 to 1 / 2, and the total content of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide in the high-barrier PA6 masterbatch is 20wt% to 30wt%.

5. The high-barrier biaxially oriented polyamide film according to claim 1, characterized in that: The weight ratio of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide is 4 / 1 to 1 / 2, and the total content of supramolecular ionic polymer exfoliated nano-montmorillonite and supramolecular ionic polymer exfoliated layered double hydroxide in the high-barrier MXD6 masterbatch is 30wt% to 40wt%.

6. The method for preparing a high-barrier biaxially oriented polyamide film according to claim 1, characterized in that... Includes the following steps: (1) Preparation of high-barrier MXD6 masterbatch: The supramolecular ionomer exfoliated nano-montmorillonite, supramolecular ionomer exfoliated layered double hydroxide, MXD6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material. The coarse material is crushed and mixed evenly with the coupling agent. The mixture is then melt-extruded and granulated using a twin-screw extruder to obtain the masterbatch product. The extruder temperature is set to 250~290ºC and the extruder speed is 300r / min~500r / min. After dehumidification and drying, the product is ready for use. (2) Preparation of high-barrier PA6 masterbatch: The supramolecular ionomer exfoliated nano-montmorillonite, supramolecular ionomer exfoliated layered double hydroxide, PA6, antioxidant, and hyperbranched rheology modifier are mixed in proportion, added to a kneader, and stirred evenly to obtain coarse material. The coarse material is crushed and mixed evenly with the coupling agent. The mixture is then melt-extruded and granulated using a twin-screw extruder to obtain the masterbatch product. The extruder temperature is set to 240~280ºC and the extruder speed is 300r / min~500r / min. After dehumidification and drying, the product is ready for use. (3) Mix the components in layers A, B, and C according to the proportions and disperse them evenly using a high-speed mixer; (4) The above-mentioned uniformly mixed layers are melted and co-extruded through three extruders, so that the melt is cast through a T-die to a quench roll with a surface temperature of 20~35 ºC for rapid cooling. (5) The above-mentioned castings are conditioned in a water bath at 30~75 ºC for 10 minutes. After conditioning, the surface of the castings is dried with an air knife to remove residual moisture. Then, they are stretched synchronously or in stages at a temperature of 130~190 ºC and a stretching ratio of 2.5~3.

5. (6) The film obtained above is heat-set and at least one of the A layer and C layer is corona treated. Then it is wound up and slit to obtain the film, wherein the film thickness is 12~25μm and the thickness of the A layer and C layer is 2~4μm.

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