Structure for preventing surface tension decline of multi-layer co-extrusion film coating and forming method thereof

Abstract

The invention relates to the technical field of multi-layer co-extrusion films, in particular to a multi-layer co-extrusion film coating surface tension recession prevention structure and a forming method thereof.The multi-layer co-extrusion film coating surface tension recession prevention structure comprises a glue pouring groove, the lower end of an outer layer assembly is fixedly connected with a toughening structure in a bonded mode, and the glue pouring groove is formed between the outer layer assembly and the toughening structure; the inner side of the toughening structure is fixedly connected with an inner layer assembly in a bonding mode, the lower end of the inner layer assembly is fixedly connected with a moisture absorption structure in a bonding mode, the outer layer assembly comprises a diene layer, the top end of the diene layer is fixedly connected with a wear-resisting protruding block, the bottom end of the diene layer is fixedly connected with an upper connecting column, and the bottom end of the upper connecting column is fixedly connected with an upper connecting cone. According to the multi-layer co-extrusion film, the barrier property of the multi-layer co-extrusion film can be remarkably improved, it is ensured that the multi-layer co-extrusion film effectively prevents permeation of oxygen and water vapor, therefore, the internal structure is protected against the influence of moisture, and the shelf life of food is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of multi-layer co-extruded films, in particular to a structure for preventing surface tension decay of a multi-layer co-extruded film coating and a forming method thereof. Background Art

[0002] Multi-layer co-extrusion technology can combine different raw materials according to the requirements of film product performance. For example, PEN and PET belong to the same polyester category and have good compatibility. A layer of PEN can be extruded on one of the surface layers of the three-layer co-extrusion production line. The polyester film produced by this three-layer co-extrusion technology has better barrier properties, heat resistance and radiation resistance than ordinary polyester films. The structure of multi-layer co-extruded film can be divided into symmetrical structure and asymmetrical structure. The symmetrical structure layer is composed of three types of functional layers: barrier layer, adhesive layer and support layer. Among them, the role of the adhesive layer is to bond the barrier layer and the support layer to ensure the interlayer peeling force; Nylon 6 (PA6) is often used as a barrier layer in co-extruded films due to its good mechanical properties and heat resistance. In multi-layer co-extruded films, PA6 can provide barrier properties to gases and small molecules, but has poor barrier properties to water vapor. It has strong water absorption and swells with the increase of water absorption, which causes a sharp drop in gas and moisture barrier properties. Its strength and packaging size stability will also be affected. Therefore, in order to solve the above problems, a structure for preventing surface tension decay of multi-layer co-extruded film coating and a molding method thereof are proposed. Summary of the invention

[0003] The purpose of the present invention is to provide a multi-layer co-extruded film coating surface tension anti-decay structure and a molding method thereof, so as to solve the problem that PA6 can provide barrier properties for gases and small molecules, but has poor barrier properties for water vapor, strong water absorption, and swells with the increase of water absorption, which causes a sharp decline in gas and moisture barrier properties, and also affects its strength and packaging size stability.

[0004] To achieve the above object, the present invention provides the following technical solutions: A structure for preventing the surface tension of a multi-layer co-extruded film coating from decaying and a forming method thereof, comprising an outer layer component, wherein the lower end of the outer layer component is bonded and fixedly connected to a toughening structure, a glue pouring groove is arranged between the outer layer component and the toughening structure, an inner layer component is bonded and fixedly connected to the inner side of the toughening structure, a moisture absorbing structure is bonded and fixedly connected to the lower end of the inner layer component, the outer layer component comprises a diene layer, a wear-resistant bump is fixedly connected to the top of the diene layer, an upper connecting column is fixedly connected to the bottom end of the upper connecting column, an upper connecting cone is fixedly connected to the bottom end of the upper connecting column, the toughening structure comprises a lower connecting sheet, and the top end of the lower connecting sheet is fixedly connected to A middle connecting piece, wherein a grease filling hole is arranged on the inner side of the middle connecting piece, an upper connecting piece is fixedly connected to the top of the middle connecting piece, the inner layer component comprises a bonding layer structure, the bonding layer structure comprises a corona layer, a first hygroscopic layer is bonded and fixed to the bottom end of the corona layer, a lower connecting column is fixedly connected to the top end of the bonding layer structure, a lower connecting cone is fixedly connected to the top end of the lower connecting column, an outer convex column is fixedly connected to the bottom end of the bonding layer structure, an outer convex cone is fixedly connected to the bottom end of the outer convex column, the hygroscopic structure comprises a hygroscopic built-in layer, a first glue hole is opened on the inner side of the hygroscopic built-in layer, and a second glue hole is opened at the lower end of the hygroscopic built-in layer near the first glue hole.

[0005] As a further optimization content of the present invention, a glue pouring groove is set at the bottom end of the diene layer and the top end of the bonding layer structure, and the inside of the glue pouring groove is filled with Plexar® adhesive resin, and the top end of the Plexar® adhesive resin of the glue pouring groove is bonded to the bottom end of the diene layer, and the bottom end of the Plexar® adhesive resin of the glue pouring groove is bonded to the top end of the bonding layer structure.

[0006] As a further optimized content of the present invention, there are multiple wear-resistant protrusions, the wear-resistant protrusions are equidistantly arranged on the top of the diene layer, and the wear-resistant protrusions protrude from the top of the diene layer.

[0007] As a further optimization of the present invention, the upper connecting column is in the shape of a cylinder, the upper connecting cone is in the shape of a cone, and the number of the upper connecting columns is the same as the number of the upper connecting cones.

[0008] As a further optimization of the present invention, the shape of the lower connecting piece is the same as that of the upper connecting piece, a spacing is set between the bottom end of the upper connecting piece and the top end of the lower connecting piece, a plurality of middle connecting pieces are fixed at the bottom end of a single upper connecting piece, and a spacing is set between the plurality of middle connecting pieces.

[0009] As a further optimization content of the present invention, the top of the lower connecting piece is fitted with the top of the upper connecting cone, the upper connecting column is located between multiple middle connecting pieces, the lower connecting piece, the middle connecting piece and the upper connecting piece are located inside the glue pouring groove, and the upper connecting column and the upper connecting cone are located inside the glue pouring groove.

[0010] As a further optimization of the present invention, the grease filling holes provided in the middle connecting piece are filled with Plexar® adhesive resin, the top of the lower connecting piece and the bottom of the upper connecting piece are filled with Plexar® adhesive resin, and the space at the top of the lower connecting piece is connected with the space at the bottom of the upper connecting piece through the grease filling holes.

[0011] As a further optimization content of the present invention, the shapes of the lower connecting cone and the lower connecting column are the same as those of the upper connecting column and the upper connecting cone, the structural arrangement of the lower connecting cone and the lower connecting column is opposite to the structural arrangement of the upper connecting column and the upper connecting cone, the top end of the lower connecting cone is fitted with the bottom end of the upper connecting plate, and the lower connecting column is located between multiple middle connecting plates.

[0012] As a further optimization of the present invention, the shape of the external convex column is a cylinder, the shape of the external convex cone is a cone, the external convex column is bonded to the inside of the first glue hole by Plexar® adhesive resin, the external convex cone is bonded to the inside of the second glue hole by Plexar® adhesive resin, and the top of the hygroscopic built-in layer is bonded to the bottom of the bonding layer structure by Plexar® adhesive resin.

[0013] A method for forming a multi-layer co-extruded film coating surface tension anti-decay structure, S1: EVOH is used as the middle barrier layer, and then a polyolefin with good water resistance such as low-density polyethylene, linear low-density polyethylene or polypropylene is selected as the outer layer material to form a multi-layer co-extruded composite film. The structure of the multi-layer co-extruded film is designed. Typical structures include LDPE / EVOH / LDPE, LDPE / EVOH / EVA, PP / EVOH / PP, etc. These structures can effectively wrap the EVOH layer between the polyolefin layers. Through the co-extrusion process, the materials of different layers are extruded at the same time and formed into a diene layer, wear-resistant bumps, upper connecting columns and upper connecting cones. During the extrusion process, the EVOH layer is wrapped by the polyolefin layer to prevent EVOH from affecting its barrier properties due to moisture absorption, and air cooling is performed during the co-extrusion casting process; S2: Prepare PA6 as the matrix resin, dry PA6 and POE-g-MAH to remove moisture from the materials, adjust the amount of POE-g-MAH added to 20% for toughening effect, add the dried PA6 and POE-g-MAH to the twin-screw extruder in a certain proportion, heat and shear the extruder to fully mix PA6 and POE-g-MAH in a molten state, extrude the evenly mixed melt through the extruder die head, and water-cool or air-cool granulate to form a particle-shaped blend, extrude the inside of a specified mold to form a lower connecting piece, a middle connecting piece and a grease filling hole, then fit the upper connecting cone to the top of the lower connecting piece, and then fit the top of the lower connecting cone to the bottom of the upper connecting piece, and then fill the resin in the glue pouring tank; S3: PA6 and EVOH are dried to remove moisture from the materials to prevent hydrolysis or bubbles from occurring during processing. PA6 and EVOH are dried in a vacuum oven at 60°C and 90°C for 18 hours respectively. The dried EVOH and PA6 are mixed evenly in a certain proportion, and antioxidants and other additives are added. The mixed EVOH and PA6 are melt-extruded by a twin-screw extruder. The melt-blended materials are pelletized by water cooling to obtain EVOH / PA6 composite material particles. The dried masterbatch is added to the extrusion casting machine. It is squeezed into a special mold to form an overall hygroscopic structure to obtain a first composite layer and a second composite layer. The composite layer is co-extruded with the nylon layer and the EVOH barrier layer by an extruder, and then quenched and cast. After the cast sheet is humidified and blown dry, it is double-sided stretched and shaped to obtain a biaxially stretched inner layer component. Then, the hygroscopic structure is obtained, wherein the inner layer component is first produced and formed, and the upper end layer of the hygroscopic inner layer is corona-treated. At the same time, the hygroscopic inner layer is extruded between the outer convex column and the outer convex cone formed first, and the outer convex column and the outer convex cone are located inside the first glue hole and the second glue hole.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, by providing a diene layer, an upper connecting column and an upper connecting cone, and by wrapping an ethylene-vinyl alcohol copolymer (EVOH) layer between polyolefin layers with strong moisture barrier properties, the barrier properties of the multilayer co-extruded film can be significantly improved, ensuring that it effectively prevents the penetration of oxygen and water vapor, thereby protecting the internal structure from moisture and extending the shelf life of food. This structural design combines the excellent gas barrier properties of EVOH and the excellent water resistance of polyolefins to achieve a dual barrier effect against moisture and gas; 2. In the present invention, the lower connecting sheet, the middle connecting sheet and the upper connecting sheet are provided, and the application in the multi-layer co-extruded film coating provides excellent mechanical strength and toughness, excellent heat resistance and chemical resistance, while maintaining good processing performance and transparency. These characteristics make PA6 an ideal material for improving the barrier properties, wear resistance and environmental adaptability of the film coating; 3. In the present invention, by setting up the inner layer component and the hygroscopic structure, in the multi-layer co-extruded film obtained, the surface tension of the film is increased by corona treatment, and at the same time, a layer that can absorb moisture is extruded between the previously formed layers to ensure that the food is not affected by moisture and to increase the shelf life. This structural design not only enhances the surface tension of the film, but also effectively blocks moisture, thereby improving the moisture barrier properties of the film. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the structure of the outer layer component of the present invention; Figure 3 For the present invention Figure 2 A schematic diagram of the structure at A; Figure 4 It is a schematic diagram of the overall explosion structure of the present invention; Figure 5 Schematic diagram of the biolefin layer structure of the present invention; Figure 6 This is a schematic diagram of the structure of the lower connecting piece of the present invention; Figure 7 It is a schematic diagram of the connected piece structure in the present invention; Figure 8 It is a schematic diagram of the corona layer structure of the present invention; Fig. 9 This is a schematic diagram of the structure of the moisture-absorbing inner layer of the present invention; Fig.10 For the present invention Fig. 9 Schematic diagram of the structure at point B.

[0016] In the figure: 1. Glue filling tank; 2. Outer layer component; 21. Diene layer; 22. Wear-resistant bump; 23. Upper connecting column; 24. Upper connecting cone; 3. Toughening structure; 31. Lower connecting piece; 32. Middle connecting piece; 33. Grease filling hole; 34. Upper connecting piece; 4. Inner layer assembly; 41. Combination layer structure; 411. Corona layer; 412. First moisture absorption layer; 42. Lower connecting column; 43. Lower connecting cone; 44. External convex column; 45. External convex cone; 5. Hygroscopic structure; 51. Hygroscopic inner layer; 52. First glue hole; 53. Second glue hole. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0019] See also Figure 1-10 , the present invention provides a technical solution: A structure for preventing surface tension decay of a multi-layer co-extruded film coating and a forming method thereof, comprising an outer layer component 2, the lower end of the outer layer component 2 is bonded and fixedly connected to a toughening structure 3, a glue pouring groove 1 is arranged between the outer layer component 2 and the toughening structure 3, an inner layer component 4 is bonded and fixedly connected to the inner side of the toughening structure 3, a moisture absorbing structure 5 is bonded and fixedly connected to the lower end of the inner layer component 4, the outer layer component 2 comprises a diene layer 21, the top end of the diene layer 21 is fixedly connected to a wear-resistant protrusion 22, the bottom end of the diene layer 21 is fixedly connected to an upper connecting column 23, the bottom end of the upper connecting column 23 is fixedly connected to an upper connecting cone 24, the toughening structure 3 comprises a lower connecting piece 31, the top end of the lower connecting piece 31 is fixedly connected to a middle connecting piece 32, the middle connecting piece 3 2 is provided with a grease filling hole 33 on the inner side, the top of the middle connecting piece 32 is fixedly connected to the upper connecting piece 34, the inner layer component 4 includes a bonding layer structure 41, the bonding layer structure 41 includes a corona layer 411, the bottom end of the corona layer 411 is bonded and fixed to the first hygroscopic layer 412, the top of the bonding layer structure 41 is fixedly connected to the lower connecting column 42, the top of the lower connecting column 42 is fixedly connected to the lower connecting cone 43, the bottom end of the bonding layer structure 41 is fixedly connected to the outer convex column 44, the bottom end of the outer convex column 44 is fixedly connected to the outer convex cone 45, the hygroscopic structure 5 includes a hygroscopic built-in layer 51, the inner side of the hygroscopic built-in layer 51 is provided with a first glue hole 52, and the lower end of the hygroscopic built-in layer 51 near the first glue hole 52 is provided with a second glue hole 53.

[0020] As a further implementation of the present invention, a glue pouring groove 1 is provided between the bottom end of the diene layer 21 and the top end of the bonding layer structure 41, and the inside of the glue pouring groove 1 is filled with Plexar® adhesive resin. The top end of the Plexar® adhesive resin of the glue pouring groove 1 is bonded to the bottom end of the diene layer 21, and the bottom end of the Plexar® adhesive resin of the glue pouring groove 1 is bonded to the top end of the bonding layer structure 41, which can effectively bond different polymers together, especially in a multi-layer co-extrusion structure, and has excellent bonding strength to materials such as EVOH and PA; As a further implementation of the present invention, the number of the wear-resistant protrusions 22 is multiple, and the wear-resistant protrusions 22 are equidistantly arranged on the top of the diene layer 21. The wear-resistant protrusions 22 protrude from the top of the diene layer 21, which increases the friction coefficient of the film surface, improves the gripping force and stability of the film, which is very beneficial for subsequent processing and application processes; As a further implementation of the present invention, the upper connecting column 23 is in the shape of a cylinder, the upper connecting cone 24 is in the shape of a cone, and the number of the upper connecting columns 23 is the same as the number of the upper connecting cones 24, so as to improve the friction coefficient and wear resistance of the film and facilitate bonding and fixing with the toughening structure 3; As a further implementation of the present invention, the shape of the lower connecting piece 31 is the same as that of the upper connecting piece 34, a spacing is provided between the bottom end of the upper connecting piece 34 and the top end of the lower connecting piece 31, a plurality of middle connecting pieces 32 are fixed at the bottom end of a single upper connecting piece 34, a spacing is provided between the plurality of middle connecting pieces 32, the top end of the lower connecting piece 31 is fitted with the top end of the upper connecting cone 24, the upper connecting column 23 is located between the plurality of middle connecting pieces 32, the lower connecting piece 31, the middle connecting piece 32 and the upper connecting piece 34 are located inside the glue pouring groove 1, the upper connecting column 23 and the upper connecting cone 24 are located inside the glue pouring groove 1, the barrier performance and mechanical strength of the film are improved, and the stability and strength of the overall structure are enhanced; As a further implementation of the present invention, the grease filling holes 33 provided in the middle connecting piece 32 are filled with Plexar® adhesive resin, the top of the lower connecting piece 31 and the bottom of the upper connecting piece 34 are filled with Plexar® adhesive resin, and the space at the top of the lower connecting piece 31 is connected with the space at the bottom of the upper connecting piece 34 through the grease filling holes 33, thereby improving the overall stability and barrier properties of the film, and may also help to reduce material waste and improve production efficiency; As a further implementation scheme of the present scheme, the shapes of the lower connecting cone 43 and the lower connecting column 42 are the same as the shapes of the upper connecting column 23 and the upper connecting cone 24, and the structural arrangement of the lower connecting cone 43 and the lower connecting column 42 is opposite to the structural arrangement of the upper connecting column 23 and the upper connecting cone 24. The top of the lower connecting cone 43 is in contact with the bottom end of the upper connecting sheet 34, and the lower connecting column 42 is located between the plurality of middle connecting sheets 32. The outer convex column 44 is in the shape of a cylinder, and the outer convex cone 45 is in the shape of a cone. The outer convex column 44 is bonded to the inside of the first glue hole 52 by Plexar® adhesive resin, and the outer convex cone 45 is bonded to the inside of the second glue hole 53 by Plexar® adhesive resin. The top of the hygroscopic built-in layer 51 is bonded to the bottom end of the bonding layer structure 41 by Plexar® adhesive resin, thereby reducing deformation and stress concentration of the film during processing and use, thereby improving the durability and reliability of the film, absorbing moisture, ensuring that food is not affected by moisture, and improving the shelf life.

[0021] Workflow: The EVOH layer is wrapped between polyolefins with strong moisture barrier properties, such as PE or PP layers, to achieve the moisture barrier and gas barrier effects, to protect the internal structure from moisture. Ethylene-vinyl alcohol copolymer EVOH has excellent high barrier properties and can effectively prevent the penetration of gases such as oxygen and carbon dioxide. Its gas barrier property is 100 times higher than PA, 10,000 times higher than PE and PP, and dozens of times higher than the commonly used barrier material PVDC. First, EVOH is selected as the middle barrier layer, and then polyolefins with good water resistance, such as low-density polyethylene LDPE, linear low-density polyethylene LLDPE or polypropylene PP, are selected as the outer layer material to form a multi-layer co-extruded composite film, and a multi-layer co-extrusion composite film is designed. The structure of the extruded film, typical structures include LDPE / EVOH / LDPE, LDPE / EVOH / EVA, PP / EVOH / PP, etc. These structures can effectively wrap the EVOH layer between the polyolefin layers, and extrude the materials of different layers simultaneously through the co-extrusion process to form the diene layer 21, the wear-resistant protrusion 22, the upper connecting column 23 and the upper connecting cone 24. During the extrusion process, the EVOH layer is wrapped by the polyolefin layer to prevent the EVOH from affecting its barrier properties due to moisture absorption. In the co-extrusion casting process, the presence of air cooling has a significant effect on improving the tensile properties of the multi-layer composite barrier film. By controlling the air cooling process, a film with higher tensile strength and better barrier properties can be obtained; When increasing toughness under low temperature conditions, PA6 is prepared as the base resin. The application of nylon 6PA6 in multi-layer co-extruded film coatings provides excellent mechanical strength and toughness, excellent heat resistance and chemical resistance, while maintaining good processing performance and transparency. These characteristics make PA6 a good choice for improving the barrier, wear resistance and environmental adaptability of film coatings. POE-g-MAH maleic anhydride grafted polyolefin elastomer can only improve the water absorption of nylon, but also has excellent flexibility and elasticity, as well as POE-g-MAH as a toughening agent. Before blending, PA6 and POE-g-MAH need to be dried to remove moisture from the material to prevent hydrolysis or bubbles during processing. The toughening effect The addition amount of POE-g-MAH is adjusted to 20%, and the dried PA6 and POE-g-MAH are added to the twin-screw extruder in a certain proportion. The PA6 and POE-g-MAH are fully mixed in a molten state through the heating and shearing action of the extruder. The melt after uniform mixing is extruded through the extruder die head, and water-cooled or air-cooled granulated to form a particle-shaped blend, which is extruded inside a specified mold to form a lower connecting piece 31, a middle connecting piece 32 and a fat filling hole 33, and then the upper connecting cone 24 is fitted with the top end of the lower connecting piece 31, and then the top end of the lower connecting cone 43 is fitted with the bottom end of the upper connecting piece 34. At this time, the resin is filled inside the glue pouring groove 1 to form a whole, thereby improving their toughness and tensile strength; To achieve enhanced gas barrier and moisture barrier properties and ensure that the multi-layer co-extruded film has good surface tension, nylon 6PA6 and ethylene-vinyl alcohol copolymer EVOH are used to solve the hygroscopicity, toughness and gas barrier properties, which makes EVOH a barrier layer in the multi-layer co-extruded film. The combination of nylon 6PA6 and ethylene-vinyl alcohol copolymer EVOH can significantly improve the barrier properties, mechanical properties, processing properties, thermal stability, compatibility, chemical resistance and high and low temperature resistance of the material. Nylon 6PA6 and ethylene-vinyl alcohol copolymer EVOH are used for mixed molding. Before blending, PA6 and EVOH need to be dried to remove moisture from the material to prevent hydrolysis or bubbles during processing. PA6 and EVOH are dried in a vacuum oven at 60°C and 90°C for 18 hours respectively. The dried EVOH and PA6 are evenly mixed in a certain proportion. Antioxidants and other additives are also added in this process to improve the stability of the material. The mixed EVOH is extruded using a twin-screw extruder. EVOH and PA6 are melt-extruded, and the melt-blended material is water-cooled and pelletized to obtain particles of EVOH / PA6 composite material. The dried masterbatch is added to an extrusion casting machine and squeezed into a special mold to form a hygroscopic structure 5 as a whole to obtain a first composite layer and a second composite layer. The composite layer is co-extruded with a nylon layer and an EVOH barrier layer by an extruder, and then quenched and cast. After the cast sheet is humidified and blown dry, it is double-sided stretched and shaped to obtain a biaxially stretched inner layer component 4. The hygroscopic structure 5 is prepared; wherein the inner layer component 4 is first manufactured and formed, the upper end layer of the hygroscopic inner layer 51 is subjected to corona treatment, and the upper end of the corona layer 411 is subjected to corona treatment, which can increase the surface tension of the film, and at the same time, the hygroscopic inner layer 51 is squeezed out between the previously formed outer convex column 44 and the outer convex cone 45, and the outer convex column 44 and the outer convex cone 45 are located inside the first glue hole 52 and the second glue hole 53. The combined layer structure 41 and the hygroscopic inner layer 51 can absorb moisture, thereby ensuring that the food is not affected by moisture and improving the shelf life.

[0022] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A multi-layer co-extruded film coating surface tension anti-decay structure, comprising an outer layer component (2), characterized in that: The lower end of the outer layer component (2) is bonded and fixedly connected to a toughening structure (3), a glue injection groove (1) is provided between the outer layer component (2) and the toughening structure (3), the inner side of the toughening structure (3) is bonded and fixedly connected to an inner layer component (4), and the lower end of the inner layer component (4) is bonded and fixedly connected to a moisture absorption structure (5); The outer layer component (2) comprises a diene layer (21), the top end of the diene layer (21) is fixedly connected to a wear-resistant protrusion (22), the bottom end of the diene layer (21) is fixedly connected to an upper connecting column (23), the bottom end of the upper connecting column (23) is fixedly connected to an upper connecting cone (24), the toughening structure (3) comprises a lower connecting piece (31), the top end of the lower connecting piece (31) is fixedly connected to a middle connecting piece (32), the inner side of the middle connecting piece (32) is provided with a grease filling hole (33), the top end of the middle connecting piece (32) is fixedly connected to the upper connecting piece (34), the inner layer component (4) comprises a bonding layer structure (41), the bonding layer structure (41) comprises A corona layer (411), the bottom end of the corona layer (411) is bonded and fixed to a first hygroscopic layer (412), the top end of the bonding layer structure (41) is fixedly connected to a lower connecting column (42), the top end of the lower connecting column (42) is fixedly connected to a lower connecting cone (43), the bottom end of the bonding layer structure (41) is fixedly connected to an outer convex column (44), the bottom end of the outer convex column (44) is fixedly connected to an outer convex cone (45), the hygroscopic structure (5) comprises a hygroscopic inner layer (51), a first glue hole (52) is provided on the inner side of the hygroscopic inner layer (51), and a second glue hole (53) is provided at the lower end of the hygroscopic inner layer (51) near the first glue hole (52).

2. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: A glue pouring groove (1) is provided at the bottom end of the diene layer (21) and the top end of the bonding layer structure (41), and the inside of the glue pouring groove (1) is filled with Plexar® adhesive resin. The top end of the Plexar® adhesive resin of the glue pouring groove (1) is bonded to the bottom end of the diene layer (21), and the bottom end of the Plexar® adhesive resin of the glue pouring groove (1) is bonded to the top end of the bonding layer structure (41).

3. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The number of the wear-resistant protrusions (22) is plural, and the wear-resistant protrusions (22) are arranged at equal intervals on the top of the diene layer (21), and the wear-resistant protrusions (22) protrude from the top of the diene layer (21).

4. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The upper connecting column (23) is in the shape of a cylinder, the upper connecting cone (24) is in the shape of a cone, and the number of the upper connecting columns (23) is the same as the number of the upper connecting cones (24).

5. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The shape of the lower connecting piece (31) is the same as that of the upper connecting piece (34); a spacing is provided between the bottom end of the upper connecting piece (34) and the top end of the lower connecting piece (31); a plurality of middle connecting pieces (32) are fixed at the bottom end of a single upper connecting piece (34); and a spacing is provided between the plurality of middle connecting pieces (32).

6. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The top end of the lower connecting piece (31) is fitted with the top end of the upper connecting cone (24); the upper connecting column (23) is located between the plurality of middle connecting pieces (32); the lower connecting piece (31), the middle connecting piece (32) and the upper connecting piece (34) are located inside the glue pouring groove (1); and the upper connecting column (23) and the upper connecting cone (24) are located inside the glue pouring groove (1).

7. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The grease filling hole (33) provided in the middle connecting piece (32) is filled with Plexar® adhesive resin, the top end of the lower connecting piece (31) and the bottom end of the upper connecting piece (34) are filled with Plexar® adhesive resin, and the space at the top end of the lower connecting piece (31) is connected to the space at the bottom end of the upper connecting piece (34) through the grease filling hole (33).

8. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The shapes of the lower connecting cone (43) and the lower connecting column (42) are the same as those of the upper connecting column (23) and the upper connecting cone (24); the structural arrangement of the lower connecting cone (43) and the lower connecting column (42) is opposite to that of the upper connecting column (23) and the upper connecting cone (24); the top end of the lower connecting cone (43) is in contact with the bottom end of the upper connecting sheet (34); and the lower connecting column (42) is located between the plurality of middle connecting sheets (32).

9. The structure for preventing surface tension decay of a multi-layer co-extruded film coating according to claim 1, characterized in that: The outer convex column (44) is in the shape of a cylinder, and the outer convex cone (45) is in the shape of a cone. The outer convex column (44) is bonded to the inside of the first glue hole (52) by Plexar® adhesive resin, and the outer convex cone (45) is bonded to the inside of the second glue hole (53) by Plexar® adhesive resin. The top end of the hygroscopic built-in layer (51) is bonded to the bottom end of the bonding layer structure (41) by Plexar® adhesive resin.

10. A method for forming a structure for preventing surface tension decay of a multi-layer co-extruded film coating according to any one of claims 1 to 9, characterized in that: S1: EVOH is used as the middle barrier layer, and then a polyolefin with good water resistance such as low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE) or polypropylene (PP) is selected as the outer layer material to form a multi-layer co-extruded composite film. The structure of the multi-layer co-extruded film is designed. Typical structures include LDPE / EVOH / LDPE, LDPE / EVOH / EVA, PP / EVOH / PP, etc. These structures can effectively wrap the EVOH layer between the polyolefin layers. Through the co-extrusion process, the materials of different layers are extruded simultaneously and formed into a diene layer (21), a wear-resistant bump (22), an upper connecting column (23) and an upper connecting cone (24). During the extrusion process, the EVOH layer is wrapped by the polyolefin layer to prevent the EVOH from affecting its barrier properties due to moisture absorption, and air cooling is performed during the co-extrusion casting process; S2: PA6 is prepared as a matrix resin, and PA6 and POE-g-MAH are dried to remove moisture from the materials. The amount of POE-g-MAH added is adjusted to 20% for toughening effect. The dried PA6 and POE-g-MAH are added to a twin-screw extruder in a certain proportion. The extruder is heated and sheared to fully mix PA6 and POE-g-MAH in a molten state. The mixed melt is extruded through the extruder die head and granulated by water or air cooling to form a particle-shaped blend. The mixture is extruded into a designated mold to form a lower connecting piece (31), a middle connecting piece (32) and a grease filling hole (33). The upper connecting cone (24) is then fitted with the top of the lower connecting piece (31), and the top of the lower connecting cone (43) is then fitted with the bottom of the upper connecting piece (34). At this time, the resin is filled into the glue filling groove (1); S3: PA6 and EVOH are dried to remove moisture from the materials to prevent hydrolysis or bubbles from occurring during processing. PA6 and EVOH are dried in a vacuum oven at 60°C and 90°C for 18 hours respectively. The dried EVOH and PA6 are mixed evenly in a certain proportion, and antioxidants and other additives are added. The mixed EVOH and PA6 are melt-extruded by a twin-screw extruder. The melt-blended material is pelletized by water cooling to obtain EVOH / PA6 composite material particles. The dried masterbatch is added to an extrusion casting machine and squeezed into a special mold to form a hygroscopic structure (5) as a whole. A first composite layer and a second composite layer are prepared, and the prepared composite layer, a nylon layer and an EVOH barrier layer are co-extruded by an extruder, and then quenched and cast. After the cast sheet is humidified and blown dry, it is double-sided stretched and shaped to obtain a biaxially stretched inner layer component (4). Then, a hygroscopic structure (5) is prepared, wherein the inner layer component (4) is first formed, and the upper end layer of the hygroscopic inner layer (51) is corona-treated. At the same time, the hygroscopic inner layer (51) is extruded between the previously formed outer convex column (44) and the outer convex cone (45), and the outer convex column (44) and the outer convex cone (45) are located inside the first glue hole (52) and the second glue hole (53).

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