Micro-foaming flexible package composite film

Abstract

The utility model relates to the technical field of composite films, in particular to a micro-foaming flexible package composite film which comprises an outer layer film which is arranged on the outer surface, is in contact with the external environment and is resistant to abrasion, a middle layer film which is fixed on the outer layer film and is used for isolating gas, moisture and light, and an inner layer film which is in contact with package contents, adsorbs gas through a porous structure and insulates heat. The porous structure comprises an open pore structure for adsorbing gas and a closed pore structure for heat insulation and heat preservation, and the open pore structure and the closed pore structure are in gradient change; the utility model has the beneficial effects that: at the opening part of the foaming PE, foam holes are communicated with one another, and gas can be diffused through channels between hole walls, so that the internal air pressure of the package is adjusted, and the risk of bag expansion is reduced; the foam holes in the closed hole structure are mutually closed, heat conduction can be effectively blocked, heat insulation and heat preservation effects are provided, meanwhile, the impact strength of the material can be improved through the foam hole structure, and the material has the buffering performance in the transportation process.

Description

Technical Field

[0001] This utility model relates to the field of composite film technology, specifically to a micro-foamed flexible packaging composite film. Background Technology

[0002] In the field of flexible packaging such as wet wipes and hygiene products, traditional packaging materials (such as ordinary PE, CPP or aluminum-plastic composite film) have the following problems during temperature changes and transportation:

[0003] Summer issues with bulging and bursting packaging: In high-temperature environments, liquid-containing products such as wet wipes are prone to evaporation or gas generation, leading to increased internal pressure. This gas accumulation can cause the packaging to bulge, and during express delivery, compression can cause it to burst, resulting in leakage, product contamination, and microbial growth, impacting product safety and consumer experience.

[0004] Winter freezing issue: In cold environments (such as below freezing), the liquid inside the wipes may freeze, causing the product to harden, lose its softness and moisture, and severely impacting the user experience. This is because traditional packaging materials (such as single-layer PE or aluminum foil composite film) have insufficient thermal insulation properties and cannot effectively delay the impact of low temperatures on the contents.

[0005] Therefore, a micro-foamed flexible packaging composite film is needed to overcome the above problems. Utility Model Content

[0006] To address the aforementioned problems, this utility model provides a micro-foamed flexible packaging composite film, achieving the goal of solving the problems mentioned in the background art.

[0007] To achieve the above objectives, this utility model embodiment adopts the following technical solution: a micro-foamed flexible packaging composite film, comprising, from the outside to the inside: an outer film, disposed on the outer surface, in contact with the external environment, and wear-resistant; a middle film, fixed on the outer film, isolating gas, moisture, and light; and an inner film, in contact with the packaging contents, adsorbing gas and providing heat insulation through a porous structure; the porous structure includes an open-cell structure for adsorbing gas and a closed-cell structure for heat insulation, wherein the open-cell structure and the closed-cell structure exhibit a gradient change.

[0008] As a further improvement to the above technical solution:

[0009] The outer membrane is made of OPP material.

[0010] The middle layer membrane is made of VMPET material.

[0011] The inner membrane is made of foamed PE material.

[0012] The outer and middle layers, as well as the middle and inner layers, are all laminated using a dry lamination process.

[0013] The porous structure is a three-layer gradient structure, with the inner and middle layers being open-pore structures and the outer layer being a closed-pore structure, with a pore size of 20-50 micrometers.

[0014] The beneficial effects of this utility model embodiment are as follows:

[0015] In the open-cell portion of foamed PE, the cells are interconnected, allowing gas to diffuse through the channels between the pore walls, thereby regulating the internal air pressure of the packaging and reducing the risk of bag bulging. In the closed-cell structure, the cells are sealed off from each other, effectively blocking heat conduction and providing heat insulation. At the same time, the cell structure can improve the impact strength of the material, giving it cushioning properties during transportation. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is a schematic diagram of the multilayer structure in the inner membrane of this utility model.

[0018] In the diagram: 1. Outer membrane; 2. Middle membrane; 3. Inner membrane. Detailed Implementation

[0019] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0020] See Figures 1 to 2 This utility model discloses a micro-foamed flexible packaging composite film, comprising an outer film 1, a middle film 2, and an inner film 3 from the outside to the inside. The outer film 1 is disposed on the outer surface and is in direct contact with the external environment. It is made of OPP material and has excellent wear resistance and printability. The middle film 2 is fixed on the outer film 1 and is made of VMPET material, which can effectively isolate gases, moisture, and light, improving the barrier performance of the packaging. The inner film 3 is made of foamed PE material and is in direct contact with the contents of the packaging. It has a porous structure inside, including open-cell structures for gas adsorption and closed-cell structures for heat insulation. The open-cell and closed-cell structures are distributed in a gradient.

[0021] In the open-cell portion of foamed PE, the cells are interconnected, allowing gas to diffuse through the channels between the pore walls, thereby regulating the internal air pressure of the packaging and reducing the risk of bag bulging. In the closed-cell structure, the cells are sealed off from each other, effectively blocking heat conduction and providing heat insulation. At the same time, the cell structure can improve the impact strength of the material, giving it cushioning properties during transportation.

[0022] The outer membrane 1 and the middle membrane 2, as well as the middle membrane 2 and the inner membrane 3, are bonded using a dry lamination process. Specifically, OPP and VMPET are bonded using a conventional polyurethane adhesive, while the lamination between VMPET and foamed PE requires a lower viscosity polyurethane adhesive to ensure the adhesive can penetrate into the cell structure and enhance interlayer bonding. Furthermore, the lamination temperature must be controlled below the melting point of the foamed PE to avoid damaging the cell structure and affecting its air permeability and thermal insulation performance.

[0023] In this embodiment, the porous structure of the inner membrane 3 adopts a three-layer gradient design, wherein the inner and middle layers are open-pore structures, and the outer layer is a closed-pore structure, with the overall pore size controlled within the range of 20-50 micrometers. Its advantages are:

[0024] Inner / middle layer open structure: The cells are interconnected, allowing gases inside the packaging (such as water vapor or volatile components from wet wipes) to diffuse through the openings, absorb gases through the openings, and reduce pressure; the interconnected cell structure absorbs impact energy, provides cushioning protection, and prevents the contents from being damaged by vibration.

[0025] Outer closed-cell structure: As a buffer layer for gas diffusion, it enhances the packaging's pressure resistance. At the same time, the closed-cell structure effectively blocks heat conduction, mitigating the impact of external high or low temperatures on the contents. The closed-cell structure gives the material a higher elastic modulus, enhancing its pressure resistance and resisting external compression during transportation, thus reducing the risk of breakage.

[0026] By controlling the pore size within the range of 20-50 micrometers, it is possible to avoid thermal insulation failure due to excessively large pore size or gas diffusion efficiency due to excessively small pore size.

[0027] The three-layer gradient design gradually transitions from open to closed pores from the inside out, avoiding abrupt performance changes, reducing interlayer stress concentration, and improving the overall durability of the composite membrane.

[0028] Open-cell structures are prepared using a chemical foaming method. A chemical foaming agent (such as azodicarbonamide, ADCA) is added to the PE formulation. Upon heating, ADCA decomposes to generate gas (such as nitrogen). The released gas forms interconnected cells, which are then cooled and solidified to obtain the final open-cell structure. Closed-cell structures are prepared by adjusting the PE formulation, appropriately increasing the amounts of HDPE and m-PE to improve melt strength and stabilize the cell walls, thus forming a closed-cell structure.

[0029] This composite membrane structure, through optimized interlayer materials and foaming process, combines breathability, heat insulation, and impact resistance, effectively solving problems such as high-temperature swelling, low-temperature freezing, and transportation damage for products like wet wipes, thereby improving packaging safety and user experience.

[0030] It should be noted that in the description of this utility model, terms such as "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate direction or positional relationships, are based on the direction or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0031] Furthermore, it should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0032] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to those processes, articles, or apparatus / devices.

[0033] The technical solution of this utility model has been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the protection scope of this utility model is obviously not limited to these specific embodiments. Without departing from the principle of this utility model, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the protection scope of this utility model.

Claims

1. A micro-foamed flexible packaging composite film, characterized in that, From the outside to the inside, the following are included: The outer membrane (1) is set on the outer surface, in contact with the external environment, and is wear-resistant. The middle layer membrane (2) is fixed on the outer layer membrane (1) to isolate gas, moisture and light, and the inner layer membrane (3) is in contact with the contents of the packaging and adsorbs gas and provides heat insulation through its porous structure. The porous structure includes an open-pore structure for gas adsorption and a closed-pore structure for heat insulation, wherein the open-pore structure and the closed-pore structure exhibit a gradient change.

2. The micro-foamed flexible packaging composite film according to claim 1, characterized in that, The outer membrane (1) is made of OPP material.

3. The micro-foamed flexible packaging composite film according to claim 1, characterized in that, The middle layer membrane (2) is made of VMPET material.

4. The micro-foamed flexible packaging composite film according to claim 1, characterized in that, The inner membrane (3) is made of foamed PE material.

5. The microfoamed flexible packaging composite film according to any one of claims 1-4, characterized in that, The outer membrane (1) and the middle membrane (2), as well as the middle membrane (2) and the inner membrane (3), are all composited using a dry method.

6. The micro-foamed flexible packaging composite film according to claim 4, characterized in that, The porous structure is a three-layer gradient structure, with the inner and middle layers being open-pore structures and the outer layer being a closed-pore structure, with a pore size of 20-50 micrometers.

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