A lightweight impact-resistant film material and a method for making the same

Abstract

The application discloses a light impact-resistant film material and a preparation method thereof. The preparation method comprises the following steps: S100, providing an outer base film and a core base film, foaming the outer base film and the core base film by using a supercritical fluid foaming method respectively to obtain an outer layer with one side surface foamed and a core layer with both side surfaces foamed, the outer layer has a first cell region on one side surface, the core layer has a second cell region on each of two sides, and the first cell region and the second cell region have cell structures inside; S200, arranging an adhesive on the surfaces of the outer layer and the core layer with cells respectively, so that the adhesive enters the cell structures exposed inside the first cell region and the second cell region; and S300, clamping the core layer between two outer layers to obtain the light impact-resistant film material, and the adhesive between the core layer and the outer layer forms an adhesive layer. The film material provided by the application is beneficial to preventing delamination of each layer of the film material and improving the use performance.

Description

Technical Field

[0001] This application relates to the field of polymer materials technology, and in particular to a lightweight impact-resistant membrane material and its preparation method. Background Technology

[0002] Currently, with the increasing demands for performance in the materials industry, single-function polymer materials are no longer sufficient to meet the increasingly stringent application requirements. Multilayer composite films, by stacking two or more polymer films with different functions, achieve performance integration and complementarity. This not only combines the advantages of each layer but also facilitates a synergistic performance effect of "1+1>2". Due to their superior designability and comprehensive performance, multilayer composite films have been widely used in high-end food packaging, aseptic pharmaceutical packaging, flexible electronic devices, automotive interiors, new energy battery separators, and aerospace.

[0003] However, existing multilayer films are prone to peeling, debonding, or interface cracking between adjacent layers when subjected to external stress or environmental factors. In other words, the inherent delamination defects of multilayer films have always been the core technical bottleneck restricting their reliability, durability, and application range.

[0004] Therefore, there is an urgent need to develop a lightweight, impact-resistant multilayer film material with good stability, service life, and mechanical properties, as well as a preparation method. Summary of the Invention

[0005] One objective of this application is to provide a lightweight impact-resistant membrane material and its preparation method, which helps to reduce the risk of delamination in the membrane material and further improves its stability and performance.

[0006] Another objective of this application is to provide a lightweight impact-resistant membrane material and its preparation method, which is beneficial to increasing the mechanical properties and impact resistance of the membrane material and further enhancing its market competitiveness.

[0007] To achieve the above objectives, the technical solution adopted in this application is as follows: a method for preparing a lightweight impact-resistant membrane material, comprising the following steps: S100, providing an outer base membrane and a core base membrane, immersing the outer base membrane and the core base membrane in a supercritical fluid for a preset saturation time, and then depressurizing and foaming to obtain an outer layer and a core layer, wherein the outer layer has a first pore region on the side near the core layer, and the core layer has a second pore region on the side near the outer layer, wherein the first pore region and the second pore region have a pore structure inside, the thickness of the first pore region is 1 / 4 to 1 / 2 of the thickness of the outer layer, and the thickness of the second pore region is 1 / 4 to 1 / 2 of the thickness of the core layer. S200: Apply adhesive to the surfaces of the outer layer and the core layer that have pores, such that the adhesive penetrates into the first pore region and the second pore region. The depth of the adhesive extending into the first pore region is not less than 1 / 4 of the thickness of the first pore region, and the depth of the adhesive extending into the second pore region is not less than 1 / 4 of the thickness of the second pore region. S300: Sandwich the core layer between the two outer layers to obtain a lightweight impact-resistant membrane material, wherein the adhesive between the core layer and the outer layer forms an adhesive layer.

[0008] In some embodiments, the surface of the outer layer forming the first pore region is a first contact surface, and the surface of the core layer forming the second pore region is a second contact surface, wherein the specific surface area of ​​the first contact surface is not less than the specific surface area of ​​the second contact surface.

[0009] In some embodiments, the cell size in the first cell region gradually increases from the side closer to the core layer to the side farther from the core layer, and the cell size in the second cell region gradually increases from the side closer to the outer layer to the side farther from the outer layer.

[0010] In some embodiments, the outer base film material includes polyethylene terephthalate, the core base film material includes polyethylene, the thickness of the outer layer is 100μm~300μm, and the thickness of the core layer is 150μm~500μm.

[0011] In some embodiments, in step S100, the saturation time of the outer base membrane is 5 min to 30 min, the saturation pressure is 10 MPa to 20 MPa, the saturation temperature is 100℃ to 220℃, and the pressure relief time is 1 s to 5 s; the saturation time of the core base membrane is 2 min to 30 min, the saturation pressure is 5 MPa to 20 MPa, the saturation temperature is 80℃ to 150℃, and the pressure relief time is 1 s to 5 s; the supercritical fluid is one or more of supercritical nitrogen and supercritical carbon dioxide.

[0012] In some embodiments, step S100 further includes the following steps: S110, providing an outer base film and a core base film, covering the surface of the outer base film that is not disposed opposite to the core base film with a gas barrier film, and covering the surface of the core base film that is not disposed opposite to the outer base film with a gas barrier film, so as to prevent supercritical fluid from dissolving into the outer base film and the core base film on the non-opposing surfaces; S120, immersing the outer base film and the core base film covered with the gas barrier film in supercritical fluid for a preset saturation time, and then depressurizing and foaming to obtain an outer layer and a core layer.

[0013] In some embodiments, the length of the pores in the first pore region and the second pore region in the vertical direction is not less than the length in the horizontal direction.

[0014] In some embodiments, step S200 further includes the steps of: S210, performing corona treatment on the side of the outer layer disposed relative to the core layer and the side of the core layer disposed relative to the outer layer; S220, applying an adhesive to the side of the outer layer near the core layer and the side of the core layer near the outer layer, so that the adhesive penetrates into the interior of the exposed cell structure in the first cell region and the second cell region.

[0015] In some embodiments, step S300 includes the steps of: placing and bonding the first pore area of ​​one outer layer with a second pore area of ​​the core layer, and after the adhesive has set to form an adhesive layer, placing and bonding the first pore area of ​​another outer layer with another second pore area of ​​the core layer, and after the adhesive has set to form an adhesive layer, obtaining a lightweight impact-resistant film material.

[0016] To achieve the above objectives, this application also provides a lightweight impact-resistant membrane material prepared by the aforementioned preparation method.

[0017] Compared with the prior art, the beneficial effects of this application are as follows: (1) This application introduces a pore structure into a multilayer membrane material using a supercritical fluid foaming method. The adhesive, with a certain degree of fluidity, can extend and fill the pore structure on the surface of the membrane material. This not only increases the bonding area between the membrane material surface and the adhesive, but also creates an interlocking structure between the adhesive layer formed after the adhesive cures and the adjacent layers, further enhancing the stability and mechanical properties of the membrane material. On the one hand, the introduction of a porous structure into the membrane material causes the gas inside the pores to be rapidly compressed when subjected to external forces, thus absorbing some of the impact energy. Furthermore, the pores will undergo bending, buckling, and plastic deformation under impact loads to further absorb impact energy. On the other hand, the multilayer membrane material with the introduced pore structure has lightweight characteristics, which helps reduce the overall weight of the membrane material, thereby improving economic efficiency.

[0018] (2) The multilayer membrane material prepared in this application is foamed by partially saturating the outer base membrane and the core base membrane, that is, foaming before the supercritical fluid is completely dissolved in the entire matrix, so that the pores are only distributed on a part of the surface of the matrix. This means that the pore structure will not significantly reduce the mechanical properties of the entire matrix, thereby increasing the performance of the membrane material. On the one hand, since the pore size obtained by partial saturation has a gradual increasing trend from the side closer to the adhesive to the side farther away from the adhesive, the dense pore structure is conducive to increasing the bonding area and increasing the number of interlocking structures formed between the adhesive layer and the two adjacent layers. On the other hand, the formation of vertically oriented pores in the first pore region and the second pore region is not only conducive to increasing the bonding area between the adhesive layer and the two adjacent layers, but also to increasing the depth of the adhesive layer extending into the pore structure, further increasing the interlayer bonding force, thereby reducing the risk of delamination of the multilayer membrane material, and is conducive to increasing the stability, service life and performance of the membrane material. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the layered structure of a lightweight impact-resistant membrane material in this application.

[0020] In the figure: 1. Lightweight impact-resistant membrane material; 10. Outer layer; 11. First cell area; 12. First contact surface; 20. Core layer; 21. Second cell area; 22. Second contact surface; 30. Adhesive layer. Detailed Implementation

[0021] The present application will be further described below with reference to specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0022] As used herein, the terms “prepared from” and “comprising” are synonymous. The terms “comprising,” “including,” “having,” “containing,” or any other variation thereof, as used herein, are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements and may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0023] When a quantity, concentration, or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range is disclosed as “1 to 5”, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range includes its endpoints and all integers and fractions within that range.

[0024] Approximate terms used in the specification and claims to modify quantities indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. Correspondingly, the use of "about," "approximately," etc., to modify a numerical value means that the invention is not limited to that precise value. In some instances, approximate terms may correspond to the precision of the instrument used to measure the value. In this application's specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.

[0025] like Figure 1 As shown, this application provides a method for preparing a lightweight impact-resistant membrane material 1, the method comprising the following steps: S100. Provide an outer base film and a core base film. Foam the outer base film and the core base film respectively using a supercritical fluid foaming method to obtain an outer layer with foamed one side surface and a core layer with foamed both sides surface. Specifically, one side surface of the outer layer 10 has a first pore region 11, and the two sides of the core layer 20 have second pore regions 21 respectively. The first pore region 11 and the second pore region 21 have pore structures inside. The thickness of the first pore region 11 is 1 / 4 to 1 / 2 of the thickness of the outer layer 10, and the thickness of the second pore region 21 is 1 / 3 to 2 / 3 of the thickness of the core layer 20. S200, Adhesive is applied to the surfaces of the outer layer 10 and the core layer that have pores, so that the adhesive enters the interior of the first pore region 11 and the second pore region 21; S300, a lightweight impact-resistant membrane material 1 is obtained by sandwiching the core layer 20 between two outer layers 10, wherein the adhesive between the core layer 20 and the outer layers 10 forms an adhesive layer 30.

[0026] It is worth mentioning that this application introduces a pore structure into the multilayer membrane material through a supercritical fluid foaming method. The adhesive, with a certain degree of fluidity, can extend and fill the pore structure on the surface of the membrane material. This not only increases the bonding area between the membrane material and the adhesive, but also, after the adhesive cures, the resulting adhesive layer 30 forms an interlocking structure with the adjacent layers, further enhancing the membrane material's stability and mechanical properties. On one hand, the introduction of a porous structure into the membrane material causes the gas within the pores to be rapidly compressed when subjected to external forces, thus absorbing some of the impact energy. Furthermore, the pores will undergo bending, buckling, and plastic deformation under impact loads to further absorb impact energy. On the other hand, the multilayer membrane material with the introduced pore structure is lightweight, which helps reduce the overall weight of the membrane material, thereby improving economic efficiency.

[0027] In some embodiments, the pores in the outer layer 10 are distributed only in the first pore region 11, and the pores in the core layer 20 are distributed only in the second pore region 21. The second pore region 21 is located on the upper and lower sides of the core layer 20. The thickness of the first pore region 11 is 1 / 4 to 1 / 2 of the thickness of the outer layer 10, specifically, the thickness of the first pore region 11 is 1 / 4, 1 / 3, or 1 / 2 of the thickness of the outer layer 10. The thickness of the second pore region 21 is 1 / 3 to 2 / 3 of the thickness of the core layer 20, specifically, the thickness of the second pore region 21 is 1 / 3, 1 / 2, or 2 / 3 of the thickness of the core layer 20. By providing pore regions with a certain distribution width in the outer layer 10 and the core layer 20, not only can the impact resistance of the membrane material be improved, but also the lightweighting of the membrane material can be achieved. On the other hand, since the adhesive can flow and fill the exposed cell structure within the cell region, the adhesive layer 30 formed by the adhesive can form a complex interlocking structure with the outer layer 10 and the core layer 20, further increasing the interlayer bonding performance. Furthermore, due to the tensile force generated during cell growth, certain open-cell structures may be formed between the cells, resulting in a certain cell-connected region within the cell region. Therefore, the adhesive can flow further within the cell-connected region, thereby increasing the depth of the adhesive layer 30 extending into the cell region, which is beneficial for increasing the bonding area.

[0028] In some embodiments, the adhesive extends to a depth of at least 1 / 4 of the thickness of the first cell region 11 and to a depth of at least 1 / 4 of the thickness of the second cell region 21. On the other hand, since the adhesive can flow and fill the exposed cell structure within the cell region, the adhesive layer 30 formed by the adhesive can form a complex interlocking structure with the outer layer 10 and the core layer 20, further increasing interlayer adhesion performance. Furthermore, due to the tensile force generated during cell growth, a certain open-cell structure may be formed between the cells, resulting in a certain cell-connected region within the cell region. Therefore, the adhesive can further flow within the cell-connected region, thereby increasing the depth of the adhesive layer 30 extending into the cell region, which is beneficial for increasing the bonding area.

[0029] In some embodiments, the surface of the outer layer 10 forming the first pore region 11 is the first contact surface 12, and the surface of the core layer 20 forming the second pore region 21 is the second contact surface 22. The specific surface area of ​​the first contact surface 12 is not less than the specific surface area of ​​the second contact surface 22. It is understood that the core layer 20 serves as a connecting layer between the two outer layers 10. Therefore, setting the specific surface area of ​​the first contact surface 12 to be not less than the specific surface area of ​​the second contact surface 22 can increase the bonding area between the adhesive layer 30 and the core layer 20, ensuring that the core layer 20 is securely disposed between the outer layers 10.

[0030] In some embodiments, the outer base film material is polyethylene terephthalate (PET), the core base film material is polyethylene (PE), the thickness of the outer layer 10 is 100 μm to 300 μm, the thickness of the core layer 20 is 150 μm to 500 μm, and the thickness of the adhesive layer 30 is 20 μm to 150 μm. It should be understood that polyethylene terephthalate (PET) has good mechanical strength, impact resistance, and tear resistance, making PET-made plastic bottles and packaging materials less prone to breakage during transportation and handling, thus ensuring the integrity of the packaging. Furthermore, PET has good barrier properties against oxygen and carbon dioxide, meaning that the outer layer 10 made of PET can effectively prevent oxygen from entering the packaging material, reducing the risk of food oxidation and spoilage. On the other hand, PET itself is a polymer material with good chemical stability and inertness, and is therefore widely used in packaging materials that can directly contact food, which helps improve the safety of the film material. Further, polyethylene (PE) has low water vapor permeability, which can effectively prevent the contents from becoming damp or dry. In other words, the combination of PET's good mechanical strength and PE's softness gives the packaging material good support and stiffness, as well as a certain degree of impact resistance.

[0031] In at least one specific embodiment, the outer base film material includes polyethylene terephthalate (PET) and a chain extender. Traditional PET, with its linear molecular chains, has low melt strength. During the cell growth process in the foaming process, the polymer undergoes rapid biaxial stretching, causing the cell walls to thin. If the polymer's melt strength is poor at this time, cell rupture, collapse, or coalescence can occur, resulting in uneven cell growth. Therefore, to improve the melt strength of PET, a chain extender can be used to extend the branched molecular chains of PET.

[0032] In at least one specific embodiment, the chain extender may be one or more of pyromellitic dianhydride and / or epoxy-functionalized acrylate copolymers. By selecting a suitable chain extender to perform a chain extension reaction on PET, it is beneficial to improve the foaming behavior of PET.

[0033] In some embodiments, in step S100, the saturation time of the outer base film is 5 min to 30 min, specifically, the saturation time of the outer base film is 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min; the saturation pressure is 10 MPa to 20 MPa, specifically, the saturation pressure is 10 MPa, 11 MPa, 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa, 17 MPa, 18 MPa, 19 MPa, or 20 MPa; and the saturation temperature is 100℃ to 220℃, specifically, the saturation temperature is 100℃. The temperatures range from 110℃ to 220℃, with pressure relief times of 1s to 5s, specifically 1s, 2s, 3s, 4s, and 5s. The saturation time of the core-base membrane is 2min to 30min, with saturation pressure of 5MPa to 20MPa and saturation temperature of 80℃ to 150℃. The pressure relief time is 1s to 5s, specifically 1s, 2s, 3s, 4s, and 5s. The supercritical fluid is one or more of supercritical nitrogen and supercritical carbon dioxide.

[0034] It should be understood that this application involves partially saturating the outer and core base films, meaning foaming occurs before the supercritical fluid is fully dissolved throughout the matrix, resulting in pores distributed only on a portion of the matrix surface. This implies that the pore structure does not significantly reduce the overall mechanical properties of the matrix, thereby increasing the performance of the membrane material. Furthermore, due to the gradually increasing pore size from the side closer to the adhesive to the side farther away from the adhesive, the dense pore structure helps increase the bonding area and the number of interlocking structures formed between the adhesive layer 30 and adjacent layers.

[0035] In some embodiments, the pore size in the first pore region 11 gradually increases from the side closer to the core layer 20 to the side farther from the core layer 20, and the pore size in the second pore region 21 gradually increases from the side closer to the outer layer 10 to the side farther from the outer layer 10. Since the outer base film and the core base film are not completely saturated in the supercritical fluid, meaning the solubility of the supercritical fluid in the outer base film and the core base film does not reach its extreme value but rather decreases with thickness distribution—that is, the solubility of the supercritical fluid gradually decreases from the outer side to the inner side of the first pore region 11 and the second pore region 21—during depressurization foaming, the outer side has a denser number of pore nucleation points, while the inner side has sparser pore nucleation points. This results in a large number of small-sized pore structures on the outer side and a small number of large-sized pore structures on the inner side. It should be understood that the large number of small-sized pore structures formed on the outer side increases the bonding area with the adhesive, thereby forming a dense interlocking structure with the adhesive layer 30. The formation of a small number of large-sized pores on the inner side helps to improve the impact resistance of the membrane material. Furthermore, since the large pores that absorb impact energy are located on the inner side of the membrane, the impact energy is reduced from acting on the interlayer, thereby increasing the interlayer adhesion and improving the stability of the membrane material in use.

[0036] In some embodiments, step S100 further includes the following steps: S110, providing an outer base film and a core base film, covering the surface of the outer base film that is not disposed opposite to the core base film with a gas barrier film, and covering the surface of the core base film that is not disposed opposite to the outer base film with a gas barrier film, so as to prevent the supercritical fluid from dissolving into the outer base film and the core base film on the non-opposing surfaces; S120, immersing the outer base film and the core base film covered with the gas barrier film in the supercritical fluid for a preset saturation time, and then depressurizing and foaming to obtain an outer layer and a core layer.

[0037] Understandably, by covering the non-opposing surfaces of the outer layer 10 and the core layer 20 with a gas-barrier membrane, supercritical fluid is prevented from dissolving into the outer and core base membranes on the non-opposing surfaces. This ensures that the supercritical fluid dissolves only in the outer and core base membranes on the side in contact with the adhesive layer 30, thus limiting the area containing the foam cells to the side in contact with the adhesive layer 30. This ensures that foaming occurs only on one side of the outer layer 10, while the opposite side and the side connected to the foamed side do not foam; similarly, foaming occurs only on two sides of the core layer 20, with the two sides connected to the foamed side not foaming. This improves the overall mechanical strength of the membrane material. Furthermore, since the foam cells are distributed horizontally in the first foam cell region 11 and the second foam cell region 21, when the membrane material is subjected to external impact, the horizontally distributed foam cell structure can uniformly absorb a portion of the impact energy, thereby reducing the risk of delamination between layers.

[0038] In some embodiments, the length of the cells in the first cell region 11 and the second cell region 21 in the vertical direction is not less than the length in the horizontal direction. It is worth noting that, because the gas-barrier membrane prevents the supercritical fluid from dissolving to the non-opposite side, when the supercritical fluid dissolved from the opposite side into the outer layer 10 and the core layer 20 undergoes depressurization and foaming, the gas preferentially escapes in the vertical direction. This results in vertically oriented cells forming in the first cell region 11 and the second cell region 21. This not only increases the bonding area between the adhesive layer 30 and the adjacent layers but also increases the depth of the adhesive layer 30 extending into the cell structure, forming a tree-like interlocking structure. This further increases the interlayer bonding force, thereby reducing the risk of delamination in the multilayer membrane material and improving the stability, service life, and performance of the membrane material.

[0039] In some embodiments, step S200 further includes the following steps: S210, performing corona treatment on the side of the outer layer 10 relative to the core layer 20 and the side of the core layer 20 relative to the outer layer 10; S220, applying adhesive to the side of the outer layer 10 near the core layer 20 and the side of the core layer 20 near the outer layer 10, so that the adhesive penetrates into the interior of the exposed cell structure in the first cell region 11 and the second cell region 21. By performing corona treatment on the exposed cells in the core layer 20 and the outer layer 10, the surface energy of the interior surface of the exposed cell structure can be increased, allowing the adhesive to penetrate and distribute more evenly and fully into the interior of the cell structure, which is beneficial for forming a stable interlocking structure between layers.

[0040] In at least one specific embodiment, the output power of the corona treatment is 1kW~6kW, the treatment voltage is 10kV~15kV, and the electrode spacing is not less than 1.5mm. With suitable corona treatment conditions, the surface energy of the inner surface of the cell structure can be increased, allowing the adhesive to more uniformly and fully penetrate and distribute within the cell structure, which is beneficial for forming a stable interlocking structure between layers.

[0041] In some embodiments, step S300 includes the following steps: placing and bonding a first pore region 11 of an outer layer 10 with a second pore region 21 of a core layer 20, and after the adhesive has set to form an adhesive layer 30, placing and bonding a first pore region 11 of another outer layer 10 with another second pore region 21 of the core layer 20, and after the adhesive has set to form an adhesive layer 30, a lightweight impact-resistant film material 1 is obtained. By bonding the outer layer 10 and the core layer 20 in stages, it is beneficial to improve the adhesion performance of the adhesive inside the pores.

[0042] In some embodiments, the adhesive is a water-based adhesive, such as a water-based acrylic adhesive, a water-based polyurethane adhesive, or other low-viscosity adhesive, so that the adhesive can penetrate into the interior of the cell structure.

[0043] This application also provides a lightweight impact-resistant membrane material 1 prepared by the above preparation method. The lightweight impact-resistant membrane material 1 provided by this application has a low risk of delamination in each layer and has good mechanical properties, impact resistance, stability and performance, which is conducive to further enhancing market competitiveness.

[0044] Example 1 A method for preparing a lightweight impact-resistant membrane material includes the following steps: (1) The PET foam matrix and the PE matrix are foamed by supercritical carbon dioxide method. The side of the PET matrix closer to the PE matrix is ​​the first opposite side. Polyimide film is adhered on the three non-opposite sides of the PET matrix. The two sides of the PE matrix closer to the PET matrix are the second opposite sides. Polyimide film is adhered on the two non-opposite sides of the PE matrix. The saturation time of PET is 20 min, the saturation pressure is 20 MPa, the saturation temperature is 150 ℃, and the pressure release time is 2 s. The saturation time of PE is 15 min, the saturation pressure is 15 MPa, the saturation temperature is 120 ℃, and the pressure release time is 2 s.

[0045] (2) Take a 200μm PET foam film as the outer layer, the thickness of the first foam region in the PET film is 78μm, take a 300μm PE foam film as the core layer, the thickness of the second foam region in the PE film near the upper PET layer is 71μm, and the thickness of the second foam region in the PE film near the lower PET layer is 73μm.

[0046] (3) Apply a water-based adhesive to the first contact surface of an outer layer and a second contact surface of a core layer, bond them together, and wait for the water-based adhesive to set. Then apply a water-based adhesive to the first contact surface of another outer layer and another second contact surface of the core layer, bond them together, and wait for the water-based adhesive to set to obtain a lightweight impact-resistant film material. The adhesive and adhesive layer extend to a depth of 42 μm into the first cell area, to a depth of 31 μm into the second cell area near the upper PET layer, and to a depth of 28 μm into the second cell area near the lower PET layer.

[0047] Example 2 The difference between Example 2 and Example 1 is that neither of the two PET layers was foamed in step (1).

[0048] Example 3 The difference between Example 3 and Example 1 is that the PE layer was not foamed in step (1).

[0049] Example 4 The difference between Example 4 and Example 1 is that the saturation time of PET in step (1) is 10 min, the thickness of the first cell region in the PET film is 92 μm, and the depth of the adhesive and adhesive layer extending into the first cell region is 19 μm.

[0050] Example 5 The difference between Example 5 and Example 1 is that the saturation time of PET in step (1) is 30 min, the thickness of the first cell region in the PET film is 53 μm, and the depth of the adhesive and adhesive layer extending into the first cell region is 14 μm.

[0051] Example 6 The difference between Example 6 and Example 1 is that the saturation time of PE in step (1) is 8 min, the thickness of the second pore region in the PE film near the upper PET layer is 57 μm, the thickness of the second pore region in the PE film near the lower PET layer is 55 μm, the depth of the adhesive and adhesive layer extending to the second pore region near the upper PET layer is 18 μm, and the depth of the adhesive and adhesive layer extending to the second pore region near the lower PET layer is 19 μm.

[0052] Example 7 The difference between Example 7 and Example 1 is that the saturation time of PE in step (1) is 30 min, the thickness of the second pore region in the PE film near the upper PET layer is 83 μm, the thickness of the second pore region in the PE film near the lower PET layer is 87 μm, the depth of the adhesive and adhesive layer extending to the second pore region near the upper PET layer is 38 μm, and the depth of the adhesive and adhesive layer extending to the second pore region near the lower PET layer is 40 μm.

[0053] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that neither the PET film nor the PE film is foamed.

[0054] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that one of the two PET films is not foamed.

[0055] Performance testing Tensile tests, peel force tests, oxygen permeability tests, and water vapor permeability tests were conducted on the lightweight impact-resistant membrane materials prepared in Examples 1 to 7 and Comparative Examples 1 to 2. The test results are shown in Table 1.

[0056] Table 1: Performance Tests of Lightweight Impact-Resistant Membranes

[0057] As can be seen from Examples 1 to 7 and Comparative Examples 1 to 2 in Table 1, introducing a pore structure into the multilayer membrane material by supercritical fluid foaming allows the adhesive to extend and fill the pore structure on the surface of the membrane material. This increases the bonding area between the membrane material surface and the adhesive. Furthermore, the adhesive layer formed after the adhesive has cured forms an interlocking structure with the two adjacent layers, further enhancing the stability and mechanical properties of the membrane material.

[0058] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claims. The scope of protection claimed by this application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a lightweight impact-resistant membrane material, characterized in that, Including the following steps: S100. Provide an outer base film and a core base film. Foam the outer base film and the core base film respectively using a supercritical fluid foaming method to obtain an outer layer with foamed one side surface and a core layer with foamed both sides surface. The outer layer has a first pore area on one side surface and a second pore area on each side of the core layer. The first pore area and the second pore area have pore structures inside. The thickness of the first pore area is 1 / 4 to 1 / 2 of the thickness of the outer layer and the thickness of the second pore area is 1 / 3 to 2 / 3 of the thickness of the core layer. S200. An adhesive is applied to the surfaces of the outer layer and the core layer that have pores, so that the adhesive enters into the first pore area and the second pore area. The depth of the adhesive extending into the first pore area is not less than 1 / 4 of the thickness of the first pore area, and the depth of the adhesive extending into the second pore area is not less than 1 / 4 of the thickness of the second pore area. S300. The core layer is sandwiched between the two outer layers to obtain a lightweight impact-resistant membrane material, and the adhesive between the core layer and the outer layers forms an adhesive layer. The size of the bubbles in the first bubble region gradually increases from the side closer to the core layer to the side farther from the core layer, and the size of the bubbles in the second bubble region gradually increases from the side closer to the outer layer to the side farther from the outer layer. Step S100 further includes the following steps: S110, providing an outer base film and a core base film, covering the surface of the outer base film that is not opposite to the core base film with a gas barrier film, and covering the surface of the core base film that is not opposite to the outer base film with a gas barrier film, to prevent supercritical fluid from dissolving into the outer base film and the core base film on the non-opposing surfaces; S120, immersing the outer base film and the core base film covered with the gas barrier film in supercritical fluid for a preset saturation time, and then depressurizing and foaming to obtain an outer layer and a core layer; The length of the bubbles in the first bubble region and the second bubble region in the vertical direction is not less than the length in the horizontal direction.

2. The preparation method according to claim 1, characterized in that, The surface of the outer layer forming the first pore area is the first contact surface, and the surface of the core layer forming the second pore area is the second contact surface. The specific surface area of ​​the first contact surface is not less than the specific surface area of ​​the second contact surface.

3. The preparation method according to claim 1, characterized in that, The outer base film material includes polyethylene terephthalate, the core base film material includes polyethylene, the thickness of the outer layer is 100μm~300μm, and the thickness of the core layer is 150μm~500μm.

4. The preparation method according to claim 3, characterized in that, In step S100, the saturation time of the outer base membrane is 5 min to 30 min, the saturation pressure is 10 MPa to 20 MPa, the saturation temperature is 100℃ to 220℃, and the pressure relief time is 1 s to 5 s; the saturation time of the core base membrane is 2 min to 30 min, the saturation pressure is 5 MPa to 20 MPa, the saturation temperature is 80℃ to 150℃, and the pressure relief time is 1 s to 5 s; the supercritical fluid is one or more of supercritical nitrogen and supercritical carbon dioxide.

5. The preparation method according to claim 1, characterized in that, Step S200 further includes the following steps: S210. Corona treatment is applied to the side of the outer layer that is disposed relative to the core layer and the side of the core layer that is disposed relative to the outer layer. S220. Apply an adhesive to the outer layer near the core layer and the core layer near the outer layer, so that the adhesive penetrates into the exposed cell structure in the first cell region and the second cell region.

6. The preparation method according to any one of claims 1 to 5, characterized in that, Step S300 includes the following steps: placing and bonding the first pore area of ​​one outer layer with a second pore area of ​​the core layer, and after the adhesive has set to form an adhesive layer, placing and bonding the first pore area of ​​another outer layer with another second pore area of ​​the core layer, and after the adhesive has set to form an adhesive layer, a lightweight impact-resistant film material is obtained.

7. A lightweight impact-resistant membrane material, characterized in that, It is prepared by any one of the preparation methods described in claims 1 to 6.

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