Multi-layer composite film with high barrier property
By bonding a high barrier multi-layer composite film on the polyethylene pipeline, the barrier problem after natural gas leakage is solved, and effective barriers to natural gas and pipeline stability are achieved.
Patent Information
- Application Number
- CN202422341245.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2025-07-22
- Estimated Expiration
- 2034-09-24
AI Technical Summary
The prior art is difficult to timely and effectively block polyethylene pipelines after natural gas leakage, resulting in waste of resources and safety hazards.
A high barrier-free multi-layer composite film is used, including an outer base resin layer, an outer base bonding resin layer, a metal layer and a hot melt adhesive layer. It is bonded to the damaged polyethylene pipeline peripheral surface through a hot melt adhesive layer. The total thickness of the outer base resin layer and the adhesive resin layer is 40 um to 120 um, the thickness ratio is 1:4 to 4:1, the thickness of the metal layer is 40 um to 60 um, and the metal layer has good barrier properties.
It realizes effective barriers to polyethylene pipelines after natural gas leakage, prevents natural gas leakage, ensures the stability and shelf life of the pipeline, reduces permeability, and improves safety.
Smart Images
Figure CN223134386U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of composite films, and more specifically, to a multi-layer composite film with high barrier properties. Background Art
[0002] Polyethylene pipes are commonly used for natural gas transportation. During the use of polyethylene pipes, due to the long-term exposure of polyethylene pipes to outdoor sunlight, rain, acid-base and other environments, polyethylene pipes will be affected by factors such as photo-aging, thermal aging, ultraviolet aging, and acid-base corrosion, resulting in damage to polyethylene pipes and natural gas leakage. This will not only cause waste of resources, but also may cause serious safety accidents.
[0003] Currently, the anti-leakage measures for natural gas pipelines only stay in the monitoring stage. When a polyethylene pipe is damaged, generally, the way of replacing the polyethylene pipe is adopted for repair. However, replacing the polyethylene pipe has problems such as long replacement time and affecting natural gas transportation, and it is difficult to effectively block the polyethylene pipe after natural gas leakage in a timely and effective manner. Summary of the Utility Model
[0004] In order to overcome the problem in the above-mentioned prior art that it is difficult to effectively block the polyethylene pipe after natural gas leakage in a timely and effective manner, the utility model provides a multi-layer composite film with high barrier properties, which can effectively block the polyethylene pipe after natural gas leakage.
[0005] To solve the above technical problems, the technical solution adopted by the utility model is: a multi-layer composite film with high barrier properties, the multi-layer composite film includes an outer substrate resin layer, an outer substrate adhesive resin layer, a metal layer, and a hot melt adhesive layer that are sequentially laminated and connected. The total thickness of the outer substrate resin layer and the outer substrate adhesive resin layer is 40um to 120um, the thickness ratio of the outer substrate resin layer to the outer substrate adhesive resin layer is 1:4 to 4:1, and the thickness of the metal layer is 40um to 60um.
[0006] In this technical solution, during use, by utilizing the bonding property of the hot melt adhesive layer, it can be bonded to the circumferential surface of the damaged polyethylene pipe. The outer substrate resin layer has a barrier property, and the outer substrate bonding resin layer has the property of bonding to the metal layer and can also be combined with the outer substrate resin layer simultaneously. The metal layer itself has excellent barrier effects against oxygen, water vapor, light, etc., can effectively prevent external gases and moisture from entering, ensure the stability and shelf life of the polyethylene pipe, and at the same time has a good barrier effect on the gas at the leaking part of the polyethylene pipe. Since the total thickness of the outer substrate resin layer and the outer substrate bonding resin layer is 40um to 120um, the thickness ratio of the outer substrate resin layer to the outer substrate bonding resin layer is 1:4 to 4:1, and the thickness of the metal layer is 40um to 60um, the multi-layer composite film has low permeability and high barrier property. When the multi-layer composite film is bonded to the circumferential surface of the damaged polyethylene pipe, it can effectively block the polyethylene pipe after natural gas leakage and prevent natural gas from leaking.
[0007] Preferably, the thickness of the outer substrate resin layer is 8um to 96um.
[0008] Preferably, the thickness of the outer substrate resin layer is 40um.
[0009] Preferably, the thickness of the outer substrate bonding resin layer is 8um to 96um.
[0010] Preferably, the thickness of the outer substrate bonding resin layer is 40um.
[0011] Preferably, the thickness of the metal layer is 50um.
[0012] Preferably, the metal layer is aluminum foil or alloy aluminum foil.
[0013] Preferably, the multi-layer composite film further includes an anti-corrosion layer, and the anti-corrosion layer is provided on at least one side of the metal layer.
[0014] Preferably, the thickness of the anti-corrosion layer is less than 1um, and more preferably, the thickness of the anti-corrosion layer is less than 0.2um.
[0015] Preferably, the outer substrate resin layer is high-density polyethylene.
[0016] Preferably, the permeability of the multi-layer composite film is less than 1 millidarcy, and more preferably, the permeability of the multi-layer composite film is less than 0.5 millidarcy.
[0017] Compared with the prior art, the beneficial effects of the present utility model are as follows: In the present utility model, since the total thickness of the outer substrate resin layer and the outer substrate adhesive resin layer is 40um to 120um, and the thickness ratio of the outer substrate resin layer to the outer substrate adhesive resin layer is 1:4 to 4:1, and the thickness of the metal layer is 40um to 60um, the multi-layer composite film has low permeability and high barrier properties. When the multi-layer composite film is bonded to the circumferential surface of a damaged polyethylene pipeline, it can effectively block the polyethylene pipeline after natural gas leakage and prevent natural gas leakage. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 is a schematic structural diagram of Embodiment 1 of the multi-layer composite film of the present utility model;
[0019] Figure 2 is a schematic structural diagram of Embodiment 4 of the multi-layer composite film of the present utility model.
[0020] In the drawings: 1. Outer substrate resin layer; 2. Outer substrate adhesive resin layer; 3. Anti-corrosion layer; 4. Metal layer; 5. Hot melt adhesive layer. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0021] The drawings are only for illustrative purposes and cannot be construed as a limitation of this patent; for better illustration of this embodiment, some components in the drawings will be omitted, enlarged or reduced, and do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted. The positional relationships described in the drawings are only for illustrative purposes and cannot be construed as a limitation of this patent.
[0022] In the drawings of the embodiments of the present utility model, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc. indicating the orientation or positional relationship, they are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the positional relationship in the drawings are only for illustrative purposes and cannot be construed as a limitation of this patent. For those of ordinary skill in the art, the specific meanings of the above terms can be understood according to specific circumstances.
[0023] The technical solutions of the present utility model will be further specifically described below through specific embodiments and in conjunction with the drawings:
[0024] Embodiment 1
[0025] Figure 1As shown in the figure, a multilayer composite film with high barrier properties. The multilayer composite film comprises an outer substrate resin layer 1, an outer substrate adhesive resin layer 2, a metal layer 4, and a hot melt adhesive layer 5, which are laminated and connected in sequence. The total thickness of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 is 40um to 120um, the thickness ratio of the outer substrate resin layer 1 to the outer substrate adhesive resin layer 2 is 1:4 to 4:1, and the thickness of the metal layer 4 is 40um to 60um.
[0026] In this embodiment, during use, due to the bonding property of the hot melt adhesive layer 5, it can be bonded to the circumferential surface of the damaged polyethylene pipeline. The outer substrate resin layer 1 has a barrier property, and the outer substrate adhesive resin layer 2 has the property of bonding with the metal layer 4 and can also be combined with the outer substrate resin layer 1 at the same time. The metal layer 4 itself has excellent barrier effects on oxygen, water vapor, light, etc., can effectively prevent external gases and moisture from entering, ensure the stability and shelf life of the polyethylene pipeline, and at the same time will have a good barrier effect on the gas at the place where the polyethylene pipeline has leaked. Since the total thickness of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 is 40um to 120um, the thickness ratio of the outer substrate resin layer 1 to the outer substrate adhesive resin layer 2 is 1:4 to 4:1, and the thickness of the metal layer 4 is 40um to 60um, the multilayer composite film has low permeability and high barrier properties. When the multilayer composite film is bonded to the circumferential surface of the damaged polyethylene pipeline, it can effectively block the polyethylene pipeline after natural gas leakage and prevent natural gas leakage.
[0027] It should be noted that due to the low bonding force between the metal layer 4 and the polyethylene pipeline, the hot melt adhesive layer 5 can make the composite film closely adhere to the surface of the polyethylene pipeline.
[0028] The outer substrate adhesive resin layer 2 can adopt an acid-modified polyethylene hydrocarbon resin with an MFR (190°C) of at least 2 - 25g / 10min and a modification degree of 0.5% - 1.5% by mass. This can ensure the adhesion between the outer substrate adhesive resin layer 2 and the metal layer while reducing the cost of producing the film material. The outer substrate adhesive resin layer 2 is selected as acid-modified polyethylene because the molecular weight of polyethylene is regularly arranged, with good chemical stability and low intrinsic viscosity, resulting in poor adhesion to the metal layer 4. Therefore, one or several of maleic anhydride, acrylic acid, methacrylic acid, acrylate, acrylamide, acrylonitrile, vinyl acetate, fumaric acid, etc. are used to graft-modify polyethylene to introduce active functional groups.
[0029] The outer substrate resin layer 1 can be made of high-density polyethylene. The content of high-density polyethylene in the outer substrate resin layer 1 is not less than 99.5% and not more than 99.85% by mass. Since the antioxidant used in the outer substrate resin layer 1 is a blend of polyethylene, a hindered phenol antioxidant, and a phosphite antioxidant, which are melt-extruded by co-casting, the addition amount of the hindered phenol is 0.1% - 0.3%, and the addition amount of the phosphite antioxidant is 0.05% - 0.2%. The outer substrate resin layer 1 can select an antioxidant because the outer substrate resin layer 1 is exposed to a high-temperature environment for a long time, especially in the presence of oxygen. The molecular chains in high-density polyethylene may break. This is because heat energy activates the weak bonds on the molecular chains, forming free radicals. These free radicals can initiate a chain reaction, leading to the degradation of the polymer. As the molecular chains break, the mechanical properties of the material, such as strength and toughness, will gradually decline. Ultraviolet radiation also causes the aging of high-density polyethylene. Ultraviolet light can excite the chemical bonds in the polymer, especially those in the non-crystalline regions, generating free radicals and initiating a series of oxidation reactions. These reactions will not only cause the polyethylene material to discolor and become brittle but also reduce its physical properties.
[0030] It should also be noted that the thickness of the metal layer 4 is 40um to 60um, and the thickness of the metal layer 4 is preferably 50um. The metal layer 4 can be an aluminum foil. The production process of the aluminum foil includes but is not limited to defects such as pinholes, wrinkles, uneven thickness, and slits being relatively low; and the tensile strength of the aluminum foil is above 80N / 15mm and below 150N / 15mm, which can endow the composite film with certain tensile and impact resistance properties; the aluminum foil itself has excellent barrier properties against oxygen, water vapor, light, etc., can effectively prevent external gases and moisture from entering, ensure the stability and shelf life of the polyethylene pipeline, and at the same time will have a good barrier effect on the gas at the leakage point of the polyethylene pipeline; the aluminum foil is not easily eroded by chemical substances, has relatively stable chemical properties, and is relatively easy to be compounded with polymer materials to form a composite film structure with excellent performance. The metal layer 4 can also be an alloy aluminum foil. The alloy aluminum foil can further improve the properties of the aluminum foil in terms of barrier properties, corrosion resistance, mechanical strength, ductility, etc. by adding a small amount of alloy; silicon and magnesium form the Mg2Si phase, which is distributed in the aluminum matrix and serves as a precipitation hardening phase to improve the strength and heat resistance of the material. Silicon can also improve the casting performance and corrosion resistance of the aluminum alloy. The addition of copper can further increase the strength and hardness of the alloy, but excessive copper will lead to a decrease in corrosion resistance. It can also affect the heat treatment effect of the alloy and promote the age hardening process. Manganese, as a deoxidizer, can purify the alloy, reduce oxide inclusions, and at the same time it can also improve the corrosion resistance and heat treatment effect of the alloy by forming a substitutional solid solution to strengthen the matrix. The addition amount of zinc is usually small, but it can refine the grains, improve the machining performance of the alloy, and may affect the age hardening characteristics of the alloy. Titanium and chromium are mainly used to refine the grains and improve the corrosion resistance of the alloy.
[0031] The total thickness of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 is 40 μm to 120 μm. This is because the raw material resins of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 are respectively heated and melted using an extruder, and the molten resins of the high-density polyethylene of the outer substrate resin layer 1 and the acid-modified low-density polyethylene of the outer substrate adhesive resin layer 2 are compounded by casting through a die head. The molten resin is quickly cooled into a film by a cooling roll with a smooth surface.
[0032] It should also be noted that the multi-layer composite film can be prepared by the following method. First, the metal layer 4 close to the outer substrate adhesive resin layer 2 is subjected to anti-corrosion treatment. The raw material particles of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 are respectively melted at high temperature by an extruder A and an extruder B. The molten particles from the extruder A and the extruder B are cast into a two-layer composite structure through the same distributor. The outer substrate adhesive resin layer 2 is bonded to the anti-corrosion layer 3 of the metal layer 4 through a post-heating roll and a cooling roll, so that there is a certain intermolecular force and physical riveting force between the outer substrate adhesive layer of the composite film material and the anti-corrosion layer 3. The sample is placed at a temperature of 45 °C for 2 days of curing treatment. Finally, the cured sample is coated with a hot melt adhesive layer 5, and thus the product production is completed.
[0033] To test the peel strength of the above multi-layer composite film, the following method can be used: The multi-layer composite film finished product is prepared into a straight strip shape, and the sample strip size is 100 * 15 mm. A tensile test device is used to conduct a peel test between the middle metal layer 4 and the hot melt adhesive layer 5. The film of the peeled hot melt adhesive layer 5 is placed in the upper clamping plate of the stretching test device, and the middle metal layer 4 is placed in the lower clamping plate. Then, under the condition that the stretching speed is 50 mm / min, a T-shaped peel with a peel angle of 180° is carried out, and the peel strength between the middle metal layer 4 and the hot melt adhesive layer 5 is measured. The peel strength is read in the following way: When the moving distance of the hot melt bonding resin layer and the middle metal layer 4 is 50 mm, the average value of the peel strength between 10 mm and 40 mm of the moving distance is selected. 5 samples per group are tested in parallel.
[0034] To test the permeability of the multi-layer composite film, the following method can be used: In a constant-temperature sealed container, the composite film material is used to separate the two sides. The film material is adhered to the constant-temperature sealed container using a strong sealant. Natural gas at 4 MPa and air at 0.13 MPa are continuously passed through the two sides separated by the composite film material in the constant-temperature sealed container respectively. When the gases on both sides in the sealed container pass through stably, the gas flow rate flowing out is continuously recorded.
[0035] The permeability is calculated using the following formula
[0036]
[0037] k a-- Permeability of the specimen, in millidarcies (mD); L -- Length of the specimen, in millimeters (mm); A -- Cross-sectional area of the specimen, in square millimeters (mm 2 ); P u -- Upstream gas pressure, in megapascals (MPa);
[0038] Pd -- Downstream gas pressure, in megapascals (MPa); Q d -- Downstream gas flow rate, in cubic millimeters per second (mm 3 / s); Ug - Dynamic viscosity coefficient.
[0039] The parameters for each test are as follows:
[0040] Test Example 1
[0041] In this test example, the thickness of the metal layer 4 is 40 um, the total thickness of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 40 um, the layer thickness ratio of the two is 1:4, and the actual layer ratio of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 8 um:32 um.
[0042] Test Example 2
[0043] In this test example, the thickness of the metal layer 4 is 40 um, the total thickness of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 40 um, the layer thickness ratio of the two is 4:1, the thickness of the metal layer 4 is 40 um, and the actual layer ratio of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 32 um:8 um.
[0044] Test Example 3
[0045] In this test example, the thickness of the metal layer 4 is 60 um, the total thickness of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 40 um, the layer thickness ratio of the two is 1:4, and the actual layer ratio of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 8 um:32 um.
[0046] Test Example 4
[0047] In this test example, the thickness of the metal layer 4 is 60 um, the total thickness of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 40 um, the layer thickness ratio of the two is 4:1, and the actual layer ratio of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 32 um:8 um.
[0048] Test Example 5
[0049] In this test example, the thickness of the metal layer 4 is 40 um, the total thickness of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 120 um, the layer thickness ratio of the two is 1:4, and the actual layer ratio of the outer substrate bonding resin layer 2 and the outer substrate resin layer 1 is 24 um:96 um.
[0050] Test Example 6
[0051] In this test example, the thickness of the metal layer 4 is 40 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 120 um, the layer thickness ratio of the two is 4:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 96 um:24 um.
[0052] Test Example 7
[0053] In this test example, the thickness of the metal layer 4 is 60 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 120 um, the layer thickness ratio of the two is 1:4, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 24 um:96 um.
[0054] Test Example 8
[0055] In this test example, the thickness of the metal layer 4 is 60 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 120 um, the layer thickness ratio of the two is 4:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 96 um:24 um.
[0056] Test Example 9
[0057] In this test example, the thickness of the metal layer 4 is 50 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 80 um, the layer thickness ratio of the two is 1:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 40 um:40 um.
[0058] Comparative Example 1
[0059] In this comparative example, the thickness of the metal layer 4 is 25 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 50 um, the layer thickness ratio of the two is 1:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 25 um:25 um.
[0060] Comparing Test Examples 1 - 9, in this comparative example, the thickness of the metal layer 4 is 25 um, which is relatively thin. There are pinhole defects on the metal foil film surface, and the pinholes are enlarged under the extrusion of long-term natural gas pressure, resulting in a decrease in the barrier performance of the multilayer composite film.
[0061] Comparative Example 2
[0062] In this comparative example, the thickness of the metal layer 4 is 50 um, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 40 um, the layer thickness ratio of the two is 1:5, and the actual layer ratio of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 6.67 um:33.33 um.
[0063] Comparative Test Examples 1-9. In this comparative example, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 40 μm, and the layer thickness ratio between the two is 1:5. The outer substrate adhesive resin layer 2 is relatively thin, and film surface defects occurred during the casting extrusion process, resulting in production failure.
[0064] Comparative Example 3
[0065] In this comparative example, the thickness of the metal layer 4 is 50 μm, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 40 μm, the layer thickness ratio between the two is 5:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 to the outer substrate resin layer 1 is 33.33 μm:6.67 μm.
[0066] Comparative Test Examples 1-9. In this comparative example, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 40 μm, and the layer thickness ratio between the two is 5:1. The outer substrate resin layer 1 is relatively thin, and film surface defects occurred during the casting extrusion process, resulting in production failure;
[0067] Comparative Example 4
[0068] In this comparative example, the thickness of the metal layer 4 is 90 μm, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 60 μm, the layer thickness ratio between the two is 1:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 to the outer substrate resin layer 1 is 30 μm:30 μm.
[0069] Comparative Test Examples 1-9. In this comparative example, the thickness of the metal layer 4 is 90 μm, the total thickness of the outer substrate adhesive resin layer 2 and the outer substrate resin layer 1 is 60 μm, the layer thickness ratio between the two is 1:1, and the actual layer ratio of the outer substrate adhesive resin layer 2 to the outer substrate resin layer 1 is 30 μm:30 μm; This solution can meet the performance requirements of the production process and permeability. However, in actual applications, with the increase in the thickness of the metal layer 4, it leads to an increase in the material manufacturing cost, and at the same time, it also increases the difficulty of subsequent construction, which is not applicable to the economy of the product.
[0070]
[0071] In the above table, ○ represents "excellent", □ represents "normal", and △ represents "poor". From the data in the above table, it can be seen that for the multilayer composite film, the total thickness of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 is 40 μm to 120 μm, the thickness ratio of the outer substrate resin layer 1 to the outer substrate adhesive resin layer 2 is 1:4 to 4:1, and the thickness of the metal layer 4 is 40 μm to 60 μm. The permeability of this multilayer composite film can meet the barrier treatment of polyethylene pipes after natural gas leakage. When the multilayer composite film is pasted on the polyethylene pipe where natural gas leakage occurs, it can prevent natural gas leakage.
[0072] Example 2
[0073] This Example 2 is similar to Example 1, the difference being that the thickness of the outer substrate resin layer 1 is 8 um to 96 um.
[0074] Among them, the thickness of the outer substrate resin layer 1 is 40 um.
[0075] Example 3
[0076] This Example 3 is similar to Example 1, the difference being that the thickness of the outer substrate adhesive resin layer 2 is 8 um to 96 um.
[0077] Among them, the thickness of the outer substrate adhesive resin layer 2 is 40 um.
[0078] In addition, the outer substrate resin layer 1 is high-density polyethylene. It should be noted that the high-density polyethylene content in the outer substrate resin layer 1 is below 99.85% and above 99.5% by mass. Since the outer substrate resin layer 1 is a blend of polyethylene and antioxidants composed of a compound use of a phenolic antioxidant and a phosphite antioxidant, which is melt-extruded by casting, the addition amount of the phenolic antioxidant is 0.1% - 0.3%, and the addition amount of the phosphite antioxidant is 0.05% - 0.2%. The outer substrate resin layer 1 can select antioxidants because the outer substrate resin layer 1 is exposed to a high-temperature environment for a long time, especially in the presence of oxygen. The molecular chains in high-density polyethylene may break. This is because heat energy activates the weak bonds on the molecular chains, forming free radicals, and these free radicals can trigger a chain reaction, leading to the degradation of the polymer. As the molecular chains break, the mechanical properties of the material, such as strength and toughness, will gradually decline. Ultraviolet radiation also causes the aging of high-density polyethylene. Ultraviolet light can excite the chemical bonds in the polymer, especially those in the non-crystalline regions, generating free radicals and triggering a series of oxidation reactions. These reactions will not only cause the polyethylene material to change color and become brittle, but also reduce its physical properties.
[0079] Example 4
[0080] Such as Figure 2As shown in the figure, a multilayer composite film with high barrier properties. The multilayer composite film includes an outer substrate resin layer 1, an outer substrate adhesive resin layer 2, a metal layer 4, and a hot melt adhesive layer 5 that are sequentially laminated and connected. The total thickness of the outer substrate resin layer 1 and the outer substrate adhesive resin layer 2 is 40um to 120um, and the thickness ratio of the outer substrate resin layer 1 to the outer substrate adhesive resin layer 2 is 1:4 to 4:1. The thickness of the metal layer 4 is 40um to 60um. The multilayer composite film further includes an anti-corrosion layer 3, and the anti-corrosion layer 3 is provided on at least one side of the metal layer 4. Specifically, there are the following situations for the setting position of the anti-corrosion layer 3: First, the anti-corrosion layer 3 can be provided between the outer substrate adhesive resin layer 2 and the metal layer 4, and the outer substrate adhesive resin layer 2 can bond the outer substrate resin layer 1 and the anti-corrosion layer 3 respectively. Second, the anti-corrosion layer 3 is provided between the metal layer 4 and the hot melt adhesive layer 5. Third, anti-corrosion layers 3 are provided both between the metal layer 4 and the hot melt adhesive layer 5 and between the outer substrate adhesive resin layer 2 and the metal layer 4. It should be noted that the anti-corrosion layer 3 mainly contains trivalent chromium compounds, inorganic acids, organic resins, crosslinking agents, solvents composed of water or organic solvents, or their mixtures. Among them, the proportions of the solvents composed of trivalent chromium compounds, inorganic acids, organic resins, water or organic solvents, or their mixtures are 1.9 - 6%, 0.3 - 6%, 0.6 - 6%, and 78.6 - 97.2% respectively. The crosslinking agent is 0.01 - 30% by mass ratio in the solid components of the anti-corrosion layer 3, or calculated based on the solid components in the solution for forming the anti-corrosion layer 3, the content is 0.05 - 15% by mass ratio. The anti-corrosion layer 3 is usually composed of trivalent chromium ions (Cr3+) and some auxiliary agents mainly because the trivalent chromium ions will undergo a reduction reaction in the acidic passivation solution to form a dense chromium oxide (Cr2O3) film. This film can cover the surface of the metal layer 4 and provide protection for the substrate of the metal layer 4 to prevent further oxidation and corrosion. The organic resin can enhance the bonding force between the passivation layer and the metal layer 4 and improve the adhesion of the passivation layer by forming a film layer; the crosslinking agent, as a cross-linking agent, can promote the formation of chemical bonds between the coating molecules or the active groups in the treatment solution in the passivation solution, thereby enhancing the network structure of the coating. This crosslinking can significantly improve the physical properties of the coating, such as water resistance, chemical resistance, abrasion resistance, and adhesion. In the passivation treatment, this helps to form a denser and more corrosion-resistant surface layer. The crosslinking agent can also increase the stability of the coating and reduce the coating damage caused by environmental factors (such as temperature changes, chemical erosion).
[0081] It should be noted that the peel strength and permeability test of the multilayer composite film in this Example 4 can also achieve the test effects of the multilayer composite film in Example 1, which will not be elaborated here one by one.
[0082] Among them, the thickness of the anti-corrosion layer 3 is less than 1um, and preferably the thickness of the anti-corrosion layer is less than 0.2um.
[0083] It should also be noted that in the above embodiments, the permeability of the multi-layer composite film is less than 1 millidarcy, and preferably less than 0.5 millidarcy. This can make the multi-layer composite film have good gas barrier properties for natural gas and prevent natural gas leakage. It should also be pointed out that the multi-layer composite film can not only be used for gas barrier of damaged pipelines for transporting natural gas, but also for pipeline barrier of transporting other gases, which will not be elaborated one by one here.
[0084] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.
Claims
1. A multilayer composite film with high barrier properties, characterized in that: The multi-layer composite film includes an outer substrate resin layer (1), an outer substrate adhesive resin layer (2), a metal layer (4), and a hot melt adhesive layer (5) that are sequentially laminated and connected. The total thickness of the outer substrate resin layer (1) and the outer substrate adhesive resin layer (2) is 40um to 120um. The thickness ratio of the outer substrate resin layer (1) to the outer substrate adhesive resin layer (2) is 1:4 to 4:
1. The thickness of the metal layer (4) is 40um to 60um.
2. The multilayer composite film with high barrier property according to claim 1, characterized in that: The thickness of the outer substrate resin layer (1) is 8um to 96um.
3. The multilayer composite film with high barrier property according to claim 2, characterized in that: The thickness of the outer substrate resin layer (1) is 40um.
4. The multilayer composite film with high barrier property according to claim 1, characterized in that: The thickness of the outer substrate adhesive resin layer (2) is 8um to 96um.
5. The multilayer composite film with high barrier property according to claim 4, characterized in that: The thickness of the outer substrate adhesive resin layer (2) is 40um.
6. The multilayer composite film with high barrier property according to claim 1, characterized in that: The thickness of the metal layer (4) is 50um.
7. The multilayer composite film with high barrier property according to claim 1, characterized in that: The metal layer (4) is an aluminum foil or an alloy aluminum foil.
8. The multilayer composite film with high barrier property according to any one of claims 1 to 7, characterized in that: The multi-layer composite film further includes an anti-corrosion layer (3), and the anti-corrosion layer (3) is provided on at least one side of the metal layer (4).
9. The multilayer composite film with high barrier property according to claim 8, characterized in that: The thickness of the anti-corrosion layer (3) is less than 1um.
10. The multilayer composite film with high barrier property according to claim 1, characterized in that: The outer substrate resin layer (1) is high-density polyethylene.
11. The multilayer composite film with high barrier property according to claim 1, characterized in that: The permeability of the multi-layer composite film is less than 1 millidarcy.