Polyethylene-based single-material composite hose and method of manufacturing the same

Abstract

The application discloses a single-material composite hose based on PE and a preparation method thereof, and belongs to the technical field of composite hoses.The single-material composite hose based on PE is prepared by butt joint or lap joint of a single-material composite sheet based on PE and injection molding of a pipe shoulder.The single-material composite sheet based on PE comprises, in sequence, an outer PE film, a bonding layer, an aluminum-plated PE film, a bonding layer and an inner PE film.The PE material used in the aluminum-plated PE film comprises the following components in parts by weight: linear low-density polyethylene 68-79 parts, low-density polyethylene 8-15 parts, grafted PE 15-25 parts and additives 0-4 parts.The grafted PE is prepared by graft copolymerization of 4-maleimide phenol and polyethylene glycol with a pyridine or bipyridine group at an end group.The modified PE material is used as the aluminum-plated film material, effectively enhances the bonding force between the aluminum-plated film and the base material, and improves the heat deformation resistance of the PE film.

Description

Technical Field

[0001] The present invention relates to the technical field of composite hoses, and in particular to a PE-based single-material composite hose and a preparation method thereof. Background Art

[0002] Flexible tube packaging refers to a type of flexible container used for pasty or viscous liquid products. It features lightweight, easy portability, durability, recyclability, ease of extrusion, excellent processability, and printability. Furthermore, it's inexpensive compared to plastic bottles, making it a popular choice for manufacturers of cosmetics and other products. Currently, the composite flexible tube packaging materials used in toothpaste, cosmetics, and pharmaceuticals are primarily aluminum-plastic or all-plastic composite structures. Aluminum-plastic composite flexible tubes are made by co-extruding aluminum foil and plastic film into sheets, which are then processed into a tubular shape using specialized tube-forming machines. A typical structure is PE / PE+EAA+AL+EAA+PE. The aluminum foil, as a barrier layer, offers excellent light, oxygen, and water barrier properties. However, aluminum foil is expensive and has poor tear resistance, making it susceptible to punctures and tears during production and processing, further increasing production costs. Compared with aluminum foil, aluminum-coated film has a greater cost advantage and has the following advantages: (1) aluminum-coated film has good physical and mechanical properties and is not prone to bending, wrinkling, breaking, etc. during composite processing, which is conducive to improving production efficiency and qualified product rate; (2) aluminum-coated film is conductive, which can avoid quality problems or failures caused by static electricity during processing, facilitating safe production. In particular, when packaging powdered items, aluminum-coated film can play a role in eliminating static electricity, ensuring good sealing performance. (3) The main energy consumed by aluminum-coated products is electricity. No wastewater or waste gas is generated during the production process, and the residual aluminum oxide can be recycled and reused; (4) The amount of aluminum deposited on the surface of the aluminum-coated film during aluminum plating is very small (generally only 350~400 angstroms), so it can be considered that the nature of its base material has not been changed. From an environmental perspective, aluminum-coated films are still a "single material", so they can be more easily classified for recycling or incineration.

[0003] The most commonly used processing method for aluminum coating is vacuum coating. Vacuum coating is a process in which the coating material is deposited on the surface of the substrate under vacuum to form a thin film. Common vacuum coating methods include evaporation coating, sputtering coating, ion coating, electron beam coating, etc. The Yanfa coating method is a method in which the coating material is heated in a high vacuum, causing it to evaporate in a very short time and deposited on the surface of the substrate to form a film layer. The plastic used for vacuum coating must meet the following conditions: (1) It should have good bonding strength with the coating material; (2) The gas volume during vacuum coating should be small; (3) The film should have good thermal stability and not be easily deformed by heat. Commonly used plastics include PET, PA, BOPP, PE, etc. Among them, PE film has low hygroscopicity and meets the condition of small gas volume during vacuum coating compared to hygroscopic film materials such as PA and PET. However, PE has low surface tension and poor coating firmness, and the aluminum coating layer is prone to transfer. In addition, PE has poor heat resistance and is prone to shrinkage and deformation when heated. Currently, there is little research on PE film modification and aluminum coating. Summary of the Invention

[0004] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a single-material composite hose based on PE and a preparation method thereof, by preparing a PE film having good bonding strength with the aluminum-plated layer and good heat resistance, thereby preparing a composite hose with a single material, so that it meets the environmental protection performance requirements of easy recycling and classification.

[0005] The technical solutions for achieving the purpose of the present invention are as follows:

[0006] A PE-based single-material composite hose, the composite hose being made by butting or overlapping PE-based single-material composite sheets and then injection-molding a tube shoulder, the PE-based single-material composite sheet sequentially comprising an outer PE film, a first adhesive layer, an aluminized PE film, a second adhesive layer, and an inner PE film;

[0007] The PE material used in the aluminized PE film includes the following components by weight: 68-79 parts of linear low-density polyethylene, 8-15 parts of low-density polyethylene, 15-25 parts of grafted PE, and 0-4 parts of an additive; the grafted PE has the structure described in Formula 1:

[0008]

[0009] Formula 1,

[0010] Where R is or A type of equation, where a:b:c is (1~5):100:(1~5), and n is a natural number from 8 to 15.

[0011] In a specific embodiment, the outer PE film is a highly transparent PE film with a thickness of 50 to 80 μm; the aluminized PE film is a high-gloss aluminized BOPE or aluminized MDOPE, the thickness of the aluminized layer is 20 to 60 nm, the PE layer is 25 to 60 μm, and the aluminized layer faces the inner layer; the thickness of the inner PE film is 250 to 300 μm.

[0012] In a specific embodiment, the first adhesive layer is selected from at least one of maleic anhydride grafted PE, ethylene-methacrylic acid copolymer resin layer, and ethylene-acrylic acid copolymer, and the second adhesive layer is selected from ethylene-acrylic acid copolymer. The thickness of the first adhesive layer and the second adhesive layer is 20~50μm.

[0013] In a specific embodiment, the low-density polyethylene or linear low-density polyethylene has a melt flow rate of 1 to 3 g / 10 min at 190° C. and 2.16 kg.

[0014] In a specific embodiment, the auxiliary agent is 0-2 parts of antioxidant and 0-2 parts of lubricant.

[0015] In a specific embodiment, the preparation method of the grafted PE is:

[0016] S1. 4-formyl-2,2-bipyridyl or isonicotinic acid is chlorinated with oxalyl chloride under anhydrous and oxygen-free conditions to obtain an intermediate. The intermediate is purified and mixed with polyethylene glycol monoallyl ether and triethylamine. The mixture is heated to 40-60° C. and reacted for 2-6 hours to obtain monomer 1.

[0017] S2. The monomer 1, 4-maleimidophenol monomer, initiator, and polyethylene particles are grafted through a torque rheometer-twin-screw extruder at a reaction temperature of 180-220°C for 5-20 minutes. After the reaction, the grafted polyethylene is refluxed in xylene and then precipitated in acetone to remove unreacted monomer, initiator, and homopolymer. Finally, the grafted PE is dried to obtain the grafted PE.

[0018] In a specific embodiment, the molar ratio of the 4-formic acid-2,2-bipyridyl or isonicotinic acid to oxalyl chloride is 1:(1.2-1.5); the molar ratio of the intermediate to polyethylene glycol monoallyl ether is 1:(1.01-1.2), and the polyethylene is metallocene polyethylene.

[0019] In a specific embodiment, the method for preparing the aluminized PE film comprises the following steps:

[0020] S1. The linear low-density polyethylene, low-density polyethylene, grafted PE, additives were mixed in proportion, added to a twin-screw extruder, extruded, cooled, pelletized, and dried to obtain the PE material used for the aluminized PE film;

[0021] S2. A BOPE or MBOPE film is obtained by a biaxial stretching process or a uniaxial stretching process;

[0022] S3. Aluminum is plated on the surface of the PE film by vacuum coating technology to obtain an aluminized PE film.

[0023] In a specific embodiment, the outer PE film, by weight, includes 70-90 parts of linear low-density polyethylene, 10-30 parts of low-density polyethylene, 0.1-0.5 parts of nucleating agent, 0.1-2 parts of antioxidant, and 0-1 parts of lubricant; the inner PE film, by weight, includes 80-90 parts of low-density polyethylene, 10-20 parts of linear low-density polyethylene, 0-1 parts of lubricant, and 0.1-2 parts of antioxidant.

[0024] The present invention also protects a method for preparing the PE-based single-material composite hose, comprising the following steps:

[0025] S1. The outer PE film, the first adhesive layer and the aluminized PE film are bonded together by a dry lamination process or an extrusion lamination process;

[0026] S2. The composite sheet obtained in step S1, the second adhesive layer and the inner PE film are bonded together by a dry lamination process or an extrusion lamination process to obtain a single material composite sheet;

[0027] S3. The edges of the single material composite sheet are welded by overlapping or butting;

[0028] S4. Injection mold the upper tube shoulder on the hose at an injection temperature of 200-260°C, a pressure of 20-50 bar, and a cooling temperature of 10-20°C.

[0029] In a specific embodiment, the butt joint is formed by adding a transparent welding strip on the weld seam and welding them together through a high-frequency induction coil, with a high-frequency energy of 30%-100%; a cooling temperature of 15-22°C; and a pressure of 2-5kg.

[0030] In a specific embodiment, the overlap size is 2-2.5 mm; the induction heating temperature is 85-95° C., and the weld compression ratio after pressurization is 5-20%.

[0031] Beneficial effects

[0032] The present invention provides a single-material composite hose based on PE and a preparation method thereof, which has the following beneficial effects: First, the outer layer, middle layer, inner layer and adhesive layer materials are all composited based on PE materials, which provides convenience for the recycling of packaging materials after the end of their use cycle; Second, the use of aluminized PE film instead of traditional aluminum foil not only saves costs, but also the characteristic of aluminized PE that is not easy to break facilitates production and processing. 3. The present invention adds a grafted PE obtained by grafting 4-maleimidophenol and polyethylene glycol with a pyridine or bipyridine group at the end to the PE film material used for the aluminum-plated PE film. The abundant ether bonds on the polyethylene glycol and the terminal hydroxyl groups of the 4-maleimidophenol greatly improve the hydrophilicity of the PE film, thereby increasing the surface tension of the PE film and making it have a stronger binding force with aluminum vapor during vacuum aluminum plating; secondly, the 4-maleimidophenol structure has heat resistance, and its grafting onto the PE chain segment can increase the heat deformation temperature of the PE composite material; finally, the nitrogen on the pyridine or bipyridine can react with the aluminum vapor in the atomic state, thereby further improving the binding force between the aluminum-plated film and the PE film, reducing aluminum migration, and increasing the density of the aluminum film layer, so that the composite hose obtained can achieve oxygen barrier properties and water vapor barrier properties close to those of aluminum foil. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of the synthetic route of monomer 1;

[0034] Figure 2 is the H NMR spectrum of monomer 1;

[0035] Figure 3 The infrared spectra of metallocene polyethylene and grafted PE. DETAILED DESCRIPTION

[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0037] In the examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0038] The raw materials used in the embodiments and comparative examples are now described as follows:

[0039] Linear low-density polyethylene: DFDC7050, Sinopec, melt flow rate at 190°C, 2.16 kg: 2 g / 10 min;

[0040] Low-density polyethylene: LD 2119.LN Molding, ExxonMobil, melt flow rate 2.1 g / 10 min at 190 °C and 2.16 kg;

[0041] Metallocene polyethylene: Exact™ 3132, ExxonMobil, melt flow rate 3.0 g / 10 min at 190°C and 2.16 kg;

[0042] Monomer 1: Homemade, preparation method is as follows:

[0043] Under anhydrous and oxygen-free conditions, 0.1 mol of 4-formyl-2,2-bipyridine was added to 100 ml of anhydrous dichloromethane. 0.12 mol of oxalyl chloride was added dropwise in an ice bath at 0-5°C. After the addition was complete, the temperature was raised to 40°C and the mixture was stirred for 1 hour. The excess oxalyl chloride and solvent were removed by distillation under reduced pressure to obtain 4-formyl-2,2-bipyridine. 0.1 mol of 4-formyl-2,2-bipyridine and 0.11 mol of polyethylene glycol monoallyl ether (molecular weight 500) were dissolved in tetrahydrofuran, 0.15 mol of triethylamine was added, the temperature was raised to 45°C, and the mixture was stirred for 4 hours. After the reaction, the reaction was quenched with a saturated sodium bicarbonate solution, and the organic phase was separated and washed three times with a saturated NaCl solution, dried over anhydrous magnesium sulfate, filtered, and then the solvent was removed by rotary evaporation to obtain a crude product. The crude product was eluted by column chromatography (silica gel column, eluent: 9:1 petroleum ether-ethyl acetate system) to obtain monomer 1 with a yield of 92%. The H NMR spectrum of monomer 1 is as follows: Figure 2 As shown, from the chemical shift and integration of H NMR spectrum, it can be seen that monomer 1 was successfully synthesized.

[0044] Monomer 2: 4-maleimidophenol, 98%, Shanghai Haohong Biopharmaceutical Technology Co., Ltd.;

[0045] Grafted PE: Monomer 1 and monomer 2 are grafted onto metallocene polyethylene using a torque rheometer-twin screw extruder. Metallocene polyethylene containing different weight percentages of monomer 1 and monomer 2 and 0.1 parts by weight of diisopropylbenzene peroxide as an initiator is added to the barrel. The specific ratio is shown in Table 1. It is maintained at 200°C for 10 minutes and the screw speed is 70-80 rpm. All grafted polyethylenes are refluxed in xylene for 4 hours and then precipitated in acetone to remove unreacted monomers, excess initiator and oligomers that may be formed during processing. Afterwards, it is dried in a vacuum oven at 70°C for 24 hours to constant weight. The grafting rate (%G) is determined by the gravimetric method according to the following relationship: %G=(W g -W0) / W0×100%; where W0 and W gare the weights of the original polyethylene and the grafted polyethylene, respectively. The grafted PE was subjected to infrared spectroscopy analysis (Fourier transform infrared spectrometer, Shimadzu 800, Kyoto, Japan), and the obtained spectrum is shown in Figure 3 Compared with pure PE, the grafted PE has a -1 The vibration absorption peak of hydroxyl (-OH) appears around 1714 cm -1 The stretching vibration of carbonyl (C=O) appears at 1569 cm -1 The stretching vibration peak of the aromatic ring carbon-carbon double bond (C=C) appears at 1100 cm -1 The vibration absorption peak of the ether bond (COC) appeared nearby, confirming that monomer 1 and 4-maleimidophenol monomer were successfully grafted onto the PE backbone;

[0046] Table 1 Types and quantities of raw materials for grafted PE (parts by weight)

[0047]

[0048] Aluminum foil: thickness 9 μm, purchased from Xiashun Aluminum Foil Co., Ltd.

[0049] Antioxidant: Antioxidant 1010 and Antioxidant 168 were mixed in a ratio of 1:1 and are commercially available.

[0050] Nucleating agent: Sorbitol nucleating agent Millad 3988, Milliken;

[0051] First bonding layer: maleic anhydride grafted PE, ADMER SF740, Mitsui Chemicals;

[0052] Second tie layer: ethylene methacrylic acid copolymer, Surlyn EMAA 7940, DuPont;

[0053] Lubricant 1: erucamide, commercially available;

[0054] Lubricant 2: zinc stearate, commercially available;

[0055] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0056] Example 1

[0057] The outer layer PE film is obtained by mixing linear low density polyethylene 70 parts, low density polyethylene 30 parts, nucleating agent 0.2 parts, antioxidant 0.2 parts, erucic acid amide 0.05 parts by weight, and then melt co-extruding through a double screw extruder at 150-180°C, cooling, granulating, drying to obtain an outer layer PE material, and then melt plasticizing the outer layer PE material through a flow casting process to obtain the outer layer PE film, and then performing corona treatment using a corona machine, and the thickness is 65μm;

[0058] The inner layer PE film is obtained by mixing low density polyethylene 80 parts, linear low density polyethylene 20 parts, zinc stearate 0.2 parts, antioxidant 0.1 parts by weight, and then melt co-extruding through a double screw extruder at 150-180°C, cooling, granulating, drying to obtain an inner layer PE material, and then melt plasticizing the inner layer PE material, and then blowing through a blowing process to obtain the inner layer PE film, and then performing corona treatment using a corona machine, and the thickness is 280μm;

[0059] The aluminum plated PE film is obtained by mixing linear low density polyethylene 70 parts, low density polyethylene 10 parts, grafted PE-1 20 parts, antioxidant 0.2 parts by weight, and then melt co-extruding through a double screw extruder at 150-180°C, cooling, granulating, drying to obtain an aluminum plated PE material, and then stretching the aluminum plated PE material through a two-way stretching process to obtain a BOPE film, wherein, first stretching longitudinally at 100°C, the longitudinal stretching multiple is 5; then stretching transversely at 130°C, the transverse stretching multiple is 8; then performing corona treatment using a corona machine, and the thickness is 40μm; and then using vacuum coating technology to plate aluminum on the surface of the BOPE film, wherein, the vacuum degree is 1.3x10 -2 ~1.3x10 -3 Pa, the running speed of the BOPE film is 300m / min, the aluminum supply speed is 0.9m / min, the winding tension is 100-300N, the aluminum plated layer thickness is 40nm, and the aluminum plated PE film is obtained;

[0060] The outer layer PE film, the first bonding layer and the aluminum plated PE film are bonded together through an extrusion compounding process, wherein, the processing temperature is 220-320°C; the unwinding tension is 15-25kg; the winding tension is 20-35kg; and the compounding pressure is 4-6kg;

[0061] S2. The composite sheet obtained in step S1, the second bonding layer and the inner layer PE film are bonded together through an extrusion compounding process to obtain a single material composite sheet, wherein, the processing temperature is 220-320°C; the unwinding tension is 15-25kg; the winding tension is 20-35kg; and the compounding pressure is 4-6kg;

[0062] S3. Butt-weld the edges of the single-material composite sheets. A transparent welding strip is added to the weld seam. The sheets are welded together using a high-frequency induction coil with a high-frequency energy of 30%-100%. The cooling temperature is 15-22°C and the pressure is 2-5kg.

[0063] S4. Injection mold the upper tube shoulder on the docking hose at an injection temperature of 200-260°C, a pressure of 20-50 bar, and a cooling temperature of 10-20°C.

[0064] Example 2

[0065] Compared with Example 1, the difference is that the grafted PE-1 in the PE material in the BOPE film is replaced by grafted PE-2;

[0066] Example 3

[0067] Compared with Example 1, the difference is that the grafted PE-1 in the PE material in the BOPE film is replaced by grafted PE-3;

[0068] Comparative Example 1

[0069] Compared with Example 1, the difference is that the grafted PE-1 in the PE material in the BOPE film is replaced by grafted PE-4;

[0070] Comparative Example 2

[0071] Compared with Example 1, the difference is that the grafted PE-1 in the PE material in the BOPE film is replaced by grafted PE-5;

[0072] Comparative Example 3

[0073] Compared with Example 1, the difference is that the grafted PE-1 in the PE material in the BOPE membrane is replaced by maleic anhydride grafted PE (ADMER SF740, Mitsui Chemicals);

[0074] Comparative Example 4

[0075] Compared with Example 1, the difference is that the PE material in the BOPE film is not grafted with PE;

[0076] Comparative Example 5

[0077] Compared with Example 1, the difference is that the aluminized PE film is replaced by aluminum foil.

[0078] The prepared BOPE film, aluminized PE film and composite hose were subjected to the following performance tests, and the results are shown in Table 2:

[0079] (1) Surface tension: At room temperature, a 4.0 μL droplet of filtered deionized distilled water was placed on the surface of the BOPE membrane. The contact angle was measured using a contact angle meter to evaluate the surface tension of the membrane.

[0080] (2) Thermal deformation shrinkage rate: The test is carried out in accordance with GB / T 13519-2016 "Polyethylene Heat Shrinkable Film for Packaging". The sample is placed between two frames and quickly immersed in the medium of a (140±2)℃ constant temperature bath and the timing is started. During the test, the sample should be kept evenly heated and freely shrinked. After 20 seconds, the sample is taken out and immersed in a constant temperature bath medium for cooling. It is cooled for 5 seconds before being taken out and left horizontally for 10 minutes. The longitudinal and transverse dimensions of the sample are measured respectively, and the transverse shrinkage rate and longitudinal shrinkage rate are calculated.

[0081] (3) Coating firmness: Use a utility knife to make a cross cut on the surface of the aluminum-coated PE film. The depth should penetrate the aluminum layer but not damage the PE substrate, forming a small square of 1mm×1mm, with a total of 10×10 grids; take 3M 600 tape and stick it tightly on the grid area. Use your fingers or a roller to apply even pressure to ensure that the tape is completely in contact with the aluminum layer. Quickly tear off the tape at an angle close to 180° and observe the shedding of the aluminum layer in the grid. According to the shedding area, grade it: Grade 0 - no shedding, Grade 1 - shedding area ≤3%, Grade 2 - shedding area ≤6%, Grade 3 - shedding area ≤10%, Grade 4 - shedding area ≤50%, Grade 5 - complete shedding.

[0082] (4) T-peel strength test: Test according to GB / T 8808-1988, with a tensile speed of 300 mm / min. Record the peel strength after hot pressing at 50°C for 10 hours. Measure three times in parallel and take the average value.

[0083] (5) Water vapor transmission rate: The water vapor barrier performance of the composite sheet was tested using a 3-33MA moisture permeability tester in accordance with GB / T 1037-1988 using the cup method. The water permeability of the composite sheet was tested under standard atmospheric pressure for 24 hours. The specific test conditions were as follows: test temperature: room temperature: 25°C, test pressure: 1 atm, ambient humidity: 90% RH, gas atmosphere: water vapor, test time: 24 hours.

[0084] (6) Oxygen permeability: According to GB / T-1038.2-2022 standard, the oxygen permeability of vacuum aluminum-coated composite film and aluminum-plastic composite film is tested using the isobaric method.

[0085] Table 2 Performance test results of composite hose

[0086]

[0087] From the data of the examples and comparative examples, the single-material composite hose provided by the present invention has the advantages of good oxygen barrier performance and water vapor barrier performance, and the aluminized film has good firmness and the aluminized layer is not easy to migrate, further ensuring the activity and safety of the contents.

[0088] Judging from the results of Examples 1 to 3 and Comparative Examples 1 to 4, the improvement in the peel strength between the BOPE film and the aluminized film is due to two aspects: first, the introduction of ether bonds and hydroxyl groups increases the surface tension of the BOPE film; second, the addition of pyridine or bipyridine introduces metal coordination to further improve the firmness of the aluminized layer.

[0089] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A single material composite hose based on PE, characterized in that: The composite hose is made by butting or overlapping a single-material composite sheet based on PE and then injection-molding a tube shoulder. The single-material composite sheet based on PE sequentially comprises an outer PE film, a first adhesive layer, an aluminized PE film, a second adhesive layer, and an inner PE film. The PE material used in the aluminized PE film includes the following components by weight: 68-79 parts of linear low-density polyethylene, 8-15 parts of low-density polyethylene, 15-25 parts of grafted PE, and 0-4 parts of an additive; the grafted PE has the structure described in Formula 1: Formula 1, Where R is or A type of equation, where a:b:c is (1~5):100:(1~5), and n is a natural number from 8 to 15.

2. The PE-based single-material composite hose according to claim 1, characterized in that: The outer PE film is a highly transparent PE film with a thickness of 50 to 80 μm; the aluminized PE film is a high-gloss aluminized BOPE or aluminized MDOPE, the aluminized layer is 20 to 60 nm thick, the PE layer is 25 to 60 μm, and the aluminized layer faces the inner layer; the inner PE film has a thickness of 250 to 300 μm.

3. The PE-based single-material composite hose according to claim 1, characterized in that: The first adhesive layer is selected from at least one of maleic anhydride grafted PE, ethylene-methacrylic acid copolymer resin layer, and ethylene-acrylic acid copolymer, and the second adhesive layer is selected from ethylene-acrylic acid copolymer. The thickness of the first adhesive layer and the second adhesive layer is 20-50 μm.

4. The PE-based single-material composite hose according to claim 1, characterized in that: The low-density polyethylene or linear low-density polyethylene has a melt flow rate of 1 to 3 g / 10 min at 190° C. and 2.16 kg.

5. The PE-based single-material composite hose according to claim 1, characterized in that: The auxiliary agent is 0-2 parts of antioxidant and 0-2 parts of lubricant.

6. The PE-based single-material composite hose according to claim 1, characterized in that: The preparation method of the grafted PE is: S1. 4-formyl-2,2-bipyridyl or isonicotinic acid is chlorinated with oxalyl chloride under anhydrous and oxygen-free conditions to obtain an intermediate. The intermediate is purified and mixed with polyethylene glycol monoallyl ether and triethylamine. The mixture is heated to 40-60° C. and reacted for 2-6 hours to obtain monomer 1. S2. The monomer 1, 4-maleimidophenol monomer, initiator, and polyethylene are grafted through a torque rheometer-twin-screw extruder at a reaction temperature of 180-220°C for 5-20 minutes. After the reaction, the grafted polyethylene is refluxed in xylene and then precipitated in acetone to remove unreacted monomer, initiator, and homopolymer. Finally, the grafted PE is dried to obtain the grafted PE.

7. The PE-based single-material composite hose according to claim 6, characterized in that: The molar ratio of the 4-formic acid-2,2-bipyridyl or isonicotinic acid to oxalyl chloride is 1:(1.2-1.5); the molar ratio of the intermediate to polyethylene glycol monoallyl ether is 1:(1.01-1.2), and the polyethylene is metallocene polyethylene.

8. The PE-based single-material composite hose according to claim 1, characterized in that: The preparation method of the aluminized PE film comprises the following steps: S1. The linear low-density polyethylene, low-density polyethylene, grafted PE, additives were mixed in proportion, added to a twin-screw extruder, extruded, cooled, pelletized, and dried to obtain the PE material used for the aluminized PE film; S2. A PE film is obtained by a biaxial stretching process or a uniaxial stretching process; S3. Aluminum is plated on the surface of the PE film by vacuum coating technology to obtain an aluminized PE film.

9. The PE-based single-material composite hose according to claim 1, characterized in that: The outer PE film comprises, by weight, 70 to 90 parts of linear low-density polyethylene, 10 to 30 parts of low-density polyethylene, 0.1 to 0.5 parts of a nucleating agent, 0.1 to 2 parts of an antioxidant, and 0 to 1 parts of a lubricant. The inner PE film comprises, by weight, 80 to 90 parts of low-density polyethylene, 10 to 20 parts of linear low-density polyethylene, 0 to 1 parts of a lubricant, and 0.1 to 2 parts of an antioxidant.

10. The method for preparing a PE-based single-material composite hose according to any one of claims 1 to 9, characterized in that: The following steps are involved: S1. The outer PE film, the first adhesive layer and the aluminized PE film are bonded together by a dry lamination process or an extrusion lamination process; S2. The composite sheet obtained in step S1, the second adhesive layer and the inner PE film are bonded together by a dry lamination process or an extrusion lamination process to obtain a single material composite sheet; S3. The edges of the single material composite sheet are welded by overlapping or butting; S4. Injection mold the upper tube shoulder on the hose at an injection temperature of 200-260°C, a pressure of 20-50 bar, and a cooling temperature of 10-20°C.

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