Multi-layer polyethylene composite inner bag for container bag and processing technology

Abstract

The invention relates to the technical field of flexible freight bag processing, and particularly discloses a multilayer polyethylene composite inner bag for a flexible freight bag and a processing technology. The multi-layer polyethylene composite inner bag comprises a multi-layer polyethylene composite film, and the multi-layer polyethylene composite film comprises an inner layer and an outer layer; the inner layer is mainly prepared from the following raw materials: high-density polyethylene, linear low-density polyethylene, a polyolefin elastomer, an ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, modified silicon dioxide and an antioxidant; the outer layer is mainly prepared from the following raw materials: linear low-density polyethylene, low-density polyethylene, an ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, polyadipic acid / butylene terephthalate and an antioxidant. The multi-layer polyethylene composite inner bag for the flexible freight bag has the advantages of high tensile strength, high peel strength, good wear resistance and good flexibility, can effectively reduce wear, reduces cracks and fractures, prolongs the service life, and meets market requirements.

Description

Technical Field

[0001] This application relates to the field of FIBC (Flexible Intermediate Bulk Container) processing technology, and more specifically, to a multi-layer polyethylene composite inner bag for FIBCs and its processing technology. Background Technology

[0002] FIBCs (Flexible Intermediate Bulk Containers), as common large transport packaging containers, are widely used in the packaging of various powdery, granular, and lumpy materials in industries such as chemicals, building materials, plastics, minerals, and new energy, playing a vital role in storage and transportation. The inner bag of the FIBC, as the part that directly contacts the material, affects the safety of material storage and transportation. Currently, polyethylene film is commonly used for the inner bags of FIBCs on the market. Although it is relatively inexpensive, friction between the material and the polyethylene film during storage and transportation can easily cause wear and tear, leading to material leakage and reducing reliability and lifespan. Furthermore, polyethylene film lacks flexibility and is prone to cracking during folding and packaging, also affecting its usability. Therefore, researching an inner bag for FIBCs with good wear resistance and flexibility is of great significance for improving the reliability and safety of storage and transportation. Summary of the Invention

[0003] To improve wear resistance and flexibility, reduce wear, and minimize cracking, this application provides a multi-layer polyethylene composite inner bag for container bags and its processing technology.

[0004] In a first aspect, this application provides a multi-layer polyethylene composite inner bag for container bags, which adopts the following technical solution: a multi-layer polyethylene composite inner bag for container bags, comprising a multi-layer polyethylene composite film, wherein the multi-layer polyethylene composite film comprises an inner layer and an outer layer. The inner layer is mainly made of the following raw materials in parts by weight: 35-45 parts high-density polyethylene, 25-35 parts linear low-density polyethylene, 5-15 parts polyolefin elastomer, 15-25 parts ethylene-vinyl acetate copolymer, 4-6 parts maleic anhydride grafted polyethylene, 7-9 parts modified silica, and 0.3-0.5 parts antioxidant; the modified silica is obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone. The outer layer is mainly made of the following raw materials in parts by weight: 55-65 parts linear low-density polyethylene, 15-25 parts low-density polyethylene, 10-20 parts ethylene-vinyl acetate copolymer, 4-6 parts maleic anhydride grafted polyethylene, 7-9 parts poly(butylene adipate / terephthalate), and 0.3-0.5 parts antioxidant.

[0005] The multi-layer polyethylene composite inner bag of this application is obtained by electro-ironing and heat-sealing a multi-layer polyethylene composite film. The multi-layer polyethylene composite film, through the interplay between the inner and outer layers, not only achieves functional layering but also exhibits tensile strength >30MPa, peel strength >5.5N / 15mm, abrasion resistance <30mg, and withstands over 800 180-degree folds without cracking. It possesses advantages such as high tensile strength, high peel strength, good abrasion resistance, and good flexibility, demonstrating excellent comprehensive performance. When used for transporting and storing materials, the multi-layer polyethylene composite inner bag can effectively reduce wear, minimize cracking, extend service life, and improve the reliability and safety of storage and transportation.

[0006] The outer layer of this application uses linear low-density polyethylene and low-density polyethylene as the matrix, and adds polybutylene adipate / terephthalate to it, which can effectively block the intrusion of oxygen, moisture and odors, and enhance the barrier performance. The inner layer of this application uses high-density polyethylene and linear low-density polyethylene as the matrix, and adds polyolefin elastomer and ethylene-vinyl acetate copolymer to it. By utilizing the synergistic effect between the two, not only is the impact resistance increased, but also the peel strength and flexibility are increased. Modified silica is also added by grafting 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone onto the silica surface. This introduces a large number of siloxy groups, ester groups, acid anhydride groups, amide groups, long-chain alkyl groups, and pyrrolidone cyclic groups on the surface, which effectively increases compatibility, reduces agglomeration, increases dispersion uniformity, improves microstructure, strengthens the network, reduces interface defects, increases network structure compactness, enhances interfacial bonding, and improves tensile strength, peel strength, and abrasion resistance, resulting in superior overall performance.

[0007] Optionally, the modified silica is prepared using the following method: T1. Mix water and silica, add 3-(methacryloyloxy)propyltrimethoxysilane, stir for 3-5 hours, filter, and obtain silane-grafted silica. T2. Mix anhydrous ethanol and silane-grafted silica, heat to 60-70℃, add maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone, add an organic initiator, stir for 4-6 hours, filter, wash, and dry to obtain modified silica.

[0008] Optionally, the weight ratio of the silica, 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone is 10:(2-4):(0.8-1.2):(0.3-0.7):(0.3-0.7).

[0009] By employing the above technical solution, silane grafting is first performed using 3-(methacryloyloxy)propyltrimethoxysilane to introduce carbon-carbon unsaturated bonds. Then, under the action of an organic initiator, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone are grafted onto silica via a polymerization reaction, introducing functional groups to obtain modified silica. This preparation method effectively grafts 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone onto silica, enhancing the properties of the modified silica, improving its performance, strengthening the mechanical properties and wear resistance of multilayer polyethylene composite films, and extending their service life.

[0010] Optionally, the weight ratio of the silica to the organic initiator is 10:(0.2-0.5).

[0011] By adopting the above technical solution, the amount of organic initiator added is limited, ensuring that the organic initiator generates sufficient free radicals, ensuring grafting efficiency and stability, reducing by-products, and ensuring the performance and application effect of modified silica.

[0012] In several implementations, the weight ratio of silica to organic initiator is 10:0.3. It can also be set to 10:0.2, 10:0.4, 10:5, etc. as needed, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0013] Optionally, the organic initiator is selected from one or more of benzoyl peroxide, di-tert-butyl peroxide, dilauryl peroxide, and tert-butyl peroxide.

[0014] By employing the above technical solution, the organic initiator is limited, facilitating its selection. Furthermore, benzoyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, and tert-butyl peroxide can all provide free radicals and initiate polymerization reactions, enabling the grafting of maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone.

[0015] Optionally, in the preparation method of modified silica, the weight ratio of silica, water and anhydrous ethanol is 1:(7-13):(7-13).

[0016] In several implementation schemes, the weight ratio of silica, water, and anhydrous ethanol in the preparation method of modified silica is 1:10:10. However, the weight ratio can also be set to 1:7:7, 1:7:10, 1:7:13, 1:10:7, 1:10:13, 1:13:7, 1:13:10, 1:13:13, etc., as needed. But it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0017] Optionally, the average particle size of the silica is 10-100 nm.

[0018] By employing the above technical solution, the particle size of silica is limited, ensuring its stability. Furthermore, selecting an average particle size between 10-100 nm allows for better dispersion in water and anhydrous ethanol, facilitating sufficient contact and reaction between silica and 3-(methacryloyloxy)propyltrimethoxysilane, as well as between silane-grafted silica and maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone. This ensures the stability of the modified silica preparation and guarantees its uniform dispersion within the inner layer, which is beneficial for improving the overall performance of the multilayer polyethylene composite film.

[0019] In several implementations, the average particle size of silica is 50 nm. It can also be set to 10 nm, 20 nm, 30 nm, 40 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, etc. as needed, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0020] Optionally, the specific surface area of ​​the silica is 100-300 m². 2 / g.

[0021] In several implementation schemes, the specific surface area of ​​silica is 150 m². 2 / g, and its specific surface area can also be set to 100m² as needed. 2 / g、200m 2 / g、250m 2 / g、300m 2 / g, etc., but not limited to the listed values; other unlisted values ​​within this range also apply.

[0022] Optionally, the antioxidant is selected from one or more of antioxidants 1010, 1076, 168, 626, B215, and B225.

[0023] Optionally, the antioxidant is selected from antioxidant 1010 and antioxidant 168, and the weight ratio of antioxidant 1010 and antioxidant 168 is (1-3):(1-3).

[0024] By adopting the above technical solution, the selection of antioxidants is simplified. Furthermore, antioxidants can effectively inhibit oxidation of both the inner and outer layers during processing and use, improving antioxidant performance and extending service life.

[0025] In several implementations, the weight ratio of antioxidant 1010 and antioxidant 168 is 2:1. However, the weight ratio can also be set to 1:1, 1:2, 1:3, 2:3, 3:1, 3:2, etc., as needed, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] Optionally, the thickness of the inner layer is 40-60 μm, and the thickness of the outer layer is 60-80 μm.

[0027] By adopting the above technical solution, the thickness of the inner and outer layers is limited, which facilitates the processing of multilayer polyethylene composite films. Furthermore, by rationally designing the thickness relationship between the inner and outer layers, the multilayer polyethylene composite film is ensured to have excellent overall performance.

[0028] In several embodiments, the inner layer has a thickness of 50 μm, but it can also be set to 40 μm, 45 μm, 55 μm, 60 μm, etc., as needed, but is not limited to the listed values; other unlisted values ​​within this range are also applicable. In several embodiments, the outer layer has a thickness of 70 μm, but it can also be set to 60 μm, 65 μm, 75 μm, 80 μm, etc., as needed, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0029] Secondly, this application provides a processing technology for the multi-layer polyethylene composite inner bag for container bags, which adopts the following technical solution: A processing method for a multi-layer polyethylene composite inner bag for container bags includes the following steps: S1. Mix high-density polyethylene, linear low-density polyethylene, polyolefin elastomer, ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, modified silica, and antioxidant, extrude, blow film, and obtain the inner layer. S2. Linear low-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, poly(butylene adipate / terephthalate) and antioxidant are mixed, extruded, and blown into film to obtain the outer layer. S3. The inner and outer layers are laminated with polyurethane adhesive and left to stand at a temperature of 40-60℃ for 45-50 hours to obtain a multilayer polyethylene composite film. S4. The multi-layer polyethylene composite film is electroplated and heat-sealed to obtain a multi-layer polyethylene composite film inner bag.

[0030] By adopting the above technical solution, the preparation of multilayer polyethylene composite film inner bags is not only facilitated, but also the electro-ironing of the multilayer polyethylene composite film can activate the surface molecular chains, remove surface impurities and moisture, which not only facilitates subsequent heat sealing, but also helps to improve the heat sealing strength, ensuring the quality and performance of the multilayer polyethylene composite film inner bag.

[0031] Optionally, in the ironing process, the ironing temperature is 110-130℃, the pressure is 0.1-0.3MPa, and the time is 3-5s; in the heat sealing process, the heat sealing temperature is 140-160℃, the pressure is 0.3-0.5MPa, and the time is 1-3s.

[0032] By adopting the above technical solutions, the temperature, pressure, and time of the electric ironing are limited, as are the temperature, pressure, and time of the heat sealing. This facilitates the processing of multi-layer polyethylene composite film inner bags, ensuring that a firm and uniform heat seal is achieved without damaging the structure and performance of the multi-layer polyethylene composite film, thus guaranteeing the quality stability and reliability of the multi-layer polyethylene composite film inner bags.

[0033] In several implementations, the ironing process uses a temperature of 120°C, a pressure of 0.2 MPa, and a time of 4 seconds. However, the temperature can be set to 110°C, 115°C, 125°C, 130°C, etc., and the pressure can be set to 0.1 MPa, 0.15 MPa, 0.25 MPa, 0.3 MPa, etc., and the time can be set to 3 seconds, 3.5 seconds, 4.5 seconds, 5 seconds, etc., as needed. However, the ironing process is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0034] In several implementation schemes, the heat sealing process uses a temperature of 150°C, a pressure of 0.4 MPa, and a time of 2 seconds. However, the temperature can be set to 140°C, 145°C, 155°C, 160°C, etc., and the pressure can be set to 0.3 MPa, 0.35 MPa, 0.45 MPa, 0.5 MPa, etc., and the time can be set to 1 second, 1.5 seconds, 2.5 seconds, 3 seconds, etc., as needed. However, the process is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] Optionally, in the composite process, the composite temperature is 70-80℃, the pressure is 0.6-0.8MPa, and the composite speed is 80-120m / min.

[0036] In several implementation schemes, the composite process is carried out at a temperature of 80°C, a pressure of 0.7 MPa, and a composite speed of 100 m / min. However, the temperature can be set to 70°C, 73°C, 75°C, 78°C, etc., the pressure can be set to 0.6 MPa, 0.65 MPa, 0.75 MPa, 0.8 MPa, etc., and the composite speed can be set to 80 m / min, 90 m / min, 110 m / min, 120 m / min, etc., as needed. However, it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0037] In summary, this application has at least the following beneficial effects: 1. The multi-layer polyethylene composite inner bag of this application is obtained by electro-ironing and heat-sealing a multi-layer polyethylene composite film. The multi-layer polyethylene composite film has advantages such as high tensile strength, high peel strength, good abrasion resistance, and good flexibility. Its tensile strength is >30MPa, peel strength is >5.5N / 15mm, abrasion amount is <30mg, and it exhibits excellent comprehensive performance after 800 180-degree folds without cracking. When transporting and storing materials, the multi-layer polyethylene composite inner bag reduces abrasion, minimizes cracking, extends service life, and meets market demands.

[0038] 2. The inner layer of this application uses high-density polyethylene and linear low-density polyethylene as the matrix, and on this basis, polyolefin elastomer and ethylene-vinyl acetate copolymer are added to increase peel strength and flexibility. Modified silica is also added, introducing a large number of groups on the silica surface, which effectively increases compatibility and dispersion uniformity, improves microstructure, reduces interface defects, enhances interfacial bonding, and improves tensile strength, peel strength and abrasion resistance, giving the multilayer polyethylene composite film superior overall performance. Attached Figure Description

[0039] Figure 1 This is the multilayer polyethylene composite inner bag of Embodiment 1 of this application. Detailed Implementation

[0040] The present application will be further described in detail below with reference to the embodiments.

[0041] Preparation Example Preparation Example 1 A modified silica, prepared by the following method: T1. At a rotation speed of 500 r / min, add 10 kg of silica to 100 kg of water and stir for 5 min. Then add 3 kg of 3-(methacryloyloxy)propyltrimethoxysilane and stir for 4 h. Finally, filter to obtain silane-grafted silica.

[0042] The average particle size of silica is 50 nm, and the specific surface area is 150 m². 2 / g.

[0043] T2. At a rotation speed of 500 r / min, add the silane-grafted silica obtained in step T1 to 100 kg of anhydrous ethanol and stir for 5 min. Raise the temperature to 65℃, add 1 kg of maleic anhydride, 0.5 kg of erucamide, and 0.5 kg of 3-acetyl-N-vinylpyrrolidone, and stir for 10 min. Add 0.3 kg of organic initiator and stir for 5 h. Then filter and wash three times with ethanol, using 20 kg of ethanol each time. Finally, dry at 80℃ to obtain modified silica.

[0044] The organic initiator is selected from benzoyl peroxide.

[0045] Preparation Example 2 A modified silica differs from that of Preparation Example 1 in the amount of 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone added. The amount of 3-(methacryloyloxy)propyltrimethoxysilane added is 2 kg, maleic anhydride added is 0.8 kg, erucamide added is 0.7 kg, and 3-acetyl-N-vinylpyrrolidone added is 0.3 kg.

[0046] Preparation Example 3 A modified silica differs from that of Preparation Example 1 in the amount of 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone added. The amount of 3-(methacryloyloxy)propyltrimethoxysilane added is 4 kg, maleic anhydride added is 1.2 kg, erucamide added is 0.3 kg, and 3-acetyl-N-vinylpyrrolidone added is 0.7 kg. Example

[0047] Table 1. Raw material usage for the inner layer (unit: kg) Table 2. Raw material usage for the outer layer (unit: kg) Example Example 1 Example 2 Example 3 Linear low-density polyethylene 60 55 65 Low-density polyethylene 20 25 15 Ethylene-vinyl acetate copolymer 15 10 20 Maleic anhydride-grafted polyethylene 5 6 4 Poly(butylene adipate) terephthalate 8 7 9 antioxidants 0.4 0.5 0.3 Example 1 A multi-layer polyethylene composite inner bag for container bags, as described in the reference. Figure 1It comprises a multilayer polyethylene composite film, which includes an inner layer and an outer layer. The thickness of the inner layer is 50 μm, and the thickness of the outer layer is 70 μm. The raw materials and their proportions for the inner layer are shown in Table 1. The raw materials and their proportions for the outer layer are shown in Table 2.

[0048] Among them, high-density polyethylene is selected from Dow DMDH 6400 HDPE; linear low-density polyethylene is selected from Shanghai SECCO LL0209AA LLDPE; polyolefin elastomer is selected from Dow ENGAGE 8150 POE; ethylene-vinyl acetate copolymer is selected from DuPont Elvax 410 EVA; maleic anhydride grafted polyethylene is selected from PE-g-MAH Dow AMPLIFY GR 202; low-density polyethylene is selected from CNOOC Shell 2420D LDPE; and poly(butylene adipate / terephthalate) is selected from BASF BX 7011 PBAT.

[0049] The modified silica was prepared by the method of Preparation Example 1; the antioxidant was selected from antioxidant 1010 and antioxidant 168, and the weight ratio of antioxidant 1010 and antioxidant 168 was 2:1.

[0050] A processing technology for a multi-layer polyethylene composite inner bag for container bags includes the following steps: S1. Add linear low-density polyethylene, polyolefin elastomer, ethylene-vinyl acetate copolymer, maleic anhydride-grafted polyethylene, modified silica, and antioxidant to high-density polyethylene, and stir for 5 minutes. Then, use a blown film extruder at 185℃ to obtain the inner layer.

[0051] S2. Add low-density polyethylene, ethylene-vinyl acetate copolymer, maleic anhydride-grafted polyethylene, poly(butylene adipate / terephthalate), and antioxidant to linear low-density polyethylene, and stir for 5 minutes. Then, use a blown film extruder at 185°C to obtain the outer layer.

[0052] S3. The inner and outer layers are laminated with polyurethane adhesive and left to stand at 50°C for 48 hours to obtain a multilayer polyethylene composite film.

[0053] The polyurethane adhesive used is selected from polyurethane adhesive JYE1500A / B, sourced from Zhejiang Jianyang Polymer Technology Co., Ltd. Polyurethane adhesive JYE1500A / B comprises polyurethane adhesives JYE1500A and JYE1500B, with a weight ratio of 100:85. The usage amount of polyurethane adhesive is 1.5 g / m³. 2 During the composite process, the composite temperature was 50℃, the pressure was 0.7MPa, and the composite speed was 100m / min.

[0054] S4. The multi-layer polyethylene composite film is electroplated and heat-sealed to obtain a multi-layer polyethylene composite film inner bag.

[0055] In the ironing process, the temperature was 120℃, the pressure was 0.2MPa, and the time was 4s. In the heat-sealing process, the temperature was 150℃, the pressure was 0.4MPa, and the time was 2s.

[0056] Example 2 A multi-layer polyethylene composite inner bag for container bags differs from Example 1 in that the raw material ratios of the inner and outer layers are different. The raw material ratio of the inner layer is shown in Table 1, and the raw material ratio of the outer layer is shown in Table 2.

[0057] Example 3 A multi-layer polyethylene composite inner bag for container bags differs from Example 1 in that the raw material ratios of the inner and outer layers are different. The raw material ratio of the inner layer is shown in Table 1, and the raw material ratio of the outer layer is shown in Table 2.

[0058] Example 4 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that the source of modified silica in the inner layer is different, and the modified silica is prepared using the method of Preparation Example 2.

[0059] Example 5 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that the source of modified silica in the inner layer is different, and the modified silica is prepared using the method of Preparation Example 3.

[0060] Comparative Example Comparative Example 1 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that an equal amount of polyolefin elastomer is used to replace the ethylene-vinyl acetate copolymer in the inner layer material.

[0061] Comparative Example 2 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that an equal amount of ethylene-vinyl acetate copolymer is used to replace the polyolefin elastomer in the inner layer.

[0062] Comparative Example 3 A multi-layer polyethylene composite inner bag for container bags differs from Example 1 in that the modified silica is replaced with an equal amount of silica in the inner layer material.

[0063] Comparative Example 4 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that, in the preparation method of modified silica, an equal amount of 3-(methacryloyloxy)propyltrimethoxysilane is used to replace maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone.

[0064] Comparative Example 5 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that, in the preparation method of modified silica, an equal amount of maleic anhydride is used to replace erucamide and 3-acetyl-N-vinylpyrrolidone in the raw materials of the inner layer.

[0065] Comparative Example 6 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that, in the preparation method of modified silica, an equal amount of erucamide is used to replace 3-acetyl-N-vinylpyrrolidone in the raw material of the inner layer.

[0066] Comparative Example 7 A multilayer polyethylene composite inner bag for container bags differs from Example 1 in that, in the preparation method of modified silica in the inner layer, an equal amount of 3-acetyl-N-vinylpyrrolidone is used to replace erucamide.

[0067] Performance testing Multilayer polyethylene composite films obtained in Examples 1-5 and Comparative Examples 1-7 were used as samples, and the following performance tests were performed on the multilayer polyethylene composite films. The test results are shown in Table 3.

[0068] In accordance with GB / T1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", the transverse tensile strength and longitudinal tensile strength of multilayer polyethylene composite films were tested.

[0069] According to GB8808-1988 "Peel Test Method for Flexible Composite Plastic Materials", the peel strength between the inner and outer layers of a multilayer polyethylene composite film was tested.

[0070] According to GB / T3960-2016 "Test Method for Sliding Friction and Wear of Plastics", the wear amount of the inner layer of multilayer polyethylene composite film was tested.

[0071] Flexibility was assessed using the following method: At -30℃, the multilayer polyethylene composite film was folded 180 degrees at a speed of 10 times / min. The number of folds was recorded until cracks appeared in the film, and this number was used to represent flexibility. A higher number of folds indicates better flexibility of the multilayer polyethylene composite film.

[0072] Table 3 Detection Results As shown in Table 3, the multilayer polyethylene composite film of this application exhibits high tensile and peel strength, with a transverse tensile strength of 30.84-32.18 MPa, a longitudinal tensile strength of 34.33-35.86 MPa, and a peel strength of 5.76-5.84 N / 15 mm, demonstrating high tensile and peel strength. Furthermore, it exhibits low abrasion resistance, with an abrasion amount of 26.6-29.5 mg. It also boasts a high folding count, exceeding 800 times, demonstrating good flexibility. In short, the multilayer polyethylene composite film inner bag of this application, through the interplay between the inner and outer layers, possesses advantages such as high tensile strength, high peel strength, good abrasion resistance, and good flexibility, exhibiting excellent comprehensive performance and meeting market demands.

[0073] Comparative Examples 1-2 and Example 1 were compared. In Comparative Example 1, a polyolefin elastomer was added to the inner layer raw material; in Comparative Example 2, an ethylene-vinyl acetate copolymer was added to the inner layer raw material; and in Example 1, both a polyolefin elastomer and an ethylene-vinyl acetate copolymer were added to the inner layer raw material. This demonstrates that simultaneously adding a polyolefin elastomer and an ethylene-vinyl acetate copolymer to the raw material, and utilizing their synergistic effect, can effectively increase peel strength and flexibility.

[0074] Comparative Examples 3 and 4 were compared. In Comparative Example 3, silica was added to the inner layer raw material; in Comparative Example 4, modified silica was added to the inner layer raw material, obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane. This shows that modifying silica can improve its performance and enhance the properties of the multilayer polyethylene composite film. Furthermore, Comparative Example 5, whose modified silica was obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane and maleic anhydride, demonstrates that further grafting maleic anhydride onto the silica surface, in addition to grafting 3-(methacryloyloxy)propyltrimethoxysilane, can further improve the performance of the modified silica, increasing tensile and peel strength and reducing wear, but its effect on the performance of the multilayer polyethylene composite film is limited.

[0075] Comparative Examples 6-7 and Example 1 were compared. The modified silica of Comparative Example 6 was obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, and erucamide; the modified silica of Comparative Example 7 was obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, and 3-acetyl-N-vinylpyrrolidone; the modified silica of Example 1 was obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone. This demonstrates that by grafting 3-(methacryloyloxy)propyltrimethoxysilane and maleic anhydride onto the surface of silica, further grafting erucamide and 3-acetyl-N-vinylpyrrolidone onto the surface results in a large number of siloxy groups, ester groups, anhydride groups, amide groups, long-chain alkyl groups, and pyrrolidone cyclic groups, which can improve tensile strength, peel strength, and abrasion resistance, thus giving the multilayer polyethylene composite film superior overall performance.

[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A multi-layer polyethylene composite inner bag for container bags, characterized in that: It includes a multilayer polyethylene composite film, which includes an inner layer and an outer layer; The inner layer is mainly made of the following raw materials in parts by weight: 35-45 parts high-density polyethylene, 25-35 parts linear low-density polyethylene, 5-15 parts polyolefin elastomer, 15-25 parts ethylene-vinyl acetate copolymer, 4-6 parts maleic anhydride grafted polyethylene, 7-9 parts modified silica, and 0.3-0.5 parts antioxidant; the modified silica is obtained by treating silica with 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone. The outer layer is mainly made of the following raw materials in parts by weight: 55-65 parts linear low-density polyethylene, 15-25 parts low-density polyethylene, 10-20 parts ethylene-vinyl acetate copolymer, 4-6 parts maleic anhydride grafted polyethylene, 7-9 parts poly(butylene adipate / terephthalate), and 0.3-0.5 parts antioxidant.

2. The multi-layer polyethylene composite inner bag for container bags according to claim 1, characterized in that: The modified silica is prepared by the following method: T1. Mix water and silica, add 3-(methacryloyloxy)propyltrimethoxysilane, stir for 3-5 hours, filter, and obtain silane-grafted silica. T2. Mix anhydrous ethanol and silane-grafted silica, heat to 60-70℃, add maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone, add an organic initiator, stir for 4-6 hours, filter, wash, and dry to obtain modified silica.

3. The multi-layer polyethylene composite inner bag for container bags according to claim 2, characterized in that: The weight ratio of the silica, 3-(methacryloyloxy)propyltrimethoxysilane, maleic anhydride, erucamide, and 3-acetyl-N-vinylpyrrolidone is 10:(2-4):(0.8-1.2):(0.3-0.7):(0.3-0.7).

4. The multi-layer polyethylene composite inner bag for container bags according to claim 2, characterized in that: The weight ratio of silica to organic initiator is 10:(0.2-0.5).

5. The multi-layer polyethylene composite inner bag for container bags according to claim 2, characterized in that: The organic initiator is selected from one or more of benzoyl peroxide, di-tert-butyl peroxide, dilauroyl peroxide, and tert-butyl peroxide.

6. The multi-layer polyethylene composite inner bag for container bags according to claim 2, characterized in that: The average particle size of the silica is 10-100 nm.

7. The multi-layer polyethylene composite inner bag for container bags according to claim 1, characterized in that: The antioxidant is selected from one or more of antioxidants 1010, 1076, 168, 626, B215, and B225.

8. The multi-layer polyethylene composite inner bag for container bags according to claim 1, characterized in that: The inner layer has a thickness of 40-60 μm, and the outer layer has a thickness of 60-80 μm.

9. A processing method for a multi-layer polyethylene composite inner bag for container bags as described in any one of claims 1-8, characterized in that: Includes the following steps: S1. Mix high-density polyethylene, linear low-density polyethylene, polyolefin elastomer, ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, modified silica, and antioxidant, extrude, blow film, and obtain the inner layer. S2. Linear low-density polyethylene, low-density polyethylene, ethylene-vinyl acetate copolymer, maleic anhydride grafted polyethylene, poly(butylene adipate / terephthalate) and antioxidant are mixed, extruded, and blown into film to obtain the outer layer. S3. The inner and outer layers are laminated with polyurethane adhesive and left to stand at a temperature of 40-60℃ for 45-50 hours to obtain a multilayer polyethylene composite film. S4. The multi-layer polyethylene composite film is electroplated and heat-sealed to obtain a multi-layer polyethylene composite film inner bag.

10. The processing technology of a multi-layer polyethylene composite inner bag for container bags according to claim 9, characterized in that: During the ironing process, the ironing temperature is 110-130℃, the pressure is 0.1-0.3MPa, and the time is 3-5s; During the heat sealing process, the temperature is 140-160℃, the pressure is 0.3-0.5MPa, and the time is 1-3s.

Images