High-buffering drop-resistant thermal insulation PE film, preparation method thereof, and composite film and bag

Abstract

The application relates to the technical field of composite films, and provides a high-buffering anti-falling heat-insulating PE film, a preparation method of the high-buffering anti-falling heat-insulating PE film, a composite film and a bag. At least one of the outer layer, the middle layer and the inner layer of the high-buffering anti-falling heat-insulating PE film is a foaming structure, the cells can play the effect of blocking cold and hot air, the thawing time of frozen beverages and the cooling time of hot beverages are prolonged, and the PE film is comfortable in hand feeling and cannot have the feeling of ice-cold and scalding; meanwhile, the foaming structure makes the PE film have the buffering effect and is not easy to be damaged after falling; and the PE film provided by the application is light in weight, good in softness, high in appearance, and better in customer experience. Further, the application further provides a specific formula of the three-layer structure of the high-buffering anti-falling heat-insulating PE film; and through strict control of the formula, the PE film can have high mechanical properties on the basis of obtaining dense cells.

Description

Technical Field

[0001] This invention relates to the field of composite film technology, and in particular to a high-buffering, drop-resistant, heat-insulating PE film, its preparation method, and composite films and bags. Background Technology

[0002] Cold drinks are a popular choice among consumers in summer, as they have a cooling effect. Hot drinks are beverages that are prepared by boiling or steeping in hot water and have a certain temperature, such as tea, coffee, and herbal health drinks. These drinks are usually enjoyed hot to fully appreciate their unique flavor.

[0003] Cold and hot drinks have a certain temperature. Currently, some commercially available packaging bags for cold and hot drinks have poor heat insulation. In particular, cold drinks with ice melt quickly and feel cold to the touch; hot drinks cool down easily and are very hot when you first hold them. At the same time, current packaging bags do not have cushioning and drop resistance properties, and are easily damaged after being dropped. Summary of the Invention

[0004] In view of this, the present invention provides a high-buffering, drop-resistant, heat-insulating PE film, its preparation method, and composite film and bag. The high-buffering, drop-resistant, heat-insulating PE film provided by the present invention has excellent heat insulation and cold insulation effects, and also has cushioning properties, making it less prone to damage after a drop.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] A high-buffered, drop-resistant, heat-insulating PE film is made by co-extrusion blown film of three layers: outer layer, middle layer, and inner layer; at least one of the outer layer, middle layer, and inner layer is a foamed structure.

[0007] Preferably, at least one of the outer, middle, and inner layers is prepared using foaming masterbatch as the raw material.

[0008] The foaming masterbatch has a melt index of 4–7 g / 10 min and a density of 0.913–0.955 g / cm³. 3 .

[0009] Preferably, when only the outer layer's raw materials include foaming masterbatch, the mass of the foaming masterbatch is 2-8% of the total mass of the outer layer's raw materials; when only the middle layer's raw materials include foaming masterbatch, the mass of the foaming masterbatch is 1.5-8% of the total mass of the middle layer's raw materials; when only the inner layer's raw materials include foaming masterbatch, the mass of the foaming masterbatch is 2-6% of the total mass of the inner layer's raw materials; when any two of the outer, middle, and inner layers contain foaming masterbatch, or all three layers contain foaming masterbatch, the mass of the foaming masterbatch in each layer is 1-11% of the total mass of the raw materials in that layer.

[0010] Preferably, the foaming masterbatch is of type CFE-3361G and / or FM10PE.

[0011] Preferably, the raw materials for preparing the outer layer, by mass parts, include: 10-60 parts of low-density polyethylene, 20-80 parts of linear low-density polyethylene, 15-60 parts of metallocene low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids.

[0012] The raw materials for preparing the middle layer, by mass parts, include: 10-98 parts of low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids;

[0013] The raw materials for preparing the inner layer, by mass parts, include: 15-50 parts of low-density polyethylene, 20-80 parts of metallocene low-density polyethylene, 10-80 parts of linear low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids.

[0014] The mass fraction of foaming masterbatch in the raw materials for preparing the outer, middle, and inner layers is not all 0.

[0015] Preferably, the outer layer uses low-density polyethylene with a melt index of 0.2–5 g / 10 min and a density of 0.920–0.935 g / cm³. 3 The outer layer is made of linear low-density polyethylene with a melt index of 0.3–3.5 g / 10 min and a density of 0.912–0.930 g / cm³. 3 The outer layer uses metallocene low-density polyethylene with a melt index of 0.5–2.5 g / 10 min and a density of 0.908–0.930 g / cm³. 3 ;

[0016] The middle layer uses low-density polyethylene with a melt index of 0.1–3.5 g / 10 min and a density of 0.920–0.940 g / cm³. 3 ;

[0017] The inner layer uses low-density polyethylene with a melt index of 0.3–3.5 g / 10 min and a density of 0.920–0.930 g / cm³. 3 The inner layer uses metallocene low-density polyethylene with a melt index of 0.5–2 g / 10 min and a density of 0.91–0.92 g / cm³. 3 The inner layer uses linear low-density polyethylene with a melt index of 1.5–2.5 g / 10 min and a density of 0.912–0.925 g / cm³. 3 ;

[0018] The processing aids used in the outer, middle, and inner layers have a melt index of 1.5–2.5 g / 10 min and a density of 0.910–0.925 g / cm³. 3 .

[0019] The present invention also provides a method for preparing the high-buffered, drop-resistant, heat-insulating PE film described above, comprising the following steps:

[0020] The raw materials for the preparation of the outer layer, middle layer and inner layer are co-extruded and blown into a film to obtain the high-buffering, drop-resistant, heat-insulating PE film; among the raw materials for the preparation of the outer layer, middle layer and inner layer, at least one of the raw materials includes foaming masterbatch.

[0021] The present invention also provides a composite film, the composite film including a heat insulation layer, the heat insulation layer being the high-buffered drop-resistant heat-insulating PE film described in the above scheme or the high-buffered drop-resistant heat-insulating PE film prepared by the preparation method described in the above scheme.

[0022] Preferably, the composite film has a three-layer or four-layer structure; the three-layer structure includes a printing layer, a barrier layer, and a heat insulation layer arranged in sequence; the four-layer structure includes a printing layer, a barrier layer, a heat insulation layer, and a PE heat-sealing layer arranged in sequence; or, the four-layer structure includes a paper layer, a barrier layer, a printing layer, and a heat insulation layer arranged in sequence.

[0023] The present invention also provides a composite bag, which is prepared from the composite film described in the above scheme.

[0024] This invention provides a high-buffering, drop-resistant, and heat-insulating PE film, which is made by co-extrusion blown film of three layers: an outer layer, a middle layer, and an inner layer. At least one of the outer, middle, and inner layers is a foamed structure. The high-buffering, drop-resistant, and heat-insulating PE film provided by this invention has at least one foamed structure in its outer, middle, and inner layers, thus forming dense pores in the PE film, effectively blocking hot and cold air. This extends the thawing time of some frozen beverages and the cooling time of hot drinks. Due to its good heat and cold insulation effect, it has a comfortable feel without the sensation of being cold or hot to the touch, and its appearance is more upscale, resulting in a better customer experience. Furthermore, the foamed structure gives the PE film of this invention a cushioning effect, making it less prone to damage after a drop. The results of the embodiments show that after being composited with the high-buffering, drop-resistant, and heat-insulating PE film of this invention, the thawing and cooling time of cold and hot drinks is extended by 3-4 hours compared to ordinary bags, and the bag does not break after being dropped from a height of 1.5m with 1kg of water inside, indicating that it has good cushioning and drop-resistant performance. In summary, the high-buffered, drop-resistant, heat-insulating PE film provided by this invention has the characteristics of excellent heat insulation effect, light weight, softness, drop resistance, good feel, higher appearance, better customer experience, and solves the timeliness problem of some products that need to extend the heat preservation and cooling time, and has broad market prospects.

[0025] Furthermore, the present invention also provides a specific formula for a three-layer structure of a high-buffered, drop-resistant, heat-insulating PE film. Through strict control of the formula, the present invention can ensure that the PE film has high mechanical properties, high tensile strength, and high elongation at break while obtaining dense pores. Detailed Implementation

[0026] This invention provides a high-buffering, drop-resistant, heat-insulating PE film, which is made of three layers: an outer layer, a middle layer, and an inner layer, by co-extrusion blown film; at least one of the outer, middle, and inner layers is a foamed structure.

[0027] In a specific embodiment of the present invention, the foaming structure has spindle-shaped pores, which are not easily perforated and have good stability.

[0028] In this invention, at least one of the outer, middle, and inner layers comprises foaming masterbatch as its raw material. Specifically, when only the outer layer comprises foaming masterbatch, the mass of the foaming masterbatch is preferably 2-8% of the total mass of the outer layer's raw materials, more preferably 3-5%. When only the middle layer comprises foaming masterbatch, the mass of the foaming masterbatch is preferably 1.5-8% of the total mass of the middle layer's raw materials, more preferably 3-6%. When only the inner layer comprises foaming masterbatch, the mass of the foaming masterbatch is preferably 2-6% of the total mass of the inner layer's raw materials, more preferably 4-5%. When any two of the outer, middle, and inner layers contain foaming masterbatch, or all three layers contain foaming masterbatch, the mass of the foaming masterbatch in each layer is preferably 1-11% of the total mass of the raw materials in that layer, more preferably 3-8%.

[0029] In this invention, the melt index of the foaming masterbatch is preferably 4-7 g / 10 min, more preferably 4.5-6 g / 10 min, and the density is preferably 0.913-0.955 g / cm³. 3 More preferably, it is 0.916–0.955 g / cm³. 3 Specifically, the preferred type of the foaming masterbatch is CFE-3361G and / or FM10PE; in a specific embodiment of the present invention, the foaming masterbatch of type CFE-3361G was purchased from Guangzhou Benqi New Material Co., Ltd., and its melt index is 6.0 g / 10 min and its density is 0.916 g / cm³. 3 The foaming masterbatch, model FM10PE, was purchased from Foshan Jingxi New Material Technology Co., Ltd., with a melt index of 4.5 g / 10 min and a density of 0.955 g / cm³. 3 The foaming masterbatch used in this invention has the characteristics of uniform and fine pores and high closed-cell rate.

[0030] In this invention, the raw materials for the outer, middle and inner layers of the high-buffered, drop-resistant, heat-insulating PE film preferably also include polyethylene and processing aids. The polyethylene used in the outer layer is preferably low-density polyethylene, linear low-density polyethylene and metallocene low-density polyethylene. The polyethylene used in the inner layer is preferably low-density polyethylene, linear low-density polyethylene and metallocene low-density polyethylene.

[0031] In this invention, the raw materials for preparing the outer layer, by mass parts, include: 10-60 parts of low-density polyethylene, 20-80 parts of linear low-density polyethylene, 15-60 parts of metallocene low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids.

[0032] The raw materials for preparing the middle layer, by mass parts, include: 10-80 parts of low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids;

[0033] The raw materials for preparing the inner layer, by mass fraction, include: 15-50 parts of low-density polyethylene, 20-80 parts of metallocene low-density polyethylene, 10-80 parts of linear low-density polyethylene; 0-8 parts of foaming masterbatch; and 0.5-1.5 parts of processing aids. The mass fraction of foaming masterbatch in the raw materials for preparing the outer layer, middle layer, and inner layer is not simultaneously 0.

[0034] The outer layer is prepared from 10 to 60 parts by weight, preferably 20 to 50 parts, of low-density polyethylene. The melt index of the low-density polyethylene used in the outer layer is preferably 0.2 to 5 g / 10 min, more preferably 0.3 to 4 g / 10 min, and the density is preferably 0.920 to 0.935 g / cm³. 3 More preferably, it is 0.924–0.927 g / cm³. 3 The outer layer is preferably made of one or more of the following low-density polyethylene types: 951-000, PE3020D, 2420K, and HP4024ZN. The 951-000 type low-density polyethylene is purchased from Maoming Petrochemical and has a melt index of 2.0 g / 10 min and a density of 0.924 g / cm³. 3 The low-density polyethylene, model PE3020D, was purchased from Basel, with a melt index of 0.3 g / 10 min and a density of 0.927 g / cm³. 3 The low-density polyethylene (LDPE) of model 2420K was purchased from Daqing Petrochemical. Its melt index is 4.0 g / 10 min, and its density is 0.924 g / cm³. 3 The low-density polyethylene (LDPE) model HP4024ZN was purchased from Saudi Arabian suppliers; its melt index is 4 g / 10 min and its density is 0.923 g / cm³. 3In specific embodiments of the present invention, when the outer layer uses low-density polyethylene of type 951-000, its mass fraction is preferably 20-40 parts, more preferably 25-35 parts; when the outer layer uses low-density polyethylene of type PE3020D, its mass fraction is preferably 10-50 parts, more preferably 20-40 parts; when the outer layer uses low-density polyethylene of type 2420K, its mass fraction is preferably 15-60 parts, more preferably 25-45 parts; when the outer layer uses low-density polyethylene of type HP4024ZN, its mass fraction is preferably 40-60 parts. The low-density polyethylene used in the outer layer of the present invention has the characteristics of few crystal points and good processability.

[0035] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw materials for preparing the outer layer include 20-80 parts of linear low-density polyethylene, preferably 30-70 parts; the melt index of the linear low-density polyethylene used in the outer layer is preferably 0.3-3.5 g / 10 min, more preferably 2-3 g / 10 min, and the density is preferably 0.912-0.930 g / cm³. 3 More preferably, it is 0.918–0.925 g / cm³. 3 The outer layer is preferably made of one or more of the following linear low-density polyethylene types: 7042, 1002YB, and 2505H; wherein the 7042 type linear low-density polyethylene is purchased from Maoming Petrochemical, and has a melt index of 2.0 g / 10 min and a density of 0.918 g / cm³. 3 The linear low-density polyethylene (LDPE) of model 1002YB was purchased from ExxonMobil, with a melt index of 2.0 g / 10 min and a density of 0.918 g / cm³. 3 The linear low-density polyethylene (LDPE) of model 2505H was purchased from CNOOC Shell Petrochemicals Co., Ltd., with a melt index of 0.5 g / 10 min and a density of 0.925 g / cm³. 3 In specific embodiments of the present invention, when the outer layer uses linear low-density polyethylene of type 7042, its mass fraction is preferably 30-80 parts, more preferably 40-60 parts; when the outer layer uses linear low-density polyethylene of type 1002YB, its mass fraction is preferably 20-80 parts, more preferably 40-60 parts; when the outer layer uses linear low-density polyethylene of type 2505H, its mass fraction is preferably 25-80 parts, more preferably 40-60 parts. The linear low-density polyethylene used in the outer layer of the present invention has high composite strength and good processing properties.

[0036] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw materials for preparing the outer layer include 15 to 60 parts of metallocene low-density polyethylene, preferably 20 to 50 parts. In this invention, the melt index of the metallocene low-density polyethylene used in the outer layer is preferably 0.5 to 2.5 g / 10 min, more preferably 1 to 2 g / 10 min, and the density is preferably 0.908 to 0.930 g / cm³. 3 More preferably, it is 0.912–0.925 g / cm³. 3 In a specific embodiment of the present invention, the metallocene low-density polyethylene used in the outer layer is preferably one or more of 2012MA, 5400G, and SP2520; wherein, the 2012MA metallocene low-density polyethylene is purchased from ExxonMobil, with a melt index of 2.0 g / 10 min and a density of 0.912 g / cm³. 3 The metallocene low-density polyethylene (MDPE) of model 5400G was purchased from Dow Chemical, with a melt index of 1.0 g / 10 min and a density of 0.916 g / cm³. 3 The metallocene low-density polyethylene, model SP2520, was purchased from Mitsui Chemicals. Its melt index is 2.0 g / 10 min, and its density is 0.925 g / cm³. 3 In specific embodiments of the present invention, when the outer layer uses metallocene low-density polyethylene of type 2012MA, its mass fraction is preferably 15-30 parts, more preferably 20-25 parts; when the outer layer uses metallocene low-density polyethylene of type 5400G, its mass fraction is preferably 20-50 parts, more preferably 30-40 parts; when the outer layer uses metallocene low-density polyethylene of type SP2520, its mass fraction is preferably 20-60 parts, more preferably 30-50 parts. The metallocene low-density polyethylene used in the outer layer of the present invention has the properties of high composite strength and good transparency.

[0037] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw materials for preparing the outer layer include 0 to 8 parts of foaming masterbatch. The melt index, type, and manufacturer of the foaming masterbatch will not be elaborated further. In specific embodiments of the present invention, the raw materials for preparing the outer layer may or may not include foaming masterbatch. Specifically, when the outer layer includes foaming masterbatch, the mass fraction of the foaming masterbatch is preferably 1 to 8 parts. More specifically, when using foaming masterbatch of type CFE-3361G, its mass fraction is preferably 1 to 2.5 parts, more preferably 1.5 to 2 parts. When using foaming masterbatch of type FM10PE, its mass fraction is preferably 5 to 8 parts, more preferably 6 to 7 parts.

[0038] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw materials for preparing the outer layer include 0.5 to 1.5 parts of processing aids, preferably 0.8 to 1.2 parts; the melt index of the processing aids used in the outer layer is preferably 1.5 to 2.5 g / 10 min, more preferably 2 to 2.1 g / 10 min, and the density is preferably 0.910 to 0.925 g / cm³. 3 More preferably, it is 0.915–0.920 g / cm³. 3 The processing aid is preferably a functional masterbatch prepared from fluoropolymer and polyolefin resin; the preferred type of the processing aid is PA0895LD and / or PEA-3S. In a specific embodiment of the present invention, the processing aid PA0895LD was purchased from Suzhou Constance Engineering Plastics Co., Ltd., and its melt index is 2.1 g / min and density is 0.915 g / cm³. 3 The processing aid, model PEA-3S, was purchased from Huayi Technology Co., Ltd., with a melt index of 2.1 g / min and a density of 0.920 g / cm³. 3 In a specific embodiment of the present invention, when the outer layer uses a processing aid of type PA0895LD, its mass fraction is preferably 0.5 to 1 part, more preferably 0.6 to 0.8 parts; when the outer layer uses a processing aid of type PEA-3S, its mass fraction is preferably 0.5 to 1.5 parts, more preferably 0.6 to 1.2 parts. The processing aid used in the present invention can effectively reduce die accumulation, reduce crystal points, lower extrusion pressure, and improve production efficiency.

[0039] The raw materials for preparing the intermediate layer, by weight, comprise 10-98 parts, preferably 20-80 parts, of low-density polyethylene. In this invention, the melt index of the low-density polyethylene used in the intermediate layer is preferably 0.1-3.5 g / 10 min, more preferably 0.25-3 g / 10 min, and the density is preferably 0.920-0.940 g / cm³. 3 More preferably, it is 0.924–0.933 g / cm³. 3 The low-density polyethylene used in the middle layer is preferably one or more of 2420D, 2420F, and 151BW, more preferably a combination of any two of them; wherein, the 2420D low-density polyethylene is purchased from CNOOC Shell, with a melt index of 0.25 g / 10 min and a density of 0.924 g / cm³. 3 The low-density polyethylene (LDPE) of model 2420F was purchased from CNOOC Shell, with a melt index of 0.75 g / 10 min and a density of 0.924 g / cm³. 3 The low-density polyethylene (LDPE) of model 151BW was purchased from ExxonMobil, with a melt index of 3 g / 10 min and a density of 0.933 g / cm³. 3In specific embodiments of the present invention, when the intermediate layer uses low-density polyethylene of type 2420D, its mass fraction is preferably 10 to 40 parts, more preferably 20 to 30 parts; when the intermediate layer uses low-density polyethylene of type 2420F, its mass fraction is preferably 30 to 80 parts, more preferably 50 to 70 parts; when the intermediate layer uses low-density polyethylene of type 151BW, its mass fraction is preferably 15 to 50 parts, more preferably 20 to 40 parts; the low-density polyethylene used in the intermediate layer of the present invention has the characteristics of having few crystal points, being able to form uniform and dense cells when reacting with the foaming agent, and having good processability.

[0040] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw materials for preparing the middle layer include 0 to 8 parts of foaming masterbatch; the melt index, model, and manufacturer of the foaming masterbatch will not be elaborated further; in specific embodiments of the present invention, the raw materials for preparing the middle layer may include or may not include foaming masterbatch. Specifically, when the middle layer includes foaming masterbatch, the mass fraction of the foaming masterbatch is preferably 1 to 8 parts. More specifically, when using foaming masterbatch of model CFE-3361G, its mass fraction is preferably 1 to 2.5 parts, more preferably 1.5 to 2 parts. When using foaming masterbatch of model FM10PE, its mass fraction is preferably 5 to 8 parts, more preferably 6 to 7 parts.

[0041] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw materials for preparing the middle layer include 0.5 to 1.5 parts of processing aids, preferably 0.8 to 1.2 parts. The melt index, model, and manufacturer of the processing aids used in the middle layer are preferably the same as those used in the outer layer, and will not be repeated here. In a specific embodiment of the present invention, when the middle layer uses a processing aid of model PA0895LD, its mass fraction is preferably 0.5 to 1 part, more preferably 0.6 to 0.8 parts. When the middle layer uses a processing aid of model PEA-3S, its mass fraction is preferably 0.5 to 1.5 parts, more preferably 0.6 to 1.2 parts.

[0042] The inner layer is prepared from 15-50 parts by weight of low-density polyethylene, preferably 20-40 parts; the melt index of the low-density polyethylene used in the inner layer is preferably 0.3-3.5 g / 10 min, more preferably 0.8-2.5 g / 10 min, and the density is preferably 0.920-0.930 g / cm³. 3 More preferably, it is 0.923–0.924 g / cm³. 3 The inner layer preferably uses one or more of the following low-density polyethylene types: 2420H, Q281, and HP0823J. Specifically, the 2420H type low-density polyethylene is purchased from CNOOC Shell, with a melt index of 2.0 g / 10 min and a density of 0.924 g / cm³.3 The low-density polyethylene (LDPE) of model Q281 was purchased from Shanghai Petrochemical, with a melt index of 2.8 g / 10 min and a density of 0.924 g / cm³. 3 The low-density polyethylene (LDPE) model HP0823J was purchased from Saudi Basic Industries Corporation (SABIC), with a melt index of 0.8 g / 10 min and a density of 0.923 g / cm³. 3 In specific embodiments of the present invention, when the inner layer uses low-density polyethylene of type 2426H, its mass fraction is preferably 15-40 parts, more preferably 20-35 parts; when the inner layer uses low-density polyethylene of type Q281, its mass fraction is preferably 20-40 parts, more preferably 25-35 parts; when the inner layer uses low-density polyethylene of type HP0823J, its mass fraction is preferably 25-50 parts, more preferably 30-45 parts. The low-density polyethylene used in the inner layer of the present invention has the characteristics of good opening properties and easy processing.

[0043] Based on the mass fraction of low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 20-80 parts, preferably 30-60 parts, of metallocene low-density polyethylene; the melt index of the metallocene low-density polyethylene used in the inner layer is preferably 0.5-2 g / 10 min, preferably 0.8-1.5 g / 10 min, and the density is preferably 0.91-0.92 g / cm³. 3 More preferably, it is 0.914–0.918 g / cm³. 3 The inner layer preferably uses metallocene low-density polyethylene of type XP8784MK, FK1826, or 1018BM; specifically, the low-density polyethylene of type XP8784MK is purchased from ExxonMobil, with a melt index of 0.8 g / 10 min and a density of 0.914 g / cm³. 3 The low-density polyethylene, model FK1826, was purchased from Borouge, with a melt index of 1.5 g / 10 min and a density of 0.918 g / cm³. 3 The low-density polyethylene (LDPE) of model 1018BM was purchased from LG Chem, with a melt index of 1.0 g / 10 min and a density of 0.918 g / cm³. 3 In specific embodiments of the present invention, when the inner layer uses metallocene low-density polyethylene of type XP8784MK, its mass fraction is 25-50 parts, preferably 30-40 parts; when the inner layer uses metallocene low-density polyethylene of type FK1826, its mass fraction is 20-80 parts, preferably 30-50 parts; and when the inner layer uses metallocene low-density polyethylene of type 1018BM, its mass fraction is 30-70 parts, preferably 40-50 parts. The metallocene low-density polyethylene used in the inner layer of the present invention has the properties of high strength, good toughness, low initial sealing temperature, and high heat-sealing strength.

[0044] Based on the mass fraction of low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 10-80 parts of linear low-density polyethylene, more preferably 10-40 parts or 30-80 parts; the melt index of the linear low-density polyethylene used in the inner layer is preferably 1.5-2.5 g / 10 min, more preferably 1.8-2 g / 10 min, and the density is preferably 0.912-0.925 g / cm³. 3 More preferably, it is 0.918–0.920 g / cm³. 3 The linear low-density polyethylene used in the inner layer is preferably one or more of 7042, 1002BU, and 218WJ; wherein, the 7042 linear low-density polyethylene is purchased from Maoming Petrochemical, and has a melt index of 2.0 g / 10 min and a density of 0.918 g / cm³. 3 The linear low-density polyethylene (LLDPE) of model 1002BU was purchased from ExxonMobil, with a melt index of 2.0 g / 10 min and a density of 0.918 g / cm³. 3 The linear low-density polyethylene (LDPE) of model 218WJ was purchased from Saudi Basic Industries Corporation (SABIC), with a melt index of 2.0 g / 10 min and a density of 0.918 g / cm³. 3 In specific embodiments of the present invention, when linear low-density polyethylene of type 7042 is used, its mass fraction is preferably 30-80 parts, more preferably 40-60 parts; when linear low-density polyethylene of type 1002BU or 218WJ is used, its mass fraction is preferably 10-40 parts, more preferably 20-30 parts. The low-density polyethylene used in the inner layer of the present invention has good open-end slip properties and good strength.

[0045] Based on the mass fraction of low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 0 to 8 parts of foaming masterbatch. In a specific embodiment of the present invention, the raw materials for preparing the middle layer may or may not include foaming masterbatch. Specifically, when the middle layer includes foaming masterbatch, the mass fraction of the foaming masterbatch is preferably 1 to 8 parts. More specifically, when using foaming masterbatch of model CFE-3361G, its mass fraction is preferably 1 to 2.5 parts, more preferably 1.5 to 2 parts. When using foaming masterbatch of model FM10PE, its mass fraction is preferably 5 to 8 parts, more preferably 6 to 7 parts.

[0046] Based on the mass fraction of low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 0.5 to 1.5 parts of processing aids, preferably 0.8 to 1.2 parts; the melt index, model, and manufacturer of the processing aids used in the middle layer are preferably the same as those used in the outer layer, and will not be repeated here; in a specific embodiment of the present invention, when the inner layer uses processing aid of model PA0895LD, its mass fraction is preferably 0.5 to 1 part, more preferably 0.6 to 0.8 parts; when the inner layer uses processing aid of model PEA-3S, its mass fraction is preferably 0.5 to 1.5 parts, more preferably 0.6 to 1.2 parts.

[0047] In this invention, taking the total mass of the outer layer, middle layer and inner layer as 100%, the mass fraction of the outer layer is preferably 15-30%, the mass fraction of the middle layer is preferably 40-70%, and the mass fraction of the inner layer is preferably 15-30%; the thickness of the high-buffering, drop-resistant, heat-insulating PE film is preferably 100-200 μm, more preferably 150 μm; the thickness ratio of the outer layer, middle layer and inner layer is preferably 1-3:2-4:1-3, more preferably 3:4:3, 1:2:1, 1:3:1 or 1:4:1.

[0048] In this invention, the longitudinal tensile strength of the high-buffering, drop-resistant, heat-insulating PE film is preferably 23–24.5 MPa, more preferably 23.7–24.1 MPa; the transverse tensile strength is preferably 21–23 MPa, more preferably 21.5–22.5 MPa; the longitudinal elongation at break is preferably 415–435%, more preferably 420–425%; the transverse elongation at break is preferably 615–640%, more preferably 620–630%; and the density is preferably 0.5–0.6 g / cm³. 3 More preferably, it is 0.565–0.59 g / cm³. 3 .

[0049] The present invention also provides a method for preparing the high-buffered, drop-resistant, heat-insulating PE film described above, comprising the following steps:

[0050] The raw materials for the preparation of the outer layer, middle layer and inner layer are co-extruded and blown into a film to obtain the high-buffering, drop-resistant, heat-insulating PE film; among the raw materials for the preparation of the outer layer, middle layer and inner layer, at least one of the raw materials includes foaming masterbatch.

[0051] In this invention, the process of three-layer co-extrusion blown film specifically includes: mixing the raw materials for the outer layer, middle layer and inner layer in proportion through an automatic batching system and then feeding them into the outer layer, middle layer and inner layer extruders for melt plasticization; conveying the resulting adhesive liquid to the die head and extruding blown film to obtain a film bubble; after being cooled by air cooling, the film bubble passes through a stabilizing ring and a herringbone pattern to the upper traction rotation, flattening the cylinder and then entering the corona treatment device through guide rollers for corona treatment; and then undergoing edge trimming, lower traction and winding to obtain the high-buffered anti-drop heat insulation PE film.

[0052] In this invention, the outer extruder, middle extruder, and inner extruder are each equipped with five heating zones, which are designated as zones 1 to 5 according to the order in which the raw materials pass through. The preferred temperatures for zones 1, 2, 3, 4, and 5 of the outer extruder are 170±5℃, 175±5℃, 165±5℃, and 160±5℃, respectively. For the middle extruder, the preferred temperatures for zones 1, 2, 3, 4, and 5 are 165±5℃, 162±5℃, and 160±5℃, respectively. For the inner extruder, the preferred temperatures for zones 1, 2, 3, 4, and 5 are 175±5℃, 178±5℃, 172±5℃, 170±5℃, and 165±5℃, respectively.

[0053] In this invention, the pressure of the outer extruder is preferably 220-285 bar, more preferably 245 bar; the pressure of the middle extruder is preferably 280-360 bar, more preferably 320 bar; and the pressure of the inner extruder is preferably 245-320 bar, more preferably 295 bar.

[0054] In this invention, the mold head is divided into 4 heating zones, which are numbered 1 to 4 according to the order in which the adhesive passes through. The temperature of zone 1 is preferably 180±5℃, the temperature of zone 2 is preferably 185±5℃, the temperature of zone 3 is preferably 188±5℃, and the temperature of zone 4 is preferably 182±5℃.

[0055] The present invention also provides a composite film (referred to as a high-buffered drop-resistant heat-insulating composite film), the composite film including a heat-insulating layer, the heat-insulating layer being the high-buffered drop-resistant heat-insulating PE film described in the above scheme or the high-buffered drop-resistant heat-insulating PE film prepared by the preparation method described in the above scheme.

[0056] In this invention, the composite film is preferably a three-layer or four-layer structure; the three-layer structure preferably includes a printing layer, a barrier layer, and a heat insulation layer arranged sequentially; the printing layer is preferably a polyester film (PET), and the thickness of the polyester film is preferably 12-15 μm; the barrier layer is preferably an aluminum foil or a metallized polyester film (VMPET), the thickness of the aluminum foil is preferably 7-25 μm, and the thickness of the VMPET is preferably 12 μm; when the barrier layer is aluminum foil, the thickness ratio of the printing layer, the barrier layer, and the heat insulation layer is preferably 12-15:7-25:100-200; when the barrier layer is VMPET, the thickness ratio of the printing layer, the barrier layer, and the heat insulation layer is preferably 12-15:12:100-200.

[0057] In this invention, the four-layer structure preferably includes a printed layer, a barrier layer, a heat insulation layer, and a PE heat-sealing layer arranged sequentially. The printed layer, barrier layer, and heat insulation layer are consistent with those in the three-layer structure and will not be described again here. This invention does not have special requirements for the PE heat-sealing layer; any material well-known to those skilled in the art can be used. The thickness of the PE heat-sealing layer is preferably 40–60 μm. When the barrier layer is aluminum foil, the thickness ratio of the printed layer, barrier layer, heat insulation layer, and PE heat-sealing layer is preferably 12–15:7–25:100–150:40–60. When the barrier layer is VMPET, the thickness ratio of the printed layer, barrier layer, heat insulation layer, and PE heat-sealing layer is preferably 12–15:12:100–150:40–60.

[0058] Alternatively, the four-layer structure includes a paper layer, a barrier layer, a printing layer, and a heat insulation layer arranged sequentially. The type of barrier layer is the same as in the three-layer structure and will not be described again here. The paper layer is preferably kraft paper for printing, and the thickness of the paper layer is preferably 60-80 μm. The printing layer is preferably a PET layer or a nylon layer. In this invention, PET or nylon is used as the printing layer because the material has good temperature resistance, is easy to print, and is easy to make bags. The thickness of the PET layer is preferably 12 μm, and the thickness of the nylon layer is preferably 15 μm. This invention does not have special requirements for the PET layer or nylon layer, and any material well known to those skilled in the art can be used.

[0059] In this invention, the method for preparing the three-layer composite membrane preferably includes the following steps:

[0060] The printed layer and the barrier layer are bonded together with an adhesive to obtain a printed layer / barrier layer composite film;

[0061] The three-layer composite film is obtained by bonding the printed layer / barrier layer composite film and the high-buffered, drop-resistant, heat-insulating PE film together with a solvent-free adhesive.

[0062] In this invention, the printing layer is preferably printed as needed before lamination. The printing method is not particularly important; gravure printing, a process well-known to those skilled in the art, is sufficient. The amount of adhesive applied when laminating the printing layer and the barrier layer is preferably 3.0–3.8 g / m³. 2 The lamination of the printed layer and the barrier layer is preferably a dry lamination. This invention does not have special requirements for the specific operating conditions of the dry lamination; a dry lamination process well-known to those skilled in the art can be used. In a specific embodiment of this invention, the adhesive is applied to the printed layer, and then the barrier layer is laminated. In this invention, the adhesive used when laminating the printed layer and the barrier layer is preferably TAKELACTM PP-3111 / TAKENATETM I-3000 dry lamination adhesive from Tianjin Tianhuan Polyurethane Co., Ltd. When using the dry lamination adhesive, it is preferred to mix PP-3111, I-3000, and ethyl acetate, with the preferred mass ratio of PP-3111, I-3000, and ethyl acetate being 8:1:10.8. After lamination, curing is preferred, with the curing temperature preferably 50℃±5℃ and the curing time preferably 72 hours.

[0063] In this invention, the solvent-free adhesive is preferably the two-component solvent-free polyurethane composite adhesive I-2450A / PP-2450FX from Tianjin Tianhuan Polyurethane Co., Ltd., with a solid content of 100%. The process conditions for laminating the printed layer / barrier layer composite film and the high-buffered, drop-resistant, heat-insulating PE film include: a mixing temperature preferably of 50°C, specifically setting the temperature of both I-2450A and PP-2450FX to 50°C before mixing; a coating temperature preferably of 50°C, specifically setting the temperature of each steel roller in the coating system to 50°C; an adhesive ratio: the mass ratio of I-2450A to PP-2450FX is preferably 100:50; and an adhesive application rate preferably of 1.6–2.2 g / m³. 2 More preferably, it is 1.6–2.0 g / m 2 After compounding, it is preferable to perform curing, the curing temperature is preferably 45℃±5℃, the curing time is preferably 48h, and after curing is completed, it is preferable to take it out and place it at room temperature for 12 hours before proceeding with subsequent slitting and bag making.

[0064] In this invention, when the composite film has a four-layer structure, and the four-layer structure includes a printing layer, a barrier layer, a heat insulation layer, and a PE heat-sealing layer arranged sequentially, the method for preparing the composite film preferably includes the following steps:

[0065] The printed layer and the barrier layer are bonded together with an adhesive to obtain a printed layer / barrier layer composite film;

[0066] The printed layer / barrier layer composite film and the high-buffered, drop-resistant, heat-insulating PE film are bonded together using a solvent-free adhesive to obtain the printed layer / barrier layer / heat-insulating layer composite film.

[0067] The printed layer / barrier layer / heat insulation layer composite film is bonded to the PE heat-sealing layer using a solvent-free adhesive to obtain a four-layer composite film.

[0068] In this invention, the method of laminating the printed layer and the barrier layer, as well as the method of laminating the printed layer / barrier layer composite film and the high-buffered, drop-resistant, heat-insulating PE film, are consistent with the preparation process of the three-layer composite film, and will not be repeated here. The printed layer / barrier layer / heat-insulating layer composite film is laminated with the PE heat-sealing layer using a solvent-free adhesive. The specific lamination conditions are consistent with the conditions for laminating the printed layer / barrier layer composite film and the high-buffered, drop-resistant, heat-insulating PE film using a solvent-free adhesive during the preparation process of the three-layer composite film, and will not be repeated here.

[0069] In this invention, when the composite film has a four-layer structure, and the four-layer structure includes a paper layer, a barrier layer, a printing layer, and a heat insulation layer arranged sequentially, the method for preparing the composite film preferably includes the following steps:

[0070] The paper layer and the barrier layer are bonded together with an adhesive to obtain a paper layer / barrier layer composite film;

[0071] The paper layer / barrier layer composite film is laminated with an adhesive and a printing layer to obtain a paper layer / barrier layer / printing layer composite film;

[0072] The paper layer / barrier layer / printed layer composite film is bonded to the high-buffered, drop-resistant, heat-insulating PE film using a solvent-free adhesive to obtain a four-layer composite film.

[0073] In this invention, the paper layer is preferably printed before lamination, and the printing method is preferably gravure printing; the paper layer and the barrier layer are preferably laminated using a solvent-free lamination process, and the adhesive used is preferably a solvent-free single-component adhesive. In a specific embodiment of this invention, the solvent-free single-component adhesive is preferably Wanhua Chemical's solvent-free single-component adhesive 6091; the amount of adhesive applied when laminating the paper layer and the barrier layer is preferably 3.5–5.5 g / m³. 2 After compounding, it is preferable to perform curing, and the curing temperature is preferably 55℃±5℃, and the curing time is preferably 48h.

[0074] In this invention, when the paper layer / barrier layer composite film is laminated with the printed layer, the preferred method is dry lamination, and the amount of adhesive applied is preferably 3.0-4 g / m³. 2The adhesive used in the dry lamination is preferably TAKELACTM PP-3111 / TAKENATETM I-3000 dry lamination adhesive from Tianjin Tianhuan Polyurethane Co., Ltd. When using the dry lamination adhesive, it is preferred to mix PP-3111, I-3000 and ethyl acetate, and the mass ratio of PP-3111, I-3000 and ethyl acetate is preferably 8:1:10.8. After lamination, it is preferred to cure the adhesive, and the curing temperature is preferably 50℃±5℃, and the curing time is preferably 72 hours.

[0075] In this invention, the solvent-free adhesive used for laminating the paper layer / barrier layer / printed layer composite film with the high-buffered, drop-resistant, heat-insulating PE film preferably has an application rate of 1.6–2.2 g / m³. 2 The type of solvent-free adhesive and the composite conditions are the same as those in the preparation process of the three-layer composite film, and will not be repeated here.

[0076] This invention also provides a composite bag, prepared by composite film according to the above-described method. This invention does not have special requirements for the bag shape of the composite bag; any shape well-known to those skilled in the art can be used.

[0077] This invention does not specify a particular method for preparing the composite bag; methods well-known to those skilled in the art can be used to cut the composite film into bags. In a specific embodiment of this invention, the preferred bag-making conditions include: a transverse sealing temperature of 175℃–195℃, a transverse sealing heat-sealing pressure of 4–6 kg, a heat-sealing time of 0.5–1 second, and a sealing line width of 10 ± 1.5 mm; a longitudinal sealing temperature of 170℃–190℃, a longitudinal sealing heat-sealing pressure of 4–6 kg, a heat-sealing time of 0.5–1 second, and a sealing line width of 10 ± 1.5 mm; and a nozzle-filling temperature of 180–200℃, a nozzle-filling heat-sealing pressure of 4.5–6.5 kg, and a heat-sealing time of 0.5–1 second.

[0078] The composite bag provided by this invention has good heat and cold insulation properties, which can extend the thawing time of frozen beverages and the cooling time of hot beverages; it is also comfortable to the touch, without feeling cold or hot, providing a good customer experience; in specific embodiments of this invention, the composite bag provided by this invention can be used for food packaging that has better flavor after refrigeration, such as juice, fruit puree, jelly, herbal jelly, wine, milk, water, specialty beverages, and specialty liquid foods; or for food packaging that has better flavor after heating, such as coffee, juice, fruit puree, wine, milk, water, specialty beverages, and specialty liquid foods; or for other flexible packaging that requires heat insulation, such as health products or medicines.

[0079] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0080] The properties and suppliers of the raw materials used in the embodiments of this invention are shown in Table 1.

[0081] Table 1 Raw Material Properties and Suppliers

[0082]

[0083] Example 1

[0084] 1. Preparation of high-buffering, drop-resistant, heat-insulating PE film

[0085] The high-buffering, drop-resistant, heat-insulating PE film of this embodiment is made of three layers: outer layer, middle layer, and inner layer, which are co-extruded blown film. The weight percentage of each layer is as follows: outer layer 30%, middle layer 40%, and inner layer 30%.

[0086] The raw material usage for each layer is shown in Table 2. The total thickness of the high-buffering, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is as follows:

[0087] The raw materials for the outer, middle, and inner layers are mixed in proportion by an automatic batching system and then fed into the outer, middle, and inner layer extruders. The raw materials for the outer, middle, and inner layers are melted and plasticized and then fed into the die head for extrusion and blown film. After being cooled by air, the film is flattened by the stabilizing ring and herringbone arrangement and then enters the corona treatment device for corona treatment via guide rollers. After being trimmed, the film is wound into the front and rear winding device via the lower traction clamping rollers to obtain a 150μm high-buffering, drop-resistant, and heat-insulating PE film.

[0088] The temperatures and pressures of the outer, middle, and inner layer extruders and dies are shown in Table 3.

[0089] Table 2. Raw material ratios for Examples 1-8 and Comparative Examples 2-4

[0090]

[0091]

[0092] Table 3 Temperature and pressure of extruder and die head

[0093] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ Zone 4 / ℃ 5 zones / ℃ Pressure (bar) outer layer 170 175 170 165 160 245 Middle layer 165 170 165 162 160 320 Inner layer 175 178 172 170 165 295 mold head 180 185 188 182 / /

[0094] 2. Preparation of three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag

[0095] The composite film has a three-layer structure, consisting of a printed layer, a barrier layer, and a heat insulation layer arranged sequentially. The printed layer is a polyester (PET) film; 12μm printed film was purchased from DuPont Hutchison. The barrier layer is an aluminum foil; 7μm aluminum foil for packaging was purchased from Shanghai Shenhuo Aluminum Foil Co., Ltd. The heat insulation layer is a 150μm thick high-buffering, drop-resistant, heat-insulating PE film layer prepared in the above steps. The three-layer composite film is designated as PET12 / AL7 / heat-insulating PE film 150.

[0096] The preparation method of high-buffered, drop-resistant, and heat-insulating composite film and bag is as follows:

[0097] (1) The printed layer polyester film is printed using gravure printing according to customer requirements.

[0098] (2) The printed polyester film and aluminum foil are laminated using a dry lamination process. The adhesive used is TAKELACTM PP-3111 / TAKENATETM I-3000 dry lamination adhesive from Tianjin Tianhuan Polyurethane Co., Ltd. During use, PP-3111, I-3000, and ethyl acetate are mixed in a mass ratio of 8:1:10.8; the adhesive application rate is 3.5 g / m³. 2 After compounding, the mixture is placed in a curing room at 50℃±5℃ for 72 hours.

[0099] (3) The cured PET / AL two-layer composite film is laminated with a high-buffered, drop-resistant, heat-insulating PE film using a solvent-free adhesive. The adhesive used is Tianjin Tianhuan Polyurethane Co., Ltd.'s two-component solvent-free polyurethane composite adhesive I-2450A / PP-2450FX, with a solid content of 100%. The lamination process conditions are as follows: mixing temperature: both components A and B are set to 50℃; coating temperature: each steel roller of the coating system is set to 50℃; adhesive ratio I-2450A / PP-2450FX = 100 / 50 (mass ratio); ④, the amount of adhesive applied is 2g / m 2 After compounding, the mixture is placed in a curing room at 45℃±5℃ for 48 hours, then removed and left at room temperature for 12 hours before being cut and bagged.

[0100] (4) Cut the cured 3-layer composite film into bags; the bag making process is as follows:

[0101] Horizontal sealing temperature: 175℃~195℃, heat sealing pressure 4.8kg, time 0.8 seconds, sealing line width 10±1.5mm;

[0102] Longitudinal sealing temperature: 170℃~190℃, heat sealing pressure: 5.2kg, time: 0.8 seconds, sealing line width: 10±1.5mm;

[0103] Nozzle temperature: 185℃, heat sealing pressure: 5.5kg, time: 1.0 second.

[0104] 3. Preparation of four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag

[0105] The composite film has a four-layer structure, consisting of a paper layer, an aluminum foil layer, a nylon layer, and a heat insulation layer arranged sequentially. The heat insulation layer is a 150μm thick high-buffer, drop-resistant heat-insulating PE film layer prepared in the above steps. The paper is composite paper purchased from Anhui Desen Special Paper Co., Ltd., the aluminum foil is 7μm packaging aluminum foil purchased from Shanghai Shenhuo Aluminum Foil Co., Ltd., and the nylon is 15μm thick nylon selected from Xiamen Changsu.

[0106] The preparation method of high-buffered, drop-resistant, and heat-insulating composite film and bag is as follows:

[0107] (1) The printed paper and aluminum foil are laminated using a solvent-free lamination process. The adhesive used is Wanhua Chemical's solvent-free single-component adhesive 6091, with an application rate of 5g / m². 2 After compounding, the mixture is placed in a curing room at 55℃±5℃ for 48 hours to cure.

[0108] (2) The paper / AL composite film is dry-laminated with nylon. The adhesive used is TAKELACTM PP-3111 / TAKENATETM I-3000 dry lamination adhesive from Tianjin Tianhuan Polyurethane Co., Ltd. During application, PP-3111, I-3000, and ethyl acetate are mixed, with a weight ratio of 8:1:10.8. The adhesive application rate is 3.5 g / m³. 2 After compounding, the mixture is placed in a curing room at 50℃±5℃ for 72 hours.

[0109] (3) The cured paper / AL / NY 3-layer composite film is laminated with a high-buffered, drop-resistant, heat-insulating PE film using a solvent-free adhesive. The adhesive used is Tianjin Tianhuan Polyurethane Co., Ltd.'s two-component solvent-free polyurethane composite adhesive I-2450A / PP-2450FX, with a solid content of 100%. The lamination process conditions are as follows: mixing temperature: both components A and B are set to 50℃; coating temperature: each steel roller of the coating system is set to 50℃; adhesive ratio I-2450A / PP-2450FX = 100 / 50 (mass ratio); adhesive application amount is 1.8g / m³. 2 After compounding, the mixture is placed in a curing room at 45℃±5℃ for 48 hours, then removed and left at room temperature for 12 hours before being cut and bagged.

[0110] (4) Cut the cured 4-layer composite film into bags; the bag making process is as follows:

[0111] Horizontal sealing temperature: 175℃~195℃, heat sealing pressure 5.0kg, time 1 second, sealing line width 10±1.5mm;

[0112] Longitudinal sealing temperature: 170℃~190℃, heat sealing pressure: 5.8kg, time: 1 second, sealing line width: 10±1.5mm;

[0113] Nozzle temperature: 192℃, heat sealing pressure: 6.0kg, time: 1.0 second.

[0114] Example 2

[0115] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 25%, middle layer 50%, and inner layer 25%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0116] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0117] Example 3

[0118] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 20%, middle layer 55%, and inner layer 25%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0119] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0120] Example 4

[0121] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 20%, middle layer 60%, and inner layer 20%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0122] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0123] Example 5

[0124] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 20%, middle layer 50%, and inner layer 30%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0125] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0126] Example 6

[0127] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 30%, middle layer 40%, and inner layer 30%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0128] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0129] Example 7

[0130] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 25%, middle layer 50%, and inner layer 25%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0131] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0132] Example 8

[0133] The raw material usage for each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 25%, middle layer 45%, and inner layer 30%. The total thickness of the high-buffered, drop-resistant, heat-insulating PE film is 150 μm. The preparation method is the same as in Example 1.

[0134] The preparation methods for the three-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, as well as the four-layer high-buffering, drop-resistant, and heat-insulating composite film and bag, are the same as in Example 1.

[0135] Comparative Example 1

[0136] The PE film in this comparative example is made by co-extrusion blown film of three layers: outer layer, middle layer and inner layer. The weight percentage of each layer is as follows: outer layer 30%, middle layer 40% and inner layer 30%.

[0137] The manufacturers, properties, and quantities of raw materials for each layer are shown in Table 4.

[0138] Table 4 lists the manufacturers, properties, and quantities (parts by mass) of the raw materials used in Comparative Example 1.

[0139]

[0140] The above PE film preparation method is as follows: the raw materials of the outer layer, middle layer and inner layer are mixed in proportion by an automatic batching system and then fed into the outer layer, middle layer and inner layer extruders. The raw materials of the outer layer, middle layer and inner layer are melted and plasticized and then fed into the die head for extrusion blown film. After air cooling, the film is flattened by the stabilizing ring and herringbone arrangement and then enters the corona treatment device for corona treatment through the guide rollers. After trimming, the film is wound into the front and rear winding device through the lower traction clamping rollers to obtain a 150μm PE film. The temperature and pressure of each zone of the extruder are shown in Table 5.

[0141] Table 5. Temperature and pressure of the extruder

[0142] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ 4 zones / ℃ 5 zones / ℃ Pressure / bar outer layer 160 165 170 160 160 215 Middle layer 170 175 170 165 160 285 Inner layer 168 172 165 160 160 320 mold head 185 190 185 180 / /

[0143] The preparation methods for the three-layer composite film and bag, as well as the four-layer composite film and bag, are the same as in Example 1, except that the high-buffered, drop-resistant, and heat-insulating PE film is replaced with the PE film prepared in Comparative Example 1.

[0144] Comparative Example 2

[0145] This comparative example is an adjustment based on Example 1. The raw material usage of each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 30%, middle layer 45%, and inner layer 25%. The total thickness of the PE film is 150 μm, and the preparation method is the same as in Example 1.

[0146] The preparation methods for the three-layer composite membrane and bag, as well as the four-layer composite membrane and bag, are the same as in Example 1.

[0147] Comparative Example 3

[0148] This comparative example is an adjustment based on Example 3. The raw material usage of each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 20%, middle layer 55%, and inner layer 25%. The total thickness of the PE film is 150 μm. The preparation method is the same as in Example 1.

[0149] The preparation methods for the three-layer composite membrane and bag, as well as the four-layer composite membrane and bag, are the same as in Example 1.

[0150] Comparative Example 4

[0151] This comparative example is an adjustment based on Example 6. The raw material usage of each layer is shown in Table 2. The weight percentage of each layer is as follows: outer layer 30%, middle layer 40%, and inner layer 30%. The total thickness of the PE film is 150 μm, and the preparation method is the same as in Example 1.

[0152] The preparation methods for the three-layer composite membrane and bag, as well as the four-layer composite membrane and bag, are the same as in Example 1.

[0153] Performance testing:

[0154] 1. Mechanical properties and drop resistance tests

[0155] The mechanical properties and density of the PE films prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were tested. The test methods and test results are shown in Table 6.

[0156] The cushioning and drop resistance performance of the three-layer composite bags prepared in Examples 1 to 8 and Comparative Examples 1 to 4 were tested. The test method was as follows: 1 kg of water was placed in the composite film bag and dropped from 1.5 meters. The test was repeated 5 times, and the bag was observed to see if it broke. The test results are shown in Table 6.

[0157] Table 6. Test results of mechanical properties and drop resistance.

[0158]

[0159]

[0160] As can be seen from the data in Table 1, the high-buffering, drop-resistant, and heat-insulating PE film prepared by this invention has low density, light weight, and high tensile strength and elongation at break, exhibiting excellent mechanical properties. Furthermore, bags made using the composite film of this invention, after being dropped 1.5 kg of water from a height of 1.5 m five times, did not break, demonstrating its excellent cushioning performance and good drop resistance. Comparative Example 1 used a conventional formulation to prepare a non-foamed PE film, resulting in a film with higher density and poorer cushioning. Comparative Examples 2-4 reduced the amount of foaming masterbatch, resulting in PE films with higher density and poorer cushioning.

[0161] 2. Thermal insulation performance test

[0162] The thermal insulation performance of the three-layer composite bags prepared in Examples 1 to 8 and Comparative Examples 1 to 4 was tested. Specifically, 150 mL of water at 85°C was placed in the composite bags, and then the bags were placed in an environment of 23–25°C. The water temperature was measured every 30 minutes. The test results are shown in Table 7. Additionally, 150 mL of water was placed in bags prepared using the composite film, frozen, and then placed in an environment of 23–25°C. The thawing time was measured every 30 minutes. The results are shown in Table 8.

[0163] Table 7 Thermal Insulation Performance Test Results - Hot Water Test / °C

[0164]

[0165] Table 8 Thermal Insulation Performance Test Results—Ice Cube Test

[0166]

[0167] As can be seen from the data in Tables 7 and 8, the composite bag prepared by this invention has high heat and cold insulation performance, and the thawing and cooling time is extended by 3 to 4 hours compared with ordinary bags after containing cold or hot drinks.

[0168] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-buffering, drop-resistant, heat-insulating PE film, characterized in that, It is made of three layers: outer layer, middle layer and inner layer, by co-extrusion blown film; by mass parts, the raw materials for preparing the outer layer include: 10-60 parts of low-density polyethylene, 20-80 parts of linear low-density polyethylene, 15-60 parts of metallocene low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids. The raw materials for preparing the middle layer, by mass, include: 10-98 parts of low-density polyethylene, 1-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids. The raw materials for preparing the inner layer, by mass parts, include: 15-50 parts of low-density polyethylene, 20-80 parts of metallocene low-density polyethylene, 10-80 parts of linear low-density polyethylene, 0-8 parts of foaming masterbatch, and 0.5-1.5 parts of processing aids. The foaming masterbatch is of type CFE-3361G and / or FM10PE; The low density polyethylene used in the outer layer has a melt index of 0.2 to 5 g / 10 min and a density of 0.920 to 0.935 g / cm 3 ; the linear low density polyethylene used in the outer layer has a melt index of 0.3 to 3.5 g / 10 min and a density of 0.912 to 0.930 g / cm 3 ; the metallocene low density polyethylene used in the outer layer has a melt index of 0.5 to 2.5 g / 10 min and a density of 0.908 to 0.930 g / cm 3 ; The low-density polyethylene used in the middle layer has a melt index of 0.1-3.5 g / 10 min and a density of 0.920-0.940 g / cm 3 ; The low density polyethylene used in the inner layer has a melt index of 0.3-3.5 g / 10 min and a density of 0.920-0.930 g / cm 3 ; the metallocene low density polyethylene used in the inner layer has a melt index of 0.5-2 g / 10 min and a density of 0.91-0.92 g / cm 3 ; the linear low density polyethylene used in the inner layer has a melt index of 1.5-2.5 g / 10 min and a density of 0.912-0.925 g / cm 3 ; The processing aids used in the outer, middle, and inner layers have a melt index of 1.5~2.5 g / 10 min and a density of 0.910~0.925 g / cm³. 3 .

2. The method for preparing the high-buffered, drop-resistant, heat-insulating PE film according to claim 1, characterized in that, Includes the following steps: The raw materials for the preparation of the outer, middle and inner layers are co-extruded and blown into a film to obtain the high-buffering, drop-resistant, heat-insulating PE film.

3. A composite membrane, characterized in that, The composite film includes a heat insulation layer, which is the high-buffered, drop-resistant heat-insulating PE film of claim 1 or the high-buffered, drop-resistant heat-insulating PE film prepared by the preparation method of claim 2.

4. The composite membrane according to claim 3, characterized in that, The composite film has a three-layer or four-layer structure; the three-layer structure includes a printing layer, a barrier layer, and a heat insulation layer arranged in sequence; the four-layer structure includes a printing layer, a barrier layer, a heat insulation layer, and a PE heat-sealing layer arranged in sequence; or, the four-layer structure includes a paper layer, a barrier layer, a printing layer, and a heat insulation layer arranged in sequence.

5. A composite bag, characterized in that, It is prepared from the composite membrane described in claim 3 or 4.

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