A double-sided corona film and a preparation method and application thereof

Abstract

The present application relates to the technical field of composite film, and provides a double-sided corona film and a preparation method and application thereof.The formula of the double-sided corona film is strictly controlled, the amount of the additive in the formula is small, opening master batch is not needed, and more pure raw materials are used for film making, while the heat resistance and mechanical properties of the film can be ensured; meanwhile, the film is subjected to double-sided corona treatment, which can not only ensure the composite fastness, but also improve the heat resistance, so that the subsequent bag making will not wrinkle due to high temperature.The double-sided corona film provided by the present application can be used as a surface layer and a PE film for compounding, and after compounding, heat sealing bag making is carried out to obtain a single-material PE composite bag, which is convenient for subsequent recycling; and after the double-sided corona film and the PE film are compounded, heat sealing bag making is carried out, the heat sealing temperature can reach 150-160 DEG C, and the bag is not prone to wrinkling, and the surface of the double-sided corona film can be printed, meeting the packaging requirements.

Description

Technical Field

[0001] This invention relates to the field of composite membrane technology, and in particular to a double-sided corona membrane, its preparation method, and its application. Background Technology

[0002] Flexible packaging refers to packaging whose shape can change after the contents are filled or removed. In the food and daily chemical packaging industries, plastic composite flexible stand-up pouches are one of the most common packaging methods on the market. Plastic composite flexible packaging has good flexibility, good water resistance, moisture resistance and gas barrier properties, stable chemical properties, and is resistant to oils and greases. It is also easy to print exquisite graphics and text, making it an ideal packaging material.

[0003] Existing flexible stand-up pouches on the market are made of composite plastic films of different materials. They generally consist of a base layer and a heat-sealing layer. The base layer mainly serves functions such as printing and moisture barrier, and is usually made of films with good heat resistance and low heat deformation, such as BOPP, PET, and KPET. The heat-sealing layer is in direct contact with the packaged goods and provides functions such as adaptability, impermeability, good heat sealing, transparency, and openability. It is usually made of PE film. However, because these composite bags are made of plastic films of different materials, they cannot be recycled after use, easily causing plastic waste pollution.

[0004] Composite bags made by laminating PE film as the face layer and PE heat-sealing layer can be produced using a single material, meeting the requirements for recyclable packaging materials. However, when PE is used as the face material, its high-temperature resistance is poor, and it is prone to wrinkling during heat sealing. Conversely, if the heat-sealing temperature is too low, a proper seal cannot be guaranteed, leading to easy opening. Currently, existing technologies can improve the heat resistance of the PE film by adjusting its formulation to avoid wrinkling. However, this typically requires the addition of significant amounts of processing aids and opening masterbatches, resulting in a complex film composition and higher costs. Furthermore, excessive processing aids can hinder subsequent recycling. Summary of the Invention

[0005] In view of this, the present invention provides a double-sided corona film, its preparation method, and its application. The double-sided corona film formulation provided by the present invention uses less additives, employs purer raw materials, facilitates recycling, and simultaneously ensures the film's heat resistance, increases heat-sealing temperature, and prevents wrinkling.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: A double-sided corona-extruded film is made by co-extruding three layers—outer layer, middle layer, and inner layer—and then subjecting them to double-sided corona treatment; the outer layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 parts of processing aids. The middle layer is prepared from the following raw materials in parts by weight: 30-70 parts high-density polyethylene, 20-60 parts medium-density polyethylene, and 0.5-1 parts processing aids; The inner layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 part of processing aids. The high-density polyethylene used in the outer, middle, and inner layers has a melt index of 0.7 g / 10 min and a density of 0.961 g / cm³. 3 The outer and inner layers use metallocene polyethylene with a melt index of 1.3 g / 10 min and a density of 0.927 g / cm³. 3 The medium-density polyethylene used in the middle layer has a melt index of 0.5 g / 10 min and a density of 0.935 g / cm³. 3 .

[0007] Preferably, based on the total mass of the outer layer, middle layer and inner layer as 100%, the mass fraction of the outer layer is preferably 25%~30%, the mass fraction of the middle layer is preferably 40~50%, and the mass fraction of the inner layer is preferably 25~30%; the thickness of the double-sided corona film is preferably 60~80μm.

[0008] Preferably, the processing aids used in the outer, middle, and inner layers have a melt index of 2.3 g / 10 min and a density of 0.932 g / cm³. 3 .

[0009] Preferably, the high-density polyethylene used in the outer, middle, and inner layers is grade HTA108; the metallocene polyethylene used in the outer and inner layers is grade 1327CA; the medium-density polyethylene used in the middle layer is grade 3505MC; and the processing aid used in the outer, middle, and inner layers is grade PA0895LD.

[0010] The present invention also provides a method for preparing the double-sided corona film described above, comprising the following steps: The raw materials for the outer, middle, and inner layers are melted and plasticized, and then co-extruded and blown to obtain a primary film. The primary membrane is subjected to double-sided corona treatment to obtain a double-sided corona-treated membrane.

[0011] Preferably, the double-sided corona treatment method specifically includes: the primary film is cooled by air, then subjected to a stabilizing ring and an integrated herringbone pattern before being pulled and rotated by an upper traction device to flatten it. The primary film then enters the corona treatment device to perform corona treatment on the outer layer of the film. After that, the film is trimmed and opened by a lower traction clamping roller in sequence. After that, the film enters the corona treatment device again to perform corona treatment on the inner layer of the film.

[0012] Preferably, the integrated herringbone strip includes a herringbone strip and a covering material covering the surface of the herringbone strip; the covering material is a dust-free cloth; After double-sided corona treatment, the dyne values ​​on both sides of the film are above 40.

[0013] The present invention also provides the application of the double-sided corona film described in the above-described scheme or the double-sided corona film prepared by the preparation method described in the above-described scheme in the preparation of PE composite bags; the double-sided corona film is used as a surface material.

[0014] Preferably, the application method is as follows: the double-sided corona film and the PE film are laminated and then heat-sealed to form a bag, and the heat-sealing temperature is 150~160℃.

[0015] Preferably, before laminating with the PE film, the process further includes printing on the surface of the double-sided corona film.

[0016] This invention provides a double-sided corona-extruded film, which is made by co-extruding and blowing an outer layer, a middle layer, and an inner layer, followed by double-sided corona extrusion. The outer layer is prepared from the following raw materials in parts by weight: 10-90 parts high-density polyethylene, 20-80 parts metallocene polyethylene, and 0.5-1 parts processing aids. The middle layer is prepared from the following raw materials in parts by weight: 30-70 parts high-density polyethylene, 20-60 parts medium-density polyethylene, and 0.5-1 parts processing aids. The inner layer is prepared from the following raw materials in parts by weight: 10-90 parts high-density polyethylene, 20-80 parts metallocene polyethylene, and 0.5-1 parts processing aids. The high-density polyethylene used in the outer, middle, and inner layers has a melt index of 0.7 g / 10 min and a density of 0.961 g / cm³. 3 The outer and inner layers use metallocene polyethylene with a melt index of 1.3 g / 10 min and a density of 0.927 g / cm³. 3 The medium-density polyethylene used in the middle layer has a melt index of 0.5 g / 10 min and a density of 0.935 g / cm³. 3 This invention strictly controls the formulation of the double-sided corona-electrode film, using less additives and eliminating the need for opening masterbatch. It utilizes purer raw materials for film production while ensuring the film's heat resistance and mechanical properties. Furthermore, this invention corona-electrodes both sides of the film, whereas conventional films typically only corona-electrode one side, using the corona-electrode side as the composite surface to improve lamination strength. This invention, by using double-sided corona-electrode, not only ensures lamination strength but also improves heat resistance, preventing wrinkling during subsequent bag making due to excessively high temperatures.

[0017] The double-sided corona film provided by this invention can be used as a surface layer and laminated with PE film. After lamination, it can be heat-sealed to form a bag, resulting in a single-material PE composite bag, which is convenient for subsequent recycling. Furthermore, when using the double-sided corona film and PE film of this invention for lamination and heat-sealing, the heat-sealing temperature can reach 150~160℃ (the traditional heat-sealing temperature is only 135~145℃ and is prone to wrinkling), making it less prone to wrinkling. The surface of the double-sided corona film can also be printed to meet packaging requirements. Attached Figure Description

[0018] Figure 1 A picture of a standard herringbone pattern; Figure 2 This is a physical image of the integrated herringbone layout used in this invention; Figure 3 This is a physical image of the integrated herringbone layout used in this invention; Figure 4 This is a photograph of a bag made using the double-sided corona film prepared in Example 1 as the surface layer. Figure 5 The image shows the actual product after bag making using the single-sided corona film prepared in Comparative Example 1 as the surface layer. Detailed Implementation

[0019] This invention provides a double-sided corona-extruded film, which is made by co-extruding three layers—outer layer, middle layer, and inner layer—and then subjecting them to double-sided corona treatment; the outer layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 parts of processing aids. The middle layer is prepared from the following raw materials in parts by weight: 30-70 parts high-density polyethylene, 20-60 parts medium-density polyethylene, and 0.5-1 parts processing aids; The inner layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 part of processing aids. The high-density polyethylene used in the outer, middle, and inner layers has a melt index of 0.7 g / 10 min and a density of 0.961 g / cm³. 3 The outer and inner layers use metallocene polyethylene with a melt index of 1.3 g / 10 min and a density of 0.927 g / cm³. 3 The medium-density polyethylene used in the middle layer has a melt index of 0.5 g / 10 min and a density of 0.935 g / cm³. 3 .

[0020] Unless otherwise specified, all raw materials used in this invention are commercially available products.

[0021] The outer layer is prepared from 30-70 parts by weight, preferably 40-60 parts, of high-density polyethylene; the high-density polyethylene has a melt index of 0.7 g / 10 min and a density of 0.961 g / cm³. 3 The high-density polyethylene is grade HTA108 and was purchased from ExxonMobil.

[0022] Based on the mass fraction of high-density polyethylene, the raw materials for preparing the outer layer include 20-80 parts of metallocene polyethylene, preferably 30-70 parts; the metallocene polyethylene has a melt index of 1.3 g / 10 min and a density of 0.927 g / cm³. 3 The preferred grade of the metallocene polyethylene is 1327CA, which is purchased from ExxonMobil.

[0023] Based on the mass fraction of high-density polyethylene, the raw materials for preparing the outer layer include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the melt index of the processing aids is preferably 2.3 g / 10 min, and the density is preferably 0.932 g / cm³. 3 The preferred grade of the processing aid is PA0895LD, purchased from Suzhou Constance Engineering Plastics Co., Ltd.; the processing aid is specifically a functional masterbatch prepared from fluoropolymer and polyolefin resin; the function of the processing aid is to improve processing performance.

[0024] The raw materials for preparing the middle layer, by weight, include 30 to 70 parts of high-density polyethylene, preferably 40 to 60 parts; the high-density polyethylene used in the middle layer is the same as that used in the outer layer, and will not be described again here.

[0025] Based on the mass fraction of high-density polyethylene, the raw materials for preparing the middle layer include 20-60 parts of medium-density polyethylene, preferably 30-50 parts; the medium-density polyethylene has a melt index of 0.5 g / 10 min and a density of 0.935 g / cm³. 3 The preferred grade of the medium-density polyethylene is 3505MC, purchased from ExxonMobil.

[0026] Based on the mass fraction of high-density polyethylene, the raw materials for preparing the middle layer include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the processing aids used in the middle layer are the same as those used in the outer layer, and will not be described again here.

[0027] The raw materials for preparing the inner layer, by weight, include 10 to 90 parts of high-density polyethylene, preferably 30 to 70 parts; the high-density polyethylene used in the inner layer is the same as that used in the outer layer, and will not be described again here.

[0028] The raw materials for preparing the inner layer, based on the mass fraction of high-density polyethylene, include 10 to 90 parts of metallocene polyethylene, preferably 30 to 70 parts; the metallocene polyethylene used in the inner layer is the same as that used in the outer layer, and will not be described again here.

[0029] The raw materials for preparing the inner layer, based on the mass fraction of high-density polyethylene, include 0.5 to 1 part of processing aids, preferably 0.6 to 0.8 parts; the processing aids used in the inner layer are the same as those used in the outer layer, and will not be described again here.

[0030] 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 25% to 30%, the mass fraction of the middle layer is preferably 40% to 50%, and the mass fraction of the inner layer is preferably 25% to 30%; the thickness of the double-sided corona film is preferably 60 to 80 μm.

[0031] The present invention also provides a method for preparing the double-sided corona film described above, comprising the following steps: The raw materials for the outer, middle, and inner layers are melted and plasticized, and then co-extruded and blown to obtain a primary film. The primary membrane is subjected to double-sided corona treatment to obtain a double-sided corona-treated membrane.

[0032] This invention involves melting and plasticizing the raw materials for the outer, middle, and inner layers, followed by co-extrusion blown film production to obtain a primary film. In this invention, the co-extrusion blown film extruder preferably includes an outer layer extruder, a middle layer extruder, and an inner layer extruder. The co-extrusion blown film process specifically includes: mixing the raw materials for the outer, middle, and inner layers according to a specified ratio using an automatic batching system, and then feeding them separately into the outer, middle, and inner layer extruders for melting and plasticizing; conveying the resulting adhesive solution to the die head for extrusion blown film production to obtain the primary film; preferably, each of the outer, middle, and inner layer extruders has five heating zones, designated as zones 1 to 5 according to the order in which the raw materials pass through; preferably, the die head has four heating zones, designated as zones 1 to 4 according to the order in which the raw materials pass through.

[0033] In this invention, the extrusion temperatures of the outer extruder, middle extruder, inner extruder, and each zone of the die are shown in Table 1: Table 1. Extrusion temperatures of various zones in the outer, middle, and inner layer extruders and die head.

[0034] In this invention, the extrusion pressure of the outer extruder is preferably 200-600 bar, preferably 300-500 bar; the extrusion pressure of the middle extruder is preferably 200-600 bar, preferably 300-500 bar; and the extrusion pressure of the inner extruder is preferably 200-600 bar, preferably 300-500 bar.

[0035] After obtaining the primary film, the present invention performs double-sided corona treatment on the primary film to obtain a double-sided corona-treated film. In the present invention, the double-sided corona treatment method specifically includes: the primary film is cooled by air, passes through a stabilizing ring and an integrated herringbone strip, and then undergoes upper traction rotation to flatten it before entering a corona treatment device to corona treat the outer layer of the film. Then, it undergoes edge trimming and lower traction clamping roller edge opening sequentially, and then re-enters the corona treatment device to corona treat the inner layer of the film. In the present invention, the air cooling temperature is preferably 10~15℃. The integrated herringbone strip preferably includes a herringbone strip and a covering material covering the surface of the herringbone strip. The covering material is preferably a cleanroom cloth, specifically a smooth, breathable cleanroom cloth that cannot scratch the film. The structure of the integrated herringbone strip is as follows... Figures 1-2 As shown; the traditional herringbone guide roller consists of a row of herringbone shaped guide rollers (structure as follows). Figure 3 As shown), the gap between the guide rollers can easily cause the film to deform. This invention wraps a smooth, dust-free cloth around the surface of the herringbone rollers, allowing the film to enter the upper traction more smoothly.

[0036] The present invention does not have special requirements for the operating parameters of the corona treatment. By adjusting the power of the corona treatment device, it is sufficient to ensure that the dyne value of both sides of the film is above 40 (preferably 40~56) after double-sided corona treatment.

[0037] The corona-treated film is preferably wound into front and rear winding devices to obtain a double-sided corona-treated film.

[0038] The present invention also provides the application of the double-sided corona film described in the above-described scheme or the double-sided corona film prepared by the preparation method described in the above-described scheme in the preparation of PE composite bags; the double-sided corona film is used as a surface material.

[0039] In this invention, the preferred method of application is to heat-seal the double-sided corona film and the PE film together to form a bag. The heat-seal temperature is preferably 150~160℃, more preferably 152~158℃. In this invention, the PE film is preferably made of high-density polyethylene, referred to as HDPE film. This invention does not have special requirements for the composite method of the double-sided corona film and the PE film; any composite method well known to those skilled in the art can be used. In a specific embodiment of this invention, a solvent-free adhesive is preferably used for composite. This invention does not have special requirements for the type of solvent-free adhesive; any adhesive well known to those skilled in the art can be used.

[0040] In this invention, the process preferably includes printing on the surface of the double-sided corona film before lamination with the PE film. This invention does not specify a particular printing method; any method well-known to those skilled in the art can be used.

[0041] 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.

[0042] The raw materials used in the examples are shown in Table 2.

[0043] Table 2. Sources and performance parameters of raw materials used in the examples.

[0044] The amount of raw materials used in each layer in each embodiment is shown in Table 3.

[0045] Table 3 Raw material ratios for each layer in Examples 1-3

[0046] Example 1 The double-sided corona film prepared in this embodiment has a three-layer structure, with the outer layer, middle layer and inner layer having the following weight percentages: outer layer 30%, middle layer 40%, inner layer 30%. The component ratios of the outer layer, middle layer and inner layer are shown in Table 3.

[0047] The preparation method is as follows: 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. After the raw materials are melted and plasticized, they are fed into the die head for extrusion and blown film production. After air cooling, the film passes through a stabilizing ring and an integrated herringbone pattern to the upper traction rotation, flattening the cylinder. It then enters the corona treatment device for corona treatment via guide rollers. After edge trimming, the film is opened by the lower traction clamping rollers and then re-enters the corona treatment device to corona treat the other side of the film. Finally, it enters the front and rear winding devices for front and rear winding to obtain a double-sided corona film for single-material printing. The corona value of both the inner and outer surfaces of the double-sided corona film is 50 dynes.

[0048] The extruder temperature and pressure, and the die temperature are shown in Table 4.

[0049] Table 4. Temperature and pressure of the extruder and die temperature in Example 1

[0050] Example 2 The double-sided corona film prepared in this embodiment has a three-layer structure, with the outer layer, middle layer and inner layer having the following weight percentages: outer layer 30%, middle layer 40%, inner layer 30%. The component ratios of the outer layer, middle layer and inner layer are shown in Table 3.

[0051] The preparation method is the same as in Example 1, and the corona value of the inner and outer surfaces of the resulting double-sided corona film is 50 dynes.

[0052] Example 3 The double-sided corona film prepared in this embodiment has a three-layer structure, with the outer layer, middle layer and inner layer having the following weight percentages: outer layer 30%, middle layer 40%, inner layer 30%. The component ratios of the outer layer, middle layer and inner layer are shown in Table 3.

[0053] The preparation method is the same as in Example 1, and the corona value of the inner and outer surfaces of the resulting double-sided corona film is 50 dynes.

[0054] Comparative Example 1 The other conditions are the same as in Example 1, except that the double-sided corona treatment is changed to a single-sided corona treatment. The specific preparation method is as follows: 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. After the raw materials are melted and plasticized, they are fed into the die head for extrusion and blown film production. After air cooling, the film passes through a stabilizing ring and an integrated herringbone roller to the upper traction rotation to flatten the cylinder. The cylinder then enters the corona treatment device via guide rollers to perform corona treatment on the outer surface. After edge trimming, the film is opened by the lower traction clamping rollers and then enters the front and rear winding devices for front and rear winding to obtain a single-sided corona-treated film. The corona value of the outer surface of the single-sided corona-treated film is 50 dynes.

[0055] Comparative Example 2 The other conditions are the same as in Example 2, except that the double-sided corona discharge is changed to a single-sided corona discharge, and the specific preparation method is the same as in Comparative Example 1.

[0056] Comparative Example 3 The other conditions are the same as in Example 2, except that the double-sided corona discharge is changed to a single-sided corona discharge, and the specific preparation method is the same as in Comparative Example 1.

[0057] The mechanical properties of the double-sided corona films prepared in Examples 1-3 and the single-sided corona film prepared in Comparative Example 1 were tested, and the results are shown in Table 5. In addition, the double-sided corona films prepared in Examples 1-3 and the single-sided corona film prepared in Comparative Example 1, along with the PE film, were laminated and then heat-sealed into bags. The specific steps are as follows: Composite Steps: First, the double-sided corona film prepared in Examples 1-3 (or the single-sided corona film prepared in Comparative Examples 1-3) is composited with HDPE film. The specific process is as follows: after unwinding the double-sided corona film, a solvent-free adhesive is coated on it. The HDPE film is then unwound. After that, the HDPE film and the double-sided corona film are bonded together. After winding, the film is placed in a curing chamber and cured at 40°C for 48 hours to obtain a semi-finished product. The cured roll film is then used for subsequent bag making steps. Bag making steps: Load the film according to requirements, start the main motor, run at low speed, then adjust the edge control to center the film; adjust the left and right clamping rollers to align the left and right films, and adjust the front and rear clamping rollers to align the pattern; adjust the heat sealing knife to heat seal within the required range of the bag; adjust the slitting blade to the required position and adjust the punching position to the scissor edge; adjust the machine speed, take a sample bag produced in one pass, and perform initial inspection; after passing inspection, package and store the bag. Specific heat sealing temperatures are shown in Table 5.

[0058] Table 5 Performance Test Data

[0059] As can be seen from the data in Table 5, the double-sided corona film prepared by the present invention has good mechanical properties, and corona treatment helps to increase the heat sealing temperature, resulting in a smooth surface of the packaging bag. In contrast, although the single-sided corona films prepared in Comparative Examples 1-3 have the same mechanical properties as those in Examples 1-3, their heat sealing temperature is lower, and wrinkling occurs after heat sealing.

[0060] Figure 4 This is a photograph of a bag made using the double-sided corona film from Example 1. Figure 5 The image shows a physical picture of a bag made using the single-sided corona film from Comparative Example 1. According to... Figures 4-5 It can be seen that the packaging bag obtained by the double-sided corona film in Example 1 is smooth and wrinkle-free, while the packaging bag prepared by the single-sided corona film in Comparative Example 1 shows obvious wrinkling.

[0061] 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 double-sided corona film, characterized in that, It is made by co-extruding blown film of three layers: outer layer, middle layer and inner layer, and then subjecting it to double-sided corona treatment; the outer layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 parts of processing aids; The middle layer is prepared from the following raw materials in parts by weight: 30-70 parts high-density polyethylene, 20-60 parts medium-density polyethylene, and 0.5-1 parts processing aids; The inner layer is prepared from the following raw materials in parts by weight: 10-90 parts of high-density polyethylene, 20-80 parts of metallocene polyethylene, and 0.5-1 part of processing aids. The high density polyethylene used in the outer layer, middle layer and inner layer has a melt index of 0.7 g / 10 min and a density of 0.961 g / cm 3 ; The outer and inner layers use metallocene polyethylene with a melt index of 1.3 g / 10 min and a density of 0.927 g / cm³. 3 The medium-density polyethylene used in the middle layer has a melt index of 0.5 g / 10 min and a density of 0.935 g / cm³. 3 ; Based on the total mass of the outer, middle, and inner layers (100%), the outer layer has a mass fraction of 25-30%, the middle layer has a mass fraction of 40-50%, and the inner layer has a mass fraction of 25-30%; the thickness of the double-sided corona film is 60-80 μm; the processing aids used in the outer, middle, and inner layers have a melt index of 2.3 g / 10 min and a density of 0.932 g / cm³. 3 .

2. The double-sided corona film according to claim 1, characterized in that, The high-density polyethylene used in the outer, middle, and inner layers is grade HTA108; the metallocene polyethylene used in the outer and inner layers is grade 1327CA; the medium-density polyethylene used in the middle layer is grade 3505MC; and the processing aid used in the outer, middle, and inner layers is grade PA0895LD.

3. The method for preparing the double-sided corona film according to any one of claims 1 to 2, characterized in that, Includes the following steps: The raw materials for the outer, middle, and inner layers are melted and plasticized, and then co-extruded and blown to obtain a primary film. The primary membrane is subjected to double-sided corona treatment to obtain a double-sided corona-treated membrane.

4. The preparation method according to claim 3, characterized in that, The method for double-sided corona treatment specifically includes: The primary film is cooled by air, then passes through a stabilizing ring and an integrated herringbone strip before being traction-rotated to flatten it. It then enters a corona treatment device to corona treat the outer layer of the film. After that, it undergoes edge trimming and edge opening by a lower traction clamping roller. Finally, it enters the corona treatment device again to corona treat the inner layer of the film. The integrated herringbone strip includes the herringbone strip itself and a covering material covering the surface of the herringbone strip.

5. The preparation method according to claim 4, characterized in that, The covering material is a dust-free cloth; After double-sided corona treatment, the dyne values ​​on both sides of the film are above 40.

6. The application of the double-sided corona film according to any one of claims 1 to 2 or the double-sided corona film prepared by the preparation method according to any one of claims 3 to 5 in the preparation of PE composite bags, wherein the double-sided corona film is used as a surface material.

7. The application according to claim 6, characterized in that, The application method is as follows: the double-sided corona film and the PE film are laminated and then heat-sealed to form a bag, and the heat-sealing temperature is 150~160℃.

8. The application according to claim 7, characterized in that, Before laminating the double-sided corona film and the PE film, the process also includes printing on the surface of the double-sided corona film.

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