PE film, preparation method thereof and application of PE film in metal powder packaging

Abstract

The invention relates to the technical field of composite films, and provides a PE film, a preparation method thereof and application of the PE film in metal powder packaging. The PE film comprises an outer layer, a middle layer and an inner layer which are sequentially arranged, preparation raw materials of the outer layer comprise low-density polyethylene, linear low-density polyethylene, metallocene medium-density polyethylene and a processing aid, and preparation raw materials of the middle layer comprise low-density polyethylene, linear low-density polyethylene, high-density polyethylene and a processing aid. And the inner layer is prepared from the following raw materials: low-density polyethylene, an antistatic agent and a processing aid. When the PE film is used for packaging metal powder, the effect that the metal powder does not adhere to a bag can be achieved, the phenomenon that a seal is not firm due to the fact that metal adheres to the seal is avoided, meanwhile, waste of the metal powder is avoided, and the PE film has wide application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of composite films, in particular to a PE film, a preparation method thereof and application thereof in metal powder packaging. Background Art

[0002] In industrial production and daily applications, metal powders are widely used due to their unique physical and chemical properties. For example, tin powder can be used as a negative electrode active material and is widely used in systems such as lithium-ion batteries.

[0003] Metal powders need to be packaged in bags during storage and transportation. Currently, commercially available bags for metal powders are typically made of plastic film. In practice, metal powders easily adhere to the bag surface. During packaging, the powder can cling to the seal, potentially causing the seal to become loose, leading to bag breakage and leakage. Furthermore, metal powders are expensive, and clinging to the bag can also lead to waste. Summary of the Invention

[0004] In view of this, the present invention provides a PE film, a preparation method thereof, and its use in metal powder packaging. The PE film provided by the present invention has good antistatic properties and can achieve a non-stick bag effect when used for metal powder packaging, reducing waste and preventing the phenomenon of loose sealing.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A PE film comprising an outer layer, a middle layer and an inner layer arranged in sequence;

[0007] In parts by mass, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 30 to 80 parts of linear low-density polyethylene, 10 to 40 parts of metallocene medium-density polyethylene, and 0.5 to 1 part of a processing aid;

[0008] In parts by mass, the raw materials for preparing the middle layer include 10 to 50 parts of low-density polyethylene, 20 to 60 parts of linear low-density polyethylene, 10 to 50 parts of high-density polyethylene, and 0.5 to 1 part of a processing aid;

[0009] Calculated by mass, the raw materials for preparing the inner layer include 95-100 parts of low-density polyethylene, 1-5 parts of antistatic agent, and 0.5-1 part of processing aid.

[0010] Preferably, the melt index of the low-density polyethylene of the outer layer and the middle layer is independently 1.5-2.5 g / 10 min, and the density is independently 0.92-0.93 g / cm 3 The outer layer and the middle layer of linear low-density polyethylene have melt indexes of 1.5 to 2.5 g / 10 min and densities of 0.915 to 0.925 g / cm3 .

[0011] Preferably, the outer layer of metallocene medium density polyethylene has a melt index of 0.2 to 1 g / 10 min and a density of 0.93 to 0.94 g / cm 3 The melt index of the high-density polyethylene in the middle layer is 0.2 to 1 g / 10 min and the density is 0.955 to 0.963 g / cm 3 .

[0012] Preferably, the melt index of the low-density polyethylene of the inner layer is 0.2-0.5 g / 10 min, and the density is 0.92-0.93 g / cm 3 The melt index of the antistatic agent is 18 to 22 g / 10 min and the density is 0.955 to 0.965 g / cm 3 .

[0013] Preferably, the processing aids of the outer layer, the middle layer and the inner layer have a melt index of 1.8 to 3 g / 10 min and a density of 0.925 to 0.94 g / cm 3 .

[0014] Preferably, the brand of the low-density polyethylene of the outer layer and the middle layer is 2426H; the brand of the linear low-density polyethylene of the outer layer and the middle layer is 201XV; the brand of the metallocene medium-density polyethylene of the outer layer is 3505MC; the brand of the high-density polyethylene of the middle layer is HTA108; the brand of the low-density polyethylene of the inner layer is FB2230; the brand of the antistatic agent of the inner layer is VLA55; the brand of the processing aid of the outer layer, the middle layer and the inner layer is PA0895LD.

[0015] Preferably, taking the total mass of the raw materials used for the outer layer, middle layer and inner layer as 100%, the mass fraction of the raw materials for the outer layer is 25-30%, the mass fraction of the raw materials for the middle layer is 40-50%, and the mass fraction of the raw materials for the inner layer is 25-30%.

[0016] The present invention also provides a method for preparing the PE film described in the above scheme, comprising the following steps:

[0017] The raw materials for the outer layer, the middle layer and the inner layer are co-extruded to obtain the PE film.

[0018] Preferably, the raw materials for the outer layer, middle layer and inner layer are melted and plasticized by the outer layer extruder, the middle layer extruder and the inner layer extruder respectively, and the obtained glue is transported to the die head for extrusion and film blowing; the outer layer extruder, the middle layer extruder and the inner layer extruder are all provided with 5 heating zones, which are respectively recorded as zones 1 to 5 according to the order in which the raw materials pass through; the temperature of zone 1 of the outer layer extruder is 150-160°C, the temperature of zone 2 is 165-175°C, the temperature of zone 3 is 165-175°C, and the temperature of zone 4 is 165-17 5°C, the temperature of zone 5 is 165-175°C; the temperature of zone 1 of the middle layer extruder is 150-160°C, the temperature of zone 2 is 165-175°C, the temperature of zone 3 is 165-175°C, the temperature of zone 4 is 165-175°C, and the temperature of zone 5 is 165-175°C; the temperature of zone 1 of the inner layer extruder is 180-190°C, the temperature of zone 2 is 200-210°C, the temperature of zone 3 is 200-210°C, the temperature of zone 4 is 200-210°C, and the temperature of zone 5 is 200-210°C;

[0019] The die head is provided with 4 heating zones, which are recorded as zones 1 to 4 in the order in which the raw materials pass through; the temperature of zone 1 of the die head is 200-210°C, the temperature of zone 2 is 200-210°C, the temperature of zone 3 is 200-210°C, and the temperature of zone 4 is 200-210°C.

[0020] The present invention also provides the use of the PE film described in the above solution or the PE film prepared by the preparation method described in the above solution in metal powder packaging.

[0021] The present invention provides a PE film, comprising an outer layer, a middle layer and an inner layer which are arranged in sequence; in parts by mass, the raw materials for preparing the outer layer comprise 10 to 40 parts of low-density polyethylene, 30 to 80 parts of linear low-density polyethylene, 10 to 40 parts of metallocene medium-density polyethylene, and 0.5 to 1 part of a processing aid; in parts by mass, the raw materials for preparing the middle layer comprise 10 to 50 parts of low-density polyethylene, 20 to 60 parts of linear low-density polyethylene, 10 to 50 parts of high-density polyethylene, and 0.5 to 1 part of a processing aid; in parts by mass, the raw materials for preparing the inner layer comprise 95 to 100 parts of low-density polyethylene, 1 to 5 parts of an antistatic agent, and 0.5 to 1 part of a processing aid. The present invention controls the types and proportions of raw materials for the outer layer, middle layer and inner layer of the PE film, and adds an antistatic agent to the inner layer, thereby improving the antistatic property of the PE film, preventing the adhesion of metal powder, achieving the effect of a non-stick bag, avoiding the phenomenon of metal adhesion at the sealing portion causing a loose seal, and avoiding the waste of metal powder. At the same time, the present invention can also enable the PE film to have good mechanical properties by controlling the raw material proportions of the PE film. Furthermore, the low-density polyethylene used in the inner layer of the present invention is brand FB2230, which has a matte and smooth surface, is not prone to adhesion, and can further improve the non-stick powder property of the PE film. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The results of the powder sticking test of the PE film of Example 1 are as follows;

[0023] Figure 2 The following are the results of the PE film powder adhesion test in Comparative Example 1. DETAILED DESCRIPTION

[0024] The present invention provides a PE film comprising an outer layer, a middle layer and an inner layer arranged in sequence;

[0025] In parts by mass, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 30 to 80 parts of linear low-density polyethylene, 10 to 40 parts of metallocene medium-density polyethylene, and 0.5 to 1 part of a processing aid;

[0026] In parts by mass, the raw materials for preparing the middle layer include 10 to 50 parts of low-density polyethylene, 20 to 60 parts of linear low-density polyethylene, 10 to 50 parts of high-density polyethylene, and 0.5 to 1 part of a processing aid;

[0027] Calculated by mass, the raw materials for preparing the inner layer include 95-100 parts of low-density polyethylene, 1-5 parts of antistatic agent, and 0.5-1 part of processing aid.

[0028] In parts by mass, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, specifically 19.5 parts, 30 parts or 35 parts; the melt index of the low-density polyethylene used in the outer layer is preferably 1.5 to 2.5 g / 10 min, more preferably 1.8 to 2.0 g / 10 min, and the density is preferably 0.920 to 0.930 g / cm 3 , more preferably 0.924 to 0.926 g / cm 3 In a specific embodiment of the present invention, the outer layer is preferably made of low-density polyethylene of grade 2426H, manufactured by CNOOC Shell, with a melt index of 2.0g / 10min and a density of 0.924g / cm 3 The low-density polyethylene used in the present invention has the characteristics of high cleanliness, good die-cutting and easy processing.

[0029] Based on the mass fraction of the low-density polyethylene used in the outer layer, the raw material for preparing the outer layer includes 30 to 80 parts of linear low-density polyethylene, specifically 60 parts, 65 parts or 70 parts; the melt index of the linear low-density polyethylene used in the outer layer is preferably 1.5 to 2.5 g / 10 min, more preferably 2 to 2.3 g / 10 min, and the density is preferably 0.915 to 0.925 g / cm 3 , more preferably 0.918 to 0.920 g / cm 3In a specific embodiment of the present invention, the outer layer is preferably made of linear low-density polyethylene of grade 201XV, manufactured by Exxon, with a melt index of 2g / 10min and a density of 0.918g / cm 3 The linear low-density polyethylene used in the present invention has good compatibility and processability.

[0030] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw material for preparing the outer layer includes 10 to 40 parts of metallocene medium-density polyethylene, specifically 10 parts, 15 parts or 20 parts; the melt index of the metallocene medium-density polyethylene is preferably 0.2 to 1 g / 10min, more preferably 0.5 to 0.8 g / 10min, and the density is preferably 0.930 to 0.940 g / cm 3 , more preferably 0.935 to 0.938 g / cm 3 In a specific embodiment of the present invention, the metallocene medium density polyethylene is preferably 3505MC, which is manufactured by Exxon, has a melt index of 0.5g / 10min and a density of 0.935g / cm 3 The metallocene medium-density polyethylene used in the present invention has good adhesiveness and can improve the composite strength of the PE film.

[0031] 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 part of a processing aid; the melt index of the processing aid is preferably 1.8 to 3 g / 10 min, more preferably 2.3 to 2.5 g / 10 min, and the density is preferably 0.925 to 0.94 g / cm 3 , more preferably 0.93 to 0.932 g / cm 3 In a specific embodiment of the present invention, the processing aid is preferably PA0895LD, manufactured by Suzhou Kangstanpu Engineering Plastics Co., Ltd., with a melt index of 2.3 g / min and a density of 0.932 g / cm3. The present invention, by adding a processing aid, can effectively reduce die buildup, reduce crystallization points, lower extrusion pressure, and improve production efficiency.

[0032] In parts by mass, the raw materials for preparing the middle layer include 10 to 50 parts of low-density polyethylene, specifically 19.5 parts, 25 parts, 30 parts or 40 parts; the melt index, density and brand of the low-density polyethylene used in the middle layer are preferably the same as those of the low-density polyethylene used in the outer layer, which will not be repeated here.

[0033] Calculated by the mass fraction of the low-density polyethylene used in the middle layer, the raw materials for preparing the middle layer include 20 to 60 parts of linear low-density polyethylene, specifically 40 parts or 50 parts; the melt index, density and brand of the linear low-density polyethylene used in the middle layer are preferably the same as those of the linear low-density polyethylene used in the outer layer, and will not be repeated here.

[0034] Based on the mass fraction of the low-density polyethylene used in the middle layer, the raw materials for preparing the middle layer include 10 to 50 parts of high-density polyethylene, specifically 30 or 40 parts; the melt index of the high-density polyethylene is preferably 0.2 to 1 g / 10min, more preferably 0.7 to 0.8 g / 10min, and the density is preferably 0.955 to 0.963 g / cm 3 , more preferably 0.961 g / cm 3 In a specific embodiment of the present invention, the high-density polyethylene is preferably HTA108, manufactured by Exxon, with a melt index of 0.7g / 10min and a density of 0.961g / cm 3 The present invention adds high-density polyethylene to the middle layer, which can improve the stiffness of the PE film.

[0035] Based on the mass fraction of the low-density polyethylene used in the middle layer, the raw materials for preparing the middle layer include 0.5 to 1 parts of processing aids; the melt index, density and brand 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.

[0036] In parts by mass, the raw materials for preparing the inner layer include 95 to 100 parts of low-density polyethylene, specifically 95 parts or 97 parts; the melt index of the low-density polyethylene is preferably 0.2 to 0.5 g / 10 min, more preferably 0.25 to 0.3 g / 10 min, and the density is preferably 0.92 to 0.93 g / cm 3 , more preferably 0.923 to 0.925 g / cm 3 In a specific embodiment of the present invention, the inner layer is preferably made of low-density polyethylene of the grade FB2230, which is manufactured by Borouge Chemical, with a melt index of 0.25g / 10min and a density of 0.923g / cm 3 The low-density polyethylene used in the inner layer of the present invention has a matte and smooth surface, is not prone to adhesion, and can improve the powder-free property of the PE film.

[0037] Based on the mass fraction of the low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 1 to 5 parts of an antistatic agent, specifically 2 parts or 4 parts; the melt index of the antistatic agent is preferably 18 to 22 g / 10 min, more preferably 20 g / 10 min, and the density is preferably 0.955 to 0.965 g / cm 3 , more preferably 0.96 g / cm3 In a specific embodiment of the present invention, the antistatic agent is preferably VLA55, which has a melt index of 20g / 10min and a density of 0.96g / cm 3 The invention adds an antistatic agent to the inner layer, which can effectively improve the antistatic performance of the PE film, reduce the adhesion of powders, and improve the heat sealing performance.

[0038] Based on the mass fraction of the low-density polyethylene used in the inner layer, the raw materials for preparing the inner layer include 0.5 to 1 parts of processing aids; the melt index, density and brand of the processing aids used in the inner layer are preferably the same as those used in the outer layer, and will not be repeated here.

[0039] In the present invention, taking the total mass of the raw materials used for the outer layer, the middle layer and the inner layer as 100%, the mass fraction of the raw materials for the outer layer is preferably 25-30%, the mass fraction of the raw materials for the middle layer is preferably 40-50%, and the mass fraction of the raw materials for the inner layer is preferably 25-30%.

[0040] In the present invention, the longitudinal tensile strength of the PE film is preferably 27-29 MPa, the transverse tensile strength is preferably 28-30 MPa, the longitudinal elongation at break is preferably 680-740%, the transverse elongation at break is preferably 780-800%, the longitudinal elastic modulus is preferably 300-325 MPa, and the transverse elastic modulus is preferably 330-365 MPa.

[0041] In the present invention, the thickness of the PE film is preferably 100-150 μm, more preferably 130 μm.

[0042] The present invention also provides a method for preparing the PE film described in the above scheme, comprising the following steps:

[0043] The raw materials for the outer layer, the middle layer and the inner layer are co-extruded to obtain the PE film.

[0044] In the present invention, the raw materials for preparing the outer layer, middle layer and inner layer are preferably melt-plasticized by an outer layer extruder, a middle layer extruder and an inner layer extruder, respectively, and the obtained glue is transported to a die head for extrusion and film blowing; in the present invention, the outer layer extruder, the middle layer extruder and the inner layer extruder are preferably provided with 5 heating zones, which are sequentially recorded as zones 1 to 5 according to the order in which the raw materials pass through; the temperature of zone 1 of the outer layer extruder is preferably 150-160°C, more preferably 150°C, the temperature of zone 2 is preferably 165-175°C, more preferably 170°C, the temperature of zone 3 is preferably 165-175°C, more preferably 170°C, the temperature of zone 4 is preferably 165-175°C, more preferably 168°C, the temperature of zone 5 is preferably 165-175°C, more preferably 165°C; the temperature of the middle layer extruder is preferably The temperature of zone 1 out of the machine is preferably 150-160°C, more preferably 160°C, the temperature of zone 2 is preferably 165-175°C, more preferably 175°C, the temperature of zone 3 is preferably 165-175°C, more preferably 175°C, the temperature of zone 4 is preferably 165-175°C, more preferably 170°C, and the temperature of zone 5 is preferably 165-175°C, more preferably 170°C; the temperature of zone 1 of the inner layer extruder is preferably 180-190°C, more preferably 185°C, the temperature of zone 2 is preferably 200-210°C, more preferably 210°C, the temperature of zone 3 is preferably 200-210°C, more preferably 208°C, the temperature of zone 4 is preferably 200-210°C, more preferably 205°C, and the temperature of zone 5 is preferably 200-210°C, more preferably 205°C.

[0045] In the present invention, the extrusion pressure of the outer layer extruder is preferably 250-600 bar, more preferably 355 bar, the extrusion pressure of the middle layer extruder is preferably 250-600 bar, more preferably 308 bar, and the extrusion pressure of the inner layer extruder is preferably 250-600 bar, more preferably 386 bar.

[0046] In the present invention, the die head is preferably provided with 4 heating zones, which are sequentially recorded as zones 1 to 4 according to the order in which the raw materials pass through; the temperature of zone 1 of the die head is preferably 200-210°C, more preferably 200°C, the temperature of zone 2 is preferably 200-210°C, more preferably 205°C, the temperature of zone 3 is preferably 200-210°C, more preferably 210°C, and the temperature of zone 4 is preferably 200-210°C, more preferably 210°C.

[0047] In the present invention, the extrusion blown film obtains a film bubble, and the film bubble is preferably air-cooled and then passed through a stabilizing ring and a herringbone arrangement to be pulled upward for rotation, and the film bubble is flattened and then subjected to corona treatment, edge trimming and winding to obtain the PE film.

[0048] The present invention also provides the use of the PE film described in the above scheme or the PE film prepared by the preparation method described in the above scheme in metal powder packaging; the PE film provided by the present invention has good antistatic effect, and when used in the packaging of metal powder, it can achieve the effect of preventing powder from sticking and reducing waste.

[0049] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0050] Example 1

[0051] A PE film for non-stick bags for metal powders consists of an outer layer, a middle layer, and an inner layer. Based on the total mass of the raw materials used to make the outer, middle, and inner layers being 100%, the mass fractions of the raw materials used to make the outer, middle, and inner layers are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer. The raw material ratios for each layer are shown in Table 1. The PE film has a thickness of 130 μm.

[0052] Table 1 Example 1 Raw material ratio

[0053]

[0054] The preparation method is as follows: The materials for the outer, middle, and inner layers are mixed in proportion using an automatic batching system and fed into the outer, middle, and inner layer extruders. The materials are melted and plasticized before being fed into the die for extrusion and film blowing. The resulting film bubble is air-cooled, passed through a stabilizing ring and a herringbone arrangement, and then rotated in an upper traction device. The bubble is flattened and passed through a guide roller into a corona treatment device for corona treatment. The trimmed edges are then passed through lower traction rollers and into a front-to-rear winding device for front-to-rear winding to produce the PE film. The temperatures and pressures of the outer, middle, and inner layer extruders, as well as the die temperature, are shown in Table 2.

[0055] Table 2 Extruder temperature and pressure and die head temperature

[0056] temperature Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ Zone 4 / ℃ Zone 5 / ℃ Pressure (bar) Outer layer 150 170 170 168 165 355 Middle level 160 175 175 170 170 308 Inner layer 185 210 208 205 205 386 die head 200 205 210 210 / /

[0057] Example 2

[0058] A PE film for non-stick bags for metal powders consists of an outer layer, a middle layer, and an inner layer. Based on the total mass of the raw materials used to make the outer, middle, and inner layers as 100%, the mass fractions of the raw materials used to make the outer, middle, and inner layers are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer. The raw material ratios for each layer are shown in Table 3. The PE film has a thickness of 130 μm.

[0059] Table 3 Example 2 Raw Material Ratio

[0060]

[0061] The preparation method is the same as that in Example 1.

[0062] Example 3

[0063] A PE film for non-stick bags for metal powders consists of an outer layer, a middle layer, and an inner layer. Based on the total mass of the raw materials used to make the outer, middle, and inner layers as 100%, the mass fractions of the raw materials used to make the outer, middle, and inner layers are: 30% for the outer layer, 40% for the middle layer, and 30% for the inner layer. The raw material ratios for each layer are shown in Table 4. The PE film has a thickness of 130 μm.

[0064] Table 4 Example 3 Raw material ratio

[0065]

[0066]

[0067] The preparation method is the same as that in Example 1.

[0068] Comparative Example 1

[0069] A PE film comprising an outer layer, a middle layer, and an inner layer. Based on the total mass of the raw materials used to make the outer, middle, and inner layers being 100%, the mass fractions of the raw materials used to make the outer, middle, and inner layers are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer. The raw material ratios for each layer are shown in Table 5. The PE film has a thickness of 130 μm.

[0070] Table 5 Raw material ratio of comparative example 1

[0071]

[0072] The preparation method is the same as that in Example 1.

[0073] Comparative Example 2

[0074] A PE film comprising an outer layer, a middle layer, and an inner layer. Based on the total mass of the raw materials used to make the outer, middle, and inner layers being 100%, the mass fractions of the raw materials used to make the outer, middle, and inner layers are: 25% for the outer layer, 50% for the middle layer, and 25% for the inner layer. The raw material ratios for each layer are shown in Table 6. The PE film has a thickness of 130 μm.

[0075] Table 6 Raw material ratio of comparative example 2

[0076]

[0077]

[0078] Preparation method: The materials for 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 materials for the outer layer, middle layer and inner layer are melted and plasticized and then fed into the die head for extrusion and film blowing. The obtained film bubbles are cooled by air and then passed through a stabilizing ring and a herringbone arrangement to be flattened by upper traction rotation and then passed through a guide roller to a corona treatment device for corona treatment. The trimmed edges are passed through the lower traction roller to the front and rear winding device for front and rear winding to obtain a PE film. The temperature and pressure of the outer layer, middle layer and inner layer extruders and the temperature of the die head are shown in Table 7.

[0079] Table 7 Extruder temperature and pressure and die head temperature

[0080] temperature Zone 1 Zone 2 Zone 3 District 4 District 5 Pressure (bar) Outer layer 150 170 170 168 165 355 Middle level 160 175 175 170 170 308 Inner layer 175 185 185 180 180 386 die head 180 180 185 185 / /

[0081] Performance testing:

[0082] The PE films prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were tested for tensile strength, elongation at break, elastic modulus, and powder adhesion. Powder adhesion was measured by evenly sprinkling metal powder onto the PE film, then pouring it out, gently shaking the film, and observing the amount of metal powder remaining on the film. The metal powder used was tin powder with a particle size of 1 to 10 μm. The test results are shown in Table 8.

[0083] Table 8 Test results

[0084]

[0085]

[0086] Figure 1 The powder sticking test results of the PE film of Example 1 are as follows: Figure 2 The PE film sticky powder test results of Comparative Example 1; Figures 1 and 2 It can be seen that the PE film prepared in Example 1 has substantially no metal powder adhered thereto, whereas a large amount of metal powder adheres to the surface of the PE film in Comparative Example 1.

[0087] According to Table 7 and Figures 1-2 It can be seen from the results in that the PE film prepared by the present invention has good mechanical properties and good resistance to metal powder adhesion. When used for metal powder packaging, it can achieve the effect of non-stick bags, reduce waste, and avoid the phenomenon of metal powder adhering to the seal and causing the seal to be loose. In Comparative Example 1, the antistatic agent in the inner layer was omitted, and in Comparative Example 2, the low-density polyethylene in the inner layer was replaced with 1327CA. The resulting PE films all had the phenomenon of powder sticking.

[0088] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A PE film, characterized in that: comprising an outer layer, a middle layer and an inner layer arranged in sequence; In parts by mass, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 30 to 80 parts of linear low-density polyethylene, 10 to 40 parts of metallocene medium-density polyethylene, and 0.5 to 1 part of a processing aid; In parts by mass, the raw materials for preparing the middle layer include 10 to 50 parts of low-density polyethylene, 20 to 60 parts of linear low-density polyethylene, 10 to 50 parts of high-density polyethylene, and 0.5 to 1 part of a processing aid; Calculated by mass, the raw materials for preparing the inner layer include 95-100 parts of low-density polyethylene, 1-5 parts of antistatic agent, and 0.5-1 part of processing aid.

2. The PE film according to claim 1, characterized in that The melt index of the low-density polyethylene of the outer layer and the middle layer is independently 1.5-2.5 g / 10 min, and the density is independently 0.92-0.93 g / cm 3 The outer layer and the middle layer of linear low-density polyethylene have melt indexes of 1.5 to 2.5 g / 10 min and densities of 0.915 to 0.925 g / cm 3 .

3. The PE film according to claim 1, characterized in that The outer layer of metallocene medium density polyethylene has a melt index of 0.2 to 1 g / 10 min and a density of 0.93 to 0.94 g / cm 3 The melt index of the high-density polyethylene in the middle layer is 0.2 to 1 g / 10 min and the density is 0.955 to 0.963 g / cm 3 .

4. The PE film according to claim 1, characterized in that The melt index of the low-density polyethylene in the inner layer is 0.2-0.5 g / 10 min, and the density is 0.92-0.93 g / cm 3 The antistatic agent has a melt index of 18 to 22 g / 10 min and a density of 0.955 to 0.965 g / cm 3 .

5. The PE film according to claim 1, characterized in that The processing aids of the outer layer, the middle layer and the inner layer have melt indices of 1.8 to 3 g / 10 min and densities of 0.925 to 0.94 g / cm 3 .

6. The PE film according to any one of claims 1 to 5, characterized in that The brand of the low-density polyethylene of the outer layer and the middle layer is 2426H; the brand of the linear low-density polyethylene of the outer layer and the middle layer is 201XV; the brand of the metallocene medium-density polyethylene of the outer layer is 3505MC; the brand of the high-density polyethylene of the middle layer is HTA108; the brand of the low-density polyethylene of the inner layer is FB2230; the brand of the antistatic agent of the inner layer is VLA55; the brand of the processing aid of the outer layer, the middle layer and the inner layer is PA0895LD.

7. The PE film according to any one of claims 1 to 5, characterized in that Taking the total mass of the raw materials used for the outer layer, middle layer and inner layer as 100%, the mass fraction of the raw materials for the outer layer is 25-30%, the mass fraction of the raw materials for the middle layer is 40-50%, and the mass fraction of the raw materials for the inner layer is 25-30%.

8. The method for preparing a PE film according to any one of claims 1 to 7, characterized in that: The following steps are involved: The raw materials for the outer layer, the middle layer and the inner layer are co-extruded to obtain the PE film.

9. The preparation method according to claim 8, characterized in that The raw materials for preparing the outer layer, middle layer and inner layer are melted and plasticized through the outer layer extruder, the middle layer extruder and the inner layer extruder respectively, and the obtained glue is transported to the die head for extrusion and film blowing; the outer layer extruder, the middle layer extruder and the inner layer extruder are all provided with 5 heating zones, which are respectively recorded as zones 1 to 5 according to the order in which the raw materials pass through; the temperature of zone 1 of the outer layer extruder is 150-160°C, the temperature of zone 2 is 165-175°C, the temperature of zone 3 is 165-175°C, and the temperature of zone 4 is 165-175°C. , the temperature of zone 5 is 165-175°C; the temperature of zone 1 of the middle layer extruder is 150-160°C, the temperature of zone 2 is 165-175°C, the temperature of zone 3 is 165-175°C, the temperature of zone 4 is 165-175°C, and the temperature of zone 5 is 165-175°C; the temperature of zone 1 of the inner layer extruder is 180-190°C, the temperature of zone 2 is 200-210°C, the temperature of zone 3 is 200-210°C, the temperature of zone 4 is 200-210°C, and the temperature of zone 5 is 200-210°C; The die head is provided with 4 heating zones, which are recorded as zones 1 to 4 in the order in which the raw materials pass through; the temperature of zone 1 of the die head is 200-210°C, the temperature of zone 2 is 200-210°C, the temperature of zone 3 is 200-210°C, and the temperature of zone 4 is 200-210°C.

10. Use of the PE film according to any one of claims 1 to 7 or the PE film prepared by the preparation method according to claim 8 or 9 in metal powder packaging.

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