Gamma-ray resistant PE film and preparation method thereof, as well as PE composite film and composite bag

Abstract

The present invention relates to the technical field of composite films, and provides a gamma-ray resistant PE film and a preparation method thereof, as well as a PE composite film and a composite bag. The present invention strictly controls the raw materials and proportions of the outer layer, middle layer and inner layer of the PE composite film, and adds gamma-ray resistant masterbatch in the middle layer and the inner layer to improve the gamma-ray resistant performance of the PE film. The obtained PE film will not turn yellow after gamma-ray sterilization, and will not affect the performance of the content; further, the present invention strictly controls the performance parameters of the raw materials used in each layer, and the finally obtained PE film maintains good mechanical properties on the basis of yellowing resistance, and has good processability, high cleanliness and good transparency.

Description

Technical Field

[0001] The invention relates to the technical field of composite films, and in particular to a gamma-ray resistant PE film and a preparation method thereof, as well as a PE composite film and a composite bag. Background Art

[0002] PE film refers to a film produced from polyethylene particles. It is moisture-proof and has low water permeability. Polyethylene is non-toxic and odorless, has excellent low-temperature resistance, good chemical stability, can withstand corrosion from most acids and alkalis, and has good insulation properties. It is widely used in various industries such as medicine, chemical industry, food, and printing.

[0003] In the pharmaceutical field, gamma ray sterilization is a common method. After gamma ray irradiation, the chemical substances in the microorganisms change, causing the cell activity to lose, thereby achieving the purpose of sterilization. However, the current PE packaging bags are prone to yellowing after gamma ray irradiation, which affects the performance of the contents after sterilization. Summary of the invention

[0004] In view of this, the present invention provides a gamma-ray resistant PE film and a preparation method thereof, as well as a PE composite film and a composite bag. The PE film provided by the present invention has the function of resisting gamma rays, does not turn yellow after being sterilized by gamma rays, and does not affect the performance of the contents.

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

[0006] A gamma-ray resistant PE film made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer;

[0007] In terms of weight, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 50 to 85 parts of linear low-density polyethylene, and 0.5 to 1 part of a processing aid;

[0008] In terms of weight, the raw materials for preparing the middle layer include 10 to 30 parts of low-density polyethylene, 10 to 40 parts of linear low-density polyethylene, 30 to 80 parts of metallocene low-density polyethylene, 1 to 2 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid;

[0009] In terms of weight, the raw materials for preparing the inner layer include 10 to 50 parts of low-density polyethylene, 35 to 80 parts of metallocene low-density polyethylene, 1 to 3 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid;

[0010] The weight ratio of the outer layer, the middle layer and the inner layer is 1:(1-4):(1-2).

[0011] Preferably, the low-density polyethylene used in the outer layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The linear low-density polyethylene used in the outer layer has a melt index of 1.5 to 2.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 .

[0012] Preferably, the low-density polyethylene used in the middle layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The linear low-density polyethylene used in the middle layer has a melt index of 1.5 to 2.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 The metallocene low-density polyethylene used in the middle layer has a melt index of 0.5 to 1.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 The gamma-ray resistant masterbatch used in the middle layer has a melt index of 24-26 g / 10 min and a density of 0.970-0.990 g / cm 3 .

[0013] Preferably, the low-density polyethylene used in the inner layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The metallocene low-density polyethylene used in the inner layer has a melt index of 0.5 to 1.5 g / 10 min and a density of 0.905 to 0.915 g / cm 3 The gamma-ray resistant masterbatch used in the inner layer has a melt index of 24-26 g / 10 min and a density of 0.970-0.990 g / cm 3 .

[0014] Preferably, the processing aids used in the outer layer, middle layer and inner layer are all functional masterbatches prepared from fluoropolymer and polyolefin resin, with a melt index of 4.0-5.0 g / 10 min and a density of 0.915-0.925 g / cm 3 .

[0015] Preferably, the brand of low-density polyethylene used in the outer layer, middle layer and inner layer is PE3020K; the brand of linear low-density polyethylene used in the outer layer is 1002YB; the brand of linear low-density polyethylene used in the middle layer is 201XV; the brand of metallocene low-density polyethylene used in the middle layer is 181; the brand of anti-gamma ray masterbatch used in the middle layer and inner layer is 2695; the brand of metallocene low-density polyethylene used in the inner layer is 121S, and the brand of processing aid used in the outer layer, middle layer and inner layer is PE103-001.

[0016] The present invention provides a method for preparing the gamma-ray resistant PE film of 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 gamma ray resistant PE film.

[0018] The present invention also provides a gamma-ray resistant PE composite film, comprising a stacked heat-sealing layer and a printing layer; the heat-sealing layer is the gamma-ray resistant PE film described in the above scheme or the gamma-ray resistant PE film prepared by the preparation method described in the above scheme; the printing layer is a polyester film.

[0019] The present invention also provides a method for preparing the gamma-ray resistant PE composite film according to the above scheme, comprising the following steps:

[0020] The polyester film and the gamma-ray resistant PE film are compounded by using a solvent-free adhesive and then ripened to obtain the gamma-ray resistant PE composite film.

[0021] The present invention also provides a gamma-ray resistant PE composite bag, which is prepared from the gamma-ray resistant PE composite film described in the above scheme or the gamma-ray resistant PE composite film prepared by the preparation method described in the above scheme.

[0022] The invention provides an anti-gamma ray PE film, which is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer; in terms of weight percentage, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 50 to 85 parts of linear low-density polyethylene, and 0.5 to 1 part of a processing aid; the raw materials for preparing the middle layer include 10 to 30 parts of low-density polyethylene, 10 to 40 parts of linear low-density polyethylene, 30 to 80 parts of metallocene low-density polyethylene, 1 to 2 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of a processing aid; the raw materials for preparing the inner layer include 10 to 50 parts of low-density polyethylene, 35 to 80 parts of metallocene low-density polyethylene, 1 to 3 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of a processing aid; the thickness ratio of the outer layer, the middle layer and the inner layer is 1:(1 to 4):(1 to 3). The present invention strictly controls the raw materials and proportions of the outer layer, middle layer and inner layer of the PE composite film, and adds anti-gamma ray masterbatch to the middle layer and the inner layer to improve the anti-gamma ray performance of the PE film. The obtained PE film will not turn yellow after gamma ray sterilization, and will not affect the performance of the content; further, the present invention strictly controls the performance parameters of the raw materials used in each layer, and the finally obtained PE film maintains good mechanical properties on the basis of yellowing resistance, and has good processability, high cleanliness and good transparency. DETAILED DESCRIPTION

[0023] The present invention provides a gamma ray resistant PE film, which is made of a three-layer co-extruded blown film of an outer layer, a middle layer and an inner layer;

[0024] In terms of weight, the raw materials for preparing the outer layer include 10 to 40 parts of low-density polyethylene, 50 to 85 parts of linear low-density polyethylene, and 0.5 to 1 part of a processing aid;

[0025] In terms of weight, the raw materials for preparing the middle layer include 10 to 30 parts of low-density polyethylene, 10 to 40 parts of linear low-density polyethylene, 30 to 80 parts of metallocene low-density polyethylene, 1 to 2 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid;

[0026] In terms of weight, the raw materials for preparing the inner layer include 10 to 50 parts of low-density polyethylene, 35 to 80 parts of metallocene low-density polyethylene, 1 to 3 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid;

[0027] The weight ratio of the outer layer, the middle layer and the inner layer is 1:(1-4):(1-3).

[0028] In terms of mass fraction, the raw material for preparing the outer layer includes 10 to 40 parts of low-density polyethylene, preferably 20 to 30 parts. In the present invention, the melt index of the low-density polyethylene used in the outer layer is preferably 3.5 to 4.5 g / 10 min, more preferably 3.8 to 4.2 g / 10 min, and the density is preferably 0.920 to 0.935 g / cm 3 , more preferably 0.925 to 0.930 g / cm 3 In a specific embodiment of the present invention, the low-density polyethylene used in the outer layer has a melt index of 4.0 g / 10 min and a density of 0.928 g / cm 3 , specifically, low-density polyethylene with Basel model PE3020K, which has the characteristics of high cleanliness, good transparency and easy processing.

[0029] Based on the mass fraction of low-density polyethylene used in the outer layer, the raw material for preparing the outer layer includes 50 to 85 parts of linear low-density polyethylene, preferably 60 to 80 parts. In the present invention, 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 1.8 to 2.2 g / 10 min, and the density is preferably 0.912 to 0.925 g / cm 3 , more preferably 0.915 to 0.920 g / cm 3 In a specific embodiment of the present invention, the linear low-density polyethylene used in the outer layer has a melt index of 2.0 g / 10 min and a density of 0.918 g / cm 3 , specifically ExxonMobil linear low-density polyethylene model 1002YB, which has the properties of high composite strength and easy processing.

[0030] 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 processing aid, preferably 0.6 to 0.8 part. In the present invention, the processing aid used in the outer layer is preferably a functional masterbatch prepared from fluoropolymer and polyolefin resin, with a melt index of preferably 4.0 to 5.0 g / 10 min, more preferably 4.3 to 4.8 g / 10 min, and a density of preferably 0.915 to 0.925 g / cm 3 , more preferably 0.918 to 0.920 g / cm 3 In a specific embodiment of the present invention, the functional masterbatch used in the outer layer has a melt index of 4.5 g / 10 min and a density of 0.920 g / cm 3 Specifically, it is the processing aid model PE103-001 of Daikin Industries, Ltd., which can effectively reduce the material accumulation at the die mouth, reduce the crystal point, reduce the extrusion pressure and improve the production efficiency.

[0031] The raw material for preparing the middle layer includes 10 to 30 parts of low-density polyethylene, preferably 15 to 25 parts by weight. In the present invention, the melt index, density and specific model of the low-density polyethylene used in the middle layer are preferably consistent with those of the low-density polyethylene used in the outer layer, which will not be repeated here.

[0032] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw material for preparing the middle layer includes 10 to 40 parts of linear low-density polyethylene, preferably 20 to 30 parts. In the present invention, the melt index of the linear low-density polyethylene used in the middle layer is preferably 1.5 to 2.5 g / 10min, more preferably 1.8 to 2.2 g / 10min, and the density is preferably 0.912 to 0.925 g / cm 3 , more preferably 0.915 to 0.920 g / cm 3 In a specific embodiment of the present invention, the linear low-density polyethylene used in the middle layer has a melt index of 2.0 g / 10 min and a density of 0.918 g / cm 3 , specifically ExxonMobil's linear low-density polyethylene model 201XV, which has the properties of good transparency, few crystal points and easy processing.

[0033] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw material for preparing the middle layer includes 30 to 80 parts of metallocene low-density polyethylene, preferably 40 to 60 parts. In the present invention, the melt index of the metallocene low-density polyethylene used in the middle layer is preferably 0.5 to 1.5 g / 10 min, more preferably 0.8 to 1.2 g / 10 min, and the density is preferably 0.912 to 0.925 g / cm 3 , more preferably 0.915 to 0.920 g / cm 3In a specific embodiment of the present invention, the metallocene low-density polyethylene used in the middle layer has a melt index of 1.0 g / 10 min and a density of 0.918 g / cm 3 , specifically, the metallocene low-density polyethylene with model number 181 of SK Chemical, which has the properties of good transparency, few crystal points and easy processing.

[0034] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw material for preparing the middle layer includes 1 to 2 parts of anti-gamma ray masterbatch, preferably 1.3 to 1.5 parts. In the present invention, the melt index of the anti-gamma ray masterbatch used in the middle layer is preferably 24 to 26 g / 10min, more preferably 24.5 to 25.5 g / 10min, and the density is preferably 0.970 to 0.990 g / cm 3 , more preferably 0.975 to 0.985 g / cm 3 In a specific embodiment of the present invention, the gamma ray resistant masterbatch used in the middle layer has a melt index of 25 g / 10 min and a density of 0.980 g / cm 3 Specifically, the anti-gamma ray masterbatch model 2695 of Huayi Technology Development Co., Ltd. is preferred.

[0035] Based on the mass fraction of low-density polyethylene used in the middle layer, the raw material for preparing the middle layer includes 0.5 to 1 part of processing aid, preferably 0.6 to 0.8 part. In the present invention, the melt index, density and specific model of the processing aid used in the middle layer are preferably consistent with those of the processing aid used in the outer layer, and will not be repeated here.

[0036] In terms of mass percentage, the raw materials for preparing the inner layer include 10 to 50 parts of low-density polyethylene, preferably 20 to 40 parts. In the present invention, the melt index, density and specific model of the low-density polyethylene used in the inner layer are preferably consistent with those of the low-density polyethylene used in the outer layer, which will not be repeated here.

[0037] The raw material for preparing the inner layer includes 35 to 80 parts of metallocene low-density polyethylene, preferably 50 to 70 parts, based on the mass fraction of low-density polyethylene used in the inner layer. In the present invention, the melt index of the metallocene low-density polyethylene used in the inner layer is preferably 0.5 to 1.5 g / 10 min, more preferably 0.8 to 1.2 g / 10 min, and the density is preferably 0.905 to 0.915 g / cm 3 , more preferably 0.910 to 0.912 g / cm 3 In a specific embodiment of the present invention, the metallocene low-density polyethylene used in the inner layer has a melt index of 1.0 g / 10 min and a density of 0.912 g / cm 3 Specifically, it is SK Chemical's metallocene low-density polyethylene model 121S, which has the properties of good transparency, low sealing temperature, few crystal points and easy processing.

[0038] The raw materials for preparing the inner layer include 1 to 3 parts of anti-gamma ray masterbatch, preferably 1.5 to 2.5 parts, based on the mass fraction of low-density polyethylene used in the inner layer. In the present invention, the melt index, density and specific model of the anti-gamma ray masterbatch used in the inner layer are preferably consistent with those of the anti-gamma ray masterbatch used in the middle layer, and will not be repeated here.

[0039] The raw materials for preparing the inner layer include 0.5 to 1 part of processing aid, preferably 0.6 to 0.8 part, based on the mass fraction of low-density polyethylene used in the inner layer. In the present invention, the melt index, density and specific type of the processing aid used in the inner layer are preferably consistent with those of the processing aid used in the outer layer, and will not be repeated here.

[0040] In the present invention, the weight ratio of the outer layer, the middle layer and the inner layer is 1:(1-4):(1-2), preferably 5:9:6, 3:4:3, 1:2:1, 1:3:1 or 1:4:1; in the present invention, the weight ratio of the outer layer, the middle layer and the inner layer is the thickness ratio thereof. In a specific embodiment of the present invention, the mass of the raw materials required for each layer can be determined according to the total thickness of the target composite film and the thickness ratio of the three layers; the total thickness of the PE composite film is preferably 40-100 μm, more preferably 50-80 μm.

[0041] The present invention also provides a method for preparing the gamma-ray resistant PE film of the above scheme, comprising the following steps:

[0042] The raw materials for the outer layer, the middle layer and the inner layer are co-extruded to obtain the gamma ray resistant PE film.

[0043] In a specific embodiment of the present invention, the three-layer co-extrusion process specifically includes: sending the prepared raw materials of the outer layer, the middle layer and the inner layer into the outer layer, the middle layer and the inner layer extruders respectively for melting and plasticization, conveying the obtained glue solution to the die head, extruding and blowing the film to obtain a film bubble, and after the film bubble is air-cooled, it is passed through a stabilizing ring and a herringbone arrangement to the upper traction rotation, and after the film bubble is flattened, it enters the corona treatment device through a guide roller for corona treatment, and then trims the edge, and then enters the front and rear winding device through the lower traction clamping roller for front and rear winding, so as to obtain a gamma ray resistant PE film.

[0044] 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 recorded as zones 1 to 5 in the order in which the raw materials pass through; 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.

[0045] In the present invention, the extrusion temperatures of the outer layer extruder, the middle layer extruder, the inner layer extruder and each zone of the die head are shown in Table 1:

[0046] Table 1 Extrusion temperatures of the outer layer, middle layer, inner layer extruders and each zone of the die head

[0047] Temperature(℃) Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Outer Layer 160±5℃ 168±5℃ 172±5℃ 165±5℃ 160±5℃ Middle level 163±5℃ 168±5℃ 170±5℃ 165±5℃ 162±5℃ Inner Layer 165±5℃ 172±5℃ 168±5℃ 163±5℃ 160±5℃ Die head 175±5℃ 180±5℃ 185±5℃ 183±5℃

[0048] In the present invention, the extrusion pressure of the outer layer extruder is preferably 210 to 305 bar, the extrusion pressure of the middle layer extruder is preferably 215 to 355 bar, and the extrusion pressure of the inner layer extruder is preferably 205 to 290 bar.

[0049] The present invention also provides a gamma-ray resistant PE composite film, comprising a stacked heat-sealing layer and a printing layer; the heat-sealing layer is the gamma-ray resistant PE film described in the above scheme or the gamma-ray resistant PE film prepared by the preparation method described in the above scheme; the printing layer is a polyester film.

[0050] In the present invention, the thickness of the polyester film is preferably 12 μm, and the layer thickness ratio of the polyester film to the gamma-ray resistant PE film is preferably 12:75; the present invention has no special requirements on the source of the polyester film, and a commercially available polyester film can be used; the heat sealing layer and the printing layer are bonded by an adhesive.

[0051] The present invention also provides a method for preparing the gamma-ray resistant PE composite film according to the above scheme, comprising the following steps:

[0052] The polyester film and the gamma-ray resistant PE film are compounded by using a solvent-free adhesive and then ripened to obtain the gamma-ray resistant PE composite film.

[0053] In the present invention, the polyester film is preferably printed according to the requirements before bonding with the anti-gamma ray PE film. The present invention has no special requirements for the printing method, and the gravure printing process well known to those skilled in the art can be used. In the present invention, the solvent-free adhesive is preferably a two-component solvent-free polyurethane adhesive of Wanhua Chemical (Beijing) Co., Ltd., and the components include 6039A and 739B. The present invention has no special requirements for the specific process of compounding, and the solvent-free compounding process well known to those skilled in the art can be used. In a specific embodiment of the present invention, the glue is specifically applied on the polyester film, and then the anti-gamma ray PE film is compounded. In a specific embodiment of the present invention, the operating parameters of the compounding process preferably include: mixing temperature: both components A and B are 38°C; coating temperature: the temperature of each steel roller of the coating and gluing system is 45°C; glue ratio: the mass ratio of component A (i.e., 6039A) and component B (i.e., 739B) is 100:60; the amount of glue is 2.0-2.3g / m 2 , preferably 2.1 g / m 2 .

[0054] In the present invention, the aging temperature is preferably 40±5° C., and the aging time is preferably 48 hours. After aging, the aging is preferably cooled for 12 hours.

[0055] The present invention also provides a gamma-ray resistant PE composite bag, which is prepared from the gamma-ray resistant PE composite film described in the above scheme or the gamma-ray resistant PE composite film prepared by the preparation method described in the above scheme. The present invention has no special requirements for the method for preparing the composite bag, and a bag making process familiar to those skilled in the art can be used.

[0056] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but this should not be construed as limiting the protection scope of the present invention.

[0057] The sources of raw materials and performance parameters used in the examples are shown in Table 2.

[0058] Table 2 Sources of raw materials and performance parameters used in the examples

[0059]

[0060] Example 1

[0061] The amount of raw materials used in each layer and the layer thickness ratio are shown in Table 4. The total thickness of the gamma-ray resistant PE film is 75 μm. The preparation method is as follows:

[0062] The raw materials of the outer layer, middle layer and inner layer are mixed in proportion by an automatic batching system and sent to 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 sent to the die head for extrusion and film blowing. Then, the film is cooled by air cooling, and then the film is flattened by the upper traction rotation through a stabilizing ring and a herringbone arrangement, and then sent to the corona treatment device through a guide roller for corona treatment. Then, the trimmed film is sent to the front and rear winding device through the lower traction roller for front and rear winding, and a 75μm gamma ray resistant PE film can be obtained.

[0063] The temperature and pressure of the outer layer, middle layer and inner layer extruder and die head are shown in Table 3:

[0064] Table 3 Extruder temperature and pressure

[0065] condition Zone 1 / ℃ Zone 2 / ℃ Zone 3 / ℃ Zone 4 / ℃ Zone 5 / ℃ Pressure / bar Outer Layer 160 168 172 165 160 210-305 Middle level 163 168 170 165 162 215-355 Inner Layer 165 172 168 163 160 205-290 Die head 175 180 185 183

[0066] The above-mentioned gamma-ray resistant PE film is used to prepare composite films and composite bags. The polyester film (PET) used is directly purchased from the market as a 12 μm packaging polyester film from Kanghui New Material Technology Co., Ltd. The preparation method is as follows:

[0067] The printed layer polyester film is gravure printed according to the requirements and the conventional printing process is adopted;

[0068] The printed PET polyester film and PE film were compounded by solvent-free compounding process, using two-component solvent-free polyurethane adhesive 6039A / 739B of Wanhua Chemical (Beijing) Co., Ltd. The process parameters were as follows: mixing temperature: both A and B components were set to 38°C; coating temperature: all steel rollers of the coating and gluing system were set to 45°C; glue ratio: the mass ratio of A component to B component was 100:60, and the glue amount was 2.1g / m 2 .

[0069] After compounding, the obtained composite film is placed in a curing room at 40±5°C for aging for 48 hours, and then cooled for 12 hours to obtain a gamma-ray resistant PE composite film. The gamma-ray resistant PE composite film is used to make bags to obtain gamma-ray resistant PE composite bags.

[0070] Embodiment 2-3

[0071] The amount of raw materials used for each layer and the layer thickness ratio are shown in Table 4. The total thickness of the anti-gamma ray PE film is 75 μm. The preparation method is the same as that in Example 1 to obtain an anti-gamma ray PE film, a composite film and a composite bag.

[0072] Comparative Examples 1-2

[0073] The amount of raw materials used in each layer and the layer thickness ratio are shown in Table 4. The total thickness of the PE film is 75 μm. The preparation method is the same as that in Example 1 to obtain a PE film, a composite film and a composite bag.

[0074] Table 4 Raw material dosage of Examples 1 to 3 and Comparative Examples 1 to 2 (in parts by mass)

[0075]

[0076]

[0077] Performance Test:

[0078] The tensile strength and elongation at break of the gamma-ray resistant PE films prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested, as well as the gamma-ray resistant performance. The gamma-ray resistant performance was tested under the following conditions: the obtained PE films were irradiated with 25 kJ gamma rays and then placed in an oven at 70° C. for 8 weeks to observe whether they turned yellow. The results are shown in Table 5.

[0079] Table 5 Performance test results

[0080]

[0081] According to the data in Table 5, it can be seen that the PE films prepared in Examples 1 to 3 of the present invention have high mechanical properties and do not turn yellow after gamma ray irradiation, indicating that after the anti-gamma ray performance, the performance of the contents will not be affected after gamma ray sterilization. The only difference between Comparative Example 1 and Example 1 is that no anti-gamma ray masterbatch is added to the middle layer and the inner layer, and the resulting PE film turns yellow after gamma ray irradiation. The amount of anti-gamma ray masterbatch used in Comparative Example 2 is relatively small, and the resulting PE film also turns yellow after gamma ray irradiation. In addition, after adding the anti-gamma ray masterbatch, the mechanical properties of the PE films obtained in Examples 1 to 3 are also slightly improved, especially the longitudinal elongation at break is higher than that of the PE films obtained in Comparative Examples 1 to 2.

[0082] 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 principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A gamma ray resistant PE film, characterized in that: Made of three layers of co-extruded blown film: outer layer, middle layer and inner layer; In terms of weight, the outer layer is prepared from 10 to 40 parts of low-density polyethylene, 50 to 85 parts of linear low-density polyethylene, and 0.5 to 1 part of a processing aid; In terms of weight, the raw materials for preparing the middle layer are 10 to 30 parts of low-density polyethylene, 10 to 40 parts of linear low-density polyethylene, 30 to 80 parts of metallocene low-density polyethylene, 1 to 2 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid; In terms of weight, the raw materials for preparing the inner layer are 10 to 50 parts of low-density polyethylene, 35 to 80 parts of metallocene low-density polyethylene, 1 to 3 parts of anti-gamma ray masterbatch, and 0.5 to 1 part of processing aid; The weight ratio of the outer layer, the middle layer and the inner layer is 1:(1-4):(1-2); The low-density polyethylene used in the outer layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The linear low-density polyethylene used in the outer layer has a melt index of 1.5 to 2.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 ; The low-density polyethylene used in the middle layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The linear low-density polyethylene used in the middle layer has a melt index of 1.5 to 2.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 The metallocene low-density polyethylene used in the middle layer has a melt index of 0.5 to 1.5 g / 10 min and a density of 0.912 to 0.925 g / cm 3 The gamma-ray resistant masterbatch used in the middle layer has a melt index of 24-26 g / 10 min and a density of 0.970-0.990 g / cm 3 ; The low-density polyethylene used in the inner layer has a melt index of 3.5-4.5 g / 10 min and a density of 0.920-0.935 g / cm 3 The metallocene low-density polyethylene used in the inner layer has a melt index of 0.5 to 1.5 g / 10 min and a density of 0.905 to 0.915 g / cm 3 The gamma-ray resistant masterbatch used in the inner layer has a melt index of 24-26 g / 10 min and a density of 0.970-0.990 g / cm 3 .

2. The gamma ray resistant PE film according to claim 1, characterized in that: The processing aids used in the outer layer, middle layer and inner layer are all functional masterbatches made from fluoropolymer and polyolefin resin, with a melt index of 4.0-5.0 g / 10 min and a density of 0.915-0.925 g / cm 3 .

3. The gamma ray resistant PE film according to any one of claims 1 to 2, characterized in that: The brand of low-density polyethylene used in the outer layer, middle layer and inner layer is PE3020K; the brand of linear low-density polyethylene used in the outer layer is 1002YB; the brand of linear low-density polyethylene used in the middle layer is 201XV; the brand of metallocene low-density polyethylene used in the middle layer is 181; the brand of anti-gamma ray masterbatch used in the middle layer and inner layer is 2695; the brand of metallocene low-density polyethylene used in the inner layer is 121S, and the brand of processing aid used in the outer layer, middle layer and inner layer is PE103-001.

4. The method for preparing the gamma-ray resistant PE film according to any one of claims 1 to 3, characterized in that: The following steps are involved: The raw materials for the outer layer, the middle layer and the inner layer are subjected to three-layer co-extrusion to obtain the gamma ray resistant PE film.

5. A gamma-ray resistant PE composite film, characterized in that: It comprises a stacked heat-sealing layer and a printing layer; the heat-sealing layer is the gamma-ray resistant PE film according to any one of claims 1 to 3 or the gamma-ray resistant PE film prepared by the preparation method according to claim 4; the printing layer is a polyester film.

6. The method for preparing the gamma-ray resistant PE composite film according to claim 5, characterized in that: The following steps are involved: The polyester film and the gamma-ray resistant PE film are compounded by using a solvent-free adhesive and then ripened to obtain the gamma-ray resistant PE composite film.

7. A gamma-ray resistant PE composite bag, characterized in that: It is prepared from the gamma-ray resistant PE composite film described in claim 5 or the gamma-ray resistant PE composite film prepared by the preparation method described in claim 6.

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