A puncture-resistant cold-stretch film and a method for producing the same

Abstract

The application discloses a kind of puncture-resistant cold-stretching film and preparation method thereof, the puncture-resistant cold-stretching film includes inner layer and outer layer, the inner layer and the outer layer respectively account for 60%~80% and 20%~40% of total weight;Wherein, the inner layer includes 80~95 parts of low-density polyethylene, 2~5 parts of polyethylene glycol, 2~5 parts of ethylene-vinyl acetate copolymer by mass parts;The outer layer includes 80~95 parts of low-density polyethylene, 5~12 parts of titanium dioxide loaded with slip agent, 2~5 parts of polyurethane acrylate by mass parts.The titanium dioxide loaded with slip agent component of the application obtains titanium dioxide loaded with slip agent, which can reduce the existence of polyethylene agglomerates or even bubbles caused by directly adding slip agent.In addition, the application also introduces ionic liquid in hydrothermal reaction, improves the specific surface area of titanium dioxide, improves the loading capacity of slip agent, reduces the friction coefficient without reducing mechanical properties, and also improves the ultraviolet resistance of the film.

Description

Technical Field

[0001] This invention relates to the field of stretch film technology, and in particular to a puncture-resistant cold stretch film and its preparation method. Background Technology

[0002] Cold stretch film packaging technology has been used in the European and American home appliance industries since the 1990s. Compared with traditional cardboard packaging, plastic film packaging technology has been rapidly adopted by major home appliance companies due to its advantages such as low packaging cost, fast packaging speed, and environmental friendliness, and has become the dominant packaging technology in the European and American home appliance industries. Cold stretch film was developed based on heat shrink film packaging and stretch packaging processes and technologies, absorbing the advantages of traditional heat shrink film packaging and stretch film. Cold stretch film can be stretched from top to bottom to the bottom of the product without heating, using the film's high resilience and high clamping force to tightly wrap the entire product, forming transparent packaging.

[0003] Based on the cold-stretching film process, only films with high tensile strength and high resilience can adapt to rapid stretching speeds and large stretching ranges. CN112406238A discloses a green and environmentally friendly cold-stretching film and its preparation method, comprising an inner layer and an outer layer. The inner layer accounts for 60-80% of the film weight, and the outer layer accounts for 20-40% of the film weight. The inner layer is composed of the following components by weight: 9-15 parts cyclopentene, 2-7 parts polyethylene glycol, 17-22 parts polyethylene, 2-6 parts vinyl acetate, and 3-8 parts glyceryl butyrate. The outer layer is composed of the following components by weight: 16-24 parts low-density polyethylene, 2-7 parts high-density polyethylene, 1.5-2.4 parts toluene diisocyanate, 0.1-0.4 parts polybutadiene, 0.3-0.6 parts plasticizer, and 0.7-1.2 parts modified polyisobutylene. This cold-stretched film achieves high tensile strength by adjusting the proportion of each layer of material, making it resistant to deformation at high temperatures. However, the formulation of this cold-stretched film contains a high proportion of organic additives. CN109094163A discloses a high-strength cold-stretched film and its preparation method. The high-strength cold-stretched film includes an outer layer, a middle layer, and an inner layer. The outer layer accounts for 10-30% of the total weight of the film, the middle layer accounts for 50-70%, and the inner layer accounts for 10-30%. The raw materials for preparing the outer layer consist of 30-50% MLLDPE 1018MF and 50-70% MLLDPE 1018MA; the raw materials for preparing the middle layer consist of 70-90% LLDPE / LL6101 and 10-30% VM6102; and the raw materials for preparing the inner layer consist of 20-40% MLLDPE 1018MA and 60-80% MLLDPE 1018MF. This cold-stretched film is flexible, has high tensile strength, and is not easily deformed. However, it requires polyethylene produced by a specific manufacturer, which limits its applications. Summary of the Invention

[0004] In order to overcome the problems existing in the prior art, the present invention provides a composite material for puncture-resistant cold stretch film, comprising an inner layer and an outer layer, wherein the inner layer and the outer layer account for 60% to 80% and 20% to 40% of the total weight, respectively;

[0005] The inner layer comprises, by weight, 80-95 parts low-density polyethylene, 2-5 parts polyethylene glycol, and 2-5 parts ethylene-vinyl acetate copolymer.

[0006] The outer layer comprises, by weight, 80-95 parts of low-density polyethylene, 5-12 parts of titanium dioxide loaded with slip agent, and 2-5 parts of polyurethane acrylate.

[0007] Cold-stretched films made from low-density polyethylene (LDPE) are widely used in the manufacture of various products. To improve the surface and mechanical properties of the film, erucamide or oleamide are often added as slip agents. Erucamide and oleamide molecules are incompatible with polyethylene and polypropylene polymers due to their polar functional groups. This characteristic makes them difficult to distribute and homogenize on the polyethylene matrix, leading to the formation of large aggregates on the polyethylene surface. Therefore, the addition of slip agents may impair the mechanical properties of the polyethylene film.

[0008] The addition of titanium dioxide to a polypropylene matrix can improve the mechanical properties of polypropylene. Some published literature has shown that flower-shaped titanium dioxide can be prepared using a hydrothermal reaction of tetrabutyl titanate and glacial acetic acid. This structure exhibits better adsorption performance compared to spherical, rod-shaped, or blocky structures, making it suitable as a catalyst for loading catalytic components. The titanium dioxide prepared by the same method of this invention, loaded with a slip agent, reduces the presence of polyethylene agglomerates and even bubbles caused by directly adding slip agents. Furthermore, the morphology and structure of titanium dioxide materials have a significant impact on their performance. This invention introduces an ionic liquid during the hydrothermal reaction, improving the specific surface area of ​​titanium dioxide, increasing the loading of slip agents, reducing the coefficient of friction without compromising mechanical properties, and simultaneously enhancing the film's UV resistance.

[0009] Furthermore, the method for preparing the titanium dioxide loaded with the slip agent includes, by weight, the following:

[0010] Mix 5-10 parts of titanium dioxide, 1-5 parts of slip agent, and 60-80 parts of organic solvent for 2-5 hours, then filter and collect the titanium dioxide loaded with slip agent.

[0011] Furthermore, the slip agent is at least one of erucamide and oleamide.

[0012] Furthermore, the organic solvent is at least one selected from ethanol, methanol, acetone, and diethyl ether.

[0013] Furthermore, the method for preparing the titanium dioxide includes,

[0014] The precursor was obtained by hydrothermal reaction of a mixture of tetrabutyl titanate and glacial acetic acid in a mass ratio of 1-3:20-50.

[0015] The precursor was calcined to obtain titanium dioxide.

[0016] Furthermore, after mixing tetrabutyl titanate with glacial acetic acid, an ionic liquid is added, wherein the mass of the ionic liquid is 0.1 to 0.3 times that of the tetrabutyl titanate.

[0017] The ionic liquid is at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, N-n-butylpyridine tetrafluoroborate, and 1-isobutyl-3-methylimidazolium tetrafluoroborate.

[0018] Furthermore, the hydrothermal reaction is maintained at 140–180°C for 10–18 hours.

[0019] Furthermore, the calcination is carried out at 300–500°C for 1–3 hours.

[0020] Furthermore, the low-density polyethylene has a melt flow rate of 0.2–0.3 g / 10 min and a density of 0.920–0.940 g / cm³. 3 .

[0021] This invention also provides a method for preparing the above-mentioned puncture-resistant cold-stretching film, comprising:

[0022] Weigh the raw materials for the inner and outer layers according to the formula and mix them separately to obtain an inner layer raw material mixture and an outer layer raw material mixture;

[0023] The inner layer material mixture and the outer layer material mixture are co-extruded and blow-molded to obtain a puncture-resistant cold stretch film.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] This invention loads a slip agent onto titanium dioxide to obtain slip-loaded titanium dioxide, which can reduce the presence of polyethylene agglomerates and even bubbles caused by directly adding slip agents. Furthermore, the morphology and structure of titanium dioxide materials have a significant impact on their performance. This invention introduces an ionic liquid during the hydrothermal reaction, improving the specific surface area of ​​titanium dioxide, increasing the slip agent loading, reducing the coefficient of friction without compromising mechanical properties, and simultaneously enhancing the film's UV resistance. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0027] Description of some of the raw materials used in the embodiments and comparative examples of this invention:

[0028] Low-density polyethylene, type M2320, with a melt flow rate of 0.2 g / 10 min and a density of 0.926 g / cm³. 3 Purchased from China Petroleum & Chemical Corporation Guangzhou Branch;

[0029] Polyethylene glycol, with a molecular weight of approximately 4000, type PEG-4000, was purchased from Haian Petrochemical Plant in Jiangsu Province.

[0030] Ethylene-vinyl acetate copolymer, model number 7470M, purchased from Dongguan Wenteng Plastic Raw Materials Co., Ltd.

[0031] Erucamide, model number ER-CH, was purchased from Dongguan Dinghai Plastic & Chemical Co., Ltd.

[0032] Polyurethane acrylate, model UV-3633, was purchased from Dongguan Jingshang New Materials Development Co., Ltd.

[0033] 1-Ethyl-3-methylimidazolium tetrafluoroborate, N-n-butylpyridine tetrafluoroborate, and 1-isobutyl-3-methylimidazolium tetrafluoroborate were all purchased from Hubei Maidehao Chemical Co., Ltd. Other raw materials not mentioned are common raw materials. The above content is only for illustrative purposes and should not be construed as a strict limitation of the invention. Those skilled in the art can directly purchase commercially available materials or prepare the same / similar materials themselves. These details will not be elaborated further in the examples.

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] A method for preparing a puncture-resistant cold-stretch film, comprising the following steps in parts by weight:

[0037] Step 1: Mix 90 parts of low-density polyethylene, 3 parts of polyethylene glycol, and 3 parts of ethylene-vinyl acetate copolymer at 120°C and a stirring rate of 60 rpm for 15 min to obtain the inner layer raw material mixture.

[0038] Step 2: Mix 90 parts of low-density polyethylene, 10.4 parts of titanium dioxide loaded with slip agent, and 3 parts of polyurethane acrylate at 120°C and stirring at 80 rpm for 30 min to obtain the outer layer raw material mixture.

[0039] Step 3: Transfer the inner layer raw material mixture and the outer layer raw material mixture obtained in Step 1 and Step 2 to the blown film unit for co-extrusion blow molding at a mass ratio of 7:3 to obtain a puncture-resistant cold stretch film.

[0040] The preparation method of titanium dioxide loaded with slip agent is as follows:

[0041] S1. Tetrabutyl titanate and glacial acetic acid were mixed at a mass ratio of 1:25 at a stirring speed of 200 rpm for 10 min and then subjected to hydrothermal reaction. The hydrothermal reaction was maintained at 160℃ for 14 h. After the reaction was completed, the mixture was naturally cooled, filtered, and the insoluble matter was collected. The mixture was washed three times with water and three times with ethanol and then dried in a constant temperature oven at 100℃ for 8 h to obtain the precursor.

[0042] S2. The precursor obtained in S1 is calcined at 450℃ for 2 hours to obtain titanium dioxide.

[0043] S3. Mix 8g of titanium dioxide, 5g of erucamide, and 75g of acetone at a stirring speed of 400rpm for 3.5h, then filter and collect the insoluble matter and dry it in an oven at 80℃ for 10h to obtain 9.6g of titanium dioxide loaded with slip agent.

[0044] Example 2

[0045] A method for preparing a puncture-resistant cold-stretch film, comprising the following steps in parts by weight:

[0046] Step 1: Mix 90 parts of low-density polyethylene, 3 parts of polyethylene glycol, and 3 parts of ethylene-vinyl acetate copolymer at 120°C and a stirring rate of 60 rpm for 15 min to obtain the inner layer raw material mixture.

[0047] Step 2: Mix 90 parts of low-density polyethylene, 10.4 parts of titanium dioxide loaded with slip agent, and 3 parts of polyurethane acrylate at 120°C and stirring at 80 rpm for 30 min to obtain the outer layer raw material mixture.

[0048] Step 3: Transfer the inner layer raw material mixture and the outer layer raw material mixture obtained in Step 1 and Step 2 to the blown film unit for co-extrusion blow molding at a mass ratio of 7:3 to obtain a puncture-resistant cold stretch film.

[0049] The preparation method of titanium dioxide loaded with slip agent is as follows:

[0050] S1. Tetrabutyl titanate and glacial acetic acid were mixed at a mass ratio of 1:25 at a stirring speed of 200 rpm for 5 min. Then, 1-ethyl-3-methylimidazolium tetrafluoroborate, which accounted for 0.2 times the mass of tetrabutyl titanate, was added. The mixture was then subjected to a hydrothermal reaction at 160 °C for 14 h. After the reaction was completed, the mixture was allowed to cool naturally. The insoluble matter was collected by filtration and washed three times each with water and ethanol. The mixture was then dried in a constant temperature oven at 100 °C for 8 h to obtain the precursor.

[0051] S2. The precursor obtained in S1 is calcined at 450℃ for 2 hours to obtain titanium dioxide.

[0052] S3. Mix 8g of titanium dioxide, 5g of erucamide, and 75g of acetone at a stirring speed of 400rpm for 3.5h, then filter and collect the insoluble matter and dry it in a constant temperature oven at 80℃ for 10h to obtain 10.4g of titanium dioxide loaded with slip agent.

[0053] Example 3

[0054] A method for preparing a puncture-resistant cold-stretched film is basically the same as that in Example 2, except that in step S1 of the method for preparing titanium dioxide loaded with slip agent, 1-ethyl-3-methylimidazolium tetrafluoroborate is replaced with N-n-butylpyridine tetrafluoroborate, and 10.1g of titanium dioxide loaded with slip agent is obtained in the final step S3.

[0055] Example 4

[0056] A method for preparing a puncture-resistant cold-stretched film is basically the same as that in Example 2, except that in step S1 of the method for preparing titanium dioxide loaded with slip agent, 1-isobutyl-3-methylimidazolium tetrafluoroborate is replaced with 1-ethyl-3-methylimidazolium tetrafluoroborate, and in the final step S3, 10.3g of titanium dioxide loaded with slip agent is obtained.

[0057] Comparative Example 1

[0058] A method for preparing a puncture-resistant cold-stretch film, comprising the following steps in parts by weight:

[0059] Step 1: Mix 90 parts of low-density polyethylene, 3 parts of polyethylene glycol, and 3 parts of ethylene-vinyl acetate copolymer at 120°C and a stirring rate of 60 rpm for 15 min to obtain the inner layer raw material mixture.

[0060] Step 2: Mix 98 parts of low-density polyethylene, 2.4 parts of erucamide, and 3 parts of polyurethane acrylate at 120°C and a stirring rate of 80 rpm for 30 minutes to obtain the outer layer raw material mixture.

[0061] Step 3: Transfer the inner layer raw material mixture and the outer layer raw material mixture obtained in Step 1 and Step 2 to the blown film unit for co-extrusion blow molding at a mass ratio of 7:3 to obtain a puncture-resistant cold stretch film.

[0062] Comparative Example 2

[0063] A method for preparing a puncture-resistant cold-stretch film, comprising the following steps in parts by weight:

[0064] Step 1: Mix 90 parts of low-density polyethylene, 3 parts of polyethylene glycol, and 3 parts of ethylene-vinyl acetate copolymer at 120°C and a stirring rate of 60 rpm for 15 min to obtain the inner layer raw material mixture.

[0065] Step 2: Mix 90 parts of low-density polyethylene, 2.4 parts of erucamide, 8 parts of titanium dioxide, and 3 parts of polyurethane acrylate at 120°C and a stirring rate of 80 rpm for 30 minutes to obtain the outer layer raw material mixture.

[0066] Step 3: Transfer the inner layer raw material mixture and the outer layer raw material mixture obtained in Step 1 and Step 2 to the blown film unit for co-extrusion blow molding at a mass ratio of 7:3 to obtain a puncture-resistant cold stretch film.

[0067] The preparation method of titanium dioxide is as follows:

[0068] S1. Tetrabutyl titanate and glacial acetic acid were mixed at a mass ratio of 1:25 at a stirring speed of 200 rpm for 10 min and then subjected to hydrothermal reaction. The hydrothermal reaction was maintained at 160℃ for 14 h. After the reaction was completed, the mixture was naturally cooled, filtered, and the insoluble matter was collected. The mixture was washed three times with water and three times with ethanol and then dried in a constant temperature oven at 100℃ for 8 h to obtain the precursor.

[0069] S2. The precursor obtained in S1 is calcined at 450℃ for 2 hours to obtain titanium dioxide.

[0070] It should be noted that the mass of titanium dioxide loaded with slip agent is different in Examples 1 to 4, which indicates that their loading rates are different. Since the mass of titanium dioxide is constant, the loading rate of erucamide can be obtained based on the mass of titanium dioxide and the mass of titanium dioxide loaded with slip agent, as shown in Table 1.

[0071] Table 1. Loading rate results of titanium dioxide with slip agent in Examples 1-4

[0072] Load rate (%) Example 1 20.00 Example 2 30.00 Example 3 26.25 Example 4 28.75

[0073] Therefore, taking Example 2 as an example, 10.4 parts by weight of titanium dioxide loaded with slip agent includes 2.4 parts by weight of erucamide and 8 parts by weight of titanium dioxide. Other examples are different, but the amount of slip agent erucamide is lower than that in Example 2. A larger proportion of erucamide may have a negative impact.

[0074] Test case

[0075] The nitrogen isothermal adsorption-desorption curves of the titanium dioxide material in the examples were tested, and the specific surface area and pore size were obtained. The results are shown in Table 2.

[0076] Table 2. Specific surface area and pore size results of titanium dioxide materials

[0077] <![CDATA[Specific surface area (m 2 / g)]]> Average pore size (nm) Example 1 65.3 22.5 Example 2 78.8 28.6 Example 3 72.7 26.3 Example 4 76.1 26.9

[0078] As can be seen from the results in Table 2, the introduction of ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate, N-n-butylpyridine tetrafluoroborate, and 1-isobutyl-3-methylimidazolium tetrafluoroborate into the hydrothermal reaction, followed by calcination treatment, improved the specific surface area and pore size of titanium dioxide, which corresponds to the increase in the loading of the slip agent.

[0079] The puncture strength, tensile strength, and tear strength of puncture-resistant cold-stretch film at -40℃ were tested according to the following standards: GB / T 10004-2008 "Dry lamination and extrusion lamination of plastic composite films and bags for packaging", GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", and GB / T16578.1-2008 "Determination of tear resistance of plastic films and sheets - Part 1: Pants tear test". The results are shown in Table 3.

[0080] Table 3 Results of puncture strength, tensile strength, and tear strength

[0081] Puncture intensity (N) Tensile strength (MPa) Tear strength (MPa) Example 1 3.3 95.8 27.8 Example 2 3.5 102.3 32.3 Example 3 3.4 96.7 30.5 Example 4 3.4 98.6 31.1 Comparative Example 1 2.3 86.5 22.5 Comparative Example 2 2.9 91.5 24.2

[0082] As can be seen from the test results in Table 3, the puncture-resistant cold-stretch film prepared by adding erucic acid amide to titanium dioxide in the formulation of the embodiments of the present invention has higher puncture resistance, tensile strength, and tear strength. The performance of Comparative Example 1, which did not add titanium dioxide, was the worst. Comparative Example 2, which mixed titanium dioxide with erucic acid amide, showed some improvement, but not as good as the embodiments. In particular, Example 2 had the best performance. According to the above analysis of the loading amount, it had the same amount of erucic acid amide as Comparative Example 2, and the proportion of erucic acid amide was larger than that of other examples. This is because the addition of 1-ethyl-3-methylimidazolium tetrafluoroborate effectively regulated the structure of the titanium dioxide precursor in the hydrothermal process, so that it had a larger specific surface area after calcination. It could not only load more erucic acid amide, but also react better with polypropylene. While avoiding the disadvantages of polyethylene agglomerates or even bubbles caused by the addition of erucic acid amide, it also improved the mechanical properties of the film.

[0083] Referring to the national standard GB / T 10006-2021 "Determination of the coefficient of friction of plastic films and sheets", the static friction coefficients of the puncture-resistant cold-stretched films prepared in the examples and comparative examples were tested, and the results are shown in Table 4.

[0084] Table 4. Static friction coefficient test results

[0085] static friction coefficient Example 1 0.270 Example 2 0.254 Example 3 0.269 Example 4 0.261 Comparative Example 1 0.312 Comparative Example 2 0.291

[0086] As can be seen from the test results in Table 4, the heat shrink film of the present invention has a smaller static friction coefficient, which indicates that adding titanium dioxide with erucamide as a slip agent or loading erucamide onto titanium dioxide can improve the friction reduction performance of erucamide.

[0087] The UV stability of the puncture-resistant cold-stretch films prepared in the examples and comparative examples was tested in accordance with the standard GB / T 16422.3-2022 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent UV Lamp". The results are expressed as the tear strength retention rate before and after the test, as shown in Table 5.

[0088] Table 5 Results of tear strength retention rate

[0089]

[0090]

[0091] As can be seen from the test results in Table 5, the puncture-resistant cold stretch film of Example 2 of the present invention also has good resistance to ultraviolet aging.

[0092] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A puncture-resistant cold-stretch film, characterized in that, It includes an inner layer and an outer layer, wherein the inner layer and the outer layer account for 60%~80% and 20%~40% of the total weight, respectively; The inner layer comprises, by weight, 80-95 parts low-density polyethylene, 2-5 parts polyethylene glycol, and 2-5 parts ethylene-vinyl acetate copolymer. The outer layer comprises, by weight, 80-95 parts low-density polyethylene, 5-12 parts titanium dioxide loaded with slip agent, and 2-5 parts polyurethane acrylate; The method for preparing the titanium dioxide loaded with the slip agent includes, by weight, the following: 5-10 parts of titanium dioxide, 1-5 parts of slip agent, and 60-80 parts of organic solvent are stirred and mixed for 2-5 hours, and then filtered to collect titanium dioxide loaded with slip agent. The slip agent is at least one of erucamide and oleamide; The method for preparing the titanium dioxide includes, Tetrabutyl titanate and glacial acetic acid were mixed at a mass ratio of 1~3:20~50, and then an ionic liquid was added and mixed evenly. The mixture was subjected to hydrothermal reaction to obtain a precursor. The precursor was then calcined to obtain titanium dioxide. The mass of the ionic liquid is 0.1 to 0.3 times that of the tetrabutyl titanate; The ionic liquid is at least one of 1-ethyl-3-methylimidazolium tetrafluoroborate, N-n-butylpyridine tetrafluoroborate, and 1-isobutyl-3-methylimidazolium tetrafluoroborate.

2. The puncture-resistant cold-stretch film according to claim 1, characterized in that, The organic solvent is at least one of ethanol, methanol, acetone, and diethyl ether.

3. The puncture-resistant cold-stretch film according to claim 1, characterized in that, The hydrothermal reaction is maintained at 140~180℃ for 10~18h.

4. The puncture-resistant cold-stretch film according to claim 1, characterized in that, The calcination is carried out at 300~500℃ for 1~3 hours.

5. The puncture-resistant cold-stretch film according to claim 1, characterized in that, The low-density polyethylene has a melt flow rate of 0.2~0.3 g / 10 min and a density of 0.920~0.940 g / cm³. 3 .

6. A method for preparing a puncture-resistant cold-stretch film as described in any one of claims 1 to 5, characterized in that, include, Weigh the raw materials for the inner and outer layers according to the formula and mix them separately to obtain an inner layer raw material mixture and an outer layer raw material mixture; The inner layer material mixture and the outer layer material mixture are co-extruded and blow-molded to obtain a puncture-resistant cold stretch film.

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