Winding film and preparation method thereof

Abstract

The invention relates to a wrapping film and a preparation method thereof, and relates to the technical field of film materials, the wrapping film comprises the following raw materials by weight: 40-60 parts of a polyvinyl base material, 5-10 parts of fluorinated graphene, 0.5-1.0 part of a dispersant, 1-5 parts of a lubricant and 2-5 parts of a stabilizer; the polyethylene base material is obtained by sequentially carrying out freeze-thaw cycle treatment and pulsed electron beam irradiation treatment on ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100: (11-17). According to the invention, ultra-low density polyethylene and ultra-high molecular weight polyethylene with a proper ratio are selected as a polyethylene base material system, freeze-thaw cycle and pulsed electron beam irradiation are introduced to carry out combined modification on the polyethylene base material system, and fluorinated graphene is used as a filler, so that double improvement of thinning and mechanical properties of the wrapping film is realized; the contradiction between thinning and performance improvement of the wrapping film is effectively solved, and the defects in the prior art are overcome.

Description

Technical Field

[0001] The invention relates to the technical field of film materials, and in particular to a wrapping film and a preparation method thereof. Background Art

[0002] In the process of packaging, fixing and protecting various items, stretch film is a vital material, and its performance directly affects the packaging efficiency, the safety of items and the transportation cost. Although traditional stretch film has met the basic needs of the market to a certain extent, with the rapid development of the logistics industry and the increasing awareness of environmental protection, more stringent requirements have been put forward for the performance of stretch film. Specifically, the market urgently needs a stretch film that is both light and thin and has excellent mechanical properties, so as to reduce material consumption and reduce costs while ensuring the safety and stability of packaged items.

[0003] However, the existing stretch film often faces the contradiction between thinning and performance improvement. On the one hand, in order to reduce costs and resource consumption, the stretch film needs to be as thin as possible; on the other hand, thinning often leads to a decrease in mechanical properties, such as tensile strength, tear strength, and abrasion resistance, thereby affecting the packaging effect and the safety of the goods. In addition, the traditional stretch film may also have problems such as difficulty in processing, high energy consumption, and environmental pollution during processing.

[0004] In response to the above problems, the industry has made many attempts and improvements, such as improving the performance of stretch film by changing the raw material formula, optimizing the processing technology, etc. However, these improvements can only alleviate the contradiction between thinning and performance improvement to a certain extent, but cannot fundamentally solve this problem.

[0005] Therefore, there is an urgent need for a new type of stretch film and its preparation method, which can significantly improve the mechanical properties while maintaining the light and thin characteristics, and meet the market's urgent demand for high-performance, lightweight stretch film. Summary of the invention

[0006] In order to solve the above problems, the present invention provides a stretch film and a preparation method thereof.

[0007] In a first aspect, the present invention provides a stretch film, wherein the stretch film comprises the following raw materials in parts by weight: 40-60 parts of polyethylene base material, 5-10 parts of fluorinated graphene, 0.5-1.0 parts of dispersant, 1-5 parts of lubricant and 2-5 parts of stabilizer; The polyethylene base material is obtained by sequentially subjecting ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:(11-17) to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; The density of the ultra-low density polyethylene is 0.904-0.912 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 3 million to 5 million.

[0008] Furthermore, the stretch film comprises the following raw materials in parts by weight: 52 parts of polyethylene base material, 7 parts of fluorinated graphene, 0.8 parts of dispersant, 2 parts of lubricant and 3.5 parts of stabilizer.

[0009] Furthermore, the weight ratio of the ultra-low density polyethylene to the ultra-high molecular weight polyethylene is 100:14.5.

[0010] Furthermore, the working condition parameters of the freeze-thaw cycle treatment include: freezing temperature of -35~-20°C, freezing time of 60~120 minutes; thawing temperature of 35~45°C, thawing time of 60~120 minutes; and the number of cycle treatments is 3~6 times.

[0011] Furthermore, the working condition parameters of the pulse electron beam irradiation treatment include: electron beam energy density of 15-40 J / cm, electron energy of 10 keV, pulse number of 3-5 times, pulse time of 50-90 μs, and frequency of 0.2-0.6 Hz.

[0012] Furthermore, the dispersant includes at least one of polyvinyl pyrrolidone and polyethylene wax, the lubricant includes at least one of ethylene bis stearamide and pentaerythritol stearamide, and the stabilizer includes at least one of dibutyltin dilaurate and octyltin maleate.

[0013] Furthermore, the thickness of the stretch film is ≤10 μm.

[0014] In a second aspect, the present invention provides a method for preparing the stretch film according to any one of the first aspects, the preparation method comprising the following steps: The raw materials are mixed in proportion, and then added into a screw extruder for melt blending to obtain a melt; The melt is fed into an extrusion die for co-extrusion, and then sequentially passed through a forming roller and a cooling roller for cooling and solidification, and a traction roller and a winding roller for traction and winding, to obtain the stretch film.

[0015] Furthermore, the heating temperature of the screw extruder is divided into 8 sections: the temperature of zone I is 275~285℃, the temperature of zone II is 250~265℃, the temperature of zone III is 210~220℃, the temperature of zone IV is 220~235℃, the temperature of zone V is 230~245℃, the temperature of zone VI is 245~260℃, the temperature of zone VII is 260~275℃, and the temperature of zone VIII is 275~285℃; the cooling roller includes a first cooling roller and a second cooling roller, and the temperatures of the first cooling roller and the second cooling roller are both 20~30℃.

[0016] Furthermore, the film discharge speed of the wrapping film is 300-500 m / min, and the rotation speed ratio of the forming roller, the cooling roller, the traction roller and the winding roller is set to 1: (1-1.1): (1-1.2): (0.8-1.0).

[0017] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art: The embodiment of the present invention provides a stretch film, which selects ultra-low density polyethylene and ultra-high molecular weight polyethylene with appropriate proportions as the polyethylene base material system, and introduces freeze-thaw cycles and pulsed electron beam irradiation to jointly modify the polyethylene base material system and uses fluorinated graphene as a filler, thereby achieving a dual improvement in the thinning of the stretch film and the mechanical properties, effectively solving the contradiction between the thinning of the stretch film and the improvement of its performance, and making up for the deficiencies of the prior art. Specifically: 1. Selection of raw materials for polyethylene base material system Ultra-low density polyethylene (ULDPE) has excellent flexibility and processability, which helps to reduce the thickness of the stretch film without sacrificing its ductility; at the same time, ultra-high molecular weight polyethylene (UHMWPE) is known for its extremely high molecular weight and chain strength, which can significantly improve the mechanical properties of the stretch film, such as tensile strength, and make up for the decline in mechanical properties caused by thinning. The two are mixed in an appropriate proportion to achieve a balance between flexibility and mechanical properties, laying the foundation for the dual improvement of the thinning of the stretch film and the mechanical properties.

[0018] 2. Combined modification of polyethylene base material ULDPE is easy to deform at high temperature due to its low density and molecular chain structure; at the same time, although UHMWPE has excellent mechanical properties, its extremely high molecular weight makes processing difficult. On the one hand, the present invention promotes the relaxation and rearrangement of polyethylene molecular chains through pre-treatment of freeze-thaw cycle treatment, especially reduces the entanglement between UHMWPE molecular chains, and lays the foundation for subsequent pulse electron beam irradiation treatment; on the other hand, through the deep modification of pulse electron beam irradiation, the polyethylene base material is irradiated instantly with a high-energy electron beam to produce cross-linking and chain breaking reactions, introduce cross-linking points between ULDPE molecular chains, form a three-dimensional network structure, enhance its thermal stability, so that it can maintain the stability of shape and size during subsequent processing and use, strengthen the mutual synergy between different polyethylene base material molecules and the overall performance and stability of the winding film, and also provide favorable conditions for the uniform dispersion and effective action of fluorinated graphene.

[0019] 3. Introducing fluorinated graphene as filler As a high-performance filler, the interaction between fluorinated graphene and the polyethylene base material not only enhances the lubricity and antistatic properties of the film, but also forms an effective reinforcing phase in the polyethylene base material through its unique two-dimensional structure, further improving the mechanical strength and thermal stability of the stretch film.

[0020] In summary, the present invention achieves significant improvement in mechanical properties while reducing the thickness of the stretch film by selecting a suitable proportion of polyethylene base material and a unique combined modification technology. The synergistic effect between the components and the modification technologies together constitutes the core advantage of the technical solution of the present invention, effectively solving the contradiction between the thinning of the stretch film and the improvement of its performance, and providing new ideas and methods for the development of the membrane material field. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 A schematic flow chart of a method for preparing a stretch film provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0026] In a first aspect, the present invention provides a stretch film, wherein the stretch film comprises the following raw materials in parts by weight: 40-60 parts of polyethylene base material, 5-10 parts of fluorinated graphene, 0.5-1.0 parts of dispersant, 1-5 parts of lubricant and 2-5 parts of stabilizer; The polyethylene base material is obtained by sequentially subjecting ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:(11-17) to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; The density of the ultra-low density polyethylene is 0.904-0.912 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 3 million to 5 million.

[0027] The embodiment of the present invention provides a stretch film. The present invention selects ultra-low density polyethylene and ultra-high molecular weight polyethylene with a suitable ratio as the polyethylene base material system, and introduces freeze-thaw cycles and pulsed electron beam irradiation to jointly modify the polyethylene base material system and uses fluorinated graphene as a filler, thereby achieving a dual improvement in the thinning and mechanical properties of the stretch film, effectively solving the contradiction between the thinning and performance improvement of the stretch film, and making up for the shortcomings of the prior art.

[0028] The ultra low density polyethylene (ULDPE) in the present invention is a modified material of polyethylene (PE). Its polymerization mechanism is similar to that of LLDPE. Both are linear structures without long chain branches, so it is also called the second generation LLDPE. In some specific embodiments, the ultra low density polyethylene can be prepared according to the existing disclosed preparation process or can be directly used, such as the product model ATTANE of the Dow Chemical Company of the United States. TM 4203 (density 0.905 g / cm³), ATTANE TM 4404G (density 0.904 g / cm³), ATTANE TM 4201G (density 0.912 g / cm³) and other commercially available products, preferably the product model ATTANE from Dow Chemical Company of the United States TM 4203 (density 0.905 g / cm³).

[0029] The ultra-high molecular weight polyethylene (UHMWPE) in the present invention is a thermoplastic engineering plastic with excellent comprehensive properties. Its molecular weight is usually above 1 million, and can even reach millions, but its molding processability is poor, which limits its widespread use. The ultra-high molecular weight polyethylene can be made by itself according to the existing disclosed preparation process or can be directly used, such as the product model UHMWPEU050 (weight average molecular weight of 5 million), the product model UHMWPEU050 H (weight average molecular weight of 3.7 million) of Korea Petrochemical Corporation and the product model 9300CG (weight average molecular weight of 3 million) of Beijing Zhonglai Chemical Co., Ltd. The product model is preferably UHMWPEU050 H of Korea Petrochemical Corporation.

[0030] The fluorinated graphene in the present invention is an important new type of graphene derivative, which is a two-dimensional material formed by covalent bonding of carbon atoms and fluorine atoms in graphene. This substitution not only changes the chemical composition of graphene, but also profoundly affects its physical and chemical properties, making the fluorinated graphene show unique application value in many fields. The fluorinated graphene can be prepared by itself according to the existing disclosed preparation process or can be directly used as a commercial product such as CAS No. 51311-17-2 (powder).

[0031] The weight proportions of the polyethylene base material in the present invention may be 40 parts, 41 parts, 42 parts, 43 parts, 44 parts, 45 parts, 46 parts, 47 parts, 48 ​​parts, 49 parts, 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, etc.

[0032] The weight proportion of fluorinated graphene in the present invention may be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts, etc.

[0033] The weight proportion of the dispersant in the present invention can be 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part, 1.0 part, etc.

[0034] The weight proportion of the lubricant in the present invention can be 1 part, 2 parts, 3 parts, 4 parts, 5 parts, etc.

[0035] The weight proportion of the stabilizer in the present invention can be 2 parts, 3 parts, 4 parts, 5 parts, etc.

[0036] In some specific embodiments, the stretch film includes the following raw materials in parts by weight: 52 parts of polyethylene base material, 7 parts of fluorinated graphene, 0.8 parts of dispersant, 2 parts of lubricant and 3.5 parts of stabilizer.

[0037] In some specific embodiments, the weight ratio of the ultra-low density polyethylene to the ultra-high molecular weight polyethylene is 100:14.5.

[0038] In some specific embodiments, the working condition parameters of the freeze-thaw cycle treatment include: freezing temperature of -35~-20°C, freezing time of 60~120 minutes; thawing temperature of 35~45°C, thawing time of 60~120 minutes; number of cycle treatments is 3~6 times.

[0039] In some specific embodiments, the working condition parameters of the pulse electron beam irradiation treatment include: electron beam energy density of 15~40J / cm, electron energy of 10kev, pulse number of 3~5 times, pulse time of 50~90μs, and frequency of 0.2~0.6Hz.

[0040] In some specific embodiments, the dispersant includes at least one of polyvinyl pyrrolidone and polyethylene wax, the lubricant includes at least one of ethylene bis stearamide and pentaerythritol stearamide, and the stabilizer includes at least one of dibutyl tin dilaurate and octyl tin maleate.

[0041] In some specific embodiments, the thickness of the wrapping film is ≤10 μm, preferably 5-10 μm.

[0042] In a second aspect, the present invention provides a method for preparing the stretch film according to any one of the first aspects, such as Figure 1 As shown, the preparation method comprises the following steps: The raw materials are mixed in proportion, and then added into a screw extruder for melt blending to obtain a melt; The melt is fed into an extrusion die for co-extrusion, and then sequentially passed through a forming roller and a cooling roller for cooling and solidification, and a traction roller and a winding roller for traction and winding, to obtain the stretch film.

[0043] The preparation method of the stretch film provided by the present invention is simple to operate, does not require additional specific equipment, and is suitable for industrial mass production. At the same time, the preparation method is implemented based on the stretch film described in any one of the first aspects, so it has at least the beneficial effects of the stretch film described in any one of the first aspects, which will not be described one by one here.

[0044] In some specific embodiments, the heating temperature of the screw extruder is divided into 8 sections: the temperature of zone I is 275~285℃, the temperature of zone II is 250~265℃, the temperature of zone III is 210~220℃, the temperature of zone IV is 220~235℃, the temperature of zone V is 230~245℃, the temperature of zone VI is 245~260℃, the temperature of zone VII is 260~275℃, and the temperature of zone VIII is 275~285℃; the cooling roller includes a first cooling roller and a second cooling roller, and the temperatures of the first cooling roller and the second cooling roller are both 20~30℃.

[0045] In some specific embodiments, the film delivery speed of the wrapping film is 300~500m / min, and the rotation speed ratio of the forming roller, the cooling roller, the traction roller and the winding roller is set to 1: (1~1.1): (1~1.2): (0.8~1.0).

[0046] It should be noted that the raw material components involved in the stretch film and the preparation method thereof provided in the embodiments of the present invention, unless otherwise specified or described, can be directly purchased from the market or made in-house according to existing preparation methods; at the same time, the operating steps involved in the preparation method, unless otherwise specified or described, can be carried out according to existing stretch film preparation methods or directly using commercially available equipment, and the present invention document will not describe them one by one.

[0047] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0048] Embodiment 1: This embodiment provides a stretch film, which comprises the following raw materials in parts by weight: 52 parts of polyethylene base material, 7 parts of fluorinated graphene, 0.8 parts of dispersant, 2 parts of lubricant and 3.5 parts of stabilizer; The polyethylene base material is obtained by mixing ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:14.5, and then sequentially subjected to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; wherein the working condition parameters of the freeze-thaw cycle treatment include: a freezing temperature of -30°C, a freezing time of 90 minutes; a thawing temperature of 40°C, a thawing time of 90 minutes; and a number of cycle treatments of 5 times; and the working condition parameters of the pulse electron beam irradiation treatment include: an electron beam energy density of 25 J / cm, an electron energy of 10 kev, a pulse number of 4 times, a pulse time of 80 μs, and a frequency of 0.5 Hz; The density of the ultra-low density polyethylene is 0.905 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 3.7 million; The dispersant is polyethylene wax; The lubricant is ethylene bis stearamide; The stabilizer is octyltin maleate.

[0049] The preparation method of the above-mentioned stretch film comprises the following steps: The raw materials are mixed in proportion, and then added into a screw extruder for melt blending to obtain a melt; The melt is fed into an extrusion die for co-extrusion, and then cooled and solidified by a forming roller and a cooling roller, and is pulled and wound by a pulling roller and a winding roller to obtain the stretch film; Among them, the heating temperature of the screw extruder is divided into 8 sections: the temperature of zone I is 280°C, the temperature of zone II is 260°C, the temperature of zone III is 215°C, the temperature of zone IV is 230°C, the temperature of zone V is 240°C, the temperature of zone VI is 250°C, the temperature of zone VII is 270°C, and the temperature of zone VIII is 280°C; the cooling roller includes a first cooling roller and a second cooling roller, and the temperatures of the first cooling roller and the second cooling roller are both 25°C; the film discharge speed of the wrapping film is 400m / min, and the speed ratio of the forming roller, the cooling roller, the traction roller and the winding roller is set to 1:1.05:1.18:0.9.

[0050] Example 2: This example provides a stretch film, which includes the following raw materials in parts by weight: 40 parts of polyethylene base material, 5 parts of fluorinated graphene, 0.5 parts of dispersant, 1 part of lubricant and 2 parts of stabilizer; The polyethylene base material is obtained by mixing ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:11, and then sequentially subjected to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; wherein the working condition parameters of the freeze-thaw cycle treatment include: a freezing temperature of -35°C, a freezing time of 60 minutes; a thawing temperature of 45°C, a thawing time of 60 minutes; and a number of cycle treatments of 6 times; and the working condition parameters of the pulse electron beam irradiation treatment include: an electron beam energy density of 15 J / cm, an electron energy of 10 kev, a pulse number of 5 times, a pulse time of 50 μs, and a frequency of 0.2 Hz; The density of the ultra-low density polyethylene is 0.904 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 5 million; The dispersant is polyvinyl pyrrolidone; The lubricant is pentaerythritol stearamide; The stabilizer is dibutyltin dilaurate.

[0051] The preparation method of the above-mentioned stretch film is the same as that of Example 1.

[0052] Embodiment 3: This embodiment provides a stretch film, which includes the following raw materials in parts by weight: 60 parts of polyethylene base material, 10 parts of fluorinated graphene, 1.0 parts of dispersant, 5 parts of lubricant and 5 parts of stabilizer; The polyethylene base material is obtained by mixing ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:17, and then sequentially subjected to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; wherein the working condition parameters of the freeze-thaw cycle treatment include: a freezing temperature of -20°C, a freezing time of 120 minutes; a thawing temperature of 35°C, a thawing time of 120 minutes; and a number of cycle treatments of 3 times; and the working condition parameters of the pulse electron beam irradiation treatment include: an electron beam energy density of 40 J / cm, an electron energy of 10 kev, a pulse number of 3 times, a pulse time of 90 μs, and a frequency of 0.6 Hz; The density of the ultra-low density polyethylene is 0.912 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 3 million; The dispersant is polyethylene wax; The lubricant is pentaerythritol stearamide; The stabilizer is dibutyltin dilaurate.

[0053] The preparation method of the above-mentioned stretch film is the same as that of Example 1.

[0054] Comparative Example 1: This example provides a stretch film and a preparation method thereof, which is different from Example 1 only in that the weight ratio of the ultra-low density polyethylene to the ultra-high molecular weight polyethylene is 87.5:27 (that is, the weight ratio of the ultra-low density polyethylene to the ultra-high molecular weight polyethylene is different); the remaining steps and parameters are the same.

[0055] Comparative Example 2: This example provides a stretch film and a preparation method thereof, which differs from Example 1 only in that: the polyethylene base material is obtained by mixing ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:14.5, and then sequentially subjected to pulse electron beam irradiation treatment and freeze-thaw cycle treatment (i.e., the order of pulse electron beam irradiation treatment and freeze-thaw cycle treatment is different); the remaining steps and parameters are the same.

[0056] Test Case In this example, the performance evaluation test of the stretch films provided in Examples 1 to 3 and Comparative Examples 1 to 2 was carried out according to the test method disclosed in the prior art. The specific test results are shown in Table 1; wherein, the test standards for each item are as follows: 1) Thickness test was carried out with reference to GB / T6672-2001 Mechanical measurement method for thickness determination of plastic film and sheet; 2) Tensile strength test was carried out with reference to GB / T 1040-2006 Determination of tensile properties of plastics.

[0057] Table 1 Test samples Thickness (μm) Tensile strength (Mpa) Example 1 5 46.1 Example 2 5 40.8 Example 3 5 42.4 Comparative Example 1 5 27.9 Comparative Example 2 5 30.5 It can be seen from Table 1 that, compared with Comparative Examples 1-2, the tensile strength of the stretch film provided in the embodiment of the present invention is still maintained above 40 MPa under the premise that the thickness is only 5 μm, thereby achieving a dual improvement in the thinning of the stretch film and the mechanical properties, effectively solving the contradiction between the thinning of the stretch film and the improvement of the performance, and providing new ideas and methods for the development of the field of membrane materials.

[0058] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0059] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A stretch film, characterized in that: The stretch film comprises the following raw materials in parts by weight: 40-60 parts of polyethylene base material, 5-10 parts of fluorinated graphene, 0.5-1.0 parts of dispersant, 1-5 parts of lubricant and 2-5 parts of stabilizer; The polyethylene base material is obtained by sequentially subjecting ultra-low density polyethylene and ultra-high molecular weight polyethylene in a weight ratio of 100:(11-17) to freeze-thaw cycle treatment and pulse electron beam irradiation treatment; The density of the ultra-low density polyethylene is 0.904-0.912 g / cm³; The weight average molecular weight of the ultra-high molecular weight polyethylene is 3 million to 5 million.

2. The stretch film according to claim 1, characterized in that: The stretch film comprises the following raw materials in parts by weight: 52 parts of polyethylene base material, 7 parts of fluorinated graphene, 0.8 parts of dispersant, 2 parts of lubricant and 3.5 parts of stabilizer.

3. The stretch film according to claim 1, characterized in that: The weight ratio of the ultra-low density polyethylene to the ultra-high molecular weight polyethylene is 100:14.

5.

4. The stretch film according to claim 1, characterized in that: The working condition parameters of the freeze-thaw cycle treatment include: freezing temperature of -35~-20°C, freezing time of 60~120 minutes; thawing temperature of 35~45°C, thawing time of 60~120 minutes; and the number of cycle treatments is 3~6 times.

5. The stretch film according to claim 1, characterized in that: The working condition parameters of the pulse electron beam irradiation treatment include: electron beam energy density of 15-40 J / cm, electron energy of 10 keV, pulse number of 3-5 times, pulse time of 50-90 μs, and frequency of 0.2-0.6 Hz.

6. The stretch film according to claim 1, characterized in that: The dispersant includes at least one of polyvinyl pyrrolidone and polyethylene wax, the lubricant includes at least one of ethylene bis stearic acid amide and pentaerythritol stearic acid amide, and the stabilizer includes at least one of dibutyl tin dilaurate and octyl tin maleate.

7. The stretch film according to claim 1, characterized in that: The thickness of the stretch film is ≤10 μm.

8. A method for preparing a stretch film according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The raw materials are mixed in proportion, and then added into a screw extruder for melt blending to obtain a melt; The melt is fed into an extrusion die for co-extrusion, and then sequentially passed through a forming roller and a cooling roller for cooling and solidification, and a traction roller and a winding roller for traction and winding, to obtain the stretch film.

9. The method for preparing a stretch film according to claim 8, characterized in that: The heating temperature of the screw extruder is divided into 8 sections: the temperature of zone I is 275~285℃, the temperature of zone II is 250~265℃, the temperature of zone III is 210~220℃, the temperature of zone IV is 220~235℃, the temperature of zone V is 230~245℃, the temperature of zone VI is 245~260℃, the temperature of zone VII is 260~275℃, and the temperature of zone VIII is 275~285℃; the cooling roller includes a first cooling roller and a second cooling roller, and the temperatures of the first cooling roller and the second cooling roller are both 20~30℃.

10. The method for preparing a stretch film according to claim 8, characterized in that: The film discharge speed of the wrapping film is 300-500 m / min, and the rotation speed ratio of the forming roller, the cooling roller, the traction roller and the winding roller is 1: (1-1.1): (1-1.2): (0.8-1.0).

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