Wrap film

Abstract

To provide a wrap film.SOLUTION: According to a cross-section structure of a wrap film, the wrap film comprises an inner layer part, and a surface layer part that completely covers the inner layer part. The inner layer part contains 40 to 60 wt.% of an ethylene elastomer, 35 to 55 wt.% of a propylene random copolymer, and 1 to 10 wt.% of a hydrogenated petroleum resin, based on 100 wt.% of a total weight of the inner layer part. The surface layer part contains ethylene-vinyl acetate.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a wrap film, and more particularly to a wrap film adapted for use in a fully automatic packaging machine. [Background technology]

[0002] Compared to other polymer wrap films, polyvinyl chloride (PVC) wrap films have excellent tensile properties and can be widely used in automatic packaging machines. However, PVC wrap films contain chlorine, which is environmentally hazardous.

[0003] In order to prevent environmental pollution, various countries have proposed corresponding policies one after another. For example, Australia plans to ban polyvinyl chloride wrap film in 2025. Unfortunately, the non-PVC wrap film (such as polyethylene wrap film) currently on the market does not contain chlorine, but it cannot be applied to fully automatic packaging machines.

[0004] Take polyethylene wrap film as an example. The polyethylene has high crystallinity, and after stretching, crystal deformation may occur. After the wrap film is stretched through a fully automatic packaging machine, horizontal stripes or obvious wrinkles may appear on the surface of the wrap film. As a result, the product packaging appearance is poor and unacceptable to consumers.

[0005] Therefore, an important issue for this project is to improve the tensile properties of polyethylene wrap film through material improvements so that it can be used as a replacement for polyvinyl chloride wrap film. Summary of the Invention [Problem to be solved by the invention]

[0006] The technical problem that the present invention aims to solve is to provide a wrap film to address the shortcomings of the prior art. [Means for solving the problem]

[0007] In order to solve the above technical problems, one technical means adopted by the present invention provides a wrap film. In the cross-sectional structure of the wrap film, the wrap film includes an inner layer portion and a surface layer portion that completely covers the inner layer portion. The inner layer portion includes 40% by weight to 60% by weight of an ethylene elastomer, 35% by weight to 55% by weight of a propylene random copolymer, and 1% by weight to 10% by weight of a hydrogenated petroleum resin, with the total weight of the inner layer portion being 100% by weight. The surface layer portion includes ethylene vinyl acetate.

[0008] In one embodiment, the ethylene elastomer, the propylene random copolymer, and the hydrogenated petroleum resin contained in the inner layer portion are uniformly mixed to form a continuous phase.

[0009] In one embodiment, the melting point of the propylene random copolymer is 130°C to 150°C.

[0010] In one embodiment, the melt index of the propylene random copolymer is 1 g / 10 mm to 10 g / 10 mm.

[0011] In one embodiment, the propylene random copolymer is prepared by copolymerization of propylene and ethylene monomers.

[0012] In one embodiment, the hydrogenated petroleum resin is a hydrogenated petroleum resin polymerized with a monomer having 5 carbon atoms, or a hydrogenated petroleum resin polymerized with a monomer having 9 carbon atoms.

[0013] In one embodiment, the inner layer portion further contains 4 wt % to 8 wt % of an anti-fogging agent, with the total weight of the inner layer portion being 100 wt %.

[0014] In one embodiment, the surface layer portion further contains 2 wt % to 5 wt % of an antifogging agent, with the total weight of the surface layer portion being 100 wt %.

[0015] In one embodiment, the total thickness of the wrap film is taken as 100%, and the inner layer portion accounts for 50% to 70% of the total thickness of the wrap film.

[0016] In one embodiment, the Young's modulus of the wrap film is 3.5 MPa to 5.6 MPa. Effect of the Invention

[0017] An advantageous effect of the present invention is that the wrap film of the present invention improves the tensile properties of the wrap film due to the technical feature that "the inner layer portion contains 40% by weight to 60% by weight of ethylene elastomer, 35% by weight to 55% by weight of propylene random copolymer, and 1% by weight to 10% by weight of hydrogenated petroleum resin, with the total weight of the inner layer portion being 100% by weight." [Brief description of the drawings]

[0018] [Figure 1] 1 is a three-dimensional view of a wrap film according to the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In order to better understand the features and technical contents of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings, which are provided for reference and explanation only and are not intended to limit the scope of the present invention.

[0020] The wrap film according to the embodiment of the present invention will be described below by way of certain specific embodiments, and those skilled in the art will be able to understand the advantages and effects of the present invention based on the contents disclosed herein. The present invention can be implemented or applied by other different specific embodiments, and various modifications and changes can be made to each detail in the present specification based on different perspectives and applications without departing from the concept of the present invention. In addition, as described in advance, the accompanying drawings of the present invention are simple schematic illustrations and are not drawn based on actual size. The technical contents of the present invention will be described in more detail based on the following embodiments, but the disclosure does not limit the scope of protection of the present invention. In addition, the term "or" used in the present specification may include any one or more combinations of the related items listed according to the actual situation.

[0021] In order to solve the problem of poor stretchability and stretched appearance of polyethylene wrap films, the present invention provides a wrap film with good stretchability and good stretched appearance (i.e., suitable tensile properties) and applicable to fully automatic packaging machines, and thus the wrap film of the present invention can be used as a replacement for commercially available polyvinyl chloride wrap films.

[0022] Generally, tensile properties and Young's modulus are directly proportional. Therefore, in this specification, the tensile properties of the wrap film are quantified by Young's modulus. Specifically, the Young's modulus of the wrap film is measured by the international standard measurement method of ASTM D638, and the Young's modulus of the wrap film according to the present invention can reach 3.5 MPa to 5.6 MPa.

[0023] The wrap film of the present invention has suitable tensile properties and can maintain a low haze value, and the transparency of the wrap film is not affected by changes in tensile properties. Specifically, the wrap film may have a haze value of less than 5%, and preferably, the wrap film may have a haze value of less than 2%.

[0024] As shown in FIGS. 1 and 2, in the cross-sectional structure of the wrap film Z according to the present invention, the wrap film Z includes an inner layer portion 1 and a surface layer portion 2 that completely covers the inner layer portion 1.

[0025] From the outside, the product appears to have an inner layer 1 and a surface layer 2 molded as a single unit, but when the components contained therein are analyzed, wrap film Z can be divided into an inner layer 1 and a surface layer 2.

[0026] For example, the wrap film Z may be formed by laminating a three-layer film structure. The three-layer film structure includes two surface layer films and an inner layer film between the two surface layer films. After lamination, the inner layer film forms the inner layer part 1, and the two surface layer films form the surface layer part 2 that covers the inner layer part 1, but the present invention is not limited to this.

[0027] By adjusting the component composition of the inner layer 1 and the surface layer 2, the wrap film Z of the present invention has functional properties similar to those of ordinary wrap films, and as a result, the wrap film Z of the present invention has appropriate tensile properties, making it possible to apply it to fully automatic packaging machines, and no horizontal stripes are produced during the stretching process.

[0028] That is, by dividing the wrap film Z into an inner layer portion 1 and a surface layer portion 2 based on the material, the wrap film Z can be used as a substitute for commercially available polyvinyl chloride wrap films, on the premise that the wrap film Z maintains its original functional properties.

[0029] The wrap film of the present invention is an improvement over polyethylene wrap film in particular. To improve the problem of poor appearance of conventional polyethylene wrap films after stretching, the present invention employs an ethylene elastomer as one of the materials for the inner layer portion 1.

[0030] The ethylene elastomer contains a soft segment portion and a hard segment portion, and therefore, compared to the ethylene polymer, the ethylene elastomer can impart superior tensile properties and elastic recovery force to the wrap film Z.

[0031] However, because ethylene elastomer itself is hard, if the ethylene elastomer content is too high, the film (film of 15 μm or less) becomes easily torn during the production process. Therefore, in the inner layer portion 1 of the wrap film Z, the ethylene elastomer content must be less than 65% by weight, and preferably the ethylene elastomer content is 60% by weight or less, assuming the total weight of the inner layer portion to be 100% by weight.

[0032] Specifically, the ethylene elastomer content in the inner layer portion 1 of the wrap film Z is 40% to 60% by weight. The ethylene elastomer content is preferably 40% to 50% by weight. For example, the ethylene elastomer content may be 42%, 44%, 46% or 48% by weight.

[0033] In order to achieve a balance between the tensile properties and texture of the wrap film Z, the melt index (melt flow index, MI) of the ethylene elastomer is 0.5 g / 10 mm to 10 g / 10 mm, and preferably 1 g / 10 mm to 3 g / 10 mm.

[0034] As described above, since there is an upper limit to the content of ethylene elastomer, a film cannot be produced from a single material including ethylene elastomer. Therefore, in the present invention, a mixture of propylene random copolymer and ethylene elastomer is used as the material for the inner layer portion 1.

[0035] By adding the propylene random copolymer, the improved tensile properties of the ethylene elastomer are maintained while the material of the inner layer 1 does not become hard or brittle, thereby preventing the problem of the film bursting during the film formation process.

[0036] Compared with other polymer structures (such as alternating copolymers or block copolymers), random copolymers have a relatively large amount of amorphous phase, which can prevent the occurrence of crystal deformation. Therefore, the addition of propylene random copolymers can prevent the occurrence of horizontal stripes.

[0037] Specifically, in the inner layer portion 1 of the wrap film, the content of the propylene random copolymer is 35% to 55% by weight, and preferably 40% to 50% by weight, relative to the total weight of the inner layer portion being 100% by weight. For example, the content of the propylene random copolymer may be 42%, 44%, 46% or 48% by weight.

[0038] In one preferred embodiment, the propylene random copolymer is synthesized from ethylene monomer and propylene monomer. Since a part of the propylene random copolymer is synthesized from ethylene monomer, it has relatively good compatibility with ethylene elastomer, and can reduce the possibility of horizontal stripes occurring after stretching the wrap film.

[0039] The total weight of the monomers for synthesizing the propylene random copolymer is taken as 100% by weight, and the content of the ethylene monomer is 1% by weight to 5% by weight, and the content of the propylene monomer is 95% by weight to 99% by weight. An appropriate amount of ethylene monomer can improve the compatibility between the propylene random copolymer and the ethylene elastomer, but if the content of the ethylene monomer is too high, the texture of the wrap film becomes soft.

[0040] Furthermore, in the present invention, the melting point of the propylene random copolymer is controlled to be less than 150° C. Preferably, the melting point of the propylene random copolymer is 130° C. to 150° C. More preferably, the melting point of the propylene random copolymer is 130° C. to 135° C.

[0041] Usually, the melting point and the crystallinity are directly proportional. If the crystallinity of the material is high, horizontal stripes may be formed when the wrap film Z is pulled with high strength, which has a negative effect on the packaging. By adjusting the melting point of the propylene random copolymer, the tensile properties and texture of the wrap film Z can be balanced.

[0042] In addition to the melting point, the melt index (melt flow index, MI) of the propylene random copolymer may be controlled to 1 g / 10 mm to 10 g / 10 mm. The melt index of the propylene random copolymer is related to the fluidity of the material, and controlling the MI within the above range is advantageous for the production of the film.

[0043] In order to balance the elastic recovery force, Young's modulus, appropriate softness, hardness, and appropriate crystallinity of the wrap film Z, the weight ratio of the ethylene elastomer to the propylene random copolymer is controlled to 0.9 to 1.1 in the present invention, thereby ensuring the complementary properties of the ethylene elastomer and the propylene random copolymer. If the content of the ethylene elastomer is too high, the texture of the wrap film is too hard, which is disadvantageous for film formation. If the content of the random copolymer is too high, the tensile properties of the wrap film are reduced, making it impossible to apply it to a fully automatic packaging machine.

[0044] Furthermore, hydrogenated petroleum resin may be further added to the inner layer portion 1. The addition of hydrogenated petroleum resin can improve the elastic recovery force of the wrap film Z and can also improve the compatibility between the ethylene elastomer and the propylene random copolymer. After the compatibility is improved, horizontal stripes are less likely to form when the wrap film is pulled. Furthermore, after the compatibility is improved, the wrap film can maintain a certain level of transparency, and the wrap film can have a haze value of less than 2%.

[0045] After being used for a certain period of time, the hydrogenated petroleum resin may migrate to the surface of the wrap film Z. Therefore, the addition of the hydrogenated petroleum resin also has the effect of improving the surface adhesion of the wrap film Z.

[0046] However, if too much hydrogenated petroleum resin is added, the viscosity of the material increases, which is disadvantageous for processing and film formation. Therefore, the content of hydrogenated petroleum resin in the inner layer portion 1 of the wrap film Z must be less than 10% by weight.

[0047] Specifically, in the inner layer portion 1 of the wrap film Z, the content of the hydrogenated petroleum resin is 1 to 10% by weight, and preferably 3 to 7% by weight, relative to the total weight of the inner layer portion being 100% by weight. For example, the content of the hydrogenated petroleum resin may be 4, 5 or 6% by weight.

[0048] In one embodiment, the hydrogenated petroleum resin is a hydrogenated petroleum resin polymerized with a monomer having 5 carbon atoms, or a hydrogenated petroleum resin polymerized with a monomer having 9 carbon atoms.

[0049] For example, the petroleum resin may be, for example, a piperylene hydrogenated resin or a dicyclopentadiene (DCPD) hydrogenated resin, or may be an aqueous white thermoplastic resin obtained by polymerizing and hydrogenating a C9 fraction, which is a by-product of ethylene decomposition, but the present invention is not limited thereto.

[0050] It is noteworthy that after the ethylene elastomer, the propylene random copolymer, and the hydrogenated petroleum resin are uniformly mixed, a uniform continuous phase is formed in the inner layer 1, thereby imparting excellent tensile properties to the inner layer 1. Therefore, the wrap film Z according to the present invention can be used in place of conventional polyvinyl chloride wrap films and can be applied to fully automatic packaging machines.

[0051] Because the inner layer portion 1 mainly plays a supporting role in the wrap film Z, the thickness of the inner layer portion 1 accounts for a large proportion of the overall thickness of the wrap film Z. With the total thickness of the wrap film Z being 100%, the thickness of the inner layer portion 1 is 50% to 70%, and the total thickness of the surface layer portions 2 (located above and below the inner layer portion 1) is 30% to 50%.

[0052] In one example, the total thickness of the wrap film Z is 8 μm to 12 μm, and preferably 9 μm to 11 μm. That is, the thickness of the inner layer portion 1 may be 4 μm to 8.4 μm, and the total thickness of the surface layer portion 2 may be 2.4 μm to 6 μm.

[0053] The surface layer 2 of the wrap film Z uses ethylene vinyl acetate (EVA) as the main component. Ethylene vinyl acetate provides a slight adhesive force to the surface of the wrap film Z, improving its packaging properties as a packaging material. In one exemplary example, the melt index of ethylene vinyl acetate is 1g / 10mm to 5g / 10mm.

[0054] In order to meet the requirements of the application, functional auxiliaries may be added to the wrap film Z so as to impart good transparency, anti-fogging properties and packaging properties (hereinafter also referred to as functional properties) to the wrap film Z.

[0055] In one example, both the inner layer 1 and the outer layer 2 of the wrap film Z may contain an anti-fog agent to prevent fogging in a low temperature environment (refrigerated state) of the wrap film Z. The wrap film Z contains 3% to 5% by weight of the anti-fog agent, with the total weight of the wrap film Z being 100% by weight.

[0056] Preferably, both the inner layer portion 1 and the surface layer portion 2 contain an anti-fogging agent. After long-term use, the anti-fogging agent migrates to the surface of the wrap film, causing the anti-fogging effect to be lost. Therefore, if both the inner layer portion 1 and the surface layer portion 2 contain an anti-fogging agent, even if the anti-fogging agent in the surface layer portion 2 migrates to the surface of the wrap film, the anti-fogging effect of the wrap film Z can be extended due to the presence of the anti-fogging agent in the inner layer portion 1.

[0057] The antifogging agents added to the inner layer portion 1 and the surface layer portion 2 may be the same or different.

[0058] For example, the anti-fogging agent added to the inner layer portion 1 may be a glyceride compound, and the glyceride compound may be sorbitan monooleate.

[0059] Preferably, the molecular weight of the glyceride compound may be 350 g / mol to 450 g / mol, for example, the molecular weight of the glyceride compound may be 375 g / mol, 400 g / mol or 425 g / mol. By controlling the molecular weight of the glyceride compound, the time it takes for the glyceride compound to migrate to the surface of the wrap film Z can be extended.

[0060] The anti-fogging agent added to the surface layer portion 2 may be a glyceride compound or an ether compound. The types and properties of the glyceride compounds are as described above, and will not be described here. The molecular weight of the ether compound is 150 g / mol to 250 g / mol, and for example, the molecular weight of the ether compound may be 175 g / mol, 200 g / mol, or 225 g / mol. By controlling the molecular weight of the anti-fogging agent, the time it takes for the anti-fogging agent to migrate to the surface of the wrap film Z can be extended.

[0061] Due to the difference in position, the anti-fogging agent in the inner layer portion 1 can remain in the wrap film Z for a relatively longer period of time than the anti-fogging agent in the surface layer portion 2. Furthermore, by controlling the molecular weight, both the anti-fogging agent in the inner layer portion 1 and the anti-fogging agent in the surface layer portion 2 can maintain the anti-fogging properties of the wrap film Z.

[0062] In this example, even though the anti-fog agent in surface layer 2 has already migrated to the surface of wrap film Z, wrap film Z still contains the anti-fog agent in inner layer 1. Therefore, by adding anti-fog agent to different portions of wrap film Z (inner layer 1 and surface layer 2), the anti-fog effect of wrap film Z can be extended.

[0063] In one exemplary embodiment, the content of the antifogging agent in the inner layer portion 1 is 4% by weight to 8% by weight, for example, 5% by weight, 6% by weight, or 7% by weight, where the total weight of the inner layer portion 1 is 100% by weight. The content of the antifogging agent in the surface layer portion 2 is 2% by weight to 5% by weight, for example, 3% by weight, or 4% by weight, where the total weight of the surface layer portion 2 is 100% by weight.

[0064] [Experimental data] In order to prove that the wrap film of the present invention has good tensile properties, can be applied to fully automatic packaging machines, and does not produce horizontal stripes when stretched, the wrap films of Examples 1 to 3 and Comparative Examples 1 to 3 were produced by casting extrusion based on the composition ratios in Table 1, and a model polyethylene wrap film (product number: Miaojie Plastic Wrap) was used as Comparative Example 4.

[0065] In Table 1, propylene random copolymer (product number: 5050) manufactured by Taiwan Plastics, ethylene elastomer (product number: ENGAGE (registered trademark) 8100) manufactured by DOW, hydrogenated petroleum resin (product number: P-125) manufactured by Idemitsu Japan, glyceride compound (product number: EAR-770) manufactured by RIKEN, and ethylene vinyl acetate (product number: 630) manufactured by Tosoh Japan were used. In addition, the anti-fogging agent used in the inner layer and the surface layer was the same.

[0066] In Examples 1 to 3 and Comparative Examples 1 to 3, the ethylene elastomer, propylene random copolymer, hydrogenated petroleum resin, and antifogging agent were weighed out based on the specific contents (as shown in Table 1) using a loss-in-weight feeder, and melt-mixed in a mixer to form the inner layer material. Also, the ethylene vinyl acetate and antifogging agent were weighed out based on the specific contents (as shown in Table 1) using a loss-in-weight feeder, and melt-mixed in a mixer to form the outer layer material.

[0067] Next, the inner layer material and the surface layer material were melted by single screw extrusion, and passed through a T-die molding die to form an inner layer film and a surface layer film. The thicknesses of the inner layer film and the surface layer film were measured and are shown in Table 2.

[0068] After producing the inner layer film and the surface layer film, a three-layer film structure was formed in which the inner layer film was placed between the two surface layer films, and the three-layer film structure was laminated by co-extrusion to produce wrap film Z. Specifically, the co-extruded inner layer film and the two surface layer films were integrated so that the inner layer film was covered by the two surface layer films. Here, the inner layer film constituted the inner layer portion 1, and the two outer layer films constituted the surface portion 2.

[0069] The physical properties of the wrap films according to Examples 1 to 3 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 2.

[0070] In Table 2, the Young's modulus of the wrap film was measured based on the standard measurement method of ASTM-D638.

[0071] The automatic wrapping properties of the wrap film were evaluated after wrapping using a Teraoka Seiko wrapping machine (model number: AW4600). If the appearance after wrapping was smooth and there were no horizontal stripes or obvious wrinkles, it was marked as "○". If the appearance after wrapping was free of horizontal stripes or obvious wrinkles, it was marked as "×".

[0072] To evaluate the anti-fogging properties of the wrap film, 100 ml of water was measured into a 250 ml beaker. The wrap film was placed in the beaker and placed in a refrigerator at 4°C for 10 minutes, and the adhesion of water droplets to the surface of the packaging bag was observed. In Table 1, if the moisture formed a water film on the surface of the packaging bag and no fogging occurred, it was indicated with "O". If the moisture formed droplets on the surface of the packaging bag and could not be seen through, it was indicated with "X".

[0073] [Table 1]

[0074] [Table 2]

[0075] According to the results in Tables 1 and 2, the wrap film according to the present invention has an appropriate Young's modulus. The Young's modulus of the wrap film in the machine direction (MD) is 4.8 MPa to 5.6 MPa, and the Young's modulus in the cross direction (CD) is 3.5 MPa to 4.5 MPa. Preferably, the Young's modulus of the wrap film in the machine direction (MD) is 4.9 MPa to 5.5 MPa, and the Young's modulus in the cross direction (CD) is 3.8 MPa to 4.2 MPa.

[0076] According to Comparative Example 1, the addition of hydrogenated petroleum resin can prevent the wrap film from having horizontal stripes or obvious wrinkles when stretched. According to Comparative Examples 2 and 3, the addition of an anti-fogging agent to both the inner layer and the surface layer simultaneously can achieve excellent anti-fogging effects. According to Comparative Example 4, the wrap film of the present invention can solve the problem of horizontal stripes and obvious wrinkles appearing when a conventional polyethylene wrap film is stretched.

[0077] [Advantageous Effects of the Embodiments] An advantageous effect of the present invention is that the wrap film of the present invention improves the tensile properties of the wrap film due to the technical feature that "the inner layer portion contains 40% by weight to 60% by weight of ethylene elastomer, 35% by weight to 55% by weight of propylene random copolymer, and 1% by weight to 10% by weight of hydrogenated petroleum resin, with the total weight of the inner layer portion being 100% by weight."

[0078] More specifically, when an ethylene elastomer, a propylene random copolymer, and a hydrogenated petroleum resin are uniformly mixed as the inner layer material, the wrap film according to the present invention can be given suitable tensile properties and has a good appearance even when stretched by a fully automatic packaging machine, and therefore can be used as a substitute for conventional polyvinyl chloride wrap films.

[0079] In the present invention, the ethylene elastomer, the propylene random copolymer and the hydrogenated petroleum resin are respectively controlled to optimize the overall properties of the inner layer material, for example, the content and weight average molecular weight of the ethylene elastomer are controlled, the monomer for synthesizing the propylene random copolymer, the melting point and melt index of the propylene random copolymer are controlled, and the monomer for synthesizing the hydrogenated petroleum resin are controlled.

[0080] In addition, in the present invention, both the inner layer and the surface layer contain an anti-fogging agent. By using a specific anti-fogging agent, the anti-fogging effect can be improved without increasing the haze value of the wrap film. In addition, the molecular weight range of the anti-fogging agent can be further controlled so that the wrap film has a long-lasting anti-fogging effect.

[0081] The above disclosure is merely a preferred embodiment of the present invention, and the scope of the claims of the present invention is not limited thereto. Therefore, all equivalent technical modifications made by utilizing the specification and drawings of the present invention are included in the scope of the claims of the present invention. [Explanation of symbols]

[0082] Z...wrapping film 1...Inner layer 2...Surface layer

Claims

1. A wrap film having a cross-sectional structure including an inner layer portion and a surface layer portion completely covering the inner layer portion, The inner layer portion contains 40% by weight to 60% by weight of an ethylene elastomer, 35% by weight to 55% by weight of a propylene random copolymer, and 1% by weight to 10% by weight of a hydrogenated petroleum resin, with the total weight of the inner layer portion being 100% by weight, A wrap film, characterized in that the surface layer contains ethylene vinyl acetate.

2. The wrap film according to claim 1 , wherein the ethylene elastomer, the propylene random copolymer, and the hydrogenated petroleum resin contained in the inner layer portion are uniformly mixed to form a continuous phase.

3. The wrap film according to claim 1, wherein the melting point of the propylene random copolymer is 130°C to 150°C.

4. The wrap film according to claim 1, wherein the propylene random copolymer has a melt index of 1 g / 10 mm to 10 g / 10 mm.

5. The wrap film according to claim 1 , wherein the propylene random copolymer is synthesized by copolymerization of a propylene monomer and an ethylene monomer.

6. 2. The wrap film according to claim 1, wherein the hydrogenated petroleum resin is a hydrogenated petroleum resin polymerized with a monomer having 5 carbon atoms or a hydrogenated petroleum resin polymerized with a monomer having 9 carbon atoms.

7. The wrap film according to claim 1, wherein the inner layer portion further contains 4% by weight to 8% by weight of an anti-fogging agent, with the total weight of the inner layer portion being 100% by weight.

8. The wrap film according to claim 1, wherein the surface layer portion further contains 2% by weight to 5% by weight of an anti-fogging agent, with the total weight of the surface layer portion being 100% by weight.

9. The wrap film according to claim 1, wherein the inner layer portion accounts for 50% to 70% of the total thickness of the wrap film, assuming the total thickness of the wrap film to be 100%.

10. The wrap film according to claim 1, having a Young's modulus of 3.5 MPa to 5.6 MPa.

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