JP2019043679A - Wrap film and wrap film wound body - Google Patents

Abstract

To provide a wrap film that has excellent adhesion during its use, has resilient and firm feelings, transparency and a vertical tearing prevention effect, and reduces a rate of tearing during rewinding.SOLUTION: A wrap film has a tensile strength of 100 MPa or more in a direction (TD) perpendicular to a flow direction, a tensile elongation of 100% or less, and a tensile elasticity of 280 MPa or more, and a tensile elasticity in the flow direction (MD) of 380 MPa or more.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wrap film and a wrap film winding body using the same.

  Conventionally, wrap films are excellent in properties such as adhesion to films and adhesion to films, gas barrier properties to gases such as water vapor and oxygen, and cut properties when used in a cosmetic box, and so on. It is used in many general homes as a wrap film. Household wrap films are mainly used as an overlap in heating food stored in containers in a refrigerator or freezer or in a microwave oven.

  Among the commercially available wrap films for home use, those which have been evaluated to be the most convenient are films based on polyvinylidene chloride resins. On the other hand, films made of polyethylene resin, polypropylene resin, polyvinyl chloride resin, poly 4-methylpentene-1 resin and the like as main components are also commercially available. It is inferior to the adhesion of a resin wrap film and inferior in wrap suitability, and vinylidene chloride wraps are widely used.

  For example, Patent Literatures 1 and 2 disclose techniques relating to the characteristic of being easy to cut in the width direction, in addition to the characteristic of being hard to tear longitudinally in the film flowing direction.

  Further, Patent Document 3 discloses a technique for improving the adhesiveness and the oxygen / water vapor barrier property when depositing a metal or metal oxide by the fibril structure on the surface.

Patent No. 5501791 International Publication No. 2016/189987 Pamphlet Japanese Patent Application Laid-Open No. 11-077824

  The wrap suitability of household wrap films is required to have a sense of stiffness and stiffness as well as transparency and cuttability. In addition, it has stability with little melting perforation and large deformation or fusion to a container or deterioration of itself during cooking in a microwave oven, etc., and in particular, adhesion to wraps and containers during wrapping is required. Ru. Furthermore, along with the adhesion, there is also a strong demand from the consumer for a good drawing-out property when the wound wrap film in the cosmetic box, which is a contradictory characteristic, is drawn out of the box.

  Furthermore, household wrap films are wound on paper tubes or the like to a winding length of about several tens of meters from the state of a raw material wound for 1000 m or more, assuming that they are used by consumers. If the film strength is insufficient in the rewinding (rewinding) process to a paper tube or the like, the film may be torn, the film can not be transported, and the production efficiency may be reduced.

  However, Patent Documents 1 to 3 are wrap films that simultaneously have sufficient longitudinal tear suppression effects at the time of cutting, tear suppression effects at the time of rewinding to a paper tube, adhesion, stiffness, a sense of stiffness, and transparency. Not achieved.

  The present invention is a novel wrap film having good wrap suitability, good adhesion at the time of use, a feeling of stiffness and stiffness, transparency and a longitudinal tear preventing effect, and a wrap film having a low incidence of tearing on rewinding. To provide.

The inventors of the present invention have conducted intensive studies as a result of intensive investigations from the viewpoint of having adhesion during use, a sense of stiffness, a sense of stiffness, transparency and an effect of preventing longitudinal tearing and that the incidence of tearing during rewinding is low. It is found that the above problems can be solved by having a range of tensile strength, tensile elongation and tensile elastic modulus, and in particular, it has an effect of maintaining a sufficient breaking strength when pulled in the TD direction and suppressing tearing during rewinding. The present invention has been found out. That is, the present invention relates to the following.
(1)
The tensile strength in the direction (TD) perpendicular to the flow direction is 100 MPa or more, the tensile elongation is 100% or less, and the tensile elastic modulus is 280 MPa or more,
The wrap film whose tensile elasticity modulus of flow direction (MD) is 380 Mpa or more.
(2)
At least one surface of the layer has a network structure observed by the phase image of an atomic force microscope, the network of the network structure is constituted by fibrils, and in the network structure, the average width of the fibrils observed is 145 nm or less There is a wrap film according to the above (1).
(3)
The wrap film as described in said (1) or (2) whose crystal | crystallization long period is 12.5 nm or less.
(4)
The wrap film in any one of said (1)-(3) whose thickness is 5-15 micrometers.
(5)
The wrap film in any one of said (1)-(4) containing the copolymer which consists of 85-97 mass% of vinylidene chloride monomers, and 15-3 mass% of vinyl chloride monomers.
(6)
Stretching the unstretched sheet in the flow direction and in the direction perpendicular to the flow direction, the stretch ratio in the flow direction is 4.0 or less, and the stretch ratio in the direction perpendicular to the flow direction is 5.8 or more The manufacturing method of the wrap film in any one of said (1)-(5) which is it.
(7)
The wound body by which the wrap film in any one of said (1)-(5) was taken up by the core.

  According to the present invention, the wrap film is a novel wrap film having good wrap suitability, good adhesion at the time of use, feeling of stiffness and stiffness, transparency and longitudinal tear preventing effect, and low incidence of tearing on rewind, wrap A film can be provided.

It is a schematic diagram of the network structure observed by the phase image of an atomic force microscope (AFM). It is a phase image of the atomic force microscope (AFM) of the wrap film surface of Example 1 of this application. It is a phase image of the atomic force microscope (AFM) of the wrap film surface of the comparative example 1 of this application. It is a conceptual diagram of an example of the manufacturing method of the wrap film of this embodiment.

  Hereinafter, modes for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail below. In addition, this invention is not limited to the following embodiment, It can variously deform and implement within the range of the summary.

In the wrap film of the present embodiment, the tensile strength X ₁ (MPa) in the direction perpendicular to the flow direction (hereinafter also referred to as “TD direction”) is 100 or more, and 100 ≦ X ₁ ≦ 300. preferable. When the tensile strength in the TD direction is in the range of 100 MPa or more, the strength to break along the direction perpendicular to the TD direction when cut is sufficient, and in the case of a wound wrap for food packaging, the length when cut is longitudinal Ripping trouble is suppressed. When the tensile strength in the TD direction is 300 MPa or less, the strength to break along the direction perpendicular to the TD direction when cut is not too high, and in the case of a wound wrap for food packaging, vertical tearing trouble when cut Tend to be suppressed. From the practical sense of use, more preferably 170 ≦ X ₁ ≦ 300, and still more preferably 190 ≦ X ₁ ≦ 300.

In the wrap film of the present embodiment, the tensile elongation X ₂ (%) in the TD direction is 100 or less, and preferably 15 ≦ X ₂ ≦ 100. When the tensile elongation in the TD direction is in the range of 100% or less, the film is easily cut when cut, and in the case of a wound wrap for food packaging, the longitudinal tearing trouble is suppressed when cut. When the tensile elongation in the TD direction is in the range of 15% or more, the film is appropriately stretched when cut, making it easy to cut, and in the case of a wound wrap for food packaging, longitudinal tearing problems are suppressed when cut. Tend to From the practical sense of use, it is further preferable that 15 ≦ X ₂ ≦ 60, and more preferably 15 ≦ X ₂ ≦ 50.

Furthermore, the wrap film of the present embodiment has 380 ≦ X ₃ for the tensile elastic modulus X ₃ (MPa) in the flow direction (hereinafter also referred to as “MD direction”) and the tensile elastic modulus Y (MPa) in the TD direction. Preferably, 380 ≦ X ₃ ≦ 900, 280 ≦ Y, and 280 ≦ Y ≦ 880. When the tensile modulus in the MD direction is in the range of 380 MPa or more, the firmness and stiffness of the film are improved, and the film becomes easy to handle. In addition, when the tensile elastic modulus in the TD direction is in the range of 280 MPa or more, the stiffness and stiffness of the film are improved, and the film becomes easy to handle. When the tensile elastic modulus in the MD direction is in the range of 900 MPa or less, the film has an appropriate hardness and tends to be easy to handle. When the tensile modulus in the TD direction is in the range of 880 MPa or less, the film has an appropriate hardness and tends to be easy to handle. From the practical sense of use, more preferably 540 ≦ X ₃ ≦ 900, and still more preferably 620 ≦ X ₃ ≦ 900. Similarly, from the practical sense of use, more preferably 420 ≦ Y ≦ 880, and still more preferably 500 ≦ Y ≦ 880. The method for controlling the tensile strength in the TD direction, the tensile elongation and the tensile elastic modulus, and the tensile elastic modulus in the MD direction to the above ranges is not particularly limited. For example, the draw ratio is: flow direction: 4.0 or less, flow Direction perpendicular to the direction: A method of controlling at 5.8 or more, using a polymer having a low glass transition temperature, or adding a nucleating agent as appropriate.

  In the present embodiment, the tensile strength in the TD direction, the tensile elongation and the tensile elastic modulus, and the tensile elastic modulus in the MD direction can be measured by the methods described in the examples described later.

[Components of wrap film]
The wrap film of the present embodiment is preferably formed of a component containing a polymer.

  In the present embodiment, the polymer is a film-forming polymer. This polymer means a polymer that accounts for 50% by weight or more of the whole film.

  Amorphous polymers, which will be described later, can not form a surface network structure effective for imparting adhesion, and therefore, in the present embodiment, it is preferable not to use as a polymer that is the main component of the film.

  However, even if it is an amorphous polymer, it is possible to blend it as long as the crystalline polymer can be partially crystallized. Furthermore, it may be a crystalline polymer or a hydrogen bonding polymer such as cellulose or aromatic polyamide which does not have a clear crystalline melting point, but if the crystalline melting point is higher than the decomposition temperature, a wet film formation is attempted. A process such as recovery of the solvent is required, which is disadvantageous in terms of operation, and from the viewpoint of operability, a polymer having a crystalline melting point of 350 ° C. or less which can be melt-formed in the production process is preferably used.

  As polymers forming the wrap film of the present embodiment, polyvinylidene chloride resins, polyolefin resins, polyester resins, and polyamide resins are preferably used. For example, as a polyolefin resin, polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1 and a copolymer mainly composed of these, and as a polyester resin, polyethylene terephthalate, polypropylene terephthalate, poly-1,4-polyester Cyclohexanedimethylene terephthalate, polyethylene-2,6-naphthalate, polylactic acid, polyhydroxyglycolic acid etc., and examples of polyamide resins include nylon 6, nylon 7, nylon 66, nylon 610, nylon 612, nylon 46, nylon 6T, etc. I can do it.

  More preferably, a polyvinylidene chloride-based resin composition is included as the polymer forming the wrap film of the present embodiment. The polyvinylidene chloride resin composition may be a homopolymer of a vinylidene chloride monomer, or a copolymer of a vinylidene chloride monomer and a monomer copolymerizable therewith. In the present specification, a polyvinylidene chloride resin wrap film refers to a wrap film containing a polyvinylidene chloride resin composition. The polyvinylidene chloride resin composition may contain one polyvinylidene chloride resin, or may contain two or more polyvinylidene chloride resins.

  The monomer copolymerizable with the vinylidene chloride monomer is not particularly limited. For example, acrylic acid esters such as vinyl chloride, methyl acrylate and butyl acrylate, and methacrylic acid esters such as methyl methacrylate and butyl methacrylate , Acrylonitrile, vinyl acetate and the like. Among these, vinyl chloride is preferable from the viewpoint that the balance between the oxygen / water barrier property and the extrusion processability is easily obtained and the film adhesion is also excellent. These may be used singly or in combination of two or more.

When a copolymer of vinylidene chloride monomer and the above-mentioned monomer is used, 85 to 97% by mass of vinylidene chloride monomer and the like from the viewpoint of crystallinity, processability, film physical properties, etc. It is preferable that it is a copolymer which consists of 15-3 mass% of monomers which can be copolymerized. By setting the vinylidene chloride monomer ratio to 85% by mass or more, oxygen / water barrier properties and film cuttability can be further improved, and by setting the vinylidene chloride monomer ratio to 97% by mass or less, processability Can be further improved. The monomer ratio is a value calculated from an integral ratio of peaks derived from each monomer component in a ¹ H-NMR spectrum measured by FX-270 (manufactured by Nippon Denshi Co., Ltd.) using d-THF as a solvent.

  The weight-average molecular weight of the polyvinylidene chloride resin composition is not particularly limited, but preferably 70,000 to 110,000, more preferably 80,000 to 100,000. Better film strength can be obtained by setting the weight average molecular weight of the polyvinylidene chloride resin composition to the above lower limit or more, and processability can be further improved by setting the above upper limit or less. . Here, the weight average molecular weight is a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a mobile phase, and calibrated and converted with polystyrene of known molecular weight.

  Additives such as known plasticizers and stabilizers can be blended into the polyvinylidene chloride resin composition. The plasticizer is not particularly limited, and known ones may be used. For example, acetyl tributyl citrate, acetylated monoglyceride, dibutyl sebacate and the like can be mentioned. The stabilizer is not particularly limited, and known ones may be used. For example, epoxidized vegetable oil such as epoxidized soybean oil, epoxidized linseed oil and the like can be mentioned.

  In addition, known weathering improvers, antifogging agents, antibacterial agents, oligomers such as polyesters, and MBS (methyl methacrylate butadiene styrene) used for food packaging materials, as long as the effects of the present embodiment are not impaired. And the like may be added. The weather resistance improver is not particularly limited, and known ones can also be used. For example, ultraviolet absorbers such as 2- (2'-hydroxy-3'5'-di-tert-butylphenyl) -5-chlorobenzotriazole and the like can be mentioned. The antifogging agent is not particularly limited, and any known one may be used. For example, surfactants such as glycerin fatty acid ester, diglycerin fatty acid ester, sorbitan fatty acid ester and the like can be mentioned. The antibacterial agent is not particularly limited, and known ones may be used. For example, natural product-based antibacterial agents such as grapefruit seed extract and moso bamboo extract can be mentioned.

  The wrap film of the present embodiment does not necessarily have a single composition of one layer, and in the case of a multilayer structure, the layer in contact with the container has a network structure in which a crystalline polymer is observed and observed in the phase image of AFM. As long as it has a liquid component, the adhesion in practice does not change, and it may be composed of a multilayer structure of two or more layers.

  The wrap film of the present embodiment may contain a liquid component.

  The liquid component used differs depending on the type of polymer. And, from the viewpoint of imparting flexibility to the film, at least one kind of polymer of aliphatic hydrocarbon type, for example, one having an alkyl group or a methylene chain moiety in the liquid component is preferably used. Among ester polymers and amide polymers, those containing a functional group having a hydrogen bonding ability such as a carbonyl group, an ether group or a hydroxyl group are suitably used.

  For example, as what has an alkyl group, mineral oil, liquid paraffin, a saturated hydrocarbon compound etc. are mentioned. Aliphatic alcohols, alicyclic alcohols, polyhydric alcohols thereof, and the above-mentioned alcohol components and aliphatic or aromatic compounds (including aliphatic alcohol, alicyclic alcohol, these polyhydric alcohols, and aliphatic or aromatic compounds) as functional groups having a hydrogen bonding ability such as carbonyl group, ether group, hydroxyl group etc. And esters of aliphatic hydroxycarboxylic acids with alcohols and / or fatty acids, modified products of these esters, and polyoxyethylene alkyl ethers and / or esters thereof. More specifically, for example, polyglycerins such as glycerin, diglycerin, triglycerin, tetraglycerin and the like, and these as raw materials of alcohol components, fatty acids as acid components, such as lauric acid, palmitic acid, stearic acid, olein Or mono-, di-, tri-ester, polyester, etc. with acid, linoleic acid, etc., or ester of sorbitan with the above fatty acid, or ethylene glycol, propylene glycol, tetramethylene glycol and esters of these condensates with the above fatty acid, or An ester of citric acid, malic acid, tartaric acid and the like with a lower alcohol having 10 or less carbon atoms as aliphatic hydroxycarboxylic acid, or a polybasic carboxylic acid with malonic acid, succinic acid, glutaric acid, adipic acid and the like with aliphatic alcohol Esters or esters thereof As sex was epoxidized soybean oil, epoxidized linseed oil, and the like. In particular, when used as a food packaging wrap, a liquid component which is a food additive defined by the Food Sanitation Law is preferably used. From the viewpoint of heat resistance, the boiling point of the liquid component is preferably 200 ° C. or higher.

[Surface structure of wrap film]
The wrap film of the present embodiment preferably has a network structure observed on a phase image of an atomic force microscope (hereinafter also referred to as “AFM”) on at least one surface of the film.

  In the wrap film of the present embodiment, in the network structure, it is preferable that the average width of fibrils constituting the network observed in the phase image of AFM is 145 nm or less. When the average width of fibrils is 145 nm or less, the film strength becomes appropriate and the cuttability is improved. In addition, the improvement of the cuttability also reduces the incidence of tearing during rewinding.

  When the average width of the fibrils is 1 nm or more, the network structure is sufficient to hold the surface additive, the adhesion is appropriate, and the extraction property is also improved, which is preferable. From the practical sense of use, the average width of fibrils is more preferably 10 nm to 145 nm. Still more preferably, it is 45 nm to 145 nm.

  Here, the phase image of the AFM is obtained by imaging information of the phase to the stimulation of the cantilever of the AFM. In the wrap film of the present embodiment, the network structure is, for example, a portion where the fibrils have a small phase delay with respect to the stimulation of the cantilever and the holes are a portion with a large phase delay, as illustrated in FIG. Is a hole, the bright part is a fibril. That is, when comparing fibrils with pores, the pores are more amorphous.

  In the present embodiment, the average width of fibrils can be measured by the method described in the examples described later.

In the wrap film of the present embodiment, there are various methods for forming the surface network structure. For example, the network structure can be formed by oriented crystallization in the process of biaxial stretching. In the wrap film of the present embodiment, in order to develop the network structure, it is preferable to make the network structure described above by performing biaxial stretching. However, in the case of wet film formation or the like, even if there is no aggressive stretching, if there is a process such as desolvation under tension, the film is substantially stretched by the shrinkage stress, so free shrinkage must be caused. For example, positive biaxial stretching may not be performed.
Although it is the timing of stretching, if the crystallization rate of the polymer is high, the polymer may be melted, extruded, air-cooled, and drawn while being crystallized, but if crystallization takes time, the molten state In the stretching in the above, crystallization may not follow, orientation crystallization may not occur effectively, and a network structure may not be developed. Therefore, it is preferable to stretch once at a glass transition temperature after being in a solid state. Also, a nucleating agent may be added as appropriate to accelerate the crystallization rate.

Crystal long period of wrap film
Moreover, it is preferable that a crystal | crystallization long period is 12.5 nm or less, and, as for the wrap film of this Embodiment, 8.2 nm-12.5 nm are more preferable. When the crystal long period is 8.2 nm or more, the film has sufficient strength when cut, and in the case of a wound wrap for food packaging, the problem of longitudinal tearing is reduced when cut. In addition, when the film has sufficient strength, the tearing rate during rewinding also decreases.

  On the other hand, when the crystal long period is 12.5 nm or less, the film tends to be cut, and in the case of a wound wrap for food packaging, the trouble of longitudinal tearing is reduced when cut. In addition, since the film is easily cut, the tearing rate during rewinding is also reduced. The crystal long period is more preferably 9.0 nm to 12.5 nm, from the viewpoint of practical use.

  In the present embodiment, the crystal long period can be measured by the method described in the examples described later.

[Method of manufacturing wrap film]
Next, an example of a method of manufacturing the wrap film of the present embodiment will be described. Although various methods can be employ | adopted as a manufacturing method of the wrap film containing a polyvinylidene-chloride type-resin composition, Usually, the inflation film forming method is employ | adopted. That is, according to the present embodiment, a wrap film obtained by inflation molding can be obtained. More preferably, the wrap film of the present embodiment is a polyvinylidene chloride-based resin wrap film obtained by stretching the above-described polyvinylidene chloride-based resin composition at least in the MD direction and performing inflation molding. In the inflation film forming method, for example, a polyvinylidene chloride resin composition is melt extruded in a tubular form from a circular die, and then the outside of the tubular resin is brought into contact with a coolant such as cold water filled in a storage tank called a cold water tank. At that time, in a state where the refrigerant is injected and stored in the inside of a tubular (cylindrical) resin sandwiched between the die opening and the pinch roll, the inside is made to contact with a refrigerant such as mineral oil to solidify it into a film. To mold. In the present specification, a portion (extrudate) of a tubular resin sandwiched between the die opening and the pinch roll is referred to as "sock". The refrigerant (liquid) injected into the interior of this sock is called "sock liquid". Also, the sock is folded by the pinch roll or the like to form a tubular double-ply film, which is referred to as "parison".

  Hereinafter, the inflation film forming method will be described more specifically. FIG. 4 is a conceptual view of an example of a method for producing a wrap film of the present embodiment.

  First, in the extrusion step, the molten polyvinylidene chloride resin composition is extruded into a tubular form from the die port (3) of the circular die (2) by the extruder (1), sock (tubular polyvinylidene chloride resin composition) Object (4) is formed.

  Next, in the cooling / solidifying step, the outer side of the extruded sock (4) is brought into contact with cold water in a cold water tank (6), and the sock liquid (5) is injected into the inside of the sock (4) by a conventional method. The sock (4) is cooled and solidified from the inside and outside by storing it. At this time, the sock (4) is in a state where the sock liquid (5) is applied to the inside thereof. The solidified sock (4) is folded by the first pinch roll (7) to form a double ply sheet parison (8). The application amount of the sock liquid is controlled by the pinch pressure of the first pinch roll (7).

  As the sock liquid, water, mineral oil, alcohols, polyhydric alcohols such as propylene glycol and glycerin, and aqueous solutions of cellulose and polyvinyl alcohol can be used. These may be used alone or in combination of two or more. In addition, the above-mentioned weather resistance improver, antifogging agent, antibacterial agent and the like used in food packaging materials may be added to the sock liquid, as long as the effects of the present embodiment are not impaired.

  The application amount of the sock liquid is not particularly limited, but is preferably 50 to 20000 ppm, more preferably 100 to 15000 ppm, still more preferably 150 to 10000 ppm from the viewpoint of the openness of the parison and the adhesion of the film. Here, the application amount (ppm) is the mass of the sock liquid applied to the sock in mass ppm relative to the total mass of the sock.

  Subsequently, by injecting air inside the parison (8), the parison (8) is opened again and becomes tubular. The parison (8) is reheated to a temperature suitable for drawing by hot water (not shown). The warm water adhering to the outside of the parison (8) is squeezed off by the second pinch roll (9). Next, in the inflation step, air is injected into a tubular parison (8) heated to an appropriate temperature to form bubbles (10) by inflation stretching, and a stretched film is obtained.

  The crystal length period of the wrap film can be controlled by the draw ratio and the crystallinity of the polymer constituting the wrap film, and the crystal length period increases as the draw ratio in the TD direction increases compared to the draw ratio in the MD direction There is a tendency, and as the crystallinity of the polymer increases, the crystal long period tends to increase.

  In the method for producing a wrap film of the present embodiment, it is preferable to include the step of stretching the unstretched sheet in the flow direction and the direction perpendicular to the flow direction, and in this case, the draw ratio in the TD direction is 5.8 or more The stretch ratio in the MD direction is preferably 4.0 times or less, and from the viewpoint of film formability, the stretch ratio in the MD direction is more than 3.4 times, more preferably 3.8 times or less. Although the upper limit of the draw ratio in the TD direction is not particularly limited, it is, for example, 8.5 or less.

  It does not specifically limit as control method of a draw ratio, A well-known method is employable. For example, the method etc. which control extending | stretching temperature by changing the warm water temperature for reheating, etc. are mentioned. In order to lower the draw ratio, the lower the draw temperature, the more stable the inflation bubble is in the state of a low draw ratio, which is preferable. At that time, the stretching temperature is preferably higher than the stretching room temperature from the viewpoint of the stability of the inflation bubble. The stretching temperature is more preferably 34 ° C. or less, still more preferably 25 ° C. to 34 ° C. In addition, the stretching temperature is measured at a temperature at an intermediate point of the distance in the MD direction between the completion of the stretching in the MD direction and the TD direction and the point at which the winding starts.

  Thereafter, the stretched film is folded by the third pinch roll (11) to form a double ply film (12). The double ply film (12) is taken up by a take-up roll (13). In addition, the film is slit and peeled off into a single film (single peel). Finally, the film is wound on a core of a paper tube or the like to obtain a wrap film wound body of paper tube winding.

  The crystal long period is influenced not only by the draw ratio but also by the heat history. When the wrap film is subjected to a heat history, the crystal long period tends to decrease and the tear strength tends to decrease. Therefore, it is preferable to prevent the wrap film from receiving an excessive heat history. For example, the film is high not only in the case of aging treatment, but also in various environments such as when transporting a wrap film in summer, or placing the wrap film near a heat source such as a stove at home use. It is preferable not to receive a heat history, which can prevent the crystal long period from being too low and can prevent the film from being easily torn.

  The above description is an example of the method for producing the wrap film of the present embodiment, and may be performed according to various apparatus configurations and conditions other than those described above, and for example, other known methods may be adopted.

[Winding body]
The wrap film of the present embodiment can be used in various forms, and can be, for example, a roll-like polyvinylidene chloride resin wrap film. In the case of a roll-shaped wrap film, there may be a core or no core.

  In the case of winding around a winding core, for example, a wrap film winding body including a cylindrical winding core and the polyvinylidene chloride resin wrap film of the present embodiment wound around the winding core is used. be able to. The wound body refers to a wound film obtained by winding a wrap film around a core or the like.

  Rewind problems that occur when using a roll-shaped wrap film or the like can be effectively suppressed by the wrap film of the present embodiment. The material, size, and the like of the winding core are not particularly limited, and a known winding core such as a paper tube can be used. Furthermore, if the wrap film is in the form of a roll, the core may or may not be present. The wrap film roll of the present embodiment can be stored and used in a decorative box having a cutting blade for cutting the wrap film.

[Lap film thickness]
The thickness of the wrap film of the present embodiment is not particularly limited, but is preferably 5 to 30 μm and more preferably 5 to 15 μm from the viewpoint of feeling in use and optical properties.

[Evaluation of adhesion]
Next, in the evaluation of preferable adhesion of the wrap film of the present embodiment, the expressed work amount of adhesion X (mJ / 25 cm ² ) measured by the method described later is in the range of 1 ≦ X ≦ 2.5. When 1 ≦ X, the wrap film tends to exhibit sufficient adhesion. Moreover, peeling of a wrap film becomes easy in it being X <= 2.5, so-called excessive adhesion can be suppressed, and in the case of a winding wrap for food packaging, it tends to become easy to draw out. From the practical sense of use, it is further preferable that 1.5 ≦ X ≦ 2.4, and more preferably 1.8 ≦ X ≦ 2.3.

  In the present embodiment, the work of adhesion can be measured by the method described in the examples described later.

  Hereinafter, the present invention will be described in more detail by way of examples and comparative examples. In addition, observation of the mesh surface network structure by AFM, crystal long period of the lap film, tear strength, longitudinal tearing failure rate, adhesion, tensile strength / tensile elongation, tensile elastic modulus, stiffness, stiffness, transparency, and rewind The following measurement method was used to evaluate the incidence of tear at the time.

(1) AFM Measurement A film was attached and fixed to a Si wafer, and the surface was observed with a Bruker Dimension Icon in a tapping mode using a phase image. The measurement was performed using a cantilever of Si single crystal (spring constant catalog value: 40 N / m) under conditions of a scan rate of 0.5-2 Hz, a scan size of 1 μm × 1 μm, and a sampling point of 512 × 256 or 512 × 512. . The film controlled the contact pressure of the cantilever, and when the target amplitude was 400 mV, the Set Point was 240-320 mV, and when the target amplitude was 800 mV, the Set Point was 450-500 mV. When measuring the width (fibril diameter) of fibrils, one image is divided into four for each phase image, and five fibrils that are considered to be typical are selected in each region, and the average value of a total of 5 locations especially when the fibril diameter is large. Was adopted as the average width of fibrils.

(2) Crystal Long Period Measurement The crystal long period was determined by small angle X-ray scattering (SAXS) measurement under the following apparatus and conditions.
Equipment (Rigaku Co., Ltd.) NANOPIX
X-ray incidence direction Film normal direction X-ray wavelength 0.154 nm
Optical system point collimation
(1st: 0.55 mm 、, 2nd: Open, guard: 0.35 mm))
Detector HyPix-6000 (2D Detector)
Camera length SAXS: 1113 mm
Exposure time Comparative examples 5-8, 10, 12: 10 minutes / 1 sample
The background correction of the detector and the empty cell scattering correction were performed on the X-ray scattering patterns obtained from Examples 1 to 9 and Comparative Examples 1 to 4, 9 and 11: 1 time / 1 sample HyPix-6000. Thereafter, circular averaging was performed to obtain a SAXS profile I (q). Further, with respect SAXS profile I (q), was Lorentz correction applying q ^2. The magnitude of the scattering vector of the peak derived from the crystal long period of the SAXS profile after Lorentz correction is calculated from (Equation 1), and the Bragg angle θ is substituted into the Bragg equation (Equation 2) to obtain the crystal long period d Calculated.

q = 4π sinθ / λ equation (1)
θ: Bragg angle q: Scattering vector size λ: X-ray wavelength

2d sin θ = λ equation (2)
d: crystal long period θ: Bragg angle λ: X-ray wavelength

(3) Tear strength Measured in accordance with ASTM-D-1992. The measurement was performed in an atmosphere of 23 ° C. and 50% RH. The tear strength in the MD direction and the TD direction was measured (unit: cN) using a light load tear tester (manufactured by Toyo Seiki Co., Ltd.).

(4) Longitudinal tear trouble rate A cut test was performed using a commercially available wrap film cosmetic box (Asahi Kasei Home Products Co., Ltd., cosmetic box with a trade name Saran Wrap (registered trademark), 30 cm × 20 m). The test was performed in an atmosphere of 23 ° C. and 50% RH. The film was cut with the opening degree of the decorative box fixed at 30 °, and the probability (%) of longitudinal tearing of the film was calculated when the cut film was pulled out. N was performed 500 times (unit:%).

(5) Adhesion Assuming that the wrap film is used at home, the adhesion between the wrap films was evaluated. The measurement was performed in an atmosphere of 23 ° C. and 50% RH. First, ^two aluminum jigs having a bottom area of 25 cm ² , a height of 55 mm and a weight of 400 g were prepared, and filter papers having the same area as the bottom areas were attached to the bottoms of both jigs. A wrap film was placed on the bottom of the filter paper of both jigs so as not to get wrinkles on it, and was held down with a rubber band and fixed. The two jigs were combined so that the bottom surface of the side on which the wrap film was put would overlap, and was crimped for 1 minute with a load of 500 g. Next, the work required was measured when both wrap film surfaces were peeled off perpendicularly to each other at a speed of 5 mm / min using a tensile compression tester (manufactured by Shimadzu Corporation) (unit: mJ / 25 cm ² ).

(6) Tensile strength and tensile elongation It measured based on ASTM-D-882. The measurement was performed in an atmosphere of 23 ° C. and 50% RH. Strength (unit: MPa) and elongation at break when a wrap film set to a width of 1 cm and a distance between chucks of 10 cm is pulled up and down at a speed of 300 mm / min with a tensile compression tester (manufactured by Shimadzu Corporation) (Unit:%) was measured.

(7) Tensile modulus of elasticity Measured in accordance with ASTM-D-882. The film was cut out with a length of 12 cm and a width of 1 cm in the direction parallel to the MD direction and the TD direction of the film to prepare a measurement sample. The measurement was performed in an atmosphere of 23 ° C. and 50% RH. Using a tensile compression tester (manufactured by Shimadzu Corporation), pull the lap film set at a distance of 10 cm between the chucks at a speed of 5 mm / min to increase the strength at 50% displacement (stroke 2 mm) by 50 And 100% displacement (unit: MPa).

(8) Evaluation of stiffness and stiffness A panel of 20 skilled panelists is prepared, and a wrap film of 30 cm in length and 30 cm in width is used for a glass container having a diameter of 15 cm at the opening. Evaluation was performed according to the following procedure.
Evaluation Symbol Content A: The feeling of stiffness and stiffness is extremely excellent and the handling is extremely easy.
B: The feeling of stiffness and stiffness is excellent, and I do not feel any problems in handling.
C: The feeling of stiffness is poor, but I do not feel any problem in handling.
D: Hard and hard to use.

(9) Haze It measured based on JIS-K-7136. The measurement was performed in an atmosphere of 23 ° C. and 50% RH. The haze was measured using a turbidity meter (manufactured by Nippon Denshoku Co., Ltd.) (unit:%).

(10) Evaluation of tear occurrence rate during rewinding Double-ply film is slit and peeled off to become a single film, and then a paper tube of a commercially available wrap film (Saran Wrap (trade name: Asahi Kasei Home Products, Inc.) The film was wound onto a paper tube using a trademark paper tube (30 cm × 20 m). The film transport speed during winding was 300 m / min, and the winding length was 20 m. During the winding operation, the probability (%) of the film being torn and the film being unconveyable was calculated. The N number was 3000 times (unit:%). Evaluation was conducted as follows.

Evaluation symbol contents A: Rip incidence rate at rewinding 0.03% or less (Rip incidence number 1 or less / 3000).
B: Rip incidence rate during rewinding is higher than 0.03% and lower than or equal to 0.07% (more than 1 and less than 2/3000).
C: The incidence of tearing during rewinding is higher than 0.07% and not more than 0.10% (more than 2 occurrences of tearing and 3 or less).
D: The occurrence rate of tearing during rewinding is higher than 0.10% (more than 3 occurrences of tearing / 3000).

Example 1
A polyvinylidene chloride resin composition having a weight average molecular weight of 90,000 vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C. and melted by a melt extruder. The parison obtained was extruded and stretched by inflation to form a tubular film. The weight average molecular weight is a value measured by gel permeation chromatography (GPC) using tetrahydrofuran as a mobile phase, and calibrated and converted with polystyrene of known molecular weight. At this time, the draw ratio in the MD direction was 3.8 times, and the draw ratio in the TD direction was 5.8 times. The stretching temperature was 26 ° C. This tubular film is folded and wound, slit into a width of 300 mm, and peeled off to form a single film, and wound 20 m on a paper tube with an outer diameter of 36.6 mm and a length of 305 mm, and a thickness of about 10 μm A paper tube wrap film was produced.
The results of the evaluation of the obtained film by AFM measurement, SAXS measurement, tear strength, tensile elongation, tensile modulus, longitudinal tearing failure rate, adhesion, transparency, tearing rate during rewinding are shown in Table 1.

Example 2
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film.
The stretching ratio in the MD direction was 3.6 times, and the stretching ratio in the TD direction was 6.0 times. The stretching temperature was 25 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 3]
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film.
The draw ratio in the MD direction was 3.5 times, and the draw ratio in the TD direction was 6.1 times. The stretching temperature was 25 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

Example 4
A liquid component (15 parts by weight of glycerol diacetate monolaurate) is mixed and melted at a temperature of 220 ° C. with a crystalline polymer (85 parts by weight of polylactic acid) as a main component, and melt extruded by a melt extruder to obtain a parison Was subjected to inflation stretching to obtain a tubular film.
The stretching ratio in the MD direction was 3.8 times, and the stretching ratio in the TD direction was 8.5 times. The stretching temperature was 34 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 5]
Liquid component (15 parts by weight of glycerin triacetate) and other additives (3 parts by weight of epoxidized linseed oil, 2 parts by weight of mineral oil) are mixed at a temperature of 280 ° C. with crystalline polymer (80 parts by weight of nylon 66) The parison was melted and extruded by a melt extruder, and the obtained parison was subjected to inflation stretching to form a tubular film.
The draw ratio in the MD direction was 3.7 times, and the draw ratio in the TD direction was 8.4 times. The stretching temperature was 33 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 6]
Liquid component (10 parts by weight of mineral oil) and other additives (5 parts by weight of Malcarez (registered trademark) ○ R, 5 parts by weight of Tuftec (registered trademark) ○ R) to crystalline polymer (80 parts by weight of polypropylene) as a main component The mixture was melted at a temperature of ° C., melt extruded by a melt extruder, and the resulting parison was subjected to inflation stretching to form a tubular film.
The stretching ratio in the MD direction was 3.8 times, and the stretching ratio in the TD direction was 7.9 times. The stretching temperature was 32 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 7]
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film.
The stretching ratio in the MD direction was 3.8 times, and the stretching ratio in the TD direction was 6.4 times. The stretching temperature was 27 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 8]
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film.
The stretching ratio in the MD direction was 3.8 times, and the stretching ratio in the TD direction was 6.7 times. The stretching temperature was 28 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

[Example 9]
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film.
The stretching ratio in the MD direction was 3.8 times, and the stretching ratio in the TD direction was 6.8 times. The stretching temperature was 29 ° C. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 1.

Comparative Example 1
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 1/9 (mass ratio) is melted at a temperature of 170 ° C., melt extruded by a melt extruder, and the obtained parison is Inflation stretching was performed to obtain a tubular film. The draw ratio in the MD direction was 3.7 times, and the draw ratio in the TD direction was 4.3 times. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 2
The polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) is melted at a temperature of 170 ° C., and melt extruded by a melt extruder to obtain the obtained parison, Inflation stretching was performed to obtain a tubular film. The draw ratio in the MD direction was 5.0 times, and the draw ratio in the TD direction was 6.0. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 3
The polyethylene was melted at a temperature of 170 ° C., melt extruded by a melt extruder, and the obtained parison was subjected to inflation stretching to form a tubular film. The draw ratio in the MD direction was 5.0 times, and the draw ratio in the TD direction was 5.0 times. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 4
Liquid component (10 parts by weight of mineral oil) and other additives (5 parts by weight of Malcarez (registered trademark) ○ R, 5 parts by weight of Tuftec (registered trademark) ○ R) to crystalline polymer (80 parts by weight of polypropylene) as a main component The mixture was mixed and melted at a temperature of ° C., extruded from an extruder equipped with a die having a slit width of 20 mm × 0.5 mm T, and quenched with water to form a sheet of film.
Then, while passing through a heating zone set at 140 ° C., this raw fabric was subjected to sequential biaxial stretching of 2.0 × 2.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 5
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 140 ° C., this raw fabric was subjected to sequential biaxial stretching of 1.0 × 8.6 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 6
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 38 ° C., this raw fabric was wounded by successive biaxial stretching of 4.3 × 1.0 times with a stretcher. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 7
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 39 ° C., this raw fabric was wounded by successive biaxial stretching of 5.3 × 1.0 times with a stretcher. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 8
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 40 ° C., this raw fabric was subjected to successive biaxial stretching of 6.3 × 1.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 9
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 42 ° C., this raw fabric was subjected to sequential biaxial stretching of 8.0 × 1.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 10
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 49 ° C., this raw fabric was subjected to sequential biaxial stretching of 3.5 × 10.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 11
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 49 ° C., this raw fabric was subjected to sequential biaxial stretching of 5.0 × 7.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

Comparative Example 12
An extruder with a polyvinylidene chloride resin composition of vinylidene chloride (VDC) / vinyl chloride (VC) = 88/12 (mass ratio) mixed and melted at a temperature of 170 ° C. and a die having a slit width of 20 mm × 0.5 mm T It was further extruded and quenched with water to form a film top sheet.
Then, while passing through a heating zone set at 53 ° C., this raw fabric was subjected to sequential biaxial stretching of 5.0 × 10.0 times with a stretcher and wound up. A paper tube-wrapping wrap film having a thickness of about 10 μm was produced by the same operation as in Example 1 except for the above.
The evaluation results of the obtained film are shown in Table 2.

  Although the phase image of AFM of the film surface obtained in Example 1 is shown in FIG. 2, the uniform network structure was observed. The mesh structures were observed also in Examples 2, 3, 4, 5, 6, 7, 8, 9 and Comparative Examples 4, 9, 10, 11, 12. In the examples, since the tensile strength, the tensile elongation and the tensile modulus are within the specific ranges, the desired effects were obtained as shown in the evaluation of Table 1. However, in Comparative Examples 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12, since the tensile strength, the tensile elongation and the tensile modulus are not within the specific ranges, the evaluation of Table 2 is made. The desired effect was not obtained as shown in. The phase image of AFM of the film surface of Comparative Example 1 is shown in FIG.

  The wrap film according to the present invention is a wrap film which has good adhesion during use, a firmness, stiffness, transparency and a longitudinal tear preventing effect and a low incidence of tearing during rewinding, so it is a food packaging. Can be suitably used as various wrapping films for packaging.

1 Extruder 2 Circular Die 3 Die Port 4 Tubular Vinylidene Chloride Resin Composition (Sock)
5 Sock liquid 6 Cold water tank 7 1st pinch roll 8 parison 9 2nd pinch roll 10 bubble 11 3rd pinch roll 12 double ply film 13 winding roll 14 hole 15 fibril

Claims (7)

The tensile strength in the direction (TD) perpendicular to the flow direction is 100 MPa or more, the tensile elongation is 100% or less, and the tensile elastic modulus is 280 MPa or more,
The wrap film whose tensile elasticity modulus of flow direction (MD) is 380 Mpa or more.   At least one surface of the layer has a network structure observed by the phase image of an atomic force microscope, the network of the network structure is constituted by fibrils, and in the network structure, the average width of the fibrils observed is 145 nm or less The wrap film according to claim 1.   The wrap film of Claim 1 or 2 whose crystal | crystallization long period is 12.5 nm or less.   The wrap film according to any one of claims 1 to 3, which has a thickness of 5 to 15 m.   The wrap film of any one of Claims 1-4 containing the copolymer which consists of 85-97 mass% of vinylidene chloride monomers, and 15-3 mass% of vinyl chloride monomers.   Stretching the unstretched sheet in the flow direction and in the direction perpendicular to the flow direction, the stretch ratio in the flow direction is 4.0 or less, and the stretch ratio in the direction perpendicular to the flow direction is 5.8 or more The manufacturing method of the wrap film of any one of Claims 1-5 which is it.   The wound body by which the wrap film of any one of Claims 1-5 was wound by the core.