JP7664108B2 - Vinylidene chloride resin wrap film - Google Patents

Description

The present invention relates to vinylidene chloride resin wrap films.

Vinylidene chloride resins are used as plastic wrap films, etc., due to their excellent properties such as transparency, water resistance, and gas barrier properties. In recent years, with the spread of microwave ovens, foods wrapped in plastic wrap are being reheated in the microwave. Reheating refers to cooking refrigerated or frozen foods by heating them in a microwave oven.

For example, Patent Documents 1 and 2 disclose technology that makes the film less susceptible to vertical tearing in the machine direction, and easier to cut in the width direction.

Patent No. 5501791 International Publication No. 2016/189987

When food or containers are packaged using a wrap film, it is common to stack dishes or containers on top of the wrap film for storage. In this case, the wrap film is stretched by about 1%, and the film strength when stretched by about 1% in the TD direction, which is the direction perpendicular to the direction in which the film tears, is particularly important. By having sufficient film strength when stretched by about 1% in the TD direction, it is possible to stack dishes or containers on top of the wrap film. In addition, if a crystalline high-order structure can be formed when stretched by about 1% in the TD direction, the film strength can be increased, the gas barrier property can be improved, and the permeation of molecules that cause odors can be prevented.
Furthermore, when wrapping vegetables, etc., with a wrap film, in order to prevent the wrap film from being wrinkled, it is generally done to wrap the wrap film while pulling the film moderately. In this case, the wrap film is in a state of being stretched by about 10%, and the strength of the film when it is stretched by about 10% in the TD direction, which is the direction perpendicular to the direction in which the tear of the film propagates, is particularly important. By having sufficient film strength when stretched by about 10% in the TD direction, it becomes possible to wrap vegetables, etc. neatly without wrinkles when wrapping them with the wrap film. In addition, the state in which the wrap film is stretched by 10% imitates the state in which the wrap film is wrapped while being tightly attached so as not to wrinkle when wrapping vegetables, etc. By forming a large crystalline high-order structure in this state, it is possible to make the film less likely to tear while maintaining the freshness of the vegetables, etc., and to prevent odor leakage.
However, depending on the crystalline state of the wrap film, when stretched in the TD direction by about 1% to 10%, tearing problems may occur, and the tearing that occurs from the edge of the film may spread to the entire film. Also, depending on the crystalline state of the wrap film, when stretched in the TD direction by about 1% to 10%, the gas barrier properties may decrease, causing problems such as the smell of packaged food leaking out.

The present invention was made in consideration of the above problems, and aims to provide a vinylidene chloride resin wrap film that does not tear even when pulled about 1% to 10% in the TD direction, and does not allow the odor of the contents to leak out.

As a result of extensive research into solving the above problems, the inventors have discovered that a wrap film containing vinylidene chloride resin has a crystal long period of 8.2 nm or more and 14.5 nm or less when stretched 10% in the TD direction, so that when stretched about 10% in the TD direction, no tearing occurs and the odor of the contents does not leak out.

That is, the present invention is as follows.
[1]
A wrap film containing a vinylidene chloride resin, the wrap film having a crystal long period of 8.2 nm or more and 14.5 nm or less when stretched 10% in the TD direction.
[2]
The vinylidene chloride resin wrap film according to the above-mentioned [1], wherein the crystal long period when stretched by 1% in the TD direction is 7.5 nm or more and 13.5 nm or less.
[3]
The vinylidene chloride resin wrap film according to the above [1] or [2], having a thickness of 6 to 18 μm.
[4]
The vinylidene chloride-based resin wrap film according to any one of the above [1] to [3], wherein the vinylidene chloride-based resin contains a copolymer consisting of 85 to 97% by mass of structural units derived from vinylidene chloride and 15 to 3% by mass of structural units derived from vinyl chloride.
[5]
The wrap film includes the vinylidene chloride resin wrap film according to any one of [1] to [4] above and a core,
The vinylidene chloride resin wrap film is wound around the core to form a roll.

According to the present invention, a vinylidene chloride resin wrap film can be obtained that does not tear when pulled about 10% in the TD direction and does not allow the odor of the contents to leak out.

FIG. 1 is a schematic diagram of an apparatus used in the film-forming process of the present invention. 1 is an example of a use form of the film of the present invention.

The following describes in detail the form for carrying out the present invention (hereinafter, "the present embodiment"). Note that the present invention is not limited to the following embodiment, and can be carried out in various modifications within the scope of the gist of the invention.

[Vinylidene chloride resin wrap film]
The vinylidene chloride-based resin wrap film of this embodiment (hereinafter also simply referred to as "wrap film") is a wrap film containing a vinylidene chloride-based resin, and the size of the crystal long period when stretched 10% in the TD direction is 8.2 nm to 14.5 nm. By having such a configuration, the vinylidene chloride-based resin wrap film of this embodiment does not suffer from tearing problems when stretched about 10% in the TD direction, and the odor of the contents does not leak out. The reason for this is not clear, but is presumed to be as follows.
It is presumed that the large crystalline high-order structure can stop the propagation of the cracks that occur in the film because the size of the crystalline long period when stretched 10% in the TD direction is 8.2 nm or more and 14.5 nm or less. At this time, the wrap film is cut in the TD direction along the saw blade, so the propagation of the cracks progresses toward the MD direction, which is the perpendicular direction. Therefore, the size of the crystalline long period when stretched in the TD direction is important to stop the propagation of the cracks in the film. In addition, it is presumed that the large crystalline high-order structure can prevent the molecules that cause odors from penetrating the film. Note that the above reasons are presumed and are not limited to these.
The state where the wrap film is stretched by 10% mimics the state in which the wrap film is tightly attached to vegetables and other foods to prevent wrinkles. By forming a large crystalline high-order structure in this state, the film is less likely to tear and odor leakage can be prevented while maintaining the freshness of the vegetables and other foods.

In the vinylidene chloride-based resin wrap film of this embodiment, the crystal long period when stretched 10% in the TD direction is 8.2 nm to 14.5 nm, preferably 8.7 nm to 14.5 nm, more preferably 9.2 nm to 14.5 nm, even more preferably 9.7 nm to 14.5 nm, even more preferably 11.0 nm to 14.5 nm, and particularly preferably 12.5 nm to 14.5 nm. When the crystal long period when stretched 10% in the TD direction is 14.5 nm or less, the film tends to be sufficiently crystallized and therefore less likely to break when stretched 10%, and when it is 8.2 nm or more, the effect of suppressing breakage of the film by crystallization when stretched 10% tends to be obtained.

In addition, the vinylidene chloride-based resin wrap film of this embodiment has a crystal long period when stretched 1% in the TD direction of preferably 7.5 nm to 13.5 nm, more preferably 8.0 nm to 13.5 nm, even more preferably 8.5 nm to 13.5 nm, even more preferably 9.0 nm to 13.5 nm, even more preferably 9.4 nm to 13.5 nm, and particularly preferably 11.3 nm to 13.5 nm. When the crystal long period when stretched 1% in the TD direction is 13.5 nm or less, the film tends to be sufficiently crystallized and therefore less likely to break when stretched 1%, and when it is 7.5 nm or more, the effect of suppressing breakage of the film by crystallization when stretched 1% tends to be obtained.
The state where the wrap film is stretched by 1% mimics the state where a plate is wrapped around the wrap film while being stretched, and then the plate is placed on top of the wrap film. By forming a large crystalline high-order structure in this state, it is possible to maintain the freshness of vegetables, etc., while making the film less likely to tear and preventing odor leakage.

The long crystal period when the wrap film is stretched can be adjusted by changing the distance from the die opening to the cold water tank (hot distance). The distance from the die opening to the cold water tank (hot distance) is not particularly limited, but is preferably 40 to 80 mm.

The crystal long period when the wrap film is stretched can be obtained by measuring it by in-situ stretching small angle X-ray scattering method. In the measurement, the wrap film is measured by a transmission method.
The scattering profile by stretching in-situ small-angle X-ray scattering is obtained by irradiating the sample with X-rays and detecting the position and intensity of the scattered X-rays with a detector. The scattering profile is obtained by plotting the measured scattering intensity I(q) against the scattering vector q. This scattering profile contains information reflecting the microstructure of the sample. Specifically, it contains information such as the average particle size and average interparticle distance of particles and aggregates in the sample. Therefore, this information can be obtained by analyzing the scattering profile. In this scattering profile, the scattering angle on the horizontal axis is converted to a periodic length using the Bragg equation, and the peak position of the scattering intensity is obtained as the long period of scattering (crystal long period L).
Synchrotron radiation is light emitted by an electron synchrotron. Synchrotron radiation includes electromagnetic waves of various wavelengths that are characterized by monochromaticity, high brightness, high directivity, etc., and also includes X-rays in the X-ray region that are monochromatic, high brightness, and highly directional. Therefore, by using these X-rays, it is possible to obtain a scattering profile that includes more information than when using normal X-rays using an X-ray tube, etc.
Such synchrotron radiation can be used at various synchrotron radiation facilities, such as SPring-8 at the Japan Synchrotron Radiation Research Institute, PF Ring at the High Energy Accelerator Research Organization, UVSOR at the Institute for Molecular Science, and HiSOR at the Hiroshima University Synchrotron Radiation Research Center.

The thickness of the wrap film of this embodiment is preferably 6 to 18 μm, and more preferably 9 to 12 μm. When the thickness of the wrap film is 6 μm or more, the tensile strength of the film is high, and the film tends to be prevented from breaking during use. In addition, there is no significant decrease in tear strength, and when the film is pulled out from the roll and when the end of the film that has been rewound into the presentation box is picked up, the trouble of the film tearing from the end cut by the cutting blade attached to the presentation box tends to be reduced. On the other hand, when the thickness of the wrap film is 18 μm or less, the force required to cut the film with the film cutting blade can be reduced, the cutability is good, and the film tends to fit the shape of the container and the adhesion to the container tends to be improved. In other words, the thickness of the wrap film tends to be adjusted to a specific range from the viewpoint of the balance between the prevention of film tearing, the cutability, and the adhesion. In particular, the wrap film having a thickness of 6 to 18 μm does not have a significant decrease in tear strength, but is by no means sufficient and tends to be prone to film tearing problems, so the effect of the present invention is remarkable. The thickness of the wrap film can be measured according to the method described in the Examples below.

<Vinylidene chloride resin>
The vinylidene chloride resin wrap film of this embodiment contains a vinylidene chloride resin.
The vinylidene chloride resin used in the present embodiment is not particularly limited as long as it contains a constituent unit derived from vinylidene chloride. In addition to the constituent unit derived from vinylidene chloride, one or more monomers copolymerizable with vinylidene chloride, such as vinyl chloride, acrylic acid esters such as methyl acrylate and butyl acrylate; methacrylic acid esters such as methyl methacrylate and butyl methacrylate; acrylonitrile; and vinyl acetate, may be copolymerized therewith.

The weight average molecular weight (Mw) of the vinylidene chloride copolymer is preferably 80.000 to 200,000, more preferably 90,000 to 180,000, and even more preferably 100,000 to 170,000. By having the weight average molecular weight (Mw) within the above range, the mechanical strength of the wrap film tends to be further improved. A vinylidene chloride resin having a weight average molecular weight within the above range can be obtained, for example, by controlling the charging ratio of vinylidene chloride monomer and vinyl chloride monomer, the amount of polymerization initiator, or the polymerization temperature. In this embodiment, the weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

When the vinylidene chloride resin is a copolymer resin, the ratio of the constituent units derived from vinylidene chloride is not particularly limited, but it is preferable that the constituent units derived from vinylidene chloride are 72 to 93 mol%, and more preferably 81 to 90 mol%. When the constituent units derived from vinylidene chloride are 72 mol% or more, the glass transition temperature of the vinylidene chloride resin is low and the film becomes soft, so that the film tends to be less likely to tear even when used in a low temperature environment such as winter. On the other hand, when the constituent units derived from vinylidene chloride are 93 mol% or less, a significant increase in crystallinity is suppressed, and deterioration of molding processability during film stretching tends to be suppressed.
In particular, wrap films made of vinylidene chloride resins containing 72 mol % or more of structural units derived from vinylidene chloride tend to undergo physical deterioration due to the formation and growth of microcrystals when exposed to heat during storage and distribution at high temperatures, such as in the summer, and as a result are prone to tearing problems when the film is used, making the effects of the present invention more pronounced.

When the vinylidene chloride resin is a copolymer resin, it is preferable that the vinylidene chloride resin contains a copolymer consisting of 85 to 97% by mass of structural units derived from vinylidene chloride and 15 to 3% by mass of structural units derived from vinyl chloride. By making the vinylidene chloride monomer ratio 85% by mass or more, it tends to be possible to further improve the oxygen/water barrier properties and film cutting properties, and by making the vinylidene chloride monomer ratio 97% by mass or less, it tends to be possible to further improve the processability.

The content of the vinylidene chloride-derived structural unit and the vinyl chloride-derived structural unit is not particularly limited, but can be measured, for example, using a high-resolution proton nuclear magnetic resonance measuring device. More specifically, the re-precipitated filtrate of the wrap film is obtained according to the following procedure.
0.5 g of a sample is dissolved in 10 ml of THF (tetrahydrofuran), and about 30 ml of methanol is added to precipitate a resin content, which is then separated by filtration and dried.
The reprecipitated filtrate thus obtained is vacuum dried, and a 5% by mass solution obtained by dissolving the reprecipitated filtrate in deuterated tetrahydrofuran is subjected to H-NMR measurement (accumulation number: 512) in a measurement atmosphere of 23±2° C. and 50±10% RH. The constituent units derived from vinylidene chloride and the constituent units derived from vinyl chloride are calculated using the characteristic chemical shifts based on tetramethylsilane in the obtained spectrum.

Hereinafter, the structural unit derived from vinylidene chloride (--CH ₂ -CCl ₂ -) will be represented as A, and the structural unit derived from vinyl chloride (--CH ₂ -CHCl-) will be represented as B, and signals 1, 2 and 3 appearing in the spectrum will be assigned as follows.
Signal 1 (approximately 5.2 to 4.5 ppm) is assigned to the CH signal of B (methine (CH) group of a structural unit derived from vinyl chloride).
Signal 2 (approximately 4.2 to 3.8 ppm) is assigned to the CH ₂ signal of one of A in AA (the methylene (CH ₂ ) group of the structural unit derived from vinylidene chloride).
Signal 3 (approximately 3.5 to 2.8 ppm) is assigned to the CH ₂ signal of A in both AB and BA (the methylene (CH ₂ ) group of the structural unit derived from vinylidene chloride).

The molar fractions of the structural units are calculated from the spectral area values of these signals (areas of the signals in the NMR spectrum). Each molar fraction is expressed as follows:
Molar fraction of A (mol%): P(A)
Molar fraction of B (mol%): P(B)

From the area values (areas of peaks in the NMR spectrum) of signals 1, 2, and 3 assigned as above, the integral values of the signals on the spectrum are assigned as follows:
The integral value of signal 1 (approximately 5.2-4.5 ppm) is the equivalent of one 1H of B. The integral value of signal 2 (approximately 4.2-3.8 ppm) is the equivalent of two 1H of A. The integral value of signal 3 (approximately 3.5-2.8 ppm) is the equivalent of four 1H of A.

Each mole fraction is calculated using the following formula:
・P(A)+P(B)=100

P(A) and P(B) are calculated using the following formula.
P(B): P(A) = integral value of signal 1: (integral value of signal 2 + integral value of signal 3/2)/2
・P(A)=100-P(B)

Each mass fraction is calculated using the following formula, assuming that the molecular weight of A, which is a structural unit derived from vinylidene chloride (-CH ₂ -CCl ₂ -), is 97.0 and the molecular weight of B, which is a structural unit derived from vinyl chloride (-CH ₂ -CHCl-), is 62.5. Each mass fraction is expressed as follows:
Mass fraction of A (mass%): Q(A)
Mass fraction of B (mass%): Q(B)
・Q(A)=(P(A)×97.0)/(P(A)×97.0+P(B)×62.5)×100
・Q(B)=100-Q(A)

The content of vinylidene chloride resin is preferably 77 to 94% by mass, and more preferably 85 to 94% by mass, based on the total amount of the wrap film. By keeping the content of vinylidene chloride resin within the above range, the film is prevented from becoming easily stretched due to the plasticizing effect of additives, etc., and the cuttability of the film tends to be further improved.

The method for measuring the content of each component in the wrap film varies depending on the object to be analyzed. For example, the content of vinylidene chloride resin can be obtained by vacuum drying the reprecipitated filtrate of the wrap film and measuring the mass. On the other hand, the content of epoxidized vegetable oil can be obtained, for example, by analyzing the reprecipitated filtrate of the wrap film using gel permeation chromatography or by using NMR. The content of citrate esters and dibasic acid esters can be obtained by extracting additives from the wrap film using an organic solvent such as acetone and analyzing them using gas chromatography.

The vinylidene chloride resin wrap film of this embodiment may contain various additives as necessary in addition to the vinylidene chloride resin. The additives are not particularly limited, and examples thereof include known stabilizers such as epoxidized vegetable oils, and known plasticizers such as citrate esters and dibasic acid esters.

<Epoxidized vegetable oil>
From the viewpoint of suppressing color change in the wrap film, the vinylidene chloride resin wrap film of this embodiment preferably contains an epoxidized vegetable oil. The epoxidized vegetable oil also acts as a stabilizer for vinylidene chloride resin extrusion processing.

Epoxidized vegetable oils are not particularly limited, but generally include those produced by epoxidizing edible fats and oils. Specific examples include epoxidized soybean oil (ESO) and epoxidized linseed oil. Among these, ESO is preferred because it tends to prevent deterioration of the pull-out properties of the wrap film from the presentation box when the wrap film is stored at high temperatures.

When the wrap film of this embodiment contains epoxidized vegetable oil, its content is not particularly limited, but from the viewpoint of suppressing color change in the wrap film and preventing stickiness due to bleeding, it is preferably 0.5 to 3 mass % relative to the vinylidene chloride resin, and more preferably 1 to 2 mass %.

The method for measuring the epoxidized vegetable oil content using NMR follows the procedure below.
Weigh out 50 mg of a sample, dissolve it in a heavy solvent (solvent: deuterated THF, internal standard: dimethyl terephthalate, volume: 0.7 ml), and measure it by 400 MHz proton NMR (accumulation number: 512 times). The ratio of the integral value from 2.23 to 2.33 ppm to the integral value from 8.05 to 8.11 ppm is taken as the integral ratio, and the quantitative value is calculated by the absolute calibration curve method.
Integral ratio = integral value (2.23 to 2.33 ppm) / integral value (8.05 to 8.11 ppm)

The epoxidized vegetable oil content was measured by gel permeation chromatography according to the following procedure.
3 g of a sample is weighed out into a tall beaker, 30 ml of THF is added, and the sample is stirred with a stirrer and heated (50°C x 4 min) to completely dissolve the sample.
While stirring with a stirrer, slowly drip methanol (170 ml) to re-precipitate. After dripping all of the methanol, suction filter into a glass filter. The filtrate is concentrated and vacuum dried, then placed in a 10 ml measuring flask and made up to volume with chloroform. Filter the chloroform solution with a syringe filter (PTFE material, pore size 0.45 μm) and analyze by GPC. Three levels of standard samples are prepared by weighing ESO into a measuring flask and making up to volume with chloroform. Filter with a syringe filter in the same way as the sample, and analyze by GPC. A calibration curve is created by plotting the GPC analysis and the standard sample concentration.
The GPC area of the sample is fitted to the calibration curve to calculate the concentration and the ESO quantitative value.

<Citrate esters and dibasic acid esters>
From the viewpoint of moldability and the like, the wrap film of this embodiment preferably contains at least one compound selected from the group consisting of citrate esters and dibasic acid esters.

The citrate ester used in the wrap film of this embodiment is not particularly limited, but examples include triethyl citrate, tributyl citrate, acetyl triethyl citrate, ATBC, and tri-n-(2-ethylhexyl) acetyl citrate. Among these, ATBC is preferred because it has a high plasticizing effect on vinylidene chloride resins, sufficiently plasticizes the resin even in small amounts, and tends to improve moldability.

The dibasic acid ester contained in the wrap film of this embodiment is not particularly limited, but examples include adipate esters such as dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, and dioctyl adipate; azelaic acid esters such as di-2-ethylhexyl azelaate and octyl azelaate; and sebacic acid esters such as dibutyl sebacate (DBS) and di-2-ethylhexyl sebacate. Among these, DBS is preferred because it has a high plasticizing effect on vinylidene chloride resins and tends to sufficiently plasticize the resin even in small amounts, improving moldability.

The total content of the citrate ester and dibasic acid ester is not particularly limited, but from the viewpoint of imparting better moldability and preventing excessive adhesion of the wrap film when the additive content is high, it is preferably 3 to 8% by mass, more preferably 3 to 7% by mass, even more preferably 3 to 5% by mass, and particularly preferably 3.5 to 5% by mass, relative to the vinylidene chloride resin.

In particular, when vinylidene chloride resin wrap film contains 3% by mass or more of citrate ester or dibasic acid ester, the mobility of the molecular chains of the vinylidene chloride resin increases, making it more likely that rearrangements such as the formation and growth of microcrystals will occur, and the film will be more susceptible to physical deterioration when exposed to high temperatures. In addition, the film will be more likely to stretch, making it more difficult for the cutting blade to penetrate the film, and cutting ability will tend to decrease, making the effects of the present invention more pronounced.

<Acetylated fatty acid glyceride>
The wrap film of this embodiment may contain an acetylated fatty acid glyceride as a plasticizer. The acetylated fatty acid glyceride is not particularly limited, but examples thereof include acetylated caprylic acid glyceride, acetylated capric acid glyceride, acetylated lauric acid glyceride, acetylated myristic acid glyceride, acetylated palm kernel oil glyceride, acetylated coconut oil glyceride, acetylated castor oil glyceride, and acetylated hardened castor oil glyceride.

The acetylated fatty acid glyceride may be any of acetylated monoglycerides of fatty acids, acetylated diglycerides of fatty acids, and acetylated triglycerides of fatty acids. For example, the acetylated lauric acid glycerides include acetylated monoglycerides of lauric acid, acetylated diglycerides of lauric acid (DALG: diacetyl lauroyl glycerol), and acetylated triglycerides of lauric acid. Among these, acetylated lauric acid glycerides are preferred, and acetylated diglycerides of lauric acid are more preferred.

The content of acetylated fatty acid glyceride is preferably 3 to 8% by mass, more preferably 3.5 to 7% by mass, and even more preferably 4 to 6% by mass, based on the total amount of the wrap film. When the content of acetylated fatty acid glyceride is within the above range, molding processability tends to be improved. The method for measuring the content of each component from the wrap film varies depending on the object to be analyzed. The content of acetylated fatty acid glyceride can be obtained by extracting additives from the wrap film using an organic solvent such as acetone and analyzing the extract by gas chromatography.

The total content of at least one compound selected from the group consisting of citric acid esters, dibasic acid esters, and acetylated fatty acid glycerides is preferably 3 to 8% by mass, more preferably 3.5 to 7% by mass, and even more preferably 4 to 6% by mass, relative to the total amount of the wrap film. By having the total content of citric acid esters, dibasic acid esters, and acetylated fatty acid glycerides within the above range, molding processability is further improved, and excessive stickiness due to bleeding of the wrap film when it contains a high amount of epoxidized vegetable oil tends to be suppressed.

<Other ingredients>
The vinylidene chloride resin wrap film of this embodiment may contain compounds other than the epoxidized vegetable oil, citric acid ester, dibasic acid ester, and acetylated fatty acid glyceride (hereinafter referred to as "other compounds"), such as plasticizers, stabilizers, weather resistance improvers, colorants such as dyes or pigments, anti-fogging agents, antibacterial agents, lubricants, nucleating agents, oligomers such as polyesters, and polymers such as MBS (methyl methacrylate-butadiene-styrene copolymer).

The plasticizer is not particularly limited, but specific examples include dimethyl phthalate, diethyl phthalate, dioctyl phthalate, glycerin, glycerin esters, wax, liquid paraffin, and phosphate esters.

The stabilizer is not particularly limited, but specific examples thereof include 2,5-t-butylhydroquinone, 2,6-di-t-butyl-p-cresol, 4,4'-thiobis-(6-t-butylphenol), 2,2'-methylene-bis-(4-methyl-6-t-butylphenol), and octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl).
Antioxidants such as propionate, and 4,4'-thiobis-(6-t-butylphenol); heat stabilizers such as calcium laurate, myristate, palmitate, stearate, isostearate, oleate, ricinoleate, 2-ethyl-hexylate, isodecanoate, neodecanoate, and benzoate.

The weather resistance improver is not particularly limited, but specific examples thereof include ultraviolet absorbers such as ethylene-2-cyano-3,3'-diphenylacrylate, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone.

The coloring agent such as a dye or pigment is not particularly limited, but specific examples include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and red iron oxide.

The anti-fogging agent is not particularly limited, but specific examples include glycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene fatty acid alcohol ethers, polyoxyethylene glycerin fatty acid esters, and polyoxyethylene sorbitan fatty acid esters.

The antibacterial agent is not particularly limited, but specific examples include silver-based inorganic antibacterial agents.

The lubricant is not particularly limited, but specific examples include fatty acid hydrocarbon lubricants such as ethylene bis(steramide), butyl stearate, polyethylene wax, paraffin wax, carnauba wax, myristyl myristate, and stearyl stearate, higher fatty acid lubricants, fatty acid amide lubricants, and fatty acid ester lubricants.

The nucleating agent is not particularly limited, but specific examples include metal salts of phosphate esters.

The content of the other ingredients is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, relative to the wrap film.

[Rolled body]
The roll of the present embodiment includes the vinylidene chloride-based resin wrap film and a core, and the vinylidene chloride-based resin wrap film is wound around the core. The roll can be produced, for example, according to the production method described below.

[Method for producing wrap film]
The method for producing the wrap film of this embodiment is not particularly limited, but may include, for example, a method comprising a step of melt-extruding a composition containing a vinylidene chloride resin, an epoxidized vegetable oil, and at least one compound selected from the group consisting of a citrate ester, a dibasic acid ester, and an acetylated fatty acid glyceride to form a film, and a step of stretching the obtained film in the MD and TD directions. This will be described in detail below.

(Mixing process)
FIG. 1 shows a schematic diagram of an example of a manufacturing process for a wrap film. First, a vinylidene chloride resin is mixed with at least one compound selected from the group consisting of epoxidized vegetable oil, citric acid ester, dibasic acid ester, and acetylated fatty acid glyceride in a mixer to obtain a composition. At this time, various additives may be mixed as necessary. The mixer is not particularly limited, but for example, a ribbon blender or a Henschel mixer can be used. The obtained composition is preferably aged for about 1 to 30 hours before being used in the next step.

(Melt extrusion process)
Next, the obtained composition is melted by an extruder 1 and extruded from a die opening 3 of a die 2 into a tubular film to form a sock 4 (also called a pile).

(Cooling process)
A sock liquid 5 is poured into the inside of the sock 4, and the outside of the sock 4 is brought into contact with cold water in a cold water tank 6. As a result, the sock 4 is cooled from both the inside and outside, and the film constituting the sock 4 solidifies. The solidified sock 4 is folded by a first pinch roll 7 to form a parison 8. At this time, the distance from the die opening 3 to the cold water tank 6 is called the hot distance. By adjusting the hot distance, it is possible to adjust the long crystal period when the wrap film is pulled.

(Stretching process)
Next, air is injected into the inside of the parison 8 to open the parison 8 and form a ring-shaped film. At this time, the sock liquid 5 applied to the part that contacts the inner surface of the sock 4 acts as an opening agent for the parison 8. Next, the parison 8 is reheated with hot water in the open state to a temperature suitable for stretching. The hot water adhering to the outside of the parison 8 is squeezed out by the second pinch roll 9.

Air is injected into the parison 8 that has been heated to the appropriate temperature as described above to form a bubble 10. This air pushes the parison open from the inside, stretching the film and producing a stretched film. The film is stretched mainly in the TD direction by the amount of air, and the film is stretched in the MD direction by applying tension in the film flow direction using the second pinch roll 9, the third pinch roll 11, etc.

The process from the first pinch roll 7 to the third pinch roll 11 is called the stretching process. Since slowing down the stretching speed improves the stretchability of the parison 8, in conventional wrap film manufacturing methods, the stretching speed in the MD direction is adjusted to 0.08 times/s or less, and the stretching speed in the TD direction is adjusted to 3.0 times/s or less. In contrast, in the wrap film manufacturing method of this embodiment, in which the crystallization onset temperature is controlled to 40 to 60°C, it is preferable to adjust the stretch ratios in the MD and TD directions and the stretching speeds in the MD and TD directions to within a specified range.

Specifically, the stretch ratios in the MD and TD directions in the stretching process of this embodiment are each independently preferably 4 to 6 times, more preferably 4.5 to 5.5. Here, the stretch ratio in the MD direction refers to the stretch ratio when the parison 8 is stretched in the MD direction, and can be calculated, for example, in FIG. 1, by the ratio of the rotation speed of the third pinch roll 11 to the rotation speed of the first pinch roll 7. The stretch ratio in the TD direction refers to the stretch ratio when the parison 8 is stretched in the TD direction, and can be calculated, for example, in FIG. 1, by the ratio of the width of the double-ply film 12 to the width of the parison 8. The stretch ratio in the MD direction can be adjusted, for example, by the ratio of the rotation speeds of the first pinch roll 7 and the third pinch roll 11, and the stretch ratio in the TD direction can be adjusted, for example, by the stretching temperature of the parison 8 or the size of the bubble 10.

The stretching speed in the MD direction in the stretching step of this embodiment is preferably 0.09 to 0.12 times/s. The average stretching speed in the MD direction refers to the stretching ratio in the MD direction relative to the time it takes for the parison to pass between the first pinch roll 7 and the third pinch roll 11. For example, in FIG. 1, it can be calculated from the rotation speed of the first pinch roll 7, the rotation speed of the third pinch roll 11, and the time it takes for the parison 8 to pass between the first pinch roll 7 and the third pinch roll 11. The stretching speed in the MD direction can be adjusted, for example, by the rotation speed of the first pinch roll 7 and the third pinch roll 11, or the distance between the first pinch roll 7 and the third pinch roll 11.

Furthermore, the stretching speed in the TD direction in the stretching process of this embodiment is preferably 3.1 to 4.0 times/s. The average stretching speed in the TD direction refers to the stretching ratio in the TD direction relative to the time required for the parison 8 to expand into the bubble 10, and in FIG. 1, for example, it can be calculated from the stretching length measured using still images of the parison 8 and the bubble 10, the time required for stretching in the TD direction calculated from the rotation speed of the third pinch roll 11, and the stretching ratio in the TD direction. The stretching speed in the TD direction can be adjusted, for example, by the rotation speed of the third pinch roll 11.

The stretching temperature is not particularly limited, but is preferably 25 to 45°C.

After the above stretching process, the stretched film is folded by the third pinch roll 11 to become the double-ply film 12. The double-ply film 12 is wound up by the winding roll 13.

(Relaxation process)
The wrap film manufacturing method of this embodiment preferably includes a relaxation step in which the wrap film is relaxed immediately after stretching. A relatively common relaxation method in wrap film manufacturing methods is to relax the film after stretching by using heat from an infrared heater or the like. However, in this embodiment, instead of this relaxation step, it is preferable to use a method in which the rotation speed of the take-up roll 13 is slower than that of the third pinch roll 11 to relax the stretched film.

The relaxation ratio in the relaxation process using the third pinch roll 11 and the take-up roll 13 is preferably 7 to 15%, and more preferably 9 to 13%. A relaxation ratio of 15% or less tends to suppress the occurrence of wrinkles due to the occurrence of slack in the film between the third pinch roll 11 and the take-up roll 13. Also, a relaxation ratio of 7% or more tends to allow the wrap film to be sufficiently relaxed, and to reduce tearing problems. Here, the "relaxation ratio" refers to the ratio by which the double-ply film 12 is shrunk between the third pinch roll 11 and the take-up roll 13. For example, in the case of FIG. 1, it can be calculated using the ratio of the rotation speed of the take-up roll 13 to that of the third pinch roll 11.

The atmospheric temperature during the relaxation process using the third pinch roll 11 and the take-up roll 13 is preferably 25 to 32°C. By keeping the atmospheric temperature within the above range, the formation and growth of microcrystals tends to be suppressed.

(Slitting process)
The wrap film wound up as described above is slit and wound up while peeling it off so as to become one sheet of wrap film, and is temporarily stored in the state of the original roll for 1 to 3 days. Finally, it is rewound from the original roll onto a core such as a paper tube, and packed in a decorative box to obtain a wrap film roll stored in a decorative box.

(Storage process)
In the wrap film manufacturing method of this embodiment, after the wrap film is slit, a storage step may be carried out in which the wrap film is stored in its original roll state. The storage temperature is preferably 19° C. or lower, more preferably 5 to 19° C., and even more preferably 5 to 15° C. The storage time is preferably 20 to 50 hours, and more preferably 24 to 40 hours.

The atmospheric temperature during storage tends to suppress the formation and growth of microcrystals that lead to increased film tearing problems. In general, raw rolls are stored in locations that are relatively hot, such as adjacent to the wrap film manufacturing process or without temperature control.

In contrast, in the wrap film manufacturing method of this embodiment, by keeping the ambient temperature during storage of the slit roll at 19°C or less, physical deterioration of the film due to molecular chain rearrangement tends to be suppressed. This tends to suppress the wrap film from easily tearing at the end cut by the cutting blade attached to the presentation box when pulling the wrap film out of the roll or when picking out the end of the film that has been rewound into the presentation box.

In addition, by keeping the ambient temperature at 5°C or higher during storage of the slit roll, the wrap film is sufficiently relaxed, and if it is exposed to temperatures of 20°C or higher during subsequent distribution and storage, rearrangement of the molecular chains tends to be less likely to occur.

Therefore, it is preferable to store the slit raw roll under the above-mentioned conditions, which results in a film in which the molecular chains in the amorphous portion are relaxed in orientation while suppressing the formation and growth of microcrystals. In this way, by relaxing the orientation of the molecular chains during storage of the raw roll, microcrystals are less likely to form and grow even when the film is exposed to high temperatures during distribution and storage, and tearing problems can be suppressed.

After storage, the slit roll is wound back onto a core such as, but not limited to, a paper tube, and the wound body 16 is stored in a presentation box 1 equipped with a film cutting blade 15 as shown in FIG. 2. As shown in FIG. 2, the wrap film 17 is pulled out when in use.

The present invention will be specifically explained below using examples and comparative examples, but the present invention is not limited by these in any way. The evaluation methods used in the examples and comparative examples are as follows.

[Content of Vinylidene Chloride-Derived Structural Units and Vinyl Chloride-Derived Structural Units]
The content of vinylidene chloride-derived structural units and vinyl chloride-derived structural units was measured using a high-resolution proton nuclear magnetic resonance measurement device. The reprecipitated filtrate of the wrap film was vacuum-dried, and 5% by mass of the solution was dissolved in deuterated tetrahydrofuran and subjected to H-NMR measurement in a measurement atmosphere of 23±2°C and 50±10% RH.
For example, a structural unit derived from vinylidene chloride (--CH ₂ -CCl ₂ -) is represented as A, a structural unit derived from vinyl chloride (--CH ₂ -CHCl-) is represented as B, and signals 1, 2, and 3 appearing in the spectrum are assigned as follows:
Signal 1 (approximately 5.2 to 4.5 ppm) was assigned to the CH signal of B (methine (CH) group of a structural unit derived from vinyl chloride).
Signal 2 (approximately 4.2 to 3.8 ppm) was assigned to the CH ₂ signal of one of A in AA (the methylene (CH ₂ ) group of the structural unit derived from vinylidene chloride).
Signal 3 (approximately 3.5 to 2.8 ppm) was assigned to the CH ₂ signal of A in both AB and BA (the methylene (CH ₂ ) group of the structural unit derived from vinylidene chloride).

The molar fractions of the structural units were calculated from the spectral area values of these signals (areas of the signals in the NMR spectrum). Each molar fraction is represented as follows:
Molar fraction of A (mol%): P(A)
Molar fraction of B (mol%): P(B)

From the area values (areas of peaks in the NMR spectrum) of signals 1, 2, and 3 assigned as above, the integral values of the signals on the spectrum were assigned as follows:
The integral value of signal 1 (approximately 5.2-4.5 ppm) is the equivalent of one 1H of B. The integral value of signal 2 (approximately 4.2-3.8 ppm) is the equivalent of two 1H of A. The integral value of signal 3 (approximately 3.5-2.8 ppm) is the equivalent of four 1H of A.

Each mole fraction was calculated using the following formula:
・P(A)+P(B)=100

P(A) and P(B) were calculated by the following formula.
P(B): P(A) = integral value of signal 1: (integral value of signal 2 + integral value of signal 3/2)/2
・P(A)=100-P(B)

Each mass fraction was calculated using the following formula, assuming that the molecular weight of A, which is a structural unit derived from vinylidene chloride (-CH ₂ -CCl ₂ -), is 97.0 and the molecular weight of B, which is a structural unit derived from vinyl chloride (-CH ₂ -CHCl-), is 62.5. Each mass fraction is represented as follows:
Mass fraction of A (mass%): Q(A)
Mass fraction of B (mass%): Q(B)
・Q(A)=(P(A)×97.0)/(P(A)×97.0+P(B)×62.5)×100
・Q(B)=100-Q(A)

[Film thickness]
The thickness of the wrap film was measured using a precision dial gauge (TM-1201, manufactured by Techlock Corporation) in an atmosphere of 23±2° C. and 50±10% RH.

[Evaluation of tear resistance when pulled 10%]
The wrap film was pulled in the TD direction while wrapping vegetables, and the wrap film was stretched 10% in the TD direction to evaluate its tearability. The sensory evaluation of the tearability of the wrap film when stretched 10% in the TD direction was performed using the following method.
Ten experienced evaluators (including men and women) pulled out the wrap film by hand from the wrap film roll wound around a paper tube, cut it with scissors, cut it 5 cm in a direction parallel to the MD direction, and cut it 5 cm in a direction parallel to the TD direction to create a wrap film measuring 5 cm x 5 cm. The obtained sample was stretched 10% in the TD direction using a stretcher. The evaluators used this wrap film to wrap a plate, and evaluated whether the wrap film was easily torn on a scale of 1 to 10 (10 being the least likely to tear, and 1 being the most likely to tear). Based on the average score of the 10 evaluators, the wrap film was evaluated for its tear resistance according to the following evaluation criteria.
If the tear resistance rating is "A", the wrap film is very tear-resistant and has very excellent film strength. If the rating is "B", the wrap film is tear-resistant and has excellent film strength. If the rating is "C", the wrap film has relatively excellent tear resistance. If the rating is "D", the wrap film has good tear resistance. If the rating is "E", the wrap film has relatively good tear resistance. If the rating is "F", the wrap film has no particular problem with tear resistance. If the rating is "G", the wrap film has slightly poor tear resistance. If the rating is "X", the wrap film has poor tear resistance.
[Evaluation Criteria]
A: 8.0 points or more B: More than 7.0 points but less than 8.0 points C: More than 6.0 points but less than 7.0 points D: More than 5.0 points but less than 6.0 points E: More than 4.0 points but less than 5.0 points F: More than 3.0 points but less than 4.0 points G: More than 2.0 points but less than 3.0 points x: 2.0 points or less

[Evaluation of tear resistance when pulled 1%]
The wrap film was pulled in the TD direction, a plate was wrapped around it, and the plate was then placed on top of the wrap film. The wrap film was stretched 1% in the TD direction, and the ease of tearing was evaluated. The sensory evaluation of the ease of tearing when the wrap film was stretched 1% in the TD direction was performed and evaluated using the following method.
Ten experienced evaluators (including men and women) pulled out the wrap film by hand from the wrap film roll wound around a paper tube, cut it with scissors, cut it 5 cm in a direction parallel to the MD direction, and cut it 5 cm in a direction parallel to the TD direction to create a wrap film measuring 5 cm x 5 cm. The obtained sample was stretched 1% in the TD direction using a stretcher. The evaluators used this wrap film to wrap a plate, and evaluated whether the wrap film was easily torn on a scale of 1 to 10 (10 being the least likely to tear, and 1 being the most likely to tear). Based on the average score of the 10 evaluators, the wrap film was evaluated for its tear resistance according to the following evaluation criteria.
If the tear resistance rating is "A", the wrap film is very tear-resistant and has very excellent film strength. If the rating is "B", the wrap film is tear-resistant and has excellent film strength. If the rating is "C", the wrap film has relatively excellent tear resistance. If the rating is "D", the wrap film has good tear resistance. If the rating is "E", the wrap film has relatively good tear resistance. If the rating is "F", the wrap film has no particular problem with tear resistance. If the rating is "G", the wrap film has slightly poor tear resistance. If the rating is "X", the wrap film has poor tear resistance.
[Evaluation Criteria]
A: 8.0 points or more B: More than 7.0 points but less than 8.0 points C: More than 6.0 points but less than 7.0 points D: More than 5.0 points but less than 6.0 points E: More than 4.0 points but less than 5.0 points F: More than 3.0 points but less than 4.0 points G: More than 2.0 points but less than 3.0 points x: 2.0 points or less

[Evaluation of odor barrier properties when stretched by 10%]
Assuming the action of wrapping vegetables while pulling the wrap film in the TD direction, the wrap film was pulled 10% in the TD direction and the odor barrier property when food was wrapped was evaluated. The sensory evaluation of the odor barrier property when the wrap film was pulled 10% in the TD direction was performed and evaluated by the following method.
Ten experienced evaluators (including men and women) pulled out the wrap film by hand from the wrap film roll wound around a paper tube, cut it with scissors, cut it 5 cm in a direction parallel to the MD direction, and cut it 5 cm in a direction parallel to the TD direction to create a wrap film measuring 5 cm x 5 cm. The obtained sample was stretched 10% in the TD direction using a stretcher. The evaluators wrapped strawberries using this wrap film and evaluated each of them on a scale of 1 to 10 (10 points means no odor leakage, and 1 point means the most odor leakage). The odor barrier properties of the wrap film were evaluated based on the average scores of the 10 evaluators according to the following evaluation criteria.
If the odor barrier property is rated "A", the wrap film is very resistant to odor leakage and has very excellent odor barrier property. If the rating is "B", the wrap film is resistant to odor leakage and has excellent odor barrier property. If the rating is "C", the wrap film is relatively excellent in preventing odor leakage. If the rating is "D", the wrap film is good in preventing odor leakage. If the rating is "E", the wrap film is relatively good in preventing odor leakage. If the rating is "F", the wrap film has no particular problem in preventing odor leakage. If the rating is "G", the wrap film is slightly poor in preventing odor leakage. If the rating is "X", the wrap film has poor odor barrier property.
[Evaluation Criteria]
A: 8.0 points or more B: More than 7.0 points but less than 8.0 points C: More than 6.0 points but less than 7.0 points D: More than 5.0 points but less than 6.0 points E: More than 4.0 points but less than 5.0 points F: More than 3.0 points but less than 4.0 points G: More than 2.0 points but less than 3.0 points x: 2.0 points or less

[Evaluation of odor barrier properties when stretched by 1%]
The wrap film was pulled in the TD direction, and the odor barrier properties of the wrap film were evaluated by pulling it 1% in the TD direction to wrap a food item, assuming that the wrap film was pulled in the TD direction while wrapping a plate and then the plate was placed on top of the wrap film. The odor barrier properties of the wrap film when pulled 1% in the TD direction were evaluated by the following method.
Ten experienced evaluators (including men and women) pulled out the wrap film by hand from the wrap film roll wound around a paper tube, cut it with scissors, cut it 5 cm in a direction parallel to the MD direction, and cut it 5 cm in a direction parallel to the TD direction to create a wrap film measuring 5 cm x 5 cm. The obtained sample was stretched 1% in the TD direction using a stretcher. The evaluators wrapped strawberries using this wrap film and evaluated each of them on a scale of 1 to 10 (10 points means no odor leakage, and 1 point means the most odor leakage). The odor barrier properties of the wrap film were evaluated based on the average scores of the 10 evaluators according to the following evaluation criteria.
If the odor barrier property is rated "A", the wrap film is very resistant to odor leakage and has very excellent odor barrier property. If the rating is "B", the wrap film is resistant to odor leakage and has excellent odor barrier property. If the rating is "C", the wrap film is relatively excellent in preventing odor leakage. If the rating is "D", the wrap film is good in preventing odor leakage. If the rating is "E", the wrap film is relatively good in preventing odor leakage. If the rating is "F", the wrap film has no particular problem in preventing odor leakage. If the rating is "G", the wrap film is slightly poor in preventing odor leakage. If the rating is "X", the wrap film has poor odor barrier property.
[Evaluation Criteria]
A: 8.0 points or more B: More than 7.0 points but less than 8.0 points C: More than 6.0 points but less than 7.0 points D: More than 5.0 points but less than 6.0 points E: More than 4.0 points but less than 5.0 points F: More than 3.0 points but less than 4.0 points G: More than 2.0 points but less than 3.0 points x: 2.0 points or less

Ａ，ｃ：定数
ｗ_peak：ピーク幅
フィッティング範囲は０．３０ｎｍ^-1＜ｑ＜１．０ｎｍ^-1とした。フィッティングはＷａｖｅｍｅｔｒｉｃｓ社製Ｉｇｏｒ Ｐｒｏを用いて行った。得られたｑ_peakより、結晶長周期ｄ＝２π／ｑ_peakを算出した。

ｑ＝４πｓｉｎθ／λ 式（２）
θ：ブラッグ角
ｑ：散乱ベクトルの大きさ
λ：Ｘ線波長

ＴＤ方向に１０％引っ張った際の結晶長周期は、チャック間の長さが、初期長である２ｃｍから１０％伸長した時の結晶長周期を算出した。

また、ＴＤ方向に１％引っ張った際の結晶長周期は、チャック間の長さが、初期長である２ｃｍから１％伸長した時の結晶長周期を算出した。

また、照射ダメージを軽減するためにサンプルの中心からずれた位置にビームを当て、
引張測定中にビームの相対位置が動いていくようにした。
[Long Crystal Period during Stretching]
The crystalline long period during TD stretching was determined by performing in-situ small angle X-ray scattering (SAXS) measurement simultaneously with stretching using the following apparatus and conditions.
The measurement was carried out in an atmosphere of 26±2° C. and 50±10% RH.

Equipment: Japan Synchrotron Radiation Research Institute SPring-8 Hyogo Prefecture Beamline BL03XU
X-ray wavelength: 0.100nm
Camera length: 8m
Damping plate: Mo20μm
Detector: PLATINUM 1M
Exposure time: 0.2 s exposure + 0.4 s rest Section: Length 4 cm, width 0.5 cm Set in the stretching machine chuck so that the initial length is 2 cm Pull speed: 1 mm/s

The obtained X-ray scattering pattern was subjected to empty cell scattering correction. Then, sector averaging was performed in the range of azimuth angle ±20 deg from the stretching direction to obtain SAXS profile I(q) (the scattering vector q is defined by formula (2)). Furthermore, Lorentz correction was performed on SAXS profile I(q) by multiplying by ^q2 . The peak position _qpeak due to the crystal long period appearing in the Lorentz-corrected SAXS profile ^q2I (q) was obtained by fitting using formula (1).

A, c: constants w _peak : peak width The fitting range was set to 0.30 nm ^-1 <q<1.0 nm ^-1 . The fitting was performed using Igor Pro manufactured by Wavemetrics Corp. From the obtained q _peak , the crystal long period d=2π/q _peak was calculated.

q=4πsinθ/λ Formula (2)
θ: Bragg angle q: magnitude of scattering vector λ: X-ray wavelength

The crystal long period when stretched 10% in the TD direction was calculated as the crystal long period when the length between the chucks was elongated 10% from the initial length of 2 cm.

The crystal long period when stretched by 1% in the TD direction was calculated as the crystal long period when the length between the chucks was elongated by 1% from the initial length of 2 cm.

In addition, to reduce radiation damage, the beam is directed off-center at the sample.
The relative position of the beam was allowed to move during the tensile measurement.

[Example 1]
A vinylidene chloride resin composition was obtained by mixing 10 kg of a vinylidene chloride resin having a weight average molecular weight of 120,000 (85% by mass of constituent units derived from vinyl chloride and 15% by mass of constituent units derived from vinyl chloride), ATBC (acetyl tributyl citrate, Taoka Chemical Co., Ltd.), and ESO (Newsizer 510R, Nippon Oil & Fats Co., Ltd.) in proportions of 93.4%, 5.5%, and 1.1% by mass, respectively, in a Henschel mixer for 5 minutes and aging for 24 hours or more.
The vinylidene chloride resin composition was fed to a melt extruder to melt it, and extruded circularly at an extrusion speed of 14 kg/hr while adjusting the heating conditions of the extruder so that the molten resin temperature at the slit outlet of the annular die attached to the tip of the extruder would be 170° C. The hot distance was 80 mm.
After supercooling, the film was stretched by inflation stretching at a stretching temperature of 25°C to 4.7 times in the MD direction and 5.5 times in the TD direction to form a cylindrical film, and the two-ply film with a folding width of 270 mm was wound up at a winding speed of 18 m/min. The film was slit to a width of 80 mm, peeled off into one film, and rewound on a paper tube with an outer diameter of 97 mm. After that, the film was stored at 15°C for 30 hours, and 20 m was wound up on a paper tube with an outer diameter of 36 mm and a length of 23 cm to obtain a roll of wrap film. The evaluation results are shown in Table 1.

[Example 2]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 69 mm. The evaluation results are shown in Table 1.

[Example 3]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 65 mm. The evaluation results are shown in Table 1.

[Example 4]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 59 mm. The evaluation results are shown in Table 1.

[Example 5]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 52 mm. The evaluation results are shown in Table 1.

[Example 6]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 50 mm. The evaluation results are shown in Table 1.

[Example 7]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 49 mm. The evaluation results are shown in Table 1.

[Example 8]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 47 mm. The evaluation results are shown in Table 1.

[Example 9]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 45 mm. The evaluation results are shown in Table 1.

[Example 10]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 43 mm. The evaluation results are shown in Table 1.

[Example 11]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 42 mm. The evaluation results are shown in Table 1.

[Example 12]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 40 mm. The evaluation results are shown in Table 1.

[Example 13]
The weight average molecular weight of the vinylidene chloride resin was 105,000, the constituent units derived from vinylidene chloride were 84% by mass, the constituent units derived from vinyl chloride were 16% by mass, the amount of ATBC added was 2.3% by mass, the amount of ESO added was 2.2% by mass, the amount of DALG added was 2.8% by mass, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 3.8 times, the stretch ratio in the TD direction was 4.1 times, the folding width was 201 mm, and the hot distance was 40 mm. A wrap film roll was obtained by producing in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Example 14]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the vinylidene chloride-derived structural unit was 80% by mass, the vinyl chloride-derived structural unit was 20% by mass, the amount of ATBC added was 5.2% by mass, the amount of ESO added was 1.8% by mass, the extrusion speed was 9 kg/hr, the MD stretch ratio was 4.5 times, the TD stretch ratio was 3.6 times, the folding width was 176 mm, and the hot distance was 40 mm. The evaluation results are shown in Table 1.

[Example 15]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the constituent units derived from vinylidene chloride were 80 mol%, the constituent units derived from vinyl chloride were 20 mol%, the amount of ATBC added was 5.2 mass%, the amount of ESO added was 1.8 mass%, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 4.9 times, the stretch ratio in the TD direction was 3.1 times, the folding width was 152 mm, and the hot distance was 40 mm. The evaluation results are shown in Table 1.

[Comparative Example 1]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 35 mm. The evaluation results are shown in Table 2.

[Comparative Example 2]
A roll of wrap film was obtained by producing the wrap film in the same manner as in Example 1, except that the hot distance was set to 85 mm. The evaluation results are shown in Table 2.

[Comparative Example 3]
The weight average molecular weight of the vinylidene chloride resin was 105,000, the constituent units derived from vinylidene chloride were 84 mol%, the constituent units derived from vinyl chloride were 16 mol%, the amount of ATBC added was 2.3 mass%, the amount of ESO added was 2.2 mass%, the amount of DALG added was 2.8 mass%, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 3.8 times, the stretch ratio in the TD direction was 4.1 times, the folding width was 201 mm, and the hot distance was 35 mm. Except for this, a roll of wrap film was obtained by producing in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 4]
The weight average molecular weight of the vinylidene chloride resin was 105,000, the constituent units derived from vinylidene chloride were 84 mol%, the constituent units derived from vinyl chloride were 16 mol%, the amount of ATBC added was 2.3 mass%, the amount of ESO added was 2.2 mass%, the amount of DALG added was 2.8 mass%, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 3.8 times, the stretch ratio in the TD direction was 4.1 times, the folding width was 201 mm, and the hot distance was 85 mm. Except for this, a roll of wrap film was obtained by producing in the same manner as in Example 1. The evaluation results are shown in Table 2.

[Comparative Example 5]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the constituent units derived from vinylidene chloride were 80 mol%, the constituent units derived from vinyl chloride were 20 mol%, the amount of ATBC added was 5.2 mass%, the amount of ESO added was 1.8 mass%, the extrusion speed was 9 kg/hr, the stretch ratio in the MD direction was 4.5 times, the stretch ratio in the TD direction was 3.6 times, the folding width was 176 mm, and the hot distance was 35 mm. The evaluation results are shown in Table 2.

[Comparative Example 6]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the constituent units derived from vinylidene chloride were 80 mol%, the constituent units derived from vinyl chloride were 20 mol%, the amount of ATBC added was 5.2 mass%, the amount of ESO added was 1.8 mass%, the extrusion speed was 9 kg/hr, the stretch ratio in the MD direction was 4.5 times, the stretch ratio in the TD direction was 3.6 times, the folding width was 176 mm, and the hot distance was 85 mm. The evaluation results are shown in Table 2.

[Comparative Example 7]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the constituent units derived from vinylidene chloride were 80 mol%, the constituent units derived from vinyl chloride were 20 mol%, the amount of ATBC added was 5.2 mass%, the amount of ESO added was 1.8 mass%, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 4.9 times, the stretch ratio in the TD direction was 3.1 times, the folding width was 152 mm, and the hot distance was 35 mm. The evaluation results are shown in Table 2.

[Comparative Example 8]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the weight average molecular weight of the vinylidene chloride resin was 130,000, the constituent units derived from vinylidene chloride were 80 mol%, the constituent units derived from vinyl chloride were 20 mol%, the amount of ATBC added was 5.2 mass%, the amount of ESO added was 1.8 mass%, the extrusion speed was 8 kg/hr, the stretch ratio in the MD direction was 4.9 times, the stretch ratio in the TD direction was 3.1 times, the folding width was 152 mm, and the hot distance was 85 mm. The evaluation results are shown in Table 2.

[Comparative Example 9]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 26° C., the extrusion speed was 12 kg/hr, the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 5.8 times, the folding width was 284 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 2.

[Comparative Example 10]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 12 kg/hr, the stretch ratio in the MD direction was 3.6 times, the stretch ratio in the TD direction was 6.0 times, the folding width was 294 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 2.

[Comparative Example 11]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 11 kg/hr, the stretch ratio in the MD direction was 3.5 times, the stretch ratio in the TD direction was 6.1 times, the folding width was 299 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 2.

[Comparative Example 12]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 28° C., the extrusion speed was 12 kg/hr, the stretching ratio in the MD direction was 3.4 times, the stretching ratio in the TD direction was 6.5 times, the folding width was 319 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 2.

[Comparative Example 13]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 32° C., the extrusion speed was 13 kg/hr, the stretching ratio in the MD direction was 3.7 times, the stretching ratio in the TD direction was 6.6 times, the folding width was 323 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 2.

[Comparative Example 14]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 26° C., the extrusion speed was 12 kg/hr, the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 5.8 times, the folding width was 284 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 15]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 12 kg/hr, the stretch ratio in the MD direction was 3.6 times, the stretch ratio in the TD direction was 6.0 times, the folding width was 294 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 16]
A wrap film roll was obtained by the same production method as in Example 1, except that the extrusion speed was 11 kg/hr, the stretch ratio in the MD direction was 3.5 times, the stretch ratio in the TD direction was 6.1 times, the folding width was 299 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 17]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 27° C., the extrusion speed was 13 kg/hr, the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 6.4 times, the folding width was 313 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 18]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 28° C., the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 6.7 times, the folding width was 329 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 19]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 29° C., the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 6.8 times, the folding width was 334 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 20]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 12 kg/hr, the stretch ratio in the MD direction was 3.7 times, the stretch ratio in the TD direction was 5.8 times, the folding width was 284 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 21]
A wrap film roll was obtained by the same production method as in Example 1, except that the extrusion speed was 12 kg/hr, the stretch ratio in the MD direction was 3.6 times, the stretch ratio in the TD direction was 6.1 times, the folding width was 299 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 22]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 12 kg/hr, the stretch ratio in the MD direction was 3.5 times, the stretch ratio in the TD direction was 6.2 times, the folding width was 304 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 23]
A wrap film roll was obtained by producing in the same manner as in Example 1, except that the extrusion speed was 11 kg/hr, the stretch ratio in the MD direction was 3.4 times, the stretch ratio in the TD direction was 5.8 times, the folding width was 284 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 24]
A wrap film roll was obtained by the same production method as in Example 1, except that the extrusion speed was 11 kg/hr, the stretch ratio in the MD direction was 3.5 times, the stretch ratio in the TD direction was 5.8 times, the folding width was 284 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

[Comparative Example 25]
A roll of wrap film was obtained by producing in the same manner as in Example 1, except that the stretching temperature was 33° C., the extrusion speed was 16 kg/hr, the stretching ratio in the MD direction was 3.8 times, the stretching ratio in the TD direction was 7.6 times, the folding width was 372 mm, and the hot distance was 10 mm. The evaluation results are shown in Table 3.

As shown in Table 1, the wrap films obtained in Examples 1 to 15 did not tear when pulled about 10% in the TD direction, and the odor of the contents did not leak out.

Claims (3)

A wrap film containing a vinylidene chloride-based resin, the wrap film having a crystal long period of 8.2 nm or more and 14.5 nm or less when stretched 10% in the TD direction and a thickness of 9 to 12 μm, the vinylidene chloride-based resin comprising a copolymer consisting of 85 to 97 mass % of vinylidene chloride-derived structural units and 15 to 3 mass % of vinyl chloride-derived structural units . The vinylidene chloride resin wrap film according to claim 1, in which the crystal long period when stretched by 1% in the TD direction is 7.5 nm or more and 13.5 nm or less. A wrap film comprising the vinylidene chloride resin wrap film according to claim 1 or 2 and a core,
The vinylidene chloride resin wrap film is wound around the core to form a roll.