polyvinylidene chloride resin wrap film

Abstract

To provide a vinylidene chloride based resin wrap film which is improved in usability by exhibiting a good drawability while sufficiently ensuring an appropriate adhesiveness of the vinylidene chloride based resin wrap film.SOLUTION: A vinylidene chloride based resin wrap film, wherein the wrap film is dissolved in tetrahydrofuran, and is reprecipitated with methanol, an obtained polymer is thermally extracted with a mixed solution of chloroform and methanol (volume ratio of chloroform / methanol=65 / 35) at 50°C, an obtained heat extract has a weight average molecular weight of 3,000 to 7,000, and a content of the heat extract is 0.5 to 3.0 mass% with respect to the wrap film, and a thickness is 6 to 18 μm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a vinylidene chloride resin wrap film.

Background Art

[0002] Conventionally, polyvinylidene chloride resin wrap films have been widely used in many households as simple packaging materials for foods and the like because of their excellent adhesion, gas barrier properties, etc. In recent years, higher functions have been strongly demanded from consumers for polyvinylidene chloride resin wrap films. In particular, good drawability is required while ensuring sufficient proper adhesion.

[0003] Adhesion means the ease of adhesion between a container and a wrap film when using the wrap film. Drawability refers to the ease of drawing out a wrap film wound around a core and stored in a storage box. Usually, if the adhesion between films is too high, it is difficult to draw out the film, and there is a trade-off relationship between adhesion and drawability.

[0004] Patent Document 1 describes a technique for a polyvinylidene chloride resin wrap film having a specific molecular structure.

[0005] In addition, attempts have been made to control various properties by regulating the amount of low-molecular components contained in polyvinylidene chloride resin wrap films, and Patent Documents 2 and 3 describe techniques for defining extracts when extracting polyvinylidene chloride resin wrap films with methanol.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Patent Document 3

[0007] However, the technology described in Patent Document 1 does not provide sufficient adhesion. Furthermore, the technologies described in Patent Documents 2 and 3 do not mention achieving good drawability while ensuring sufficient adhesion.

[0008] This invention has been made in view of the above-mentioned problems, and aims to provide a vinylidene chloride-based resin wrap film that improves usability by ensuring proper adhesion while exhibiting good pullability. [Means for solving the problem]

[0009] The inventors of the present invention conducted diligent research from the perspective of achieving a balance between the conflicting challenges of ensuring adequate adhesion and having good drawability. As a result, they discovered that a vinylidene chloride-based resin wrap film, in which a polymer obtained by reprecipitation of a film dissolved in tetrahydrofuran with methanol is extracted with a chloroform and methanol mixed solution at 50°C (chloroform / methanol volume ratio = 65 / 35), has a weight-average molecular weight of 3,000 to 7,000, and the content of the heat extract is adjusted to 0.5 to 3.0% by mass or less relative to the wrap film, and the thickness is adjusted to 6 to 18 μm, can solve the above problems, and thus completed the present invention. In other words, the present invention is as follows.

[0010] [1] A vinylidene chloride-based resin wrap film, A vinylidene chloride resin wrap film, wherein the wrap film is dissolved in tetrahydrofuran, reprecipitated with methanol, and the resulting polymer is heat-extracted with a chloroform and methanol mixed solution at 50°C (chloroform / methanol volume ratio = 65 / 35), the weight-average molecular weight of the heat extract is 3,000 to 7,000, the content of the heat extract is 0.5 to 3.0% by mass relative to the wrap film, and the thickness is 6 to 18 μm. [2] The vinylidene chloride-based resin wrap film according to [1] above, wherein the peak top molecular weight of the vinylidene chloride copolymer oligomer contained in the heat extract is 4,000 to 8,000. [3] The vinylidene chloride resin wrap film according to [1] or [2] above, wherein the amount of residual additives contained in the heat extract is quantified by NMR, and the amount obtained by subtracting the total amount of residual additives from the amount of the heat extract is 0.3 to 1.8% by mass relative to the wrap film. [4] A vinylidene chloride-based resin wrap film according to any of the above [1] to [3], wherein the 2% tensile modulus in the MD direction is 250 to 600 MPa. [Effects of the Invention]

[0011] According to the present invention, a vinylidene chloride-based resin wrap film can be obtained that achieves both the conflicting goals of ensuring proper adhesion and having good pullability. [Brief explanation of the drawing]

[0012] [Figure 1] This is a schematic diagram of an example of the apparatus used in the film-forming process of the present invention. [Figure 2] This is one example of how the film of the present invention can be used. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments for implementing the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist thereof and implemented.

[0014] The polyvinylidene chloride resin wrap film according to the present embodiment is a polymer obtained by dissolving the wrap film in tetrahydrofuran and reprecipitating with methanol, and heat-extracting with a chloroform and methanol mixed solution (volume ratio of chloroform / methanol = 65 / 35) at 50 °C, wherein the weight average molecular weight of the heat extract is 3,000 to 7,000, and the content of the heat extract is 0.5 to 3.0% by mass based on the wrap film, and the thickness is 6 to 18 μm.

[0015] The polyvinylidene chloride resin wrap film according to the present embodiment contains (1) a vinylidene chloride copolymer as the main component, (2) a heat extract obtained by heat extraction under specific conditions, and (3) additives optionally blended.

[0016] When the polyvinylidene chloride resin wrap film according to the present embodiment is dissolved in tetrahydrofuran and reprecipitated with methanol, additives such as plasticizers, adhesives, tackifiers, and stabilizers (components of (3) above) are eluted into methanol. When the polymer reprecipitated with methanol is further heat-extracted with a chloroform and methanol mixed solution (volume ratio of chloroform / methanol = 65 / 35) at 50 °C, the heat extract (component of (2) above) is eluted into the chloroform and methanol mixed solution (volume ratio of chloroform / methanol = 65 / 35). And mainly the vinylidene chloride copolymer (component of (1) above) remains in the residue after extraction with the chloroform and methanol mixed solution (volume ratio of chloroform / methanol = 65 / 35).

[0017] As a result of the intensive studies by the present inventors, the heat extract obtained by further heat-extracting the polymer after methanol reprecipitation with a chloroform and methanol mixed solution at 50 °C (chloroform / methanol volume ratio = 65 / 35) is a compound having a molecular weight within a specific range. It was found that this compound exhibits adhesion and good drawability by bleeding onto the film surface and spreading throughout the film.

[0018] The heat extract obtained by further heat-extracting the polymer after methanol reprecipitation with a chloroform and methanol mixed solution at 50 °C (chloroform / methanol volume ratio = 65 / 35) is a compound having a molecular weight within a specific range, and it was found that these cannot be extracted with solvents such as acetone and methanol described in Patent Document 2 or 3.

[0019] (Vinylidene chloride resin) The vinylidene chloride resin is not particularly limited as long as it contains a vinylidene chloride repeating unit. For example, a vinylidene chloride copolymer A containing a vinylidene chloride repeating unit and a monomer repeating unit copolymerizable with this can be mentioned.

[0020] The monomers copolymerizable with the vinylidene chloride monomer are not particularly limited. For example, vinyl chloride; acrylic acid esters such as methyl acrylate and butyl acrylate; methacrylic acid esters such as methyl methacrylate and butyl methacrylate; acrylic acid, methacrylic acid; acrylonitrile; vinyl acetate, etc. can be mentioned. These monomers may be used alone or in combination of two or more. Among these, vinyl chloride is more preferable.

[0021] The content of vinylidene chloride repeating units is preferably 72 to 93 mol%, more preferably 81 to 93 mol%, and even more preferably 86 to 93 mol%, relative to the total amount of vinylidene chloride resin. When the content of vinylidene chloride repeating units is 72 mol% or more, the glass transition temperature of the vinylidene chloride resin is low, and the wrap film tends to become softer. This reduces tearing of the wrap film even when used in low-temperature environments such as in winter. On the other hand, when the content of vinylidene chloride repeating units is 93 mol% or less, a significant increase in crystallinity is suppressed, and deterioration of moldability during film stretching tends to be suppressed.

[0022] The content of constituent units derived from vinylidene chloride and vinyl chloride was measured using a high-resolution proton nuclear magnetic resonance (M / C) spectrometer (512 cumulative measurements). The re-precipitation filtrate of the wrap film was vacuum-dried, and a solution of 5% by mass dissolved in tetrahydrofuran deuterated material was measured by H-NMR under a measurement atmosphere of 23±2°C and 50±10% RH. For example, the constituent unit derived from vinylidene chloride (-CH2-CCl2-) is denoted as A, and the constituent unit derived from vinyl chloride (-CH2-CHCl-) is denoted as B. Signals 1, 2, and 3 obtained on the spectrum were assigned as follows. Signal 1 (approximately 5.2-4.5 ppm) was attributed to the CH signal of B (methine (CH) group, a constituent unit derived from vinyl chloride). Signal 2 (approximately 4.2-3.8 ppm) was attributed to the CH2 signal of one of the A components in AA (the methylene (CH2) group, a constituent unit derived from vinylidene chloride). Signal 3 (approximately 3.5–2.8 ppm) was attributed to the CH2 signal of A in both AB and BA (the methylene (CH2) group, a constituent unit derived from vinylidene chloride).

[0023] The mole fractions of the constituent units were determined from the spectral area values ​​(areas of the signals in the NMR spectrum) of these signals. The mole fractions are expressed as follows: • Mole fraction of A (mol%): P(A) • Mole fraction of B (mol%): P(B)

[0024] Based on the area values ​​(peak areas in the NMR spectrum) of signals 1, 2, and 3 assigned as described above, the integral values ​​of the signals on the spectrum were assigned as follows. The integral of signal 1 (approximately 5.2-4.5 ppm) is equivalent to one 1H of B. • The integral of signal 2 (approximately 4.2-3.8 ppm) is divided into 1H2 units of A. • The integral of signal 3 (approximately 3.5-2.8 ppm) is divided into 1H4 units of A.

[0025] The mole fractions were calculated using the following equation. P(A) + P(B) = 100

[0026] P(A) and P(B) are calculated using the following formulas. 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)

[0027] The molecular weight of A, a constituent unit derived from vinylidene chloride (-CH2-CCl2-), was set to 97.0, and the molecular weight of B, a constituent unit derived from vinyl chloride (-CH2-CHCl-), was set to 62.5. The following equation was used to calculate each mass fraction. The mass fractions are 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)

[0028] Furthermore, when the vinylidene chloride resin is a vinylidene chloride-vinyl chloride copolymer, the comonomer (vinyl chloride) content of the vinylidene chloride-vinyl chloride copolymer is preferably 7 to 28% by mass, and more preferably 10 to 19% by mass, relative to the total amount of copolymer. When the comonomer content of the vinylidene chloride copolymer is within the above range, tearing of the wrap film is reduced, and deterioration of moldability during film stretching tends to be further suppressed.

[0029] The weight-average molecular weight (Mw) of vinylidene chloride copolymer A is preferably 80,000 to 200,000, more preferably 90,000 to 180,000, and even more preferably 100,000 to 170,000. A weight-average molecular weight (Mw) within this range tends to improve the mechanical strength of the wrap film. A vinylidene chloride resin with a weight-average molecular weight within this range can be obtained, for example, by controlling the charging ratio of vinylidene chloride monomer to copolymerizable monomers, the amount of polymerization initiator, or the polymerization temperature. In this embodiment, the weight-average molecular weight (Mw) can be determined using a standard polystyrene calibration curve by gel permeation chromatography (GPC).

[0030] The polyvinylidene chloride-based resin wrap film of this embodiment is obtained by dissolving the wrap film in tetrahydrofuran, reprecipitating the polymer with methanol, and then heat-extracting the resulting polymer with a chloroform and methanol mixed solution (chloroform / methanol volume ratio = 65 / 35) at 50°C. The heat extract content of the heat extract relative to the wrap film is 0.5 to 3.0% by mass, preferably 0.5 to 2.0% by mass, and more preferably 0.9 to 2.2% by mass. When the heat extract content relative to the film is 0.5% by mass or more, the bleed material spreads uniformly, resulting in moderate adhesion and low drawability. When it is 3.0% by mass or less, the thickness of the bleed material is maintained uniformly, resulting in moderate drawability and high adhesion. The heat extract content is the content relative to the film and can be measured according to the method described in the examples below.

[0031] Here, the thermal extract obtained by thermal extraction with a chloroform and methanol mixed solution at 50°C (chloroform / methanol volume ratio = 65 / 35) is a compound having a specific molecular weight range, and its main component is an oligomer produced during polymerization. As a result of diligent research, the inventors have found that by appropriately changing the molecular weight distribution (Mw / Mn) of the vinylidene chloride resin, vinylidene chloride copolymer oligomers can be produced as compounds having a specific molecular weight range. In other words, when the polymer after methanol reprecipitation is further thermally extracted with a chloroform and methanol mixed solution at 50°C (chloroform / methanol volume ratio = 65 / 35), the content of the thermal extract can be set to 0.5 to 3.0% by mass by appropriately adjusting the weight-average molecular weight and number-average molecular weight of the vinylidene chloride resin.

[0032] Here, the thermal extract refers to a mixture of vinylidene chloride copolymer oligomer A and, for example, epoxidized soybean oil (ESO), tributyl acetyl citrate (ATBC), and acetylated diglyceride of lauric acid (DALG), and its weight-average molecular weight is 3,000 to 7,000, preferably 3,000 to 6,000, and more preferably 3,000 to 5,000. When the weight-average molecular weight of the thermal extract is 3,000 or more, the viscosity of the bleed product becomes moderately high, making it easier to maintain a uniform thickness of the bleed product and tending to improve the balance between adhesion and extraction. When it is 7,000 or less, it tends to bleed easily, providing moderate adhesion, and the extraction force tends to be low.

[0033] Furthermore, the peak-top molecular weight of vinylidene chloride copolymer oligomer A contained in the heat extract is preferably 4,000 to 8,000, more preferably 4,000 to 7,000, and even more preferably 4,000 to 6,000. When the peak-top molecular weight of vinylidene chloride copolymer oligomer A contained in the heat extract is 4,000 or more, the viscosity of vinylidene chloride copolymer oligomer A in the bleed product becomes moderately high, making it easier to maintain a uniform thickness in the bleed product and tending to improve the balance between adhesion and extraction. When it is 8,000 or less, vinylidene chloride copolymer oligomer A tends to bleed more easily, providing moderate adhesion and tending to have lower extraction force.

[0034] As mentioned above, the content of the heat extract can be adjusted to a range of 0.5 to 3.0% by mass relative to the wrap film by appropriately adjusting the weight-average molecular weight and number-average molecular weight of the vinylidene chloride copolymer, but this can also be achieved by adding a compound with a specific molecular weight range to the vinylidene chloride resin.

[0035] The compound having a specific molecular weight range is not particularly limited, but vinylidene chloride copolymer oligomer B is preferred. The vinylidene chloride copolymer oligomer B is not particularly limited, but is a compound obtained by copolymerizing a vinylidene chloride monomer with another monomer copolymerizable with it. The monomer copolymerizable with vinylidene chloride monomer is not particularly limited, but examples include vinyl chloride; acrylic acid esters such as methyl acrylate and butyl acrylate; methacrylic acid esters such as methyl methacrylate and butyl methacrylate; acrylic acid, methacrylic acid; acrylonitrile; vinyl acetate, etc. These monomers may be used individually or in combination of two or more. Among these, vinyl chloride is more preferred.

[0036] The weight-average molecular weight (Mw) of vinylidene chloride copolymer oligomer B is preferably 3,000 to 7,000, more preferably 3,000 to 6,000, and even more preferably 3,000 to 5,000. A vinylidene chloride copolymer oligomer B having a weight-average molecular weight within the above range can be obtained, for example, by controlling the charging ratio of vinylidene chloride monomer to vinyl chloride monomer, the amount of polymerization initiator, or the polymerization temperature.

[0037] For example, 0.4 to 2.2 parts by mass of vinylidene chloride copolymer oligomer B can be added to 89.5 to 92.0 parts by mass of polyvinylidene chloride copolymer A. This makes it possible to achieve a thermal extract content of 0.5 to 3.0% by mass in the film when the polymer after methanol reprecipitation is further thermally extracted with a chloroform and methanol mixed solution at 50°C (chloroform / methanol volume ratio = 65 / 35).

[0038] In this embodiment, the polystyrene-equivalent molecular weight, peak-top molecular weight, and weight-average molecular weight (Mw) can be determined using a standard polystyrene calibration curve by gel permeation chromatography (GPC).

[0039] Furthermore, the amount of residual additives contained in the heat extract is quantified by NMR, and the amount obtained by subtracting the total amount of residual additives from the amount of heat extract is preferably 0.3 to 1.8% by mass relative to the wrap film, more preferably 0.3 to 1.3% by mass, and even more preferably 0.6 to 1.3% by mass. When the amount obtained by subtracting the total amount of residual additives from the amount of heat extract is 0.3% by mass or more relative to the wrap film, the vinylidene chloride copolymer oligomer A in the bleed product spreads uniformly, resulting in moderate adhesion and low drawability. When it is 1.8% by mass or less, the thickness of the bleed product is maintained uniformly, and the vinylidene chloride copolymer oligomer A is distributed uniformly and abundantly on the surface, resulting in moderate drawability and high adhesion.

[0040] (Additives) The vinylidene chloride-based resin wrap film of this embodiment preferably contains at least one additive selected from the group consisting of epoxidized fatty acid ester compounds, citrate esters, dibasic acid esters, and acetylated fatty acid glycerides. Among these, citrate esters are preferred from the viewpoint of handling.

[0041] (Citrate ester) The citric acid ester is not particularly limited, but examples include triethyl citrate, tributyl citrate, triethyl acetyl citrate, tributyl acetyl citrate (ATBC), and tri-n-(2-ethylhexyl) acetyl citrate. Among these, tributyl acetyl citrate is preferred. By using acetylated tributyl citrate, the vinylidene chloride resin is plasticized, and the moldability tends to improve. In addition, the frequency of cuts is reduced, tearing problems are suppressed, and cutability tends to improve.

[0042] The citrate ester content is preferably more than 0% by mass and 8% by mass or less, more preferably more than 0% by mass and 7% by mass or less, and even more preferably more than 0% by mass and 6.5% by mass or less, relative to the total amount of vinylidene chloride resin wrap film. When the citrate ester content is within the above range, the moldability tends to be further improved. In addition, the frequency of cuts is reduced, tearing problems are suppressed, and cutability tends to be further improved. Note that the method for measuring the content of each component from the wrap film varies depending on the analyte. The citrate ester content can be obtained by extracting the additive from the wrap film using an organic solvent such as acetone at a temperature 5 to 10°C lower than the boiling point of the extraction solvent, and then performing gas chromatography analysis.

[0043] (Dibasic acid ester) Examples of dibasic acid esters include, but are not particularly limited, adipic acid esters such as dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, and dioctyl adipate; azelaic acid esters such as di-2-ethylhexyl azelaic acid and octyl azelaic acid; sebacate acid esters such as dibutyl sebacate (DBS) and di-2-ethylhexyl sebacate; and phthalate esters such as dimethyl phthalate, diethyl phthalate, and dioctyl phthalate.

[0044] Among these, aliphatic dibasic acid esters are preferred, and dibutyl sebacate is more preferred. By using such dibasic acid esters, the vinylidene chloride resin is plasticized, and the moldability tends to improve. In addition, the frequency of cuts is reduced, tearing problems are suppressed, and cutability also tends to improve.

[0045] The dibasic acid ester content is preferably more than 0% by mass and 8% by mass or less, more preferably more than 0% by mass and 7% by mass or less, and even more preferably more than 0% by mass and 6.5% by mass or less, relative to the total amount of the wrap film. When the dibasic acid ester content is within the above range, the processability of the wrap tends to improve. In addition, the frequency of cuts is reduced, tearing problems are suppressed, and the cutability also tends to improve. The dibasic acid ester content can be obtained by extracting the additive from the wrap film using an organic solvent such as acetone at a temperature 5 to 10°C lower than the boiling point of the extraction solvent, and then analyzing it by gas chromatography.

[0046] (Acetylated fatty acid glycerides) There are no particular limitations on the acetylated fatty acid glycerides, but examples include acetylated caprylic acid glyceride, acetylated capric acid glyceride, acetylated laurate glyceride, acetylated myristic acid glyceride, acetylated palm kernel oil glyceride, acetylated coconut oil glyceride, acetylated castor oil glyceride, and acetylated hydrogenated castor oil glyceride.

[0047] Acetylated fatty acid glycerides may be acetylated monoglycerides, acetylated diglycerides, or acetylated triglycerides of fatty acids. For example, the above-mentioned acetylated laurate glycerides include acetylated monoglycerides of lauric acid, acetylated diglycerides of lauric acid (DALG: diacetyllauroylglycerol), and acetylated triglycerides of lauric acid. Among these, acetylated laurate glycerides are preferred, and acetylated diglycerides of lauric acid are more preferred. By using such acetylated fatty acid glycerides, the frequency of cuts is reduced, tearing problems are suppressed, and cutability tends to be further improved.

[0048] The content of acetylated fatty acid glycerides is preferably more than 0% by mass and 8% by mass or less, more preferably more than 0% by mass and 7% by mass or less, and even more preferably more than 0% by mass and 6.5% by mass or less, relative to the total amount of the wrap film. When the content of acetylated fatty acid glycerides is within the above range, the processability of the wrap tends to improve. In addition, the frequency of cuts is reduced, tearing problems are suppressed, and the cutability also tends to improve. The content of acetylated fatty acid glycerides can be obtained by extracting the additive from the wrap film using an organic solvent such as acetone at a temperature 5 to 10°C lower than the boiling point of the extraction solvent, and then analyzing it by gas chromatography.

[0049] (Epoxy vegetable oil) The vinylidene chloride resin wrap film of this embodiment may contain epoxidized vegetable oil. The epoxidized vegetable oil can act as a stabilizer for vinylidene chloride resin extrusion processing. The epoxidized vegetable oil is not particularly limited, but generally, those produced by epoxidizing edible oils and fats are examples. Specifically, examples of epoxidized vegetable oils include epoxidized soybean oil (ESO) and epoxidized linseed oil. Among these, epoxidized soybean oil is preferred. By using such an epoxidized vegetable oil, color changes in the wrap film are further suppressed, and the ease of pulling the film out of the cosmetic box tends to improve.

[0050] In this embodiment, the content of epoxidized vegetable oil is preferably 0.5 to 3% by mass, more preferably 1 to 2.5% by mass, and even more preferably 1 to 2% by mass, relative to the total amount of wrap film. When the content of epoxidized vegetable oil is 0.5% by mass or more, the quality changes of the wrap film tend to be further suppressed. Furthermore, when the content of epoxidized vegetable oil is 3% by mass or less, the color changes of the wrap film tend to be further suppressed, and stickiness due to bleeding tends to be suppressed. The content of epoxidized vegetable oil can be obtained by NMR analysis of the re-precipitation filtrate of the wrap film.

[0051] Specifically, the sample is weighed to 50 mg, dissolved in a deuterated solvent (solvent: deuterated tetrahydrofuran, internal standard: dimethyl terephthalate, volume: 0.7 ml), measured using 400 MHz proton NMR (number of integrations: 512 times), the integral ratio is taken as the ratio of the integral value of 2.23 to 2.33 ppm to the integral value of 8.05 to 8.11 ppm, and the quantitative value is calculated using the absolute calibration curve method to obtain the result. Integral ratio = Integral value (2.23~2.33 ppm) / Integral value (8.05~8.11 ppm)

[0052] (others) The vinylidene chloride-based resin wrap film of this embodiment may contain additives other than those mentioned above. Such additives are not particularly limited, but examples include plasticizers other than those mentioned above, stabilizers other than those mentioned above, weather resistance improvers, colorants such as dyes or pigments, antifogging agents, antibacterial agents, lubricants, nucleating agents, oligomers such as polyester, polymers such as MBS (methyl methacrylate-butadiene-styrene copolymer), and the like.

[0053] Plasticizers other than acetylated fatty acid glycerides, citrate esters, and dibasic acid esters are not particularly limited, but specifically include glycerin, glycerin esters, waxes, liquid paraffin, and phosphate esters. These plasticizers may be used individually or in combination of two or more.

[0054] Other stabilizers besides epoxidized vegetable oils are not particularly limited, but specifically include antioxidants such as 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), octadecyl-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate, and 4,4'-thiobis-(6-t-butylphenol); and heat stabilizers such as laurate, myristicate, palmitate, stearate, isostearate, oleate, ricinoleate, 2-ethylhexylate, isodecanate, neodecanoate, and calcium benzoate. These stabilizers may be used individually or in combination of two or more.

[0055] The weather resistance improver is not particularly limited, but specific examples include ethylene-2-cyano-3,3'-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl)benzolytriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone. The weather resistance improver may be used alone or in combination of two or more types.

[0056] The colorants, such as dyes or pigments, are not particularly limited, but specific examples include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, and red iron oxide. These colorants may be used individually or in combination of two or more.

[0057] The anti-fogging agents are 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. These anti-fogging agents may be used individually or in combination of two or more.

[0058] The antibacterial agent is not particularly limited, but specific examples include silver-based inorganic antibacterial agents. The antibacterial agent may be used alone or in combination of two or more types.

[0059] The lubricant is not particularly limited, but specific examples include fatty acid hydrocarbon lubricants such as ethylene bissteramide, butyl stearate, polyethylene wax, paraffin wax, carnauba wax, myristyl myristate, and stearyl stearate, as well as higher fatty acid lubricants, fatty acid amide lubricants, and fatty acid ester lubricants. These lubricants may be used individually or in combination of two or more.

[0060] The nucleating agent is not particularly limited, and specifically, metal phosphate esters and the like can be mentioned. The nucleating agent may be used alone or in combination of two or more.

[0061] The content of other additives is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less, and particularly preferably 0.1% by mass or less, based on the total amount of the vinylidene chloride resin wrap film. The lower limit of the content of other additives is not particularly limited, but is 0% by mass or more based on the total amount of the wrap film.

[0062] (Thickness of the wrap film) The thickness of the vinylidene chloride resin wrap film of this embodiment is 6 to 18 μm, preferably 9 to 12 μm. When the thickness is 6 μm or more, the thickness of the bleed is uniformly maintained, and the balance between adhesion and drawability tends to be good.

[0063] On the other hand, when the thickness is 18 μm or less, the vinylidene chloride copolymer oligomer A and additives tend to bleed easily, and appropriate adhesion and low drawability tend to be obtained. Also, when the thickness is 18 μm or less, the wrap film tends to fit well into the container shape, and the adhesion to the container tends to be further improved.

[0064] <2% Tensile modulus in the MD direction> The vinylidene chloride resin wrap film of this embodiment preferably has a 2% tensile modulus in the MD direction of 250 to 600 MPa, more preferably 350 to 550 MPa, and still more preferably 350 to 500 MPa. Here, the MD direction refers to the direction in which the wrap film is drawn out from the wound body. The 2% tensile modulus in the MD direction can be measured by the method described in the examples below. In this embodiment, the vinylidene chloride-based resin wrap film has a 2% tensile modulus of 250 MPa or higher in the MD direction, which gives the film firmness and makes it easier to pull out with light force. On the other hand, if the 2% tensile modulus of 600 MPa or lower in the MD direction, the film is softer and tends to conform more easily to the surface irregularities of the object to be adhered to, resulting in higher adhesion.

[0065] The tensile modulus in the MD direction of the wrap film in this embodiment can be adjusted by the composition of the vinylidene chloride resin, the additive composition, the film's stretching ratio, and the stretching speed. The tensile modulus in the MD direction tends to improve by increasing the stretching ratio or decreasing the amount of additives, for example, and tends to decrease by decreasing the stretching ratio or increasing the amount of additives.

[0066] [Method for manufacturing vinylidene chloride resin wrap film] The method for manufacturing the vinylidene chloride resin wrap film of this embodiment is not particularly limited, but examples include a method comprising the steps of melt-extruding a vinylidene chloride resin to form a film, and stretching the obtained film in the MD direction and the TD direction. A detailed explanation follows below.

[0067] (Mixing process) Figure 1 shows a schematic diagram of an example of the apparatus used in the film-forming process of wrap film. First, a composition is obtained by mixing vinylidene chloride resin with, if necessary, compounds having a specific molecular weight range, acetylated fatty acid glycerides, epoxidized vegetable oils, etc., in a mixer. Various additives may be mixed in as needed. The mixer is not particularly limited, but for example, a ribbon blender or a Henschel mixer can be used. It is preferable to age the obtained composition for about 1 to 30 hours before using it in the next step.

[0068] (Melting extrusion process) Next, the obtained composition is melted by an extruder 1, and an annular film is extruded from the die opening 3 of the die 2 to form a sock 4 (also called a pile).

[0069] (cooling process) The sock liquid 5 is injected into the inside of the sock 4, and the outside of the sock 4 is brought into contact with the cold water in the cold water tank 6. As a result, the sock 4 is cooled from both the inside and the outside, and the film that makes up the sock 4 solidifies. The solidified sock 4 is folded by the first pinch roll 7 to form a parison 8.

[0070] (Stretching process) Next, air is injected into the inside of the parison 8 to open it and form a tubular film. At this time, the sock liquid 5 applied to the part that comes into contact with the inner surface of the sock 4 acts as an opening agent for the parison 8. Then, with the parison 8 open, it is reheated with hot water to a temperature suitable for stretching. The hot water adhering to the outside of the parison 8 is squeezed off by the second pinch roll 9.

[0071] As described above, air is injected into the parison 8, which has been heated to the appropriate temperature, to form a bubble 10. This air pushes the parison outward from the inside, stretching the film and obtaining a stretched film. Stretching of the film mainly in the TD direction is achieved by the amount of air, while stretching of the film in the MD direction is achieved by applying tension in the direction of film flow using the second pinch roll 9 and the third pinch roll 11, etc.

[0072] 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 methods for manufacturing wrap films, the stretching speed in the MD direction was adjusted to 0.08 times / s or less, and the stretching speed in the TD direction was adjusted to 3.0 times / s or less. In contrast, in the method for manufacturing vinylidene chloride resin wrap films of this embodiment, it is preferable to adjust the stretching ratios in the MD and TD directions, and the stretching speeds in the MD and TD directions, to a predetermined range.

[0073] Specifically, the stretching ratios in the MD direction and TD direction in the stretching process of this embodiment are preferably 4 to 6 times, and more preferably 4.5 to 5.5 times, independently of each other. Here, the stretching ratio in the MD direction refers to the stretching ratio when the parison 8 is stretched in the MD direction, and for example, in Figure 1, it can be calculated by the ratio of the rotation speed of the third pinch roll 11 to the rotation speed of the first pinch roll 7. The stretching ratio in the TD direction refers to the stretching ratio when the parison 8 is stretched in the TD direction, and for example, in Figure 1, it can be calculated by the ratio of the width of the double ply film 12 to the width of the parison 8. The stretching ratio in the MD direction can be adjusted, for example, by the rotation speed ratio of the first pinch roll 7 and the third pinch roll 11, and the stretching 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.

[0074] Furthermore, the stretching speed in the MD direction during the stretching process 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 Figure 1, it can be calculated by the rotational speed of the first pinch roll 7, the rotational speed of the third pinch roll 11, and the time required 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 rotational speed of the first pinch roll 7 or the third pinch roll 11, or by the distance between the first pinch roll 7 and the third pinch roll 11.

[0075] Furthermore, the stretching speed in the TD direction during 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 to the bubble 10. For example, in Figure 1, it can be calculated from the time required for stretching in the TD direction, which is calculated from the stretched length measured using still images of the parison 8 and bubble 10 and 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.

[0076] The stretching temperature is not particularly limited, but is preferably 30 to 45°C.

[0077] After the stretching process described above, the stretched film is folded by the third pinch roll 11 to form a double-ply film 12. The double-ply film 12 is then wound up by the winding roll 13.

[0078] (Slitting process) The wrap film, wound as described above, is slit and peeled off into individual sheets, which are then wound up and temporarily stored in its roll form for 1 to 3 days. Finally, it is wound back onto a cardboard tube and packed into a cosmetic box, resulting in a roll of wrap film stored in a cosmetic box.

[0079] (Storage process) In the method for manufacturing the wrap film of this embodiment, a storage step may be performed in which the wrap film is stored in its original roll state after slitting. 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.

[0080] After storage, the slit film roll is rewound onto a paper tube or the like (though this is not particularly limited) and stored as a rewound body 16 in a cosmetic box 1 equipped with a film saw blade 15, as shown in Figure 2. As illustrated in Figure 2, the wrap film 17 is pulled out and used when needed. [Examples]

[0081] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited in any way thereto.

[0082] The evaluation method for the wrap film in the examples and comparative examples is as follows.

[0083] [Evaluation Method] (1. Adhesion) Bottom area 25cm 2 Two cylindrical aluminum jigs, 55 mm high and weighing 400 g, were prepared, and filter paper of the same shape as the bottom surface was attached to the bottom surface of both jigs. Plastic wrap was placed over the bottom surfaces of the jigs with the attached filter paper to prevent wrinkles, and secured with rubber bands. The two jigs, covered with plastic wrap, were placed together so that the sides covered with plastic wrap were tightly overlapping, and pressed together with a load of 500 g for 1 minute. Next, the amount of work required to peel the two plastic wrap surfaces apart perpendicular to each other was measured using a tensile and compression testing machine at a speed of 5 mm / min (unit: mJ / 25cm). 2 This measurement was performed in an atmosphere of 23±2℃ and 50±10%RH.

[0084] The adhesion of the wrap film was determined by evaluating the measured amount of adhesion work on a four-point scale. [Table 1]

[0085] (2. Withdrawability) A free roll was prepared consisting of a cylindrical plastic roll approximately 310 mm long with a diameter of 40 mm, the same as the inner surface of the paper tube of the wrap film, a 330 mm long aluminum pivot shaft with the center of the cylinder as its axis, and a bearing to drive it. This roll was mounted inside the paper tube of the wrap film so that the widthwise center of the wrap film and the lengthwise center of the free roll drive unit aligned. The free roll, integrated with the wrap film, was then fixed to a bearing installed at the bottom of the tensile-compression testing machine, with the pivot shaft inserted into a hanger suspended on the load cell side at the top of the machine, so that the hanger and the pivot shaft were parallel, and the widthwise center of the wrap film was positioned vertically from the center of the hanger. Furthermore, the wrap film integrated with the free roll was peeled off, and this film was fixed to the hanger suspended on the load cell side at the top of the testing machine with double-sided tape, ensuring that there were no wrinkles. Next, the wrap film was peeled vertically from the paper tube at a speed of 1000 mm / min using the tensile-compression testing machine. At this time, the peak force required to peel the wrap film from the paper tube was measured using a pull-out force measuring jig, and this was used as the measure of pull-out performance (unit: cN / 30cm width). The pull-out performance of the wrap film was determined from the measured values ​​using the following four-level evaluation. The measurements were taken in an atmosphere of 23±2℃ and 50±10%RH.

[0086] [Table 2]

[0087] (Film thickness) The thickness of the wrap film was measured using a precision dial gauge (TM-1201, manufactured by Teclock Co., Ltd.) in an atmosphere of 23±2℃ and 50±10%RH.

[0088] (2% tensile modulus in the MD direction) The tensile modulus of the wrap film in the MD direction was evaluated using an Autograph AG-IS (Shimadzu Corporation) in an atmosphere of 23±2℃ and 50±10%RH. A 150mm long, 10mm wide strip of wrap film was cut in the MD direction to form a test specimen. To prevent damage to the specimen, the blade was replaced after each cut. The load was measured at a tensile speed of 5mm / min, a chuck distance of 100mm, and a film width of 10mm, when the tensile strain between the crossheads reached 2%. The load was then multiplied by 50 (i.e., the load was multiplied by 2%), and then the cross-sectional area of ​​the specimen was used to calculate the tensile modulus of the wrap film in the MD direction (unit: MPa). During measurement, the specimen was mounted in the grips so that the MD direction of the specimen aligned with the tensile direction of the testing machine. The specimen was evenly and firmly clamped in the grips to prevent slippage and to ensure the grips did not shift during the test. Additionally, the arithmetic mean of the three results obtained from the five measurements, excluding the highest and lowest values, was calculated and rounded to two significant figures, with the third digit rounded to the nearest tenth.

[0089] (Measurement of oligomer content) (1) Preparation of thermal extracts (Reprecipitation) 3 g of plastic wrap film was weighed into a 200 ml tall beaker, 30 ml of tetrahydrofuran was added, and the mixture was dissolved at 50°C. 170 ml of methanol was added dropwise to this solution over 2 hours while stirring, allowing the polymer to precipitate. After the methanol addition was complete, the mixture was filtered under reduced pressure through a glass filter (pore size: G4), and the filtrate was dried overnight at room temperature. The filtrate was then dried in a vacuum oven (below 100 Pa, 40°C for 7 hours) to obtain the reprecipitated polymer. (1st heat extraction) Chloroform and methanol were mixed in a volume ratio of 65 / 35 to prepare a chloroform and methanol mixture (chloroform / methanol volume ratio = 65 / 35) as the extraction solvent. The reprecipitated polymer and extraction solvent were placed in a 100 ml Erlenmeyer flask with a lid, and thermal extraction was carried out at 50°C for 1 hour. The hot extract was filtered by suction through a glass filter (pore size: G4), and the extract was transferred to a round-bottom flask. (Second heat extraction) The residue and extraction solvent remaining in the glass filter (pore size: G4) were returned to a 100 ml Erlenmeyer flask with a lid, and thermal extraction was performed in the same manner as the first time. (3rd heat extraction) After the second thermal extraction, the residue and extraction solvent remaining in the glass filter (pore size: G4) were returned to a 100 ml Erlenmeyer flask with a lid, and the same thermal extraction process as the first was performed. (concentrated) The extracts obtained from the three heat extractions described above were concentrated using an evaporator and transferred entirely to weighed 10 ml sample bottles with chloroform. The samples were concentrated by heating them in a water bath at 50°C for 3 hours, and then vacuum-dried in a vacuum constant-temperature drying oven (below 100 Pa, 40°C for 5 hours). The dried material was used as the heat extract. (Quantification of thermal extract amount) The sample bottles were weighed after vacuum drying, and the weight of the heat extract was determined by subtracting the tare weight. The amount relative to the wrap film was then quantified by dividing the weight by 3 g of wrap film. (Weight-average molecular weight of heat extract) 5 ml of chloroform was added to the sample vial containing the heat extract, and the heat extract was dissolved. The sample was filtered through a syringe filter (PTFE material, pore size 0.45 μm), and GPC measurement was performed under the following conditions. Molecular weight calibration was performed using standard polystyrene manufactured by GL Sciences Co., Ltd. (6 points in the range of weight-average molecular weight from 580 to 7,000), and the weight-average molecular weight of the heat extract was calculated. (GPC measurement conditions) Equipment: LC-9101 (manufactured by Nippon Analytical Industry Co., Ltd.) Detector: RI7 (manufactured by Nippon Analytical Industry Co., Ltd.) Column: JAIGEL-2HR+2HR (manufactured by Nippon Analytical Engineering Co., Ltd.) Mobile phase: Chloroform Column temperature: Room temperature Flow rate: 9.999ml / min Injection volume: 3ml

[0090] (Peak top molecular weight of oligomer) Components in the heat extract with a polystyrene-equivalent molecular weight of 3,500 or more are oligomers, and the peak top molecular weight of the oligomers was calculated from GPC measurements.

[0091] (Quantification of oligomer quantity) The amount of oligomers was calculated by subtracting the total amount of residual plasticizers from the amount of thermal extract. The total amount of residual plasticizers was quantified by NMR measurement as described below.

[0092] (NMR measurement) 0.7 ml of deuterated chloroform containing an internal standard (dimethyl terephthalate) was added to a sample vial containing the heat extract and dissolved. This solution was transferred to an NMR sample tube, and NMR measurements were performed under the following conditions. [NMR conditions] Equipment: JMN-ECS400 (manufactured by JEOL Ltd.) Measurement nucleus: 1H Probe: For 5ml diameter Lock solvent: Deuterated chloroform Temperature :OFF Chemical shift reference: TMS (δ-0 ppm) 0.03 vol% Total number of times: 256 Internal standard: Dimethyl terephthalate Internal standard concentration: 1.0g / l [NMR analysis] The integration ratio was based on the integrated value of the signal derived from the internal standard with a chemical shift of 8.00 to 8.20. Signals with an integration ratio of 0.1 to 3.0 relative to the internal standard signal that were not derived from vinylidene chloride resin were considered to be signals derived from residual additives, and the amount of each residual additive relative to the wrap film was quantified from the proton number of each component. The amount of oligomers was quantified by subtracting the total amount of each residual additive from the amount of thermal extract. ESO, ATBC, and DALG are the main residual additives, but are not limited to these.

[0093] (Polymerization of vinylidene chloride copolymer A1) A mixture containing vinylidene chloride and vinyl chloride in a mass ratio of 82:18 was used as the monomer to polymerize. Polymerization was started at an initial polymerization temperature of 45°C, and the relationship between time (t) and the difference between the polymerization temperature and the initial polymerization temperature (T:°C) is given by the following equation (1a): T = 0.0274t 2 +0.2234t (1a) Polymerization was carried out while increasing the temperature under the heating conditions shown, and then suspension polymerization was performed at a constant temperature of 62°C for 6 hours during the later stages of polymerization to obtain vinylidene chloride-vinyl chloride copolymer A1. The total polymerization time was 27 hours. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer A1 was 100,000.

[0094] (Polymerization of vinylidene chloride copolymer A2) A mixture containing vinylidene chloride and vinyl chloride in a mass ratio of 82:18 was used as the monomer to polymerize. Polymerization was started at an initial polymerization temperature of 45°C, and the relationship between time (t) and the difference between the polymerization temperature and the initial polymerization temperature (T:°C) is given by the following equation (1b): T = 0.0216t 2 +0.1764t (1b) Polymerization was carried out while increasing the temperature under the heating conditions shown, and then suspension polymerization was performed at a constant temperature of 62°C for 3 hours during the later stages of polymerization to obtain vinylidene chloride-vinyl chloride copolymer A2. The total polymerization time was 27 hours. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer A2 was 130,000.

[0095] (Polymerization of vinylidene chloride copolymer A3) A mixture containing vinylidene chloride and vinyl chloride in a mass ratio of 82:18 was used as the monomer to polymerize. Polymerization was started at an initial polymerization temperature of 45°C, and the relationship between time (t) and the difference between the polymerization temperature and the initial polymerization temperature (T:°C) is given by the following equation (1c): T = 0.0140t 2 +0.1100t (1c) Polymerization was carried out while increasing the temperature under the heating conditions shown, and then suspension polymerization was performed at a constant temperature of 62°C for 3 hours during the later stages of polymerization to obtain vinylidene chloride-vinyl chloride copolymer A3. The total polymerization time was 32 hours. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer A3 was 105,000.

[0096] (Polymerization of vinylidene chloride copolymer oligomer B1) A mixture containing vinylidene chloride and vinyl chloride in a mass ratio of 40:60 was used as the monomer for polymerization. Polymerization was started at an initial temperature of 60°C and suspended polymerization was carried out at a constant temperature for 15 hours to obtain vinylidene chloride-vinyl chloride copolymer B1. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer B1 was 3,800.

[0097] (Polymerization of vinylidene chloride copolymer oligomer B2) A mixture containing vinylidene chloride and vinyl chloride in a mass ratio of 30:70 was used as the monomer for polymerization. Polymerization was started at an initial temperature of 60°C and suspended polymerization was carried out at a constant temperature for 15 hours to obtain vinylidene chloride-vinyl chloride copolymer B2. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer B2 was 2,500.

[0098] (Polymerization of vinylidene chloride copolymer oligomer B3) A mixture containing vinylidene chloride and vinyl chloride in a 50:50 mass ratio was used as the monomer for polymerization. Polymerization was started at an initial temperature of 60°C and suspended polymerization was carried out at a constant temperature for 15 hours to obtain vinylidene chloride-vinyl chloride copolymer B3. The weight-average molecular weight of vinylidene chloride-vinyl chloride copolymer B3 was 8,500.

[0099] (Example 1) A mixture was obtained by mixing 91.2 parts by mass of vinylidene chloride copolymer A1 and 0.5 parts by mass of vinylidene chloride copolymer oligomer B1. To this mixture, 2.5 parts by mass of tributyl acetyl citrate (ATBC, manufactured by Taoka Chemical Industries, Ltd.), 3.0 parts by mass of diacetyl monolauryl glyceride (DALG, manufactured by Riken Vitamin Co., Ltd.), and 2.8 parts by mass of epoxidized soybean oil (ESO, manufactured by Nippon Oil & Fats Co., Ltd.) were added as additives. The above mixture was mixed in a Henschel mixer for 5 minutes and aged for 24 hours or more to obtain a vinylidene chloride-based resin composition. The above vinylidene chloride resin composition was supplied to a melt extruder and melted. The extruder was then extruded in an annular shape at an extrusion rate of 10 kg / hour while adjusting the heating conditions of the extruder so that the temperature of the molten resin composition at the slit outlet of the annular die attached to the tip of the extruder reached 170°C. After supercooling the extruded material, it was stretched 4.1 times in the length (MD) direction and 5.6 times in the width (TD) direction by inflation stretching to obtain a tubular wrap film. Various characteristics were measured as described above. The measurement results are shown in Tables 3 and 4.

[0100] (Examples 2-14), (Comparative Examples 1-10) A wrap film was obtained using the same method as in Example 1, except that the mixing ratio of each component and the stretching conditions were changed to those shown in Table 3. Various properties were measured as described above. The measurement results are shown in Tables 3 and 4. [Table 3]

[0101] [Table 4] [Explanation of symbols]

[0102] 1...Extruder, 2...Hopper, 3...Screw, 4...Circular die, 5...Cylindrical parison, 6...Cooling tank, 7...Cooling water, 8...Refrigerant inside parison, 9...Hot water tank, 20, 21, 22, 23, 24, 25...Pinch rolls, 30, 31...Winding bobbins, 14...Cosmetic box, 15...Film cutting blade, 16...Winding body, 17...Wrap film.

Claims

1. A vinylidene chloride-based resin wrap film, A vinylidene chloride-based resin wrap film comprising (A) a vinylidene chloride copolymer oligomer and (B) at least one additive selected from the group consisting of epoxidized fatty acid ester compounds, citrate esters, dibasic acid esters, and acetylated fatty acid glycerides, wherein the weight-average molecular weight of the heat extract containing (A) and (B) is 3,000 to 7,000, the content of the heat extract is 0.5 to 3.0% by mass relative to the wrap film, and the thickness is 6 to 18 μm.

2. The vinylidene chloride-based resin wrap film according to claim 1, wherein the peak top molecular weight of the vinylidene chloride copolymer oligomer contained in the heat extract is 4,000 to 8,000.

3. The vinylidene chloride-based resin wrap film according to claim 1 or 2, wherein the amount of residual additives contained in the heat extract is quantified by NMR, and the amount obtained by subtracting the total amount of residual additives from the amount of the heat extract is 0.3 to 1.8% by mass relative to the wrap film.

4. A vinylidene chloride-based resin wrap film according to any one of claims 1 to 3, wherein the 2% tensile modulus in the MD direction is 250 to 600 MPa.

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