JP2023068620A - wrap film - Google Patents

Abstract

To provide a wrap film that is easy to pick up and recover a cut end face when the film is cut in the middle when the wrap film is pulled out from a decorative box, and easy to reuse.SOLUTION: The wrap film includes polyvinylidene chloride resin. A molecular chain orientation ratio that is calculated by the following formula (1) when polarization Raman is measured is 0.3 to 3.0. A molecular chain orientation ratio=CCl2-derived peak (630-680 cm-1) intensity in an MD direction (A value)/CCl2-derived peak (630-680 cm-1) intensity in a TD direction (C value) ... (1)SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a wrap film and a wrap film roll using the same.

Conventional wrap films have excellent properties such as adhesion between films and adherends, gas barrier properties against gases such as water vapor and oxygen, and cutability when used in a cosmetic box. It is used in many households as a wrap film. Household wrap films are mainly used for food storage in refrigerators and freezers, and for heating food in containers in microwave ovens.

As such a wrap film, for example, Patent Document 1 discloses a wrap film containing a polyvinylidene chloride resin,
Formula (1) below:
Δn=n _x −n _y =Re/d (1)
(Wherein, _nx represents the refractive index in the slow axis direction in the film plane, _ny represents the refractive index in the direction perpendicular to the slow axis direction in the film plane, and Re is the in-plane retardation of the film. (unit: nm), and d represents the thickness of the film (unit: nm))
The birefringence Δn obtained by the following formula (1a):
0.0003≦Δn≦0.0013 (1a)
satisfies the condition represented by
Formula (2) below:
ΔP=(n _x +n _y )/2−n _z (2)
(Wherein, _nx represents the refractive index in the slow axis direction in the film plane, _ny represents the refractive index in the direction perpendicular to the slow axis direction in the film plane, and _nz is the thickness of the film. direction)
The planar orientation ΔP obtained by the following formula (2a):
-0.0120≤ΔP≤-0.0102 (2a)
A wrap film is disclosed that satisfies the conditions represented by the following.
Further, for example, in Patent Document 2, the tensile strength in the direction perpendicular to the machine direction (TD) is 100 MPa or more, the tensile elongation is 100% or less, the tensile elastic modulus is 280 MPa or more, and the tensile strength in the machine direction (MD) is A wrap film is disclosed having a modulus of elasticity of 380 MPa or more.

International Publication No. 2016-189987 JP 2019-43679 A

However, for example, as shown in FIG. 2, when the wrap film 17 is pulled out of the decorative box 14 or when the film is cut after being pulled out of the decorative box 14, the film cannot be cut cleanly and is torn in the middle. It may not be possible to cut perpendicularly to the direction (MD direction), and the cut end surface 18 may partially protrude. In order to solve this problem, if the projecting cut edge 18 is pinched, the film tends to deform in the TD direction (perpendicular to the MD direction). difficult.
In addition, when the breaking strength of the film is lowered, the film may break when the wrap film is used repeatedly, making it difficult to reuse.
The wrap films described in Patent Documents 1 and 2 do not consider such problems, and there is room for improvement.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a wrap film that is easy to pick up at the cut end face and recover and is easy to reuse when the film is cut halfway when the film is pulled out of a cosmetic case. .

The present inventors have made intensive studies to overcome these problems. As a result, a wrap film containing a polyvinylidene chloride resin and having a molecular chain orientation ratio satisfying a predetermined condition can be used when the wrap film is pulled out of the cosmetic box. When the film is torn in the middle, the cut end face of the wrap film is easy to pinch, and even when the cut end face is pinched, it is difficult to tear, so it is easy to solve the state where the wrap film is torn in the middle (easy to restore). Moreover, since it is difficult to break even when used repeatedly, it has been found that it is easy to reuse, and the present invention has been completed.

That is, the present invention is as follows.
[1]
including polyvinylidene chloride resin,
A wrap film having a molecular chain orientation ratio of 0.3 to 3.0 calculated by the following formula (1) when polarized Raman is measured;
Molecular chain orientation ratio = peak (630 to 680 cm ^-1 ) intensity (A value) derived from CCl ₂ in MD direction/peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in TD direction... (1).
[2]
further comprising a compound containing a methylene group ( _CH2 );
The wrap film according to [1], wherein the molecular chain orientation in the TD direction calculated by the following formula (2) is 2.0 to 5.8 when polarized Raman in the TD direction is measured;
Molecular chain orientation in the TD direction = CCl ₂ derived peak (630-680 cm ^-1 ) intensity (A value) in the MD direction / CH ₂ derived peak (2840 - 2890 cm ^-1 ) intensity (D value) in the MD direction. (2).
[3]
The wrap film according to [1] or [2], which has a tensile breaking strength in the TD direction of 100 MPa or more.
[4]
The wrap film according to any one of [1] to [3], which has a tensile elongation at break in the TD direction of 100% or less.
[5]
The wrap film according to any one of [1] to [4], which has a thickness of 6 to 18 μm.
[6]
A wound body in which the wrap film according to any one of [1] to [5] is wound around a winding core.

According to the present invention, it is possible to provide a wrap film that is easy to pick up at the cut end face, is easy to restore, and is easy to reuse when the film is cut halfway when the film is pulled out of a cosmetic box.

It is a schematic diagram of an example of the manufacturing process of the wrap film of the present invention. 1 is a schematic diagram of an example of a wrap film container containing a wrap film. FIG. FIG. 4 is a schematic diagram of an example of sampling positions when the wrap film is pulled out; FIG. 4 is a schematic diagram of an example when a measurement sample is placed on a slide glass; It is a schematic diagram of an example of a Raman microscope image. It is a schematic diagram of an example when a measurement sample is placed on a slide glass and rotated.

EMBODIMENT OF THE INVENTION Hereinafter, the form (henceforth "this embodiment") for implementing this invention is demonstrated in detail below. It should be noted that the present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

The wrap film of the present embodiment contains a polyvinylidene chloride-based resin, and has a molecular chain orientation ratio of 0.3 to 3.0 calculated by the following formula (1) when polarized Raman is measured.
Molecular chain orientation ratio = peak (630 to 680 cm ^-1 ) intensity (A value) derived from CCl ₂ in MD direction/peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in TD direction... (1)
The wrap film of the present embodiment has such characteristics, so that if the film is torn off when pulled out of the cosmetic box, the cut end face can be easily picked up and restored, and when used repeatedly, it can be reused. Cheap.
In addition, in this embodiment, each molecular chain orientation can be measured by the method described in Examples below.

<Polyvinylidene chloride resin>
The wrap film of this embodiment contains a polyvinylidene chloride resin.
The polyvinylidene chloride-based resin used in the present embodiment is not particularly limited as long as it contains structural units derived from vinylidene chloride. Acid esters; methacrylic acid esters such as methyl methacrylate and butyl methacrylate; acrylonitrile; vinyl acetate and other monomers copolymerizable with vinylidene chloride may be copolymerized one or more.

The weight average molecular weight (Mw) of the polyvinylidene chloride resin is preferably 80.000 to 200,000, more preferably 90,000 to 180,000, still more preferably 100,000 to 170,000. be. When the weight average molecular weight (Mw) is 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 the present embodiment, the weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC method) using a standard polystyrene calibration curve.

When the polyvinylidene chloride resin is a copolymer resin, the ratio of the structural units derived from vinylidene chloride is not particularly limited, but preferably contains 72 to 93% by mass of structural units derived from vinylidene chloride, and 81 to 90% by mass. More preferred are those containing When the vinylidene chloride-derived structural unit is 72% by mass or more, the glass transition temperature of the polyvinylidene chloride resin is low and the film becomes soft, so the tendency to reduce film tearing even when used in low temperature environments such as winter. It is in. On the other hand, when the vinylidene chloride-derived structural unit is 93% by mass or less, there is a tendency that a significant increase in crystallinity can be suppressed, and deterioration of moldability during film stretching can be suppressed.
In particular, wrap films made of polyvinylidene chloride-based resins containing 72% by mass or more of structural units derived from vinylidene chloride are subjected to heat when stored and distributed at high temperatures such as in the summer, and microcrystals form and grow due to heat. The effect of the present invention becomes more pronounced because the film is likely to be deteriorated over time, and as a result, the trouble of tearing during use of the film tends to be more likely to occur.

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

Hereinafter, the structural unit derived from vinylidene chloride ( _--CH.sub.2 -- _CCl.sub.2-- ) will be denoted as A, and the structural unit derived from vinyl chloride ( _--CH.sub.2-- CHCl--) will be denoted as B. Signals 1 and 2 obtained on the spectrum , and 3 are assigned as follows.
- Signal 1 (approximately 5.2 to 4.5 ppm) is attributed 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 attributed to the CH2 signal (methylene (CH ₂ ) group of the structural unit derived from vinylidene chloride) of A on one side of AA.
• Signal 3 (approximately 3.5-2.8 ppm) is attributed to the CH2 signal (methylene (CH ₂ ) group of the vinylidene chloride-derived building block) of A in both AB and BA.

From the spectral area values of these signals (signal area in NMR spectrum), the molar fraction of the structural unit is determined. In addition, each mole fraction is described as follows.
・Mole fraction of A (mol%): P (A)
・Mole fraction of B (mol%): P (B)

From the area values of signals 1, 2, and 3 assigned as described above (the areas of the peaks in the NMR spectrum), the integrated values of the signals on the spectrum are assigned as follows.
・The integrated value of signal 1 (about 5.2 to 4.5 ppm) is 1H of B ・The integrated value of signal 2 (about 4.2 to 3.8 ppm) is 1H2 of A ・Signal 3 (about 3 .5 to 2.8 ppm) for 1H4 pieces of A

Calculate each mole fraction using the following formulae:
・P(A) + P(B) = 100

P(A) and P(B) are obtained from the following equations.
・P(B): P(A) = integrated value of signal 1: (integrated value of signal 2 + integrated value of signal 3/2)/2
・P (A) = 100 - P (B)

Assuming that the molecular weight of A, which is a vinylidene chloride-derived structural unit (-CH ₂ -CCl ₂ -), is 97.0, and the molecular weight of B, which is a vinyl chloride-derived structural unit (-CH ₂ -CHCl-), is 62.5. , the following equations were used to calculate each mass fraction. In addition, each mass fraction is described as follows.
・ Mass fraction of A (% by mass): Q (A)
· Mass fraction of B (% by mass): Q (B)
・Q(A) =
(P(A) × 97.0) /
(P(A) x 97.0 + P(B) x 62.5) x 100
・Q(B) = 100 - Q(A)

The content of polyvinylidene chloride resin is preferably 77 to 94% by mass, more preferably 85 to 94% by mass, based on the total weight of the wrap film. When the content of the vinylidene chloride-based resin is within the above range, it is possible to prevent the film from becoming easily elongated due to the plasticizing effect of the additive, 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 analyte. For example, the vinylidene chloride-based resin content 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 gel permeation chromatography analysis of the reprecipitation filtrate of the wrap film, or by using NMR. In addition, the contents of the citric acid ester and the dibasic acid ester can be obtained by extracting the additive from the wrap film using an organic solvent such as acetone and performing gas chromatography analysis.

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

<Epoxidized vegetable oil>
The wrap film of the present embodiment preferably contains an epoxidized vegetable oil from the viewpoint of suppressing color tone change of the wrap film. Epoxidized vegetable oils also act as stabilizers for vinylidene chloride-based resin extrusion processing.

Epoxidized vegetable oils are not particularly limited, but generally include those produced by epoxidizing edible fats and oils. Specific examples include, but are not limited to, epoxidized soybean oil (ESO) and epoxidized linseed oil. ESO is preferred because it tends to suppress sexual aggravation.

When the wrap film of the present embodiment contains epoxidized vegetable oil, the content is not particularly limited. 5 to 3.0% by mass is preferable, and 1.0 to 2.0% by mass is more preferable.

A method for measuring the epoxidized vegetable oil content using NMR follows the procedure below.
50 mg of a sample is weighed, dissolved in a deuterated solvent (solvent: deuterated THF, internal standard: dimethyl terephthalate, volume: 0.7 ml), and measured by 400 MHz proton NMR (number of integrations: 512 times). The ratio of the integrated value of 2.23 to 2.33 ppm to the integrated value of 8.05 to 8.11 ppm is defined 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 method for measuring the content of the epoxidized vegetable oil using gel permeation chromatography follows the procedure below.
3 g of the sample is weighed in a tall beaker, 30 ml of THF is added, stirred with a stirrer and heated (50° x 4 min) to dissolve completely.
While stirring with a stirrer, methanol (170 ml) is slowly added dropwise for reprecipitation. After dropping the entire amount of methanol, the solution is suction-filtered through a glass filter. The filtrate is concentrated, dried in a vacuum, put into a 10 ml volumetric flask and diluted with chloroform. The chloroform solution is filtered through a syringe filter (material: PTFE, pore size: 0.45 μm) and analyzed by GPC. Three levels of standard samples are prepared by weighing ESO into a volumetric flask and adding chloroform to the volume. Filter with a syringe filter in the same manner as the sample, and perform GPC analysis. A calibration curve is created by plotting the GPC analysis and the standard sample concentrations.
Fit the GPC area of the sample to the standard curve, calculate the concentration, and calculate the ESO quantitation value.

<Citric acid ester and dibasic acid ester>
The wrap film of the present embodiment preferably contains at least one compound selected from the group consisting of citric acid esters and dibasic acid esters from the viewpoint of molding processability.

The citric acid ester used in the wrap film of the present embodiment is not particularly limited, but triethyl citrate, tributyl citrate, acetyl triethyl citrate, acetyl tributyl citrate (hereinafter also referred to as "ATBC"), acetyl tri-citrate and n-(2-ethylhexyl). Among these, ATBC is preferable because it has a high plasticizing effect on vinylidene chloride-based resins and tends to sufficiently plasticize the resin even in a small amount and improve moldability.

The dibasic acid ester contained in the wrap film of the present embodiment is not particularly limited, but adipate esters such as dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, and dioctyl adipate; Azelaic esters such as di-2-ethylhexyl azelate and octyl azelate; sebacate esters such as dibutyl sebacate (hereinafter also referred to as "DBS") and di-2-ethylhexyl sebacate; Among these, DBS is preferred because it has a high plasticizing effect on polyvinylidene chloride-based resins and tends to sufficiently plasticize resins even in small amounts and improve moldability.

The total content of the citric acid 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, poly 3.0 to 8.0% by mass is preferable, 3.0 to 7.0% by mass is more preferable, 3.0 to 5.5% by mass is more preferable, and 3.5 to 5 0.5% by weight is particularly preferred.

In particular, when the wrap film of the present embodiment contains 3% by mass or more of a citric acid ester or a dibasic acid ester, the mobility of the molecular chains of the polyvinylidene chloride-based resin increases, so that the formation and growth of microcrystals, etc. The rearrangement of the film tends to occur, and it is easy to physically deteriorate when exposed to high temperatures. The effect of the invention becomes more remarkable.

<Acetylated fatty acid glyceride>
The wrap film of the present embodiment may contain acetylated fatty acid glyceride as a plasticizer. Acetylated fatty acid glycerides include, but are not limited to, acetylated caprylic glyceride, acetylated capric glyceride, acetylated lauric glyceride, acetylated myristate glyceride, acetylated palm kernel oil glyceride, and acetylated coconut oil glyceride. , acetylated castor oil glycerides, and acetylated hydrogenated castor oil glycerides.

The acetylated fatty acid glyceride may be any of acetylated monoglyceride of fatty acid, acetylated diglyceride of fatty acid, and acetylated triglyceride of fatty acid. For example, the acetylated lauric acid glyceride includes acetylated monoglyceride of lauric acid, acetylated diglyceride of lauric acid (DALG: diacetyllauroylglycerol), and acetylated triglyceride of lauric acid. Among these, acetylated lauric acid glyceride is preferable, and acetylated diglyceride of lauric acid is more preferable.

The content of the acetylated fatty acid glyceride is preferably 3.0 to 8.0% by mass, more preferably 3.5 to 7.0% by mass, still more preferably 4% by mass, relative to the total amount of the wrap film. .0 to 6.0% by mass. When the content of the acetylated fatty acid glyceride is within the above range, moldability tends to be further improved. The method for measuring the content of each component from the wrap film differs depending on the object to be analyzed. The content of acetylated fatty acid glyceride can be obtained by extracting the additive from the wrap film using an organic solvent such as acetone and analyzing it 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 3.0 to 8.0% by mass relative to the total weight of the wrap film. Yes, more preferably 3.5 to 7.0% by mass, still more preferably 4.0 to 6.6% by mass. When the total content of the citric acid ester, the dibasic acid ester, and the acetylated fatty acid glyceride is within the above range, the molding processability is further improved, and the excessive bleeding of the wrap film when the epoxidized vegetable oil is contained in a high content. Stickiness tends to be suppressed.

[Other additives]
In addition to the polyvinylidene chloride resin described above, the wrap film of the present embodiment may optionally contain plasticizers, stabilizers, weather resistance improvers, colorants such as dyes or pigments, and antifogging agents used in food packaging materials. , an antibacterial agent, a lubricant, and a nucleating agent. These may be used individually by 1 type, or may use 2 or more types together.

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

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

The weather resistance improver is not particularly limited, but specific examples include ethylene-2-cyano-3,3'-diphenyl acrylate, 2-(2'-hydroxy-5'-methylphenyl)benzolithiazole, 2-(2′-hydroxy-3′-t-butyl-5′-methylphenyl)5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, and 2,2′-dihydroxy-4-methoxybenzophenone, etc. An ultraviolet absorber is mentioned.

Colorants such as dyes or pigments are not particularly limited, but specific examples include carbon black, phthalocyanine, quinacridone, indoline, azo pigments, red iron oxide, and the like.

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

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

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, and higher fatty acids. Lubricants, fatty acid amide lubricants, fatty acid ester lubricants, and the like are included.

The nucleating agent is not particularly limited, but specific examples thereof include phosphate ester metal salts and the like.

The content of the other additives described above is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, still more preferably 1.0% by mass or less, and particularly preferably 5.0% by mass or less relative to the wrap film. is 0.1% by mass or less.

The wrap film of this embodiment preferably further contains a compound containing a methylene group (CH ₂ ).
The compound containing a methylene group (CH ₂ ) used in the present embodiment is not particularly limited. Additives containing a methylene group (CH ₂ ) can be mentioned among known additives such as agents, antifogging agents, antibacterial agents, lubricants, and nucleating agents.

The total content of compounds containing a methylene group (CH ₂ ) is preferably 3.0 to 8.0% by mass, more preferably 3.5 to 7.0% by mass, based on the total amount of the wrap film. Yes, more preferably 4.0 to 6.6% by mass.

The wrap film of the present embodiment contains a polyvinylidene chloride-based resin, and has a molecular chain orientation ratio of 0.3 to 3.0 calculated by the following formula (1) when polarized Raman is measured.
Molecular chain orientation ratio = peak (630 to 680 cm ^-1 ) intensity (A value) derived from CCl ₂ in MD direction/peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in TD direction... (1).
In the wrap film of the present embodiment, by setting the molecular chain orientation ratio to 0.3 or more, the molecular chains are oriented in the TD direction, it is difficult to stretch in the TD direction, and the breaking stress is high, so discontinuities occurred. At the time, it is easy to pick up the cut end face.
Moreover, the wrap film of the present embodiment has a sufficient tear strength in the TD direction by setting the molecular chain orientation ratio to 3.0 or less, and the wrap film is less likely to tear.
From the same point of view, the molecular chain orientation ratio of the wrap film is preferably 0.5 to 3.0, more preferably 0.9 to 3.0, and 1.6 to 3.0. is more preferred, and 1.9 to 3.0 is particularly preferred.
The method for obtaining a wrap film having a molecular chain orientation ratio within the above range is not particularly limited. ) to a specific range (eg, 19° C. to 37° C.).

The wrap film of the present embodiment further contains a compound containing a methylene group (CH ₂ ), and the molecular chain orientation in the TD direction calculated by the following formula (2) is 2.0 when polarized Raman in the TD direction is measured. It is preferably 0 to 5.8.
Molecular chain orientation in the TD direction = CCl ₂ derived peak (630-680 cm ^-1 ) intensity (A value) in the MD direction / CH ₂ derived peak (2840 - 2890 cm ^-1 ) intensity (D value) in the MD direction. (2).
In the wrap film of the present embodiment, by setting the molecular chain orientation in the TD direction to 2.0 or more, the molecular chains are oriented in the TD direction, are difficult to stretch in the TD direction, and have a high breaking stress, so discontinuities occur. When cutting, it is easy to pick up the cut end face. In addition, since the breaking stress is high, it is difficult to break even when used repeatedly, and it is easy to reuse.
Further, the wrap film of the present embodiment has a molecular chain orientation of 5.8 or less in the TD direction, so that the tensile strength at break in the TD direction is sufficient, and the wrap film is less likely to tear.
From the same point of view, the molecular chain orientation in the TD direction calculated by the above formula (2) is more preferably 2.3 to 5.8, more preferably 2.9 to 5.8, It is more preferably 3.8 to 5.8, particularly preferably 4.2 to 5.8.

The thickness of the wrap film of this embodiment is preferably 5.0 to 18.0 μm, more preferably 5.0 to 15.0 μm, even more preferably 5.0 to 12.0 μm. When the thickness of the wrap film of the present embodiment is within the above range, troubles of film breakage are suppressed, cuttability is further improved, adhesiveness is further improved, and reuse tends to be facilitated.

The wrap film of the present embodiment preferably has a tensile breaking strength X1 (MPa) in the TD direction of 100 or more, preferably in the range of 100≦X1≦300. When the wrap film of the present embodiment has a tensile breaking strength in the TD direction of 100 MPa or more, it has sufficient strength to break along the direction perpendicular to the TD direction when cut, and is wound for food packaging. In the case of wraps, the problem of vertical tearing is suppressed when cut, and it tends to be easy to reuse even after repeated use. Further, in the wrap film of the present embodiment, when the tensile breaking strength in the TD direction is in the range of 300 MPa or less, the strength to break along the direction perpendicular to the TD direction when cut is not too high. In the case of wraps, the problem of vertical tearing tends to be suppressed when cut. From the viewpoint of practical use, it is more preferably 130≦X1≦300, still more preferably 150≦X1≦300, still more preferably 180≦X1≦300, and particularly preferably 190≦X1≦300. be.
The method for controlling the tensile strength at break in the TD direction within the above range is not particularly limited. A method of increasing the difference from the temperature during stretching in the process can be mentioned. In this case, the temperature of the cooling bath (cooling bath temperature) is preferably 5°C to 23°C, and the temperature of the stretching step (stretching temperature) is preferably 35°C to 42°C. Here, the stretching temperature is the resin temperature of the bubble (10). The difference between the cooling bath temperature and the stretching temperature (stretching temperature - cooling bath temperature) is preferably 19°C to 37°C, more preferably 23°C to 37°C, still more preferably 25°C to 37°C, and 28°C to 37°C. is more preferred, and 30°C to 37°C is particularly preferred. When the difference between the cooling bath temperature and the stretching temperature is within the above range, the tensile strength at break in the TD direction of the wrap film of the present embodiment tends to be controlled within the range described above.
In addition, in this embodiment, the tensile strength at break in the TD direction can be measured by the method described in Examples below.

Further, the wrap film of the present embodiment preferably has a tensile elongation at break X2 (%) in the TD direction of 100 or less, preferably 15≦X2≦100. When the wrap film of the present embodiment has a tensile elongation at break of 100% or less in the TD direction, the film is easily cut when cut. Tear trouble tends to be suppressed. In addition, in the wrap film of the present embodiment, when the tensile elongation at break in the TD direction is in the range of 15% or more, the film stretches appropriately when cut, making it easy to cut. , the problem of vertical tearing tends to be suppressed when cut. From the viewpoint of practical use, it is more preferably 15≦X2≦90, still more preferably 15≦X2≦80, even more preferably 15≦X2≦55, and particularly preferably 15≦X2≦50. be.
The method for controlling the tensile elongation at break in the TD direction within the above range is not particularly limited. A method of enlarging the difference from the temperature during stretching in the subsequent process can be mentioned. In this case, the temperature of the cooling bath (cooling bath temperature) is preferably 5°C to 23°C, and the temperature of the stretching step (stretching temperature) is preferably 35°C to 42°C. The difference between the cooling bath temperature and the stretching temperature (stretching temperature - cooling bath temperature) is preferably 19°C to 37°C, more preferably 23°C to 37°C, still more preferably 25°C to 37°C, and 28°C to 37°C. is more preferred, and 30°C to 37°C is particularly preferred. When the difference between the cooling bath temperature and the stretching temperature is within the above range, the tensile elongation at break in the TD direction of the wrap film of the present embodiment tends to be controlled within the range described above.
In the present embodiment, the tensile elongation at break in the TD direction can be measured by the method described in Examples below.

<Method for producing wrap film>
Next, an example of the method for producing the wrap film of this embodiment will be described. The method for producing a wrap film containing a polyvinylidene chloride resin is not particularly limited, and various methods can be adopted as long as the above-described molecular chain orientation in the TD direction can be satisfied. Membrane method is used. That is, according to this embodiment, a wrap film can be obtained by inflation molding. More preferably, the wrap film of the present embodiment can be obtained by stretching the composition containing the polyvinylidene chloride-based resin described above at least in the MD direction, followed by inflation molding. In the inflation film forming method, although not particularly limited, for example, a polyvinylidene chloride resin composition is melt extruded from a circular die into a tubular shape, and then the outside of the tubular resin is filled with a coolant such as cold water in a storage tank called a cooling tank. come into contact with At that time, a refrigerant such as mineral oil is injected into and stored in a tubular (cylindrical) resin sandwiched between the die port and the pinch roll, and the inside of the tubular resin is brought into contact with the refrigerant such as mineral oil. It is solidified and formed into a film. In this specification, the tubular resin portion (extrusion) sandwiched between the die mouth and the pinch roll is referred to as a "sock". The coolant (liquid) injected into the sock is called "sock liquid". The sock is folded by the pinch rolls or the like to form a tubular double-ply film, which is called a "parison".

An example of the inflation film forming method will be described in more detail below. FIG. 1 is a conceptual diagram of an example of the method for producing a wrap film according to this embodiment.

First, in the extrusion process, a composition containing a molten polyvinylidene chloride resin is extruded into a tubular shape from a die port (3) of a circular die (2) by an extruder (1) to form a sock (tubular polyvinylidene chloride resin). A composition comprising a resin) (4) is formed.

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

The sock liquid is not particularly limited, but for example, water, mineral oil, alcohols, polyhydric alcohols such as propylene glycol and glycerin, cellulose-based and polyvinyl alcohol-based aqueous solutions, and the like can be used. These may be used singly or in combination of two or more. In addition, the sock liquid may be added with the above-described weather resistance improver, antifogging agent, antibacterial agent, etc., which are used in food packaging materials, as long as they do not impair the effects of the present embodiment.

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

The tear strength in the MD direction of the wrap film can be controlled by the orientation of the polymer chains that make up the wrap film, and by rapidly cooling the sock extruded from the die in a cooling bath, the progress of crystallization of the resin is further suppressed. , the molecular chain becomes a uniform amorphous structure. After that, the film is stretched in the TD direction to promote crystallization in which the molecular chains are oriented in the TD direction.

In the method for producing a wrap film of the present embodiment, it is preferable that the difference between the temperature during cooling of the sock extruded from the die and the temperature during stretching in the subsequent process is large. The cooling bath temperature) is preferably 5°C to 23°C, and the temperature in the stretching step (stretching temperature) is preferably 35°C to 42°C. The difference between the cooling bath temperature and the stretching temperature (stretching temperature - cooling bath temperature) is preferably 19°C to 37°C, more preferably 23°C to 37°C, still more preferably 25°C to 37°C, and 28°C to 37°C. is more preferred, and 30°C to 37°C is particularly preferred. When the difference between the cooling bath temperature and the stretching temperature is within the above range, the molecular chain orientation in the TD direction of the wrap film of the present embodiment tends to be controlled within the range described above.

The method for producing the wrap film of the present embodiment preferably includes a step of stretching the unstretched sheet in the machine direction and the direction perpendicular to the machine direction. It is preferably 4.0 to 6.0 times, more preferably 4.1 to 5.6 times.
In particular, the draw ratio between the second pinch roll (9) and the third pinch roll (11) (hereinafter also referred to as "3rd/2nd draw ratio") and the draw ratio in the TD direction (hereinafter also referred to as "TD draw ratio") It is possible to control the orientation of the molecular chains in the TD direction by the ratio of . In order to orient the molecular chains in the TD direction, it is preferable that the TD draw ratio is >3rd/2nd draw ratio.

The cooling and solidification step is not particularly limited, and a known method can be adopted. For example, there is a method of controlling the temperature of the cooling bath by changing the temperature of cold water for cooling and solidification. In order to promote the orientation of the molecular chains in the TD direction, the sock extruded from the die is rapidly cooled in a cooling bath, thereby further suppressing the progress of crystallization of the resin and forming an amorphous structure in which the molecular chains are uniform. It is preferable to be The cooling bath temperature is more preferably between 5°C and 23°C. After that, the film is stretched in the TD direction to promote crystallization in which the molecular chains are oriented in the TD direction.

A method for controlling the draw ratio is not particularly limited, and a known method can be employed. For example, there is a method of controlling the stretching temperature by changing the temperature of hot water for reheating. Here, the stretching temperature is the resin temperature of the bubble (10). In order to lower the draw ratio, the lower the draw temperature, the more stable the inflation bubbles at a low draw ratio, which is preferable. At that time, the stretching temperature is preferably higher than the stretching room temperature from the viewpoint of the stability of inflation bubbles. The stretching temperature is preferably 35°C or higher, more preferably 35°C to 48°C, still more preferably 35°C to 45°C, and particularly preferably 35°C to 42°C. As the stretching temperature, the temperature is measured at an intermediate point in the MD direction between the point at which the stretching in the MD direction and the TD direction is completed and the point at which winding is started.

The stretched film is then folded by a third pinch roll (11) to form a double-ply film (12). The double-ply film (12) is wound on a winding roll (13). Further, the film is slit and peeled into one film (single peel). Finally, this film is wound around a core such as a paper tube to obtain a wrap film roll wrapped around a paper tube.

Here, it is possible to control the orientation of the molecular chains in the TD direction by adjusting the draw ratio between the second pinch roll (9) and the third pinch roll (11) and the draw ratio in the TD direction. Become.

The above description is an example of the method for manufacturing the cling film of the present embodiment, and the method may be performed using various apparatus configurations and conditions other than those described above. For example, other known methods may be employed.

[Wound body]
The wrap film of this embodiment can be used in various forms, for example, it can be a roll-shaped wrap film. When a roll-shaped wrap film is used, it may or may not have a core.

In the case of winding around a core, for example, a wrap film roll comprising a cylindrical core and the wrap film of the present embodiment wound around the core can be used. A wound body means a body in the form of a roll obtained by winding a wrap film around a core or the like.

The wrap film of the present embodiment can effectively suppress unwinding trouble that occurs when a roll-shaped wrap film or the like is used. The material, size, etc. of the core are not particularly limited, and a known core such as a paper tube can be used. Furthermore, if the wrap film is roll-shaped, it may or may not have a core. The wrap film roll of the present embodiment can be used by being stored in a decorative box having a cutting blade for cutting the wrap film.

Hereinafter, the present invention will be described more specifically using examples and comparative examples. The present invention is by no means limited by the following examples.

In Examples and Comparative Examples, physical properties and characteristics were measured as follows.

<TD direction molecular chain orientation>
The TD direction molecular chain orientation of the wrap film was measured as follows.
Using a Raman microscope (manufactured by HORIBA, Raman microscope XploRA), Raman spectroscopy of the wrap film was measured. A measurement wavelength of 532 nm was used. The measurement conditions were an exposure time of 30 seconds, an accumulation count of 2, a grating of 1800 cm ⁻¹ , a neutral density filter of 10%, an objective lens magnification of 100, a confocal hole of 500, a slit width of 100 μm, and a measurement wavelength of 200 to 3100 cm ⁻¹ . . No laser polarization was used and Raman polarization was set to "Vertical".
Moreover, the measurement of TD direction molecular chain orientation was performed as follows as an example. FIG. 3 is a schematic diagram of an example of sampling positions when the wrap film is pulled out. As shown in FIG. 3, a square sample (21) having a side length of 1 cm and an end face (20) parallel to the flow direction (19) was obtained from the wrap film.
FIG. 4 is a schematic diagram of an example when a measurement sample (21) is placed on a slide glass (22). As shown in FIG. 4, the obtained sample (21) was fixed on a slide glass (22) and measured. At this time, two glass slides on which the sample (21) is placed are used, and the end surface (20) parallel to the flow direction of the sample (21) is placed on the upper slide glass. 23) was installed in parallel.
FIG. 5 is a schematic diagram of an example of a Raman microscope image. As shown in FIG. 5, there is a horizontal direction (24) in the microscopic observation image and a vertical direction (25) in the microscopic observation image, and as shown in FIG. , the measurement was performed after rotating the upper glass slide so that it was parallel to the vertical direction (25) of the microscopic image.
In the measurement, the peak derived from CCl ₂ in the MD direction (peak of the spectrum in the wavenumber band of 630 to 680 cm ⁻¹ ) intensity (peak height) is the A value, and the peak derived from CH ₂ in the MD direction (2840 to 2890 cm ⁻ The spectral peak intensity (peak height) in the wavenumber band of ¹ was calculated as the D value. Each value was measured at 10 different fields of the same sample, A value/D value was calculated at each measurement point, and the arithmetic average was calculated as the molecular chain orientation in the TD direction by the following formula (2).
Molecular chain orientation in the TD direction = CCl ₂ derived peak (630-680 cm ^-1 ) intensity (A value) in the MD direction / CH ₂ derived peak (2840 - 2890 cm ^-1 ) intensity (D value) in the MD direction. (2)
At this time, the molecular chain orientation in the TD direction represents the orientation of the main chain oriented in the TD direction, and is orthogonal to the CCl ₂ in the MD direction.

<MD Direction Molecular Chain Orientation>
In this embodiment, the MD direction molecular chain orientation of the wrap film was measured as follows.
Using a Raman microscope (manufactured by HORIBA, Raman microscope XploRA), Raman spectroscopy of the wrap film was measured. A measurement wavelength of 532 nm was used. The measurement conditions were an exposure time of 30 seconds, an accumulation count of 2, a grating of 1800 cm ⁻¹ , a neutral density filter of 10%, an objective lens magnification of 100, a confocal hole of 500, a slit width of 100 μm, and a measurement wavelength of 200 to 3100 cm ⁻¹ . . No laser polarization was used and Raman polarization was set to "Vertical".
Moreover, the measurement of MD direction molecular chain orientation was performed as follows as an example. FIG. 3 is a schematic diagram of an example of sampling positions when the wrap film is pulled out. As shown in FIG. 3, a square sample (21) having a side length of 1 cm and an end face (20) parallel to the flow direction (19) was obtained from the wrap film.
FIG. 4 is a schematic diagram of an example when a measurement sample (21) is placed on a slide glass (22). As shown in FIG. 4, the obtained sample (21) was fixed on a slide glass (22) and measured. At this time, the slide glass on which the sample (21) is placed is used by stacking two slides, and on the upper slide glass, the end face (20) parallel to the flow direction of the sample (21) is placed on the long side of the slide glass ( 23) was installed in parallel.
FIG. 5 is a schematic diagram of an example of a Raman microscope image. As shown in FIG. 5, there is a horizontal direction (24) in the microscopic observation image and a vertical direction (25) in the microscopic observation image, and as shown in FIG. , the measurement was performed after rotating the upper glass slide so that it was parallel to the lateral direction (24) of the microscopic image.
In the measurement, the peak derived from CCl ₂ in the TD direction (peak of the spectrum in the wavenumber band of 630 to 680 cm ^-1 ) intensity (peak height) is the C value, and the peak derived from CH ₂ in the TD direction (2840 to 2890 cm ^- The peak intensity (peak height) of the spectrum in the wavenumber band of ¹ was calculated as the B value. Each value was measured at 10 different fields of view of the same sample, the C value/B value was calculated at each measurement point, and the arithmetic average was calculated as the molecular chain orientation in the MD direction by the following formula (2).
Molecular chain orientation in the MD direction = peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in the TD direction / peak (2840 to 2890 cm ^-1 ) intensity (B value) derived from CH ₂ in the TD direction (3)
At this time, the molecular chain orientation in the MD direction represents the orientation of the main chain oriented in the MD direction, and is orthogonal to the CCl ₂ in the TD direction.

<Molecular chain orientation ratio>
The molecular chain orientation ratio was calculated by the following formula (1) from the A value and C value obtained by the above measuring method.
Molecular chain orientation ratio = peak (630 to 680 cm ^-1 ) intensity (A value) derived from CCl ₂ in MD direction/peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in TD direction... (1).

<Tensile breaking strength and tensile breaking elongation in the TD direction>
The tensile strength at break and tensile elongation at break in the TD direction of the wrap film were measured in an atmosphere of 23±2° C. and 50±10% RH. A 150 mm long and 10 mm wide piece was cut from the wrap film in the TD direction to obtain a test piece. When cutting out, the blade was changed for each test piece in order to cut into strips and not to damage the test piece. Using Autograph AG-IS (manufactured by Shimadzu Corporation), a test piece set at a width of 10 mm and a distance between chucks of 100 mm was pulled up and down at a tensile speed of 300 mm/min, and the load and elongation at breakage were measured. bottom. The elongation at this time was defined as the tensile elongation at break (unit: %) in the TD direction of the wrap film. The obtained load was divided by the cross-sectional area of the test piece to calculate the tensile breaking strength (unit: MPa) of the wrap film in the TD direction. At the time of measurement, the grip was attached to the wrap film so that the TD direction of the wrap film coincided with the tensile direction of the tester. A 25 mm portion from both ends in the longitudinal direction was marked with a material (such as red ink) that does not easily damage the test material, and this was used as the chuck position. It was confirmed visually using a straight ruler and using a microscope that the test piece was not twisted, and that there were no scratches or holes on the surface or edges. Specimens that did not meet these conditions were discarded. The specimen was evenly clamped with grips to prevent slippage and to keep the grips from shifting during the test. In addition, among the 5 measurements, the arithmetic mean value of the results of 3 measurements excluding the highest value and the lowest value was calculated, and the significant figure was set to 2 digits, and the third digit was rounded off.

<Easiness of pinching the cut surface when cutting occurs midway>
When cutting the wrap film with a saw blade, if the film cannot be cut cleanly and is torn in the middle, the protruding cut end face will be pinched to restore the wrap film. A sensory evaluation was made of the easiness of picking up the protruding cut end surface that occurred when the film was not cut cleanly. The following method was used for the sensory evaluation of the easiness of picking up the protruding cut end surface of the film, which occurred when the film could not be cut cleanly. That is, 10 skilled evaluators (including men and women) hand a wrap film housed in a commercially available wrap film cosmetic box (Saran Wrap (registered trademark) cosmetic box manufactured by Asahi Kasei Home Products Co., Ltd., 22 cm × 50 m). After pulling it out and cutting it with a saw blade, the ease of picking the protruding cut end face was scored in 1-point to 10-point increments (10 points was the best ease of picking, and 1 point was the most difficult to pick). ), and each was evaluated. Based on the average score of 10 evaluators, the following evaluation criteria evaluated the easiness of picking up the projecting cut end surface of the wrap film.
If the evaluation of ease of picking is "A", it can be said that the cling film is exceptionally excellent in ease of picking and has the highest ease of picking. A rating of "B" indicates that the wrap film is very pleasant to pick up. If the evaluation is "C", it can be said that the wrap film has pleasant easiness to pick up. If the evaluation is "D", it can be said that the easiness of pinching the wrap film is good. If the evaluation is "E", there is no particular problem with the ease of picking up the wrap film. If the evaluation is "x", the wrap film is inferior in ease of picking.
[Evaluation criteria]
A: 8.0 points or more B: 6.0 points or more and less than 8.0 points C: 4.0 points or more and less than 6.0 points D: 2.0 points or more and less than 4.0 points E: 1.0 points or more Less than 2.0 points ×: less than 1.0 points

<Ease of reuse of wrap film>
After cutting the wrap film with a saw blade and using it, assuming the operation of using the wrap film again, evaluation was performed by repeatedly wrapping the dish with the wrap film. The following method was used to evaluate the action of repeatedly wrapping a dish with wrap film. That is, 10 skilled evaluators (including men and women) hand a wrap film housed in a commercially available wrap film cosmetic box (Saran Wrap (registered trademark) cosmetic box manufactured by Asahi Kasei Home Products Co., Ltd., 22 cm × 50 m). and cut with a saw blade, a porcelain bowl having a diameter of 145 mm was wrapped with a wrap film as a container, and left to stand for 10 seconds with the wrap film wrapped. After that, the wrap film was peeled off, and it was confirmed whether or not there was any breakage. Evaluation was performed in an atmosphere of 23±2° C. and 50±10% RH. A series of operations of wrapping and peeling was recorded as one operation, and the number of operations was recorded at the time when breakage occurred. The ease of reuse of the wrap film was evaluated according to the following evaluation criteria based on the average score of the number of operations until breakage occurred by 10 evaluators.
If the evaluation of ease of reuse is "A", it can be said that the wrap film has excellent ease of reuse and is most excellent in ease of reuse. If the evaluation is "B", it can be said that the wrap film is very easy to reuse. If the evaluation is "C", it can be said that the wrap film is excellent in ease of reuse. If the evaluation is "D", it can be said that the ease of reuse is good. If the evaluation is "E", there is no particular problem with ease of reuse. If the evaluation is "x", it is inferior in ease of reuse.
[Evaluation criteria]
A: 8.0 times or more B: 6.0 times or more and less than 8.0 times C: 4.0 times or more and less than 6.0 times D: 2.0 times or more and less than 4.0 times E: 1.0 times or more Less than 2.0 times x: Less than 1.0 times

<Example 1>
Polyvinylidene chloride resin with a weight average molecular weight of 120,000 (content of vinylidene chloride monomer is 85% by mass, content of vinyl chloride monomer is 15% by mass) 93.4% by mass, acetyl tributyl citrate ( 5.5 mass% epoxidized soybean oil (hereinafter also referred to as “ESO”, trade name “Newsizer 510R” manufactured by NOF Corporation) 1.1 % by mass to obtain a composition.
The resulting composition was fed to a melt extruder, melted, and melt extruded through an annular die attached to the tip of the extruder to form a sock. At this time, the heating conditions of the extruder were adjusted so that the molten resin temperature at the slit outlet of the annular die was 185° C., and the resin was extruded in a circular shape.
After cooling this with a sock liquid and a cooling bath, the parison was opened to form bubbles, and double-bubble inflation stretching was performed under the stretching conditions shown in Table 1. At this time, the 3rd/2nd draw ratio was 3.7 times and the TD direction was 5.5 times to form a cylindrical film (bubble). Here, the cooling bath temperature was 23°C, the stretching temperature was 42°C, and the difference between the cooling bath temperature and the stretching temperature (stretching temperature - cooling bath temperature) was 19°C.
After the obtained tubular film was nipped and flattened, a two-ply film was wound up. This film was slit to a width of 300 mm and rewound on a paper tube while being peeled off into one sheet of film. After that, by winding 50 m around a paper tube having a length of 307 mm, a wound body of wrap film (thickness: 10 μm) was obtained. Each evaluation was performed by the said method using this. Table 1 shows the evaluation results.

<Examples 2 to 11, Comparative Examples 1 to 10>
A wrap film roll was produced in the same manner as in Example 1 except that the raw materials, additives, stretching conditions, etc. were changed as shown in Tables 1 and 2, and each evaluation was performed by the above methods. Evaluation results are shown in Tables 1 and 2.

Comparing Examples 1 to 11 with Comparative Examples 1 to 10, by controlling the molecular chain orientation ratio calculated by the formula (1) to a specific range, the film was pulled out from the cosmetic box. It was found that, when cut halfway, the cut end face is easy to pick up and recover, and it is easy to reuse after repeated use.

In addition, when comparing Examples 1 to 11, the greater the orientation of the molecular chains in the TD direction, the easier it is to pick up the cut surface when a break occurs, and the easier it is to reuse after repeated use. I found out.

DESCRIPTION OF SYMBOLS 1... Extruder, 2... Die, 3... Die mouth, 4... Sock, 5... Sock liquid, 6... Cooling tank, 7... First pinch roll, 8... Parison, 9... Second pinch roll, 10... Bubble, DESCRIPTION OF SYMBOLS 11... 3rd pinch roll, 12... Double ply film, 13... Winding roll, 14... Cosmetic box, 15... Film cutting blade, 16... Winding body, 17... Wrap film, 18... Cut end surface, 19... Wrap film 20... end face parallel to the flow direction of the cling film, 21... square sample with a side length of 1 cm, 22... slide glass, 23... long side of slide glass,
24... Horizontal direction of microscope observation image, 25... Vertical direction of microscope observation image

Claims (6)

including polyvinylidene chloride resin,
A wrap film having a molecular chain orientation ratio of 0.3 to 3.0 calculated by the following formula (1) when polarized Raman is measured;
Molecular chain orientation ratio = peak (630 to 680 cm ^-1 ) intensity (A value) derived from CCl ₂ in MD direction/peak (630 to 680 cm ^-1 ) intensity (C value) derived from CCl ₂ in TD direction... (1). further comprising a compound containing a methylene group ( _CH2 );
The wrap film according to claim 1, wherein the molecular chain orientation in the TD direction calculated by the following formula (2) is 2.0 to 5.8 when polarized Raman in the TD direction is measured;
Molecular chain orientation in the TD direction = CCl ₂ derived peak (630-680 cm ^-1 ) intensity (A value) in the MD direction / CH ₂ derived peak (2840 - 2890 cm ^-1 ) intensity (D value) in the MD direction. (2). The wrap film according to claim 1 or 2, which has a tensile breaking strength in the TD direction of 100 MPa or more. The wrap film according to any one of claims 1 to 3, which has a tensile elongation at break in the TD direction of 100% or less. The wrap film according to any one of claims 1 to 4, which has a thickness of 6 to 18 µm. A wound body in which the wrap film according to any one of claims 1 to 5 is wound around a winding core.

Images