JP2021046255A - Vinylidene chloride resin wrap film - Google Patents

Abstract

To provide a vinylidene chloride resin wrap film that is readily cut off from the end side of the wrap film and can be satisfactorily cut even with a paper blade.SOLUTION: A wrap film containing a vinylidene chloride resin has a tear strength of less than 2.0 cN in a TD direction, and has a low-temperature crystallization initiation temperature of 40-60°C measured with a temperature-modulated differential scanning calorimeter. The wrap film has a thickness of 6-18 μm.SELECTED DRAWING: None

Description

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

Vinylidene chloride-based resins are used as wrap films and the like because they are excellent in properties such as transparency, water resistance, and gas barrier properties. In recent years, wrap films are often used for applications that require gas barrier properties and aroma-retaining properties, such as foods and wastes having a strong odor, and the above-mentioned objects are wrapped in wrap films.

For example, Patent Document 1 discloses a technique relating to a polyvinylidene chloride resin wrap film, which suppresses vertical tear trouble and has excellent adhesion and transparency.

Further, Patent Document 2 describes a vinylidene chloride-based resin wrap film that overcomes odors, suppresses thermal decomposition during extrusion molding, and has little change over time in physical properties such as excessive adhesion of the film and deterioration of drawability. The technology related to is disclosed.

Further, Patent Document 3 discloses a technique relating to a storage box with a paperboard saw blade having excellent cutting performance by processing one end of a paperboard having a normal thickness to be used as a storage box into a saw blade.

Japanese Unexamined Patent Publication No. 2011-168750 Japanese Unexamined Patent Publication No. 2008-74955 Japanese Unexamined Patent Publication No. 5-162744

When wrapping food, it is difficult for conventional household wrap film to tear freely from the end face of the wrap film, and when the wrapped wrap film is opened, the film tears in an unintended diagonal direction. Sometimes. The wrap film that is torn in an unintended direction in this way has a problem that it is difficult to wrap the food again and the same wrap film cannot be reused.
In addition, the household wrap is stored in a box provided with a cutting blade, and is cut to the length to be used and used. By the way, in recent years, from the viewpoint of recyclability, it has been studied that a paper blade is used as the cutting blade instead of the conventional metal blade. However, since a paper blade is inferior in cutability to a metal blade, it is difficult to sufficiently cut it with a conventional wrap film using vinylidene chloride resin, which is disclosed in Patent Document 3. Even with the above technology, it is not possible to achieve the same level of cutability as a metal blade.

The present invention has been made in view of the above problems, and provides a vinylidene chloride-based resin wrap film which is excellent in ease of cutting from the end face of the wrap film and can be sufficiently cut even with a paper blade. With the goal.

As a result of diligent studies by the present inventor in order to solve the above problems, the tear strength in the TD direction is set to less than 2.0 cN, and the low temperature crystallization start temperature is set to 40 ° C. or higher and 60 ° C. or lower. It has been found that a vinylidene chloride-based resin wrap film can be obtained, which is excellent in ease of cutting from the end face and can be sufficiently cut even with a paper blade.

That is, the present invention is as follows.
[1]
A wrap film containing a vinylidene chloride resin.
The tear strength in the TD direction is less than 2.0 cN,
The low temperature crystallization start temperature measured by a temperature-modulated differential scanning calorimeter is 40 to 60 ° C.
The thickness is 6-18 μm,
Vinylidene chloride resin wrap film.
[2]
The vinylidene chloride-based resin contains 72 to 93 mol% of vinylidene chloride repeating units.
The vinylidene chloride-based resin wrap film according to the above [1].
[3]
The vinylidene chloride-based resin wrap film according to any one of the above [1] or [2], which contains 0.5 to 3% by weight of an epoxidized vegetable oil with respect to the vinylidene chloride-based resin.
[4]
The item according to any one of [1] to [3] above, which contains 3 to 5% by weight of at least one compound selected from the group consisting of citric acid ester and dibasic acid ester with respect to the vinylidene chloride resin. Vinylidene chloride resin wrap film.

According to the present invention, it is possible to obtain a vinylidene chloride-based resin wrap film which is excellent in ease of cutting from the end face of the wrap film and can be sufficiently cut even with a paper blade.

It is the schematic of the apparatus used in the film forming process of this invention. This is an example of using the film of the present invention.

Hereinafter, embodiments for carrying out the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

[Vinylidene chloride resin wrap film]
The vinylidene chloride-based resin wrap film of the present embodiment (hereinafter, may be simply referred to as “wrap film”) is a wrap film containing a vinylidene chloride-based resin and has a tear strength in the TD direction of less than 2.0 cN. The low-temperature crystallization start temperature measured by a temperature-modulated differential scanning calorimeter is 40 to 60 ° C., and the thickness is 6 to 18 μm.

<Low temperature crystallization start temperature>
The low-temperature crystallization start temperature is an index showing the thermal stability after the production of the wrap film, and the degree of rearrangement of the molecular chains, that is, the easiness of tearing due to physical deterioration of the film can be evaluated.
The wrap film of the present embodiment has a low temperature crystallization start temperature of 40 to 60 ° C., preferably 40 to 52 ° C., more preferably 40 to 52 ° C., as measured by a temperature-modulated differential scanning calorimeter (temperature-modulated DSC). Is 40-47 ° C. If the low temperature crystallization start temperature is less than 40 ° C, the tear strength in the TD direction becomes excessively high, making it difficult to tear by hand from the end face of the wrap film, and cutting when cutting with a paper blade. It causes deterioration of sex. On the other hand, when the low-temperature crystallization start temperature exceeds 60 ° C., the rearrangement of the molecular chains has already progressed and physical deterioration has occurred in the film, so that troubles due to tearing of the film increase.

Here, the "low temperature crystallization start temperature" is the extrapolation start temperature (temperature rise) of the exothermic peak caused by low temperature crystallization in the temperature-heat flow curve of the irreversible component obtained by the temperature rise measurement by the temperature modulation type DSC. In the measurement, the temperature of the intersection of the line extending the baseline on the low temperature side to the high temperature side and the tangent line drawn at the point where the gradient is maximized on the curve on the low temperature side of the crystallization peak) is measured by the following method. ..
A differential scanning calorimetry device (DSC) (input-compensated double furnace DSC 8500) manufactured by PerkinElmer Co., Ltd. is used, and the temperature-heat flow curve of the irreversible component is obtained by the step scan measurement mode. The conditions for the step scan measurement at this time are that the measurement temperature is 0 to 180 ° C., the temperature rise rate is 10 ° C./min, the temperature rise step width is 4 ° C., and the isothermal time is 1 min. In the obtained temperature-heat flow curve, the external start temperature of the exothermic peak caused by low temperature crystallization is defined as the low temperature crystallization start temperature.

Since crystallization and crystal melting occur in competition during the DSC temperature rise measurement, the heat flow derived from the formation / growth and melting of microcrystals is canceled by the conventional DSC measurement method, and the thermal behavior of the microcrystals is examined. It was difficult to distinguish between the conventional wrap film and the present embodiment. On the other hand, when the temperature-modulated DSC is used, it can be separated into a heat flow of an irreversible component such as crystallization and a reversible component such as crystal melting or glass transition, and it becomes possible to evaluate the thermal behavior of microcrystals. ..

In order to set the low temperature crystallization start temperature of the wrap film to 40 to 60 ° C., for example, the product of the stretching ratio in the MD direction and the stretching ratio in the TD direction (MD stretching ratio × TD stretching ratio) and the temperature at the time of stretching are set. By adjusting, the stress applied in the stretching process can be adjusted, and the degree of orientation crystallization can be appropriately set.

The preferred range of MD stretching ratio × TD stretching ratio is 11 to 21 times, more preferably 11 to 19 times, further preferably 11 to 17 times, and particularly preferably 11 to 15 times.

The thickness of the wrap film of the present embodiment is 6 to 18 μm, preferably 9 to 12 μm. When the thickness of the wrap film is 6 μm or more, the tensile strength of the film is high and the film breakage during use can be suppressed. In addition, there is no significant decrease in tear strength, and when the film is pulled out from the winding body and when the end of the film rewound into the cosmetic box is picked out, the film is cut from the end cut by the cutting blade attached to the cosmetic box. Trouble of tearing can be reduced. On the other hand, when the thickness of the wrap film is 18 μm or less, the force required to cut the film with the film cutting blade can be reduced, the cutability is good, and the film easily fits the shape of the container, so that the film can be put into the container. Adhesion is improved. That is, the thickness of the wrap film is adjusted to a specific range from the viewpoint of suppressing troubles of film breakage, cutting property, and balance of adhesion. In particular, a wrap film having a thickness of 6 to 18 μm does not significantly reduce the tear strength, but is never sufficient, and the film tends to have tear troubles, so that the effect of the present invention becomes remarkable. The thickness of the wrap film can be adjusted by a known method, and can be adjusted, for example, by appropriately selecting the extrusion speed within the range of 3 kg / hr to 200 kg / hr.

The thickness of the wrap film can be measured according to the method described in Examples described later.

<Tear strength>
The wrap film of the present embodiment has a tear strength in the TD direction of less than 2.0 cN when measured with a single film. Here, the TD direction means a direction perpendicular to the direction in which the wrap film is pulled out from the wound body. The tear strength is measured by the method described in Examples below.

Since the wrap film of the present embodiment has a tear strength of less than 2.0 cN in the TD direction during measurement with a single film, it is possible to prevent blade spillage especially during cutting in the rewind process, and paper. It is housed in a box equipped with a cutting blade, and can be sufficiently cut when it is cut to an appropriate length during use. The tear strength in the TD direction is preferably 0.1 cN or more and less than 2.0 cN, more preferably 0.1 cN or more and 1.8 cN or less, and further preferably 0.1 cN or more and 1.5 cN or less. Even more preferably, it is 0.1 cN or more and 1.0 cN or less, and particularly preferably 0.1 cN or more and 0.5 cN or less.

The tear strength of the wrap film of the present embodiment in the TD direction can be adjusted by adjusting the composition of the vinylidene chloride resin, the additive composition, the stretching ratio of the film, the stretching speed, the stretching temperature, the thickness of the film, the inner diameter of the die slit, and the like. For example, the tear strength in the TD direction tends to be improved by lowering the stretching ratio in the TD direction, thickening the wrap film, or raising the stretching temperature, increasing the stretching ratio in the TD direction, or wrapping. It tends to decrease by thinning the film or lowering the stretching temperature. Further, if the inner diameter of the die slit is reduced, when stretching in the TD direction, the stretching speed increases even when stretching to the same magnification, so that the tear strength in the TD direction tends to decrease.

<Vinylidene chloride resin>
The vinylidene chloride-based resin wrap film of the present embodiment contains a vinylidene chloride-based resin.
The vinylidene chloride-based resin used in the present embodiment is not particularly limited as long as it contains a vinylidene chloride repeating unit, and other than the vinylidene chloride repeating unit, for example, acrylic acid esters such as vinyl chloride, methyl acrylate, and butyl acrylate; methyl meta. One or more types of monomers copolymerizable with vinylidene chloride, such as acrylate, butyl methacrylate and other methacrylic acid esters; acrylonitrile; vinyl acetate, may be copolymerized.

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

When the vinylidene chloride-based resin is a copolymer resin, the ratio of vinylidene chloride repeating units is not particularly limited, but those containing 72 to 93 mol% of vinylidene chloride repeating units are preferable, and those containing 81 to 90 mol% are more preferable. When the repeating unit of vinylidene chloride is 72 mol% or more, the glass transition temperature of the vinylidene chloride resin is low and the film becomes soft, so that the tearing of the film tends to be reduced even when used in a low temperature environment such as winter. On the other hand, when the repeating unit of vinylidene chloride is 93 mol% or less, it tends to be possible to suppress a significant increase in crystallinity and suppress deterioration of molding processability during film stretching.
In particular, a wrap film made of a vinylidene chloride resin containing 72 mol% or more of vinylidene chloride repeating units receives heat to form and grow microcrystals when stored and distributed at high temperatures such as in summer, resulting in physical deterioration. The effect of the present invention becomes more remarkable because it tends to occur easily, and as a result, tearing troubles tend to occur when the film is used.

The content of the vinylidene chloride repeating unit is not particularly limited, but can be measured using, for example, a highly decomposed proton nuclear magnetic resonance measuring device (400 MHz or more). More specifically, the reprecipitated filtrate of the wrap film is vacuum-dried, and a solution prepared by dissolving 5% by weight in deuterated tetrahydrofuran is subjected to 1 H-NMR measurement at a measurement atmosphere temperature of about 27 ° C. The vinylidene chloride repeat unit is calculated using a unique chemical shift relative to tetramethylsilane in the resulting spectrum. For example, in the case of a copolymer of vinylidene chloride and vinyl chloride, the peaks of 3.50 to 4.20 ppm, 2.80 to 3.50 ppm, and 2.00 to 2.80 ppm are used for calculation.

The content of the vinylidene chloride resin is preferably 77 to 94% by weight, more preferably 85 to 94% by weight, based on the total amount of the wrap film. When the content of the vinylidene chloride-based resin is within the above range, it is possible to suppress the film from being easily stretched due to the plasticizing effect of the additive or the like, and the cuttability of the film tends to be further improved.

The method of measuring the content of each component in the wrap film differs depending on the analysis target. For example, the content of the vinylidene chloride-based resin can be obtained by vacuum-drying the reprecipitated filter material of the wrap film and measuring the weight. On the other hand, for the content of the epoxidized vegetable oil, for example, a method using NMR can be used. The content 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 vinylidene chloride-based resin wrap film of the present embodiment may contain various additives in addition to the vinylidene chloride-based resin, if necessary. The additive is not particularly limited, and examples thereof include known stabilizers such as epoxidized vegetable oils and known plasticizers such as citric acid ester and dibasic acid ester.

<Epoxy vegetable oil>
The vinylidene chloride-based resin wrap film of the present embodiment preferably contains an epoxidized vegetable oil from the viewpoint of suppressing a change in the color tone of the wrap film. The epoxidized vegetable oil also acts as a stabilizer for extrusion of vinylidene chloride resin.

The epoxidized vegetable oil is not particularly limited, but generally includes those produced by epoxidizing edible oils and fats. Specific examples thereof include epoxidized soybean oil (ESO) and epoxidized linseed oil. Among these, when the wrap film is stored at a high temperature, deterioration of the pullability of the film from the cosmetic box can be suppressed. ESO is preferred because of its tendency.

When the wrap film of the present embodiment contains an epoxidized vegetable oil, the content thereof is not particularly limited, but from the viewpoint of suppressing the color change of the wrap film and preventing stickiness due to bleeding, the vinylidene chloride resin is 0. 5 to 3% by weight is preferable, and 1 to 2% by weight is more preferable.

The method for measuring the epoxidized vegetable oil content using NMR follows the procedure below.
A 50 mg 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 (integration number: 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 used 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 wrap film of the present embodiment preferably contains at least one compound selected from the group consisting of citric acid ester and dibasic acid ester from the viewpoint of molding processability and the like.

<Citric acid ester>
The citrate ester used in the wrap film of the present embodiment is not particularly limited, and examples thereof include triethyl citrate, tributyl citrate, triethyl acetyl citrate, ATBC, and tri-n- (2-ethylhexyl) acetyl citrate. .. Among these, ATBC is preferable because it has a high plasticizing effect on vinylidene chloride-based resin and tends to sufficiently plasticize the resin even in a small amount to improve molding processability.

<Dibasic acid ester>
The dibasic acid ester contained in the wrap film of the present embodiment is not particularly limited, but is an adipic acid ester system such as dibutyl adipate, din-hexyl adipate, di-2-ethylhexyl adipate, and dioctyl adipate; Examples include adipic acid esters such as di-2-ethylhexyl azerate and octyl azerate; sebacic acid esters such as dibutyl sebacate (DBS) and di-2-ethylhexyl sebacate. Among these, DBS is preferable because it has a high plasticizing effect on vinylidene chloride-based resin and tends to sufficiently plasticize the resin even in a small amount to improve molding processability.

The total content of the citric acid ester and the dibasic acid ester is not particularly limited, but is chloride from the viewpoint of imparting better molding processability and preventing excessive adhesion of the wrap film when the additive content is high. With respect to the vinylidene-based resin, 3 to 8% by weight is preferable, 3 to 7% by weight is more preferable, 3 to 5% by weight is further preferable, and 3.5 to 5% by weight is particularly preferable.

In particular, when the vinylidene chloride-based resin wrap film contains 3% by weight or more of citric acid ester or dibasic acid ester, the mobility of the molecular chain of the vinylidene chloride-based resin becomes high, so that fine crystals are formed and grown. Rearrangement is likely to occur, physical deterioration is likely to occur when exposed to high temperatures, and the film is likely to stretch, making it difficult for the cutting blade to bite into the film, which tends to reduce cutability. The effect of is more remarkable.

<Other formulations>
The vinylidene chloride-based resin wrap film of the present embodiment contains formulations other than the epoxidized vegetable oil, citric acid ester, and dibasic acid ester (hereinafter referred to as "other formulations"), such as plasticizers and stabilizers. Contains 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), etc. May be good.

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

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

The weather resistance improver is not particularly limited, but specifically, ethylene-2-cyano-3,3'-diphenylacrylate, 2- (2'-hydroxy-5'-methylphenyl) benzolithriazole, and the like. 2- (2'-Hydroxy-3'-t-butyl-5'-methylphenyl) 5-chlorobenzotriazole, 2-hydroxy-4-methoxybenzophenone, and 2,2'-dihydroxy-4-methoxybenzophenone, etc. Examples include UV absorbers.

The colorant of the dye or pigment is not particularly limited, and specific examples thereof include carbon black, phthalocyanine, quinacridone, indoline, azo pigment, and red iron oxide.

The antifogging agent is not particularly limited, and specific examples thereof 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, and specific examples thereof include a silver-based inorganic antibacterial agent.

The lubricant is not particularly limited, but specifically, fatty acid hydrocarbon-based lubricants such as ethylene bissteroamide, butyl stearate, polyethylene wax, paraffin wax, carnauba wax, myristyl myristate, and stearyl stearate, and higher fatty acids. Examples thereof include lubricants, fatty acid amide-based lubricants, and fatty acid ester lubricants.

The nucleating agent is not particularly limited, and specific examples thereof include a phosphoric acid ester metal salt and the like.

The content of the other formulation is preferably 5% by weight or less, more preferably 3% by weight or less, still more preferably 1% by weight or less, and particularly preferably 0.1% by weight or less with respect to the wrap film. Is.

[Manufacturing method of vinylidene chloride resin wrap film]
The method for producing the vinylidene chloride-based resin wrap film of the present embodiment is not particularly limited, but is a method for producing a vinylidene chloride-based resin wrap film in which the vinylidene chloride-based resin composition is melt-extruded and then stretched in the MD direction and the TD direction. Therefore, under the condition of a stretching temperature of 25 ° C., the stretching ratio in the MD direction is 1.0 to 2.0 times, and the stretching ratio in the TD direction is 6.5 to 12.0 times, or the stretching temperature is 10 to 22. Under the condition of ° C., the stretching ratio in the MD direction can be 2.0 to 3.8 times, the stretching ratio in the TD direction can be 5.3 to 7.0 times, and the inner diameter of the die slit can be 6 mm to 50 mm. ..

Hereinafter, a preferred method for producing the wrap film of the present embodiment will be described.
First, a vinylidene chloride-based resin, at least one compound selected from an epoxidized vegetable oil, a citric acid ester, or a dibasic acid ester, if necessary, and various additives, if necessary, are mixed with a ribbon blender or a Henschel mixer. To produce a vinylidene chloride-based resin composition, the mixture is uniformly mixed with or the like and aged for 24 hours. Then, as shown in FIG. 1 as a schematic diagram of an example of the manufacturing process of the wrap film, the resin composition is melted by an extruder (1) and extruded into a tubular shape from a die (2) to form a sock (4). Will be done. The outside of the sock (4) is brought into contact with cold water in the cold water tank (6), and the sock liquid (5) is injected into the inside of the sock (4) to cool and solidify from the inside and outside. The solidified sock (4) is folded by the first pinch roll (7) to form the parison (8).

Subsequently, by injecting air into the inside of the parison (8), the parison (8) is opened again and becomes tubular. At this time, the sock liquid (5) coated on the inner surface of the sock (4) exhibits the effect of the parison (8) as an opening agent. The parison (8) is reheated with warm water to a temperature suitable for stretching. The hot water adhering to the outside of the parison (8) is squeezed by the second pinch roll (9). Air is injected into a tubular parison (8) heated to an appropriate temperature to form a bubble (10), and a stretched film is obtained. After that, the stretched film is folded by the third pinch roll (11) to become a double ply film (12). The double ply film (12) is wound by a winding roll (13). Further, this film is slit and wound while being peeled off so as to form a single film, and temporarily stored in the original state for 1 to 3 days. Finally, the raw fabric is unwound into a paper tube and packed in a cosmetic box to obtain a vinylidene chloride-based resin wrap film wound body stored in the cosmetic box.

The process from the first pinch roll (7) to the third pinch roll (11) described above is a stretching step, and the rotation speed ratio of the first pinch roll (7) and the third pinch roll (11) is in the MD direction. The stretching ratio is determined, and the stretching ratio in the TD direction can be adjusted by the stretching temperature of the parison (8) and the size of the bubble (10).
The stretching ratio in the MD direction refers to the stretching ratio of the parison (8) stretched in the MD direction. For example, in FIG. 1, the rotation speed of the third pinch roll (11) with respect to the rotation speed of the first pinch roll (7). The stretching ratio in the MD direction can be calculated from the ratio of. Further, the draw ratio in the TD direction can be calculated from the ratio of the width length of the double ply film (12) to the width length of the parison (8).
Further, changing the rotation speed of the first pinch roll (7) or the third pinch roll (11), or changing the distance between the first pinch roll (7) and the third pinch roll (11). Therefore, the stretching speed of the parison (8), particularly the stretching speed in the MD direction, can be changed.
The average stretching speed in the MD direction refers to the stretching ratio in the MD direction with respect to the time it takes for the parison to pass between the first pinch roll (7) and the third pinch roll (11). Depending on the rotation speed of the pinch roll (7), the rotation 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). Can be calculated. The average stretching speed in the TD direction refers to the stretching ratio in the TD direction with respect to the time required for the parison (8) to expand to the bubble (10). For example, in FIG. 1, the parison (8) and the bubble (10) are stretched. It can be calculated from the stretching length measured using a still image, the time required for stretching in the TD direction calculated from the rotation speed of the third pinch roll (11), and the stretching ratio in the TD direction.

In order to stably form stretch bubbles, the conventional vinylidene chloride resin wrap film has a stretch ratio of MD and TD of 4 to 6 times under the condition of a stretch temperature of 25 to 34 ° C.
On the other hand, a film having a TD tear strength of less than 2.0 cN and a crystallization start temperature of 40 to 60 ° C., which is excellent in cutability on the end face and cutability with a paper blade, is not particularly limited. However, under the condition of a stretching temperature of 25 ° C., the stretching ratio in the MD direction is 1.0 to 2.0 times, and the stretching ratio in the TD direction is 6.5 to 12.0 times, or the stretching temperature is 10 to 22 ° C. The stretching ratio in the MD direction is 2.0 to 3.8 times, the stretching ratio in the TD direction is 5.3 to 7.0 times, and the inner diameter of the die slit is 6 to 50 mm under the above conditions. it can. The preferred range of the die slit inner diameter is 6 mm to 33 mm, more preferably 6 mm to 28 mm, even more preferably 6 mm to 20 mm, and most preferably 6 mm to 12 mm.
When the inner diameter of the die slit is as large as 40 to 50 mm, it is necessary to appropriately adjust the TD stretching ratio and the stretching temperature. Here, the preferable range of the TD stretching ratio is 6.5 to 12.0 times. The preferred range of stretching temperature is 10 to 22 ° C.

On the other hand, the stretched film can be relaxed by making the rotation speed of the take-up roll (13) slower than that of the third pinch roll (11). Generally, after stretching, the film may be relaxed by using heat from an infrared heater or the like, but when the wrap film of the present embodiment is produced, the formation of microcrystals that cause the film to tear due to heat. Growth occurs and the crystallization start temperature exceeds 60 ° C. Therefore, it is preferable to set the atmospheric temperature at the time of relaxation to 25 to 32 ° C.

The conditions for storing the film in the original state after slitting are not particularly limited, but it is preferable to store the film at 5 to 19 ° C. for 24 hours or more after stretching. In particular, the ambient temperature during storage is important in suppressing the formation and growth of microcrystals that induce an increase in film tearing troubles. The storage location of the raw fabric is often relatively high temperature because it is adjacent to the film manufacturing process and the temperature is not controlled. The fact that the atmospheric temperature during storage of the slit original fabric is 19 ° C or less can suppress the physical deterioration of the film due to the rearrangement of the molecular chains, and when the film is pulled out from the wound body and the film is rewound into the cosmetic box. When the end portion is picked out, it is preferable because the film can be prevented from being easily torn from the end portion cut by the cutting blade attached to the cosmetic box.

On the other hand, the fact that the atmospheric temperature during storage of the slit raw fabric is 5 ° C or higher sufficiently relaxes the film, and when it is exposed to 20 ° C or higher during subsequent distribution and storage, rearrangement of the molecular chains is less likely to occur. Preferred from the point of view.
Therefore, it is preferable to store the original slit fabric at 5 to 19 ° C. for 24 hours or more, whereby a film in which the molecular chains in the amorphous portion are relaxed while suppressing the formation and growth of microcrystals can be obtained. .. By relaxing the orientation of the molecular chains during storage of the raw fabric, it becomes difficult for microcrystals to form and grow even when the film is exposed to high temperatures during distribution and storage, and tearing troubles can be suppressed.

The original slit fabric is not particularly limited after storage, but is wound back on, for example, a paper tube or the like, and used as a winding body (16) in a cosmetic box (14) provided with a film cutting blade (15) as shown in FIG. It is stored. As illustrated in FIG. 2, the wrap film (17) is pulled out and used at the time of use.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto. The evaluation methods used in the examples and comparative examples are as follows.

(Measuring method)
<Content of vinylidene chloride repeating unit>
The ratio of vinylidene chloride repeating units in the wrap film was measured using a highly decomposed proton nuclear magnetic resonance measuring device. The reprecipitated filtrate of the wrap film was vacuum dried, and a solution prepared by dissolving 5% by weight in deuterated tetrahydrofuran was subjected to 1 H-NMR measurement at a measurement atmosphere temperature of about 27 ° C. For example, regarding the copolymer of vinylidene chloride and vinyl chloride, the peaks of the copolymer based on tetramethylsilane are 3.50 to 4.20 ppm, 2.80 to 3.50 ppm, and 2.00 to 2.80 ppm. The content of vinylidene chloride repeating unit was calculated using.

<Film thickness>
The thickness of the wrap film was measured using a dial gauge (manufactured by Teclock) in an atmosphere of 23 ° C. and 50% RH.

<Tear strength>
The tear strength of the wrap film was measured using a light load tear tester D type (manufactured by Toyo Seiki) in an atmosphere of 23 ° C. and 50% RH. The tear strength of the wrap film was measured both in a state where 10 wrap films were stacked and in a state where only one wrap film was used. At this time, the measurement range was appropriately selected so as to be 20 to 80% of the full scale. If it was less than 20% of full scale, the smallest measurement range was selected. When stacking the films, talc was sprinkled on the films so as not to cause wrinkles, and then 10 films were stacked. The sample length in the tear direction was 63.5 mm, and the sample width was 50.0 mm. When measuring, lift the pendulum, stop it, carefully attach the test piece or laminated test piece to the knob, and tighten the clamp firmly so that the slit position is in the center of the film width. It was. Then, after slitting the film with a knife attached to the device, the pendulum was carefully released and the value of the force required to tear the test piece was read. Tests in which the tear line deviated by 10 mm or more from the extension line of the slit were excluded, and an additional test piece was tested instead. However, in this case, this does not apply if the tear is along the line of the embossed pattern. The measurement result is rounded off to the second decimal place.

<Low temperature crystallization start temperature>
A differential scanning calorimetry device (DSC) (input compensation type double furnace DSC 8500) manufactured by PerkinElmer is used to measure the low temperature crystallization start temperature of the wrap film, and a step scan measurement mode (sample weight: 6 mg, sample pan material). : Made of aluminum, measurement temperature: 0 to 180 ° C., temperature rise rate: 10 ° C./min, temperature rise step width: 4 ° C., isothermal time: 1 min) was used. An empty aluminum sample pan was also measured under the same conditions and used as a blank. In the irreversible component of the temperature-heat flow curve, the temperature at which heat generation due to low temperature crystallization starts was defined as the low temperature crystallization start temperature.

(Evaluation methods)
<Cutability with a paper blade>
The sensory evaluation of the cuttability of the wrap film with a paper blade is carried out by the following method. That is, the cutability (film) when 10 skilled evaluators (including men and women) pull out each of the wrap films stored in the cosmetic box disclosed in Patent Document 3 by hand and cut them with a carton blade. (Whether or not it can be cut straight with a light force without stretching) in 1-point increments of 1 to 10 points (10 points are the best cutability and 1 point is the worst cutability). Then, evaluate each. Based on the average score of 10 evaluators, the cutability of the wrap film with a paper blade is evaluated according to the following evaluation criteria. If the evaluation of the cutability with the paper blade is "A", it can be said that the wrap film is very comfortable to pick and the cutability with the paper blade is very excellent. If the evaluation is "B", the wrap film has a pleasant cutability with a paper blade. If the evaluation is "C", it can be said that the wrap film has good cutability with a paper blade. If the evaluation is "D", there is no particular problem in the cuttability of the wrap film with the paper blade. If the evaluation is "x", the wrap film is inferior in cutability with a paper blade.
[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 ×: 2.0 points or less

<Easy to cut from the end face>
Assuming an operation of wrapping food or the like with a wrap film and opening the package, a sensory evaluation is performed by the following method for the ease of cutting when the end face of the wrap film is torn by hand. That is, 10 skilled evaluators (including men and women) put the wrap film stored in a commercially available wrap film cosmetic box (Asahi Kasei Home Products Co., Ltd., trade name Saran Wrap (registered trademark) cosmetic box, 30 cm x 20 m). One point about the ease of cutting from the end face when tearing the end face of the wrap film by hand (whether or not it can be cut straight with a light force in the direction of tearing by hand) by cutting out to a size of 27 cm in length and width. Each evaluation is made in 1-point increments of 10 points (10 points are the best cutability from the end face, and 1 point is the worst cut ease from the end face). Evaluate the ease of cutting from the end face of the wrap film based on the average score of 10 evaluators. If the ease of cutting from the end face is "A", the wrap film starts from a very pleasant end face. It can be said that the ease of cutting from the end face is very excellent. If the rating is "B", the wrap film is easy to cut from a pleasant end face. If the evaluation is "C", it can be said that the wrap film has good ease of cutting from the end face. If the evaluation is "D", there is no particular problem in the ease of cutting from the end face of the wrap film. If the evaluation is "x", the wrap film is inferior in ease of cutting from the end face.
[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 ×: 2.0 points or less

[Example 1]
Hereinafter, a preferred method for producing the wrap film of the present embodiment will be described.
Vinylidene chloride resin with a weight average molecular weight of 120,000 (vinylidene chloride repeating unit is 85 mol%, vinyl chloride repeating unit is 15 mol%), ATBC (tributyl acetylcitrate, Taoka Chemical Industry Co., Ltd.), ESO (Newsizer 510R, Nippon Oil & Fats Co., Ltd. mixed at a ratio of 93.4% by weight, 5.5% by weight, and 1.1% by weight, respectively. A total of 10 kg was mixed with a Henschel mixer for 5 minutes and aged for 24 hours or more to chloride. A vinylidene resin composition was obtained.
The above-mentioned vinylidene chloride resin composition is supplied to a melt extruder to be melted, and the heating conditions of the extruder are set so that the molten resin temperature at the slit outlet of the annular die attached to the tip of the extruder is 170 ° C. Was extruded cyclically at an extrusion rate of 6 kg / hr. The inner diameter of the die slit was 49 mm.
After supercooling this, by inflation stretching, the stretching temperature was 25 ° C., the MD direction was stretched 1.0 times, and the TD direction was stretched 12.0 times to form a tubular film, and the width of the double ply film was obtained. A 924 mm double-layered film was wound at a winding speed of 18 m / min. This film was slit to a width of 80 mm, peeled off into a single film, and rewound into a paper tube having an outer diameter of 97 mm. Then, it was stored at 15 ° C. for 30 hours, and wound 20 m on a paper tube having an outer diameter of 36 mm and a length of 300 mm to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Example 2]
Same as in Example 1 except that the extrusion speed is 18 kg / hr, the draw ratio in the MD direction is 1.9 times, the draw ratio in the TD direction is 7.0 times, and the width of the double ply film is 540 mm. A wound body of a wrap film was obtained by producing by the method of. The evaluation results are shown in Table 1.

[Example 3]
Same as in Example 1 except that the extrusion speed is 12 kg / hr, the draw ratio in the MD direction is 2.0 times, the draw ratio in the TD direction is 8.7 times, and the width of the double ply film is 664 mm. A wound body of a wrap film was obtained by producing by the method of. The evaluation results are shown in Table 1.

[Example 4]
Same as in Example 1 except that the extrusion speed is 9 kg / hr, the draw ratio in the MD direction is 1.7 times, the draw ratio in the TD direction is 6.5 times, and the width of the double ply film is 495 mm. A wound body of a wrap film was obtained by producing by the method of. The evaluation results are shown in Table 1.

[Example 5]
Except that the extrusion speed is 11 kg / hr, the draw ratio in the MD direction is 2.0 times, the draw ratio in the TD direction is 7.0 times, the draw temperature is 10 ° C., and the width of the double ply film is 540 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Example 6]
Except that the extrusion speed is 14 kg / hr, the draw ratio in the MD direction is 2.5 times, the draw ratio in the TD direction is 6.3 times, the draw temperature is 15 ° C., and the width of the double ply film is 483 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Example 7]
Except that the extrusion speed is 19 kg / hr, the draw ratio in the MD direction is 3.5 times, the draw ratio in the TD direction is 5.7 times, the draw temperature is 20 ° C., and the width of the double ply film is 437 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Example 8]
Except that the extrusion speed is 20 kg / hr, the draw ratio in the MD direction is 3.8 times, the draw ratio in the TD direction is 5.3 times, the draw temperature is 22 ° C., and the width of the double ply film is 409 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Example 9]
The extrusion speed is 16 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the draw temperature is 25 ° C., the inner diameter of the die slit is 14 mm, and the double ply film. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the width of the wrap film was set to 124 mm. The evaluation results are shown in Table 1.

[Example 10]
The extrusion speed is 19 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the draw temperature is 25 ° C., the inner diameter of the die slit is 23 mm, and the double ply film. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the width of the wrap film was set to 206 mm. The evaluation results are shown in Table 1.

[Example 11]
The extrusion speed is 20 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the draw temperature is 25 ° C., the inner diameter of the die slit is 28 mm, and the double ply film. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the width of the wrap film was 248 mm. The evaluation results are shown in Table 1.

[Example 12]
The extrusion speed is 20 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the draw temperature is 25 ° C., the inner diameter of the die slit is 33 mm, and the double ply film. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the width of the wrap film was 289 mm. The evaluation results are shown in Table 1.

[Comparative Example 1]
The same as in Example 1 except that the extrusion speed is 10 kg / hr, the draw ratio in the MD direction is 3.3 times, the draw ratio in the TD direction is 5.6 times, and the width of the double ply film is 429 mm. By producing by the method, a wound body of a wrap film was obtained. The evaluation results are shown in Table 1.

[Comparative Example 2]
Except that the extrusion speed is 10 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the inner diameter of the die slit is 50 mm, and the width of the double ply film is 441 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Comparative Example 3]
The weight average molecular weight of the vinylidene chloride resin was 105,000, the vinylidene chloride repeating unit was 84 mol%, the vinyl chloride repeating unit was 16 mol%, the amount of ATBC added was 2.3% by weight, and the amount of ESO added was 2. 2% by weight, 2.8% by weight of DALG added, an extrusion rate of 8 kg / hr, a draw ratio of 3.8 times in the MD direction, a draw ratio of 4.1 times in the TD direction, and a double ply. A wound body of a wrap film was obtained by producing the film in the same manner as in Example 1 except that the width of the film was 316 mm. The evaluation results are shown in Table 1.

[Comparative Example 4]
The weight average molecular weight of the vinylidene chloride resin was 105,000, the vinylidene chloride repeating unit was 84 mol%, the vinyl chloride repeating unit was 16 mol%, the amount of ATBC added was 2.3% by weight, and the amount of ESO added was 2. 2% by weight, 2.8% by weight of DALG added, an extrusion rate of 8 kg / hr, a draw ratio of 3.7 times in the MD direction, a draw ratio of 5.6 times in the TD direction, and a die slit. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the inner diameter of the double-ply film was 58 mm and the width of the double-ply film was 510 mm. The evaluation results are shown in Table 1.

[Comparative Example 5]
The weight average molecular weight of the vinylidene chloride resin was 130,000, the vinylidene chloride repeating unit was 80 mol%, the vinyl chloride repeating unit was 20 mol%, the amount of ATBC added was 5.2% by weight, and the amount of ESO added was 1. Except that the extrusion rate was 9 kg / hr, the draw ratio in the MD direction was 4.5 times, the draw ratio in the TD direction was 3.6 times, and the width of the double ply film was 279 mm, which was 8% by weight. A wound body of a wrap film was obtained by producing in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 6]
The weight average molecular weight of the vinylidene chloride resin was 130,000, the vinylidene chloride repeating unit was 80 mol%, the vinyl chloride repeating unit was 20 mol%, the amount of ATBC added was 5.2% by weight, and the amount of ESO added was 1. Assuming 8% by weight, the extrusion rate is 11 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the inner diameter of the die slit is 61 mm, and the width of the double ply film is set. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the thickness was 537 mm. The evaluation results are shown in Table 1.

[Comparative Example 7]
The weight average molecular weight of the vinylidene chloride resin was 130,000, the vinylidene chloride repeating unit was 80 mol%, the vinyl chloride repeating unit was 20 mol%, the amount of ATBC added was 5.2% by weight, and the amount of ESO added was 1. Except for setting the extrusion rate to 8 kg / hr as 8% by weight, setting the draw ratio in the MD direction to 4.9 times, setting the draw ratio in the TD direction to 3.1 times, and setting the width of the double ply film to 241 mm. A wound body of a wrap film was obtained by producing in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 8]
The weight average molecular weight of the vinylidene chloride resin was 130,000, the vinylidene chloride repeating unit was 80 mol%, the vinyl chloride repeating unit was 20 mol%, the amount of ATBC added was 5.2% by weight, and the amount of ESO added was 1. Assuming 8% by weight, the extrusion rate is 11 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the inner diameter of the die slit is 89 mm, and the width of the double ply film is set. A wound body of a wrap film was obtained by producing in the same manner as in Example 1 except that the thickness was 785 mm. The evaluation results are shown in Table 1.

[Comparative Example 9]
Except that the extrusion speed is 11 kg / hr, the draw ratio in the MD direction is 3.7 times, the draw ratio in the TD direction is 5.6 times, the inner diameter of the die slit is 89 mm, and the width of the double ply film is 468 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Comparative Example 10]
Except that the extrusion speed is 5 kg / hr, the draw ratio in the MD direction is 1.0 times, the draw ratio in the TD direction is 8.6 times, the draw temperature is 140 ° C., and the width of the double ply film is 659 mm. Was produced in the same manner as in Example 1 to obtain a wound body of a wrap film. The evaluation results are shown in Table 1.

[Comparative Example 11]
Same as in Example 1 except that the extrusion speed is 12 kg / hr, the draw ratio in the MD direction is 2.0 times, the draw ratio in the TD direction is 12.0 times, and the width of the double ply film is 924 mm. A wound body of a wrap film was obtained by producing by the method of. The evaluation results are shown in Table 1.

[Comparative Example 12]
Same as in Example 1 except that the extrusion speed is 8 kg / hr, the draw ratio in the MD direction is 1.5 times, the draw ratio in the TD direction is 6.5 times, and the width of the double ply film is 495 mm. A wound body of a wrap film was obtained by producing by the method of. The evaluation results are shown in Table 1.

As shown in Table 1, the wrap films obtained in Examples 1 to 12 were excellent in ease of cutting from the end face of the wrap film, and could be sufficiently cut even with a paper blade.

Claims (4)

A wrap film containing a vinylidene chloride resin.
The tear strength in the TD direction is less than 2.0 cN,
The low temperature crystallization start temperature measured by a temperature-modulated differential scanning calorimeter is 40 to 60 ° C.
The thickness is 6-18 μm,
Vinylidene chloride resin wrap film. The vinylidene chloride resin wrap film according to claim 1, wherein the vinylidene chloride resin contains 72 to 93 mol% of vinylidene chloride repeating units. The vinylidene chloride resin wrap film according to claim 1 or 2, which contains 0.5 to 3% by weight of an epoxidized vegetable oil with respect to the vinylidene chloride resin. The vinylidene chloride according to any one of claims 1 to 3, which contains 3 to 5% by weight of at least one compound selected from the group consisting of citric acid ester and dibasic acid ester with respect to the vinylidene chloride resin. Based resin wrap film.

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