JP2020037431A - Heat shrinkable film and sealed package - Google Patents

Abstract

To provide a heat shrinkable film which can inhibit film cutting in a production process and can give a sealed package having tension and easy-opening, and the sealed package.SOLUTION: In a heat shrinkable film including vinylidene chloride resin, each of heat shrinkage ratios of TD and MD at 120°C is 25%-40% independently, a scar line where scars that penetrate the heat shrinkable film are arranged in the longitudinal direction consists of at least one line in a side end portion that is a region of 1.0 mm-5.0 mm from an end of the heat shrinkable film, and a gap of the longitudinal direction of the scars is 4 mm-30 mm.SELECTED DRAWING: None

Description

  The present invention relates to a heat shrinkable film and a sealed package.

  2. Description of the Related Art As a cylindrical package containing ham, sausage, cheese, yokan, uiro and the like, a package using a synthetic resin film is widely known. This tubular package is overlapped with an automatic filling and packaging machine (for example, "ADP (registered trademark)" manufactured by Asahi Kasei Corporation) so that both side edges are crossed while running a belt-shaped synthetic resin film. Then, the overlapped portion is sealed to form a tubular film, the contents are filled in the tubular film, and the upper and lower ends are ligated (sealed).

  In order to peel off the tubular resin film from these tubular packages and take out the food, which is the content, the tubular resin film, along the longitudinally sealed portions of both side edges extending in the longitudinal direction, Alternatively, it is necessary to expose the contents by cutting in a direction perpendicular to the vertically sealed portion. At that time, if the consumer does not have sufficient opening properties, the consumer may not be able to open the contents only with his / her finger when taking out the contents.

  For the purpose of providing a tubular package having an easy opening property in which the contents can be easily taken out from the tubular package, for example, Patent Document 1 discloses a vertical seal portion having an outer ear portion extending in a longitudinal direction. And a cylindrical resin film in which the contents are filled and sealed in a cylindrical resin film whose both ends in the longitudinal direction are bundled, and the T of the vertical seal portion having an outer ear portion extending in the longitudinal direction. A tubular package having a mold peel strength of 23 N or less and a shear peel strength of 40 N or more is disclosed.

JP 2015-164860 A

  However, in the method described in Patent Document 1, it is difficult to say that the T-peel strength actually achieved is all high and easy-openability is sufficiently achieved. On the other hand, if the peel strength is too low, the bag is easily broken even when unintended, and cannot be used in general use.

  As one of means for solving this, it is conceivable to provide a scar on the outer ear of the tubular package. Such a tubular package having a scar on the outer ear is manufactured using a raw film film having a scar on the side edge. More specifically, the film is unwound from a roll-shaped raw film, and both side edges are overlapped and sealed to form a tube, and if necessary, cut into an appropriate length. However, mere formation of a scar causes the side edge of the film roll having the scar to stand out (the end is thicker than the center in the axial direction of the roll), and the film is flattened. It has been found that it is difficult to feed the film, and because the tension applied in the surface direction of the film is different, tension is partially applied to the edge of the film, and the film is cut. In particular, in recent years, as the filling speed has been increased, the tension applied to the edge of the film has become larger, and the problem of cutting has been a problem.

  The present invention has been made in view of the above problems, and is capable of suppressing film breakage during a manufacturing process, and is capable of providing a tightly sealed and easily-openable sealed package. And to provide the sealed package.

  The present inventors have conducted intensive studies to solve the above problems. As a result, it has been found that the above-mentioned problem can be solved by having a predetermined scar at a predetermined position and adjusting the heat shrinkage, thereby achieving the present invention.

That is, the present invention is as follows.
[1]
A heat-shrinkable film containing a vinylidene chloride-based resin,
The thermal shrinkage of TD and MD at 120 ° C. is each independently 25% to 40%,
At least a part of a side edge of 1.0 mm to 5.0 mm from an end of the heat shrinkable film has a scar line in which scars penetrating the heat shrinkable film are arranged in a longitudinal direction,
The longitudinal interval of the scar is 4.0 mm to 30 mm,
Heat shrink film.
[2]
A tubular film that overlaps both side edges of the heat-shrinkable film according to claim 1 so that the front and back surfaces of the heat-shrinkable film face each other, and seals in a longitudinal direction,
A sealing member that seals both ends of the cylindrical film filled with the contents,
The side edge portion having the scar row of the heat shrinkable film forms an outer ear piece protruding in a band shape outside the tubular film,
The longitudinal interval between the scars of the side edge portion after the heat treatment is 3.0 mm to 28 mm.
Sealed package.

  According to the present invention, it is possible to provide a heat-shrinkable film and a sealed package which can suppress film breakage in a manufacturing process and can provide a tightly sealed and easily-openable sealed package. it can.

1 shows a perspective view of a heat-shrinkable film of the present embodiment. 1 shows one aspect of a scar included in the heat shrinkable film of the present embodiment. 1 shows an aspect of a scar row of the heat shrinkable film of the present embodiment. 5 shows another aspect of the scar row of the heat shrinkable film of the present embodiment. The perspective view of the sealed package of this embodiment is shown.

  Hereinafter, embodiments of the present invention (hereinafter, referred to as “the present embodiment”) will be described in detail, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention. It is.

(Cylindrical package)
The tubular package of the present embodiment is a heat-shrinkable film containing a vinylidene chloride-based resin, and the heat shrinkage of TD and MD at 120 ° C. is 25% to 40% each independently. At least a part of the side edge of 1.0 mm to 5.0 mm from the edge of the film has a scar row in which scars penetrating the heat-shrinkable film are arranged in the longitudinal direction. 0 mm to 30 mm.

(Heat shrinkage)
The heat shrinkage of the MD at 120 ° C. is 25% to 40%, preferably 25% to 35%, and more preferably 25% to 30%. When the heat shrinkage at 120 ° C. of the MD is 25% or more, the interval between scars when the outer ear portion of the hermetically sealed package to be described later is thermally shrunk is appropriately narrowed, so that the easy-openability is further improved. It is possible to obtain a hermetically sealed package which is tight and has excellent product appearance. Further, in the state of the film before the heat shrinkage, since the interval between the scars is maintained in a state of being appropriately opened, the breakage of the film in the manufacturing process is further suppressed. Further, when the heat shrinkage at 120 ° C. of the MD is 40% or less, the bag breakage in the retort treatment is suppressed, and the interval between scars when the outer ear portion of the hermetically sealed package described later is thermally shrunk is too narrow. The deterioration of the scar condition can be suppressed.

  The thermal shrinkage of the TD at 120 ° C. is 25% to 40%, preferably 30% to 40%, and more preferably 35% to 40%. When the heat shrinkage at 120 ° C. of the TD is 25% or more, the heat shrinkability in the circumferential direction of the sealed package described later becomes good, and a tightly sealed package excellent in product appearance is obtained. be able to. Further, since the thermal shrinkage of the TD at 120 ° C. is 40% or less, the bag breakage in the retort treatment is suppressed, and the shape of the scar in the TD direction when the outer ear portion of the hermetically sealed package described later thermally shrinks is deformed. By doing so too much, the deterioration of the scar state can be suppressed.

  The heat shrinkage can be adjusted by the stretching conditions and the type of resin used.

(scar)
The scar of the heat-shrinkable film of the present embodiment will be described with reference to FIG. 1 which is a perspective view of the heat-shrinkable film, and FIGS. As shown in FIG. 1, the heat-shrinkable film 1 of the present embodiment has a scar 4 on at least a part of the side edge portion 3 which is a region 1.0 mm to 5.0 mm from the end 2. Here, it is not necessary that all the side edges have a scar, and in a preferred embodiment, one of the edges along the MD direction has a scar.

  As shown in FIG. 2, the aspect of the scar 4 penetrating the heat-shrinkable film 1 includes an aspect in which the film part before the scar formation is removed and an aspect in which the film part before the scar formation is not removed. Can be considered. The former scar is a through hole, and the latter scar can be called a notch. In the present embodiment, the latter scar is preferable in that the removed film dust is not generated. In particular, in the case of the latter scar, when the roll of film raw material, the side edge side having the scar stands out, compared to the axial center of the roll, the side edge side tends to be thicker, The problem of film breakage during the manufacturing process is likely to become prominent. However, in the present embodiment, the film breakage can be suppressed by adjusting the interval between the scars and the like.

  The scars are arranged in the longitudinal direction (MD direction in FIG. 1) to form a scar row. The number of scar lines may be one or plural. Further, as shown in FIGS. 3 and 4, when there are a plurality of scar rows 4 ′, the positions of the scars 4 of adjacent scar rows 4 ′ are shifted even if they are at the same position when viewed in the longitudinal direction. The intervals between the scars 4 in the scar row 4 ′ may be the same or different between the rows. Furthermore, the intervals between the scars 4 in the same row may be equal or unequal as long as they satisfy a predetermined range.

  The interval a between the scars 4 in the scar row 4 'is from 4.0 mm to 30 mm, preferably from 4.0 mm to 25 mm, and more preferably from 4.0 to 20 mm. When the interval between the scars 4 is 4.0 mm or more, the edge is alleviated, the film cut in the manufacturing process is suppressed, and the interval between the scars when the outer ear portion of the hermetically sealed package described later is thermally shrunk is too narrow. As a result, the deterioration of the scar state can be suppressed. When the interval between the scars is 30 mm or less, the easy-openability is further improved. When there are a plurality of scar rows 4 ', the interval b between the scar rows is preferably 0.1 mm to 1 mm.

(resin)
The heat-shrinkable film is not particularly limited as long as it contains a vinylidene chloride-based resin, and may contain another resin. The heat-shrinkable film may be a single-layer film or a laminated film.For example, a single-layer film made of a vinylidene chloride-based resin, a single-layer film containing a vinylidene chloride-based resin and another resin, a vinylidene chloride-based film A combination of a resin film and a laminated film made of another resin, a combination of a film containing a vinylidene chloride-based resin and another resin, and a laminated film made of another resin, and the like can be given. By using the vinylidene chloride-based resin, a firm appearance can be given after the heat shrinkage, and the breakage of the film in the production process can be further suppressed.

  Examples of the vinylidene chloride-based resin include a vinylidene chloride copolymer and a vinylidene chloride homopolymer. Here, the vinylidene chloride copolymer is a copolymer of a vinylidene chloride monomer and a monomer copolymerizable therewith (comonomer). The monomer copolymerizable with the vinylidene chloride monomer is not particularly limited. Examples thereof include vinyl chloride; acrylates such as methyl acrylate and butyl acrylate; acrylic acid; methyl methacrylate and butyl methacrylate; Methacrylic acid ester; methacrylic acid; methyl acrylonitrile; vinyl acetate and the like. Among them, acrylates such as vinyl chloride and methyl acrylate, methacrylates such as methyl methacrylate, and methyl acrylonitrile are preferred from the viewpoint of balance between water vapor impermeability and oxygen impermeability and extrusion processability. These copolymerizable monomers may be used alone or in combination of two or more.

  The comonomer content of the vinylidene chloride copolymer is preferably from 1 to 40% by mass, more preferably from 3.5 to 25% by mass. When the comonomer content of the vinylidene chloride copolymer is 1% by mass or more, the melting properties during extrusion tend to be further improved. When the comonomer content of the vinylidene chloride copolymer is 40% by mass or less, the water vapor impermeability and oxygen impermeability tend to be further improved.

  The weight average molecular weight (Mw) of the vinylidene chloride-based resin is preferably 50,000 to 150,000, more preferably 60,000 to 130,000, and still more preferably 70,000 to 125,000. . When the weight average molecular weight (Mw) is 50,000 or more, the melt tension required for molding tends to be further improved. Further, when the weight average molecular weight (Mw) is 150,000 or less, there is a tendency that melt extrusion while maintaining thermal stability becomes possible. In this embodiment, the weight average molecular weight (Mw) can be determined by gel permeation chromatography (GPC) using a standard polystyrene calibration curve.

  Examples of other resins include ethylene-vinyl alcohol copolymer, polyamide resin, polyolefin resin, polyvinyl chloride, and polystyrene resin. Among these, a polyamide resin is preferable, and a vinylidene chloride copolymer and a polyamide resin are more preferable, from the viewpoint of easy opening property and suppression of film breakage in the production process.

(Production method of heat shrinkable film)
The method for producing the heat-shrinkable film is not particularly limited. For example, a step of molding a vinylidene chloride-based resin on a film, a step of stretching the molded film in the MD and TD directions, and a side edge of the stretched film And a step of forming a scar. In addition, a step of winding the heat-shrinkable film after the formation of the scar into a roll may be provided.

(Sealed package)
The sealed package of the present embodiment is a tubular film in which both side edges of the heat-shrinkable film are overlapped so that the front and back surfaces of the heat-shrinkable film face each other and sealed in the longitudinal direction, and a tube filled with contents. And a sealing member for sealing both ends of the tubular film, wherein the side edge portion having the scar row of the heat-shrinkable film forms an outer ear piece protruding into a band shape outside the tubular film, and the side after the heat treatment. The longitudinal interval between the scars of the edge is 3.0 mm to 28 mm.

  FIG. 5 shows a perspective view of the sealed package 10. The tubular film is heat-sealed on both side edges of the heat-shrinkable film 1 such that the side edges 3 having the scar rows 4 ′ of the heat-shrinkable film 1 form the outer ear pieces 5 protruding outside the tubular film. The shrink films are overlapped so that the front and back surfaces face each other, and sealed in the longitudinal direction. The sealed package 1 for filling the contents is subjected to a heat shrink treatment, and the interval between the scars 4 formed on the outer ear portion 5 is such that the interval between the scars on the side edge portion of the heat shrinkable film 1 is heat. It is narrowed by contraction. The outer ear portion can be easily cut by hand starting from such a scar group.

  The interval a 'between the scars in the scar row in the sealed package is from 3.0 mm to 28 mm, preferably from 3.0 mm to 25 mm, more preferably from 3.0 to 20 mm. When the interval between the scars is 3.0 mm or more, it is possible to prevent the scar state from deteriorating, and to prevent cutting from the scar portion unintentionally. Further, when the interval between the scars is 28 mm or less, the easy-openability is further improved. Further, when there are a plurality of scar rows, the interval b between the scar rows is preferably 0.1 mm to 0.9 mm.

  The width of the outer ear portion is preferably 1.0 mm to 8.0 mm, more preferably 2.0 mm to 8.0 mm, and still more preferably 3.0 mm to 8.0 mm. When the width of the outer ear portion is within the above range, the ease of opening can be further improved, and unintended cutting or bag breakage can be suppressed.

  In addition, the sealing method is not particularly limited, and an example is ultrasonic fusion. The ultrasonic conditions can be appropriately adjusted depending on the film thickness, the material (amorphous / crystalline, and thermal properties such as melting point) and the bag making speed so as to obtain an appropriate sealing strength. By continuously controlling the pressure and the amplitude and controlling the ultrasonic output to be constant, it is easy to control the strength of the seal portion to be constant.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited at all by the following Examples.

[Packing suitability: film breakage during manufacturing process]
The rolls of the heat-shrinkable films obtained in Examples and Comparative Examples were set on an automatic filling and packaging machine (“ADP (registered trademark)” manufactured by Asahi Kasei Corporation), and the heat-shrinkable films were drawn out. While feeding out the heat-shrinkable film, both side edges extending in the longitudinal direction are overlapped, and the wound side is wound in a cylindrical shape so that the side edge formed with the scar becomes the outer ear portion, and the two sides are overlapped while running downstream. The part was sealed at high frequency to form a cylindrical film. After that, the inside of the cylindrical film is filled with fish meat surimi, and both ends are clipped with aluminum steel wires, so that a 200 mm long, 7 mm wide outer package between clips is produced at a speed of 200 / min. did. The above-mentioned filling operation was performed using the heat-shrinkable film 1500 m, and the number of times the film was cut during the filling was counted, and the suitability for packaging was evaluated according to the following evaluation criteria.
(Evaluation criteria)
：: The number of times the film breaks occurred in the manufacturing process is 0 times ×: The number of times the film breaks occurred in the manufacturing process is 1 or more times

[Retort resistance evaluation]
Using a high-temperature high-pressure cooking sterilizer (Hot water hot water / rotary: 130 type) manufactured by Hisaka Seisakusho, 1000 wrappers obtained in the above-mentioned packaging suitability test were used to adjust the gauge pressure in the heating can to 0. Under a condition of 20 MPa, a retort treatment was performed at 120 ° C. for 20 minutes to obtain a sealed package. Among the sealed packages after the retort treatment, the number of broken bags was counted, and the retort resistance was evaluated according to the following evaluation criteria.
(Evaluation criteria)
○: Number of broken bags is 0 ×: Number of broken bags is 1 or more

[Scratch condition after retort treatment]
Of the sealed packages after the retort treatment, 100 samples that did not break were sampled at random. The scar state of the outer ear of the obtained sample was visually observed, and the scar state was evaluated according to the following evaluation criteria.
(Evaluation criteria)
：: The number of cuts in the outer ear is 0 ×: The number of cuts in the outer ear is 1 or more

(Easy opening test)
Of the sealed packages after the retort treatment, 100 samples that did not break were sampled at random. About the obtained sample, the external ear piece was pinched and opened by human power. Specifically, 10 panelists each opened 10 samples of the package, and evaluated each package with a sensory test score of 0 to 2 points.
(Evaluation criteria)
2 points: Anyone can easily open 1 point: Anyone can open with force 0 points: Cannot open with bare hands

Evaluation points were obtained by rounding off the second decimal place of the average value of the sensory test scores for a total of 100 pieces. Based on the obtained evaluation points, easy-openability was evaluated according to the following criteria.
(Evaluation criteria)
：: The average value of the sensory test points is 2.0
：: The average value of the sensory test points is 1.5 or more and less than 2 Δ: The average value of the sensory test points is 1 or more and less than 1.5 ×: The average value of the sensory test points is less than 1

(Heat shrinkage)
The heat shrinkage of the heat shrinkable film was measured according to ASTM D2732. Specifically, the heat-shrinkable film was immersed in silicon oil at 120 ° C. for 10 minutes, and the dimensions of the film sample before and after immersion were measured and calculated. In addition, the average value of n = 5 was adopted for both MD and TD.

[Tension of sealed package]
Of the sealed packages after the retort treatment, 100 samples that did not break were sampled at random. The tightness of the sealed package of the obtained sample was evaluated according to the following evaluation criteria.
(Evaluation criteria)
：: No wrinkles, a state where it returns to its original state even when pressed with a finger.

[Example 1]
A vinylidene chloride-vinyl chloride copolymer (vinylidene chloride content / vinyl chloride content = 89% by weight / 11% by weight, weight average molecular weight 125,000) was melted and extruded from a circular die to produce a circular film, and a stretching temperature was obtained. Inflation biaxial stretching of 3.0 times in the longitudinal direction and 4.0 times in the width direction at 30 ° C. was performed, and the inner sides of the annular films were overlapped to form a 43 μm (thickness of two 21.5 μm thick films). A film stock was obtained. The raw film was cut into a width of 86 mm while being unwound, and a band-shaped raw film having a penetrating scar as shown in FIG. 3 was obtained at a position 1.0 mm from the end of the film. The interval a between the scars shown in FIG. 3 was 15 mm. Table 1 shows the evaluation results of various performance evaluations.

[Example 2]
A heat-shrinkable film was produced in the same manner as in Example 1, except that two lines of scars were formed so that the intervals between the lengths a and b shown in FIG. 3 were 30 mm and 0.8 mm, respectively. Table 1 shows the evaluation results of various performance evaluations.

[Example 3]
A heat-shrinkable film was produced in the same manner as in Example 1, except that two lines of scars were formed so that the distance between the lengths a and b shown in FIG. 3 was 5 mm and 0.8 mm, respectively. Table 1 shows the evaluation results of various performance evaluations.

[Example 4]
A heat-shrinkable film was produced in the same manner as in Example 1, except that the stretching temperature was 28 ° C. Table 1 shows the evaluation results of various performance evaluations.

[Comparative Example 1]
A heat-shrinkable film was produced in the same manner as in Example 1, except that the stretching temperature was 35 ° C. Table 1 shows the evaluation results of various performance evaluations.

[Comparative Example 2]
A heat-shrinkable film was produced in the same manner as in Example 1, except that two lines of scars were formed so that the intervals between the lengths a and b shown in FIG. 3 were 2 mm and 0.8 mm, respectively. Table 1 shows the evaluation results of various performance evaluations.

[Comparative Example 3]
A heat-shrinkable film was produced in the same manner as in Example 1, except that two lines of scars were formed so that the intervals between the lengths a and b shown in FIG. 3 were 35 mm and 0.8 mm, respectively. Table 1 shows the evaluation results of various performance evaluations.

[Comparative Example 4]
A heat-shrinkable film was produced in the same manner as in Example 1, except that the stretching temperature was 25 ° C. Table 1 shows the evaluation results of various performance evaluations.

[Comparative Example 5]
A heat-shrinkable film was produced in the same manner as in Example 1, except that a scar was made at a position 0.5 mm from the edge of the film. Table 1 shows the evaluation results of various performance evaluations.

  The heat shrinkable film of the present invention has industrial applicability as a film for containing ham, sausage, cheese, yokan, uiro and the like.

  DESCRIPTION OF SYMBOLS 1 ... Heat shrink film, 2 ... End, 3 ... Side edge part, 4 ... Scar, 4 '... Scar row, 5 ... Outer ear part, 6 ... Sealing member, 10 ... Sealing package.

Claims (2)

A heat-shrinkable film containing a vinylidene chloride-based resin,
The thermal shrinkage of TD and MD at 120 ° C. is each independently 25% to 40%,
At least a part of a side edge of 1.0 mm to 5.0 mm from an end of the heat shrinkable film has a scar line in which scars penetrating the heat shrinkable film are arranged in a longitudinal direction,
The longitudinal interval of the scar is 4.0 mm to 30 mm,
Heat shrink film. A tubular film that overlaps both side edges of the heat-shrinkable film according to claim 1 so that the front and back surfaces of the heat-shrinkable film face each other, and seals in a longitudinal direction,
A sealing member that seals both ends of the cylindrical film filled with the contents,
The side edge portion having the scar row of the heat shrinkable film forms an outer ear piece protruding in a band shape outside the tubular film,
The longitudinal interval between the scars of the side edge portion after the heat treatment is 3.0 mm to 28 mm.
Sealed package.