JP2020070056A - Packaging bag for microwave heating - Google Patents

Abstract

To provide a packaging bag in which a vapor venting hole can be formed by a weakened line and which can be opened by using the weakened line.SOLUTION: This packaging bag is made of a packaging material 10 in which a base material film 11 and a sealant layer 12 are stacked, and the sealant layer is formed by unwoven cloth in which polyolefin resin fibers are deposited and the intersection points of the resin fibers are joined. A weakened line x is provided to the base material film through laser beam irradiation, and the depth dof the weakened line is 40-80% of the thickness dof the base material film.SELECTED DRAWING: Figure 2

Description

  The present invention is a package in which the contents can be heated in a microwave oven while being packaged, the water vapor generated by the heating can be released to the outside of the package, and the liquid water remaining inside the package can be discharged. Regarding the bag.

  BACKGROUND ART Conventionally, a package is known in which cooked or semi-cooked food is contained and sealed in a packaging bag that can be stored at room temperature, low temperature, or in a frozen state, and is heated and cooked in a microwave oven without opening to make it ready for eating. ing.

  If the package is heated in a microwave oven without opening, the water in the package becomes water vapor and the internal pressure increases. Therefore, if there is no gap through which water vapor can escape, the package may break due to an increase in internal pressure. On the other hand, when the contents are in a semi-cooked state or the like, it may be necessary to steam the generated steam in addition to simply heating. In this case, if the holes through which steam escapes are excessively large, there is a problem that steaming is not sufficiently performed and the flavor is deteriorated.

  There are several known packages for this application. It is common to use a packaging bag composed of a laminated film in both cases, and when the internal pressure increases, a steam vent hole is formed in a part of the packaging bag, and steam is allowed to escape from this steam vent hole to break the bag. To prevent.

  As a package that can be steamed when heated by a microwave oven, for example, those described in Patent Documents 1 and 2 are known. The package described in Patent Documents 1 and 2 comprises a lid member made of a laminated film in which an inner layer film of a polyolefin resin is laminated inside an outer layer film such as a polyester film, and the lid member is provided with a laser from the outer layer film side. By irradiating the inner layer film, the weakening line for vapor removal is formed to reach the inside of the outer layer film and not penetrate the inner layer film. In this package, when heated in a microwave oven, the outer layer film is opened by the weakening line and the inner layer film is thinly stretched, and thus the thinly stretched inner layer film is partially torn and a small through hole is formed therein. Is formed. As a result, steam does not escape excessively, and steaming can be performed while preventing bag breakage.

International Publication No. 2014/061651 JP, 2005-13441, A

  As described above, these packaging bags are excellent in that they can be steamed while the contents are wrapped in a microwave oven while preventing the bags from being broken.

  However, in addition to the weakening line for forming the steam vent hole, a notch for opening and a weakening line for opening are required in order to open the packaging bag and take out the contents after heating and cooking.

  The present invention has been made in response to such circumstances, and provides a packaging bag which can form a steam vent hole with a weakening line and which can be opened by utilizing the weakening line. To aim.

That is, the invention according to claim 1 is a packaging bag formed by using a packaging material in which a base film and a sealant layer are laminated,
The sealant layer, a polyolefin-based resin fibers are deposited, and is composed of a nonwoven fabric in which the intersections of the resin fibers are joined,
A weakening line due to laser light irradiation is provided on the base film, and the weakening line has a depth of 40 to 80% of the thickness of the base film.
It is a packaging bag for heating a microwave oven, which is characterized in that

  Next, the invention according to claim 2 is the packaging bag for heating a microwave oven according to claim 1, characterized in that the base film is made of a polyester resin film.

  The invention according to claim 3 is characterized in that the breaking strength of the weakening line when pulled at a pulling speed of 100 mm / min is 2.8 to 4.9 N / 15 mm. It is the packaging bag for microwave oven heating described.

  Since the packaging bag of the present invention is provided with a weakening line at a depth of 40 to 80% of the thickness of the base film, the contents are contained and sealed in this packaging bag and heated in a microwave oven without opening. When cooked, the steam is generated to steam the contents, and when steamed enough, the internal pressure causes the base film to tear at the weakening line. On the other hand, since the sealant layer is made of a non-woven fabric in which the intersections of the resin fibers are joined together, water vapor can be transmitted. Therefore, this packaging bag can be steamed while being heated in a microwave oven to prevent the bag from being broken.

  Moreover, as described above, the sealant layer, unlike the polyolefin-based resin film, is merely composed of the non-woven fabric in which the intersections of the resin fibers are joined, so that the base film tears along the weakening line. After that, the sealant layer is also torn by pulling by sandwiching the tear. In this way, both the base material film and the sealant layer are torn along the weakening line, so that the contents can be taken out by opening the packaging bag triggered by the tear.

FIG. 1 is a perspective view showing a specific example of the packaging bag of the present invention. FIG. 2 is a cross-sectional explanatory view near the weakening line of a specific example of the packaging bag of the present invention.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings. First, FIG. 1 is a perspective view showing a specific example of the packaging bag of the present invention. As can be seen from this figure, this packaging bag 100 is formed by stacking two square packaging materials 10 on top of each other and heat-sealing them around the periphery. In the figure, a1 is a seal line on two opposite sides. In the figure, a2 indicates the seal lines on the other two sides. The interior surrounded by the seal lines a1 and a2 on the four circumferences is used as the content storage chamber b.

  A weakening line x is provided on a part of the packaging material 1 that constitutes the four-sided seal bag 100. FIG. 2 is a cross-sectional explanatory view showing the periphery of the weakening line x.

  The packaging material 10 is a laminate of a base film 11 and a sealant layer 12. The base film 11 and the sealant layer 12 can be bonded to each other, for example, via an adhesive layer (not shown).

The sealant layer 12 is melted and bonded to each other at the time of manufacturing the package to form the seal lines a1 and a2 of four circumferences. Further, when the base film 11 is torn at the weakening line x, it is necessary to be able to discharge excess water vapor to the outside of the package through the crevice and the sealant layer 12. In addition to this, it is also necessary to tear the sealant layer by pulling it while sandwiching the tear.

  In order to meet such a demand, the sealant layer 12 needs to be formed of a nonwoven fabric in which polyolefin resin fibers are deposited and the intersections of the resin fibers are joined. Since the material of this non-woven fabric is a polyolefin resin, it can be melted by heat and pressure, and the two packaging materials 10 can be overlapped with each other to form the seal lines a1 and a2 on four sides by heat and pressure.

  Further, since this non-woven fabric is formed by joining the intersecting points of the deposited resin fibers, there is a fine gap between these resin fibers, and water vapor can be transmitted through this gap. Therefore, when the base film 11 is torn along the weakening line x, excess water vapor can be discharged to the outside of the package through the fine gaps and the crevices of the nonwoven fabric.

  Further, since this non-woven fabric is formed only by joining the intersecting points of the deposited resin fibers, pulling this non-woven fabric causes the joining of the intersecting points of the resin fibers to come off, or the resin fibers are frayed and easily Can be broken. Therefore, it is possible to take out the contents by breaking by pulling while sandwiching the crack and using the broken portion as an opening.

  On the other hand, the base material film 11 seals the contents accommodated in the packaging bag 100 in the contents accommodating chamber b, and further, the contents accommodating chamber b is kept so that the contents can be steamed sufficiently even when being heated in a microwave oven. In addition to sealing, it is necessary to tear at the weakening line x when the internal pressure thereof rises excessively to form a crack for releasing water vapor.

  A resin film made of any material can be used as the base film 11, but it is preferable that the base film 11 is made of a polyester resin film. An inorganic vapor deposition layer can be provided on this polyester resin film. Although printing can be performed, if the printed layer overlaps the weakening line x, a burst noise may occur when the base film 11 is split by heating in a microwave oven. For this reason, it is desirable to arrange the print layer at a position that does not overlap the weakening line x.

The weakening line x can be formed by irradiating the base film 11 with laser light. Alternatively, the base material film 11 and the sealant layer 12 may be laminated to form the packaging material 10, and then the base material film 11 may be irradiated with laser light to form the packaging material 10. In any case, when the formed weakening line x penetrates the base material film 11, the contents accommodating chamber b cannot be sealed. Therefore, the weakening line x needs to be provided at a depth that does not penetrate the base material film 11. There is. On the other hand, if the weakening line x is shallow, it will not be sufficiently broken by heating in a microwave oven, and it will be difficult to release excess water vapor. Therefore, it is appropriate that the processing depth d _x of the weakening line x is 40 to 80% of the thickness d ₁₁ of the base film 11. For the same reason, the breaking strength of the weakening line x is preferably 2.8 to 4.9 N / 15 mm when pulled at a pulling speed of 100 mm / min.

When the base film 11 is irradiated with laser light, the resin forming the base film 11 is melted or vaporized to form holes. After that, the molten resin may be solidified and block the hole, but the solidified resin has an indeterminate shape. Therefore, the depth d _x of the formed hole can be determined by observing its cross-sectional shape under a microscope. It is measurable.

As the laser light, for example, a carbon dioxide gas laser can be used. Then, the weakened line x can be formed by linearly scanning the laser light. The weakening line x may be linear or curved. Although the length of the weakening line x is arbitrary, the length of the weakening line x serves as a trigger for taking out the contents, and thus it is preferable that the weakening line x has a sufficient length. The example described later is an example in which the linear weakening line x is provided in a length of 30 mm.

(Example)
A 16 μm thick polyester resin film was used as the base film. As the sealant layer, NTF manufactured by Uma Paper Co., Ltd. having a basis weight of 28 b / m ² was used. The NTF is a non-woven fabric in which polyolefin resin fibers are deposited so as to have a uniform weight and heated to melt and join the intersections where the resin fibers are in contact with each other. Then, the base material film and the sealant layer were laminated to manufacture a packaging material.

  Next, a carbon dioxide laser beam was irradiated from the side of the base material film of this packaging material, and scanning was performed to form weakened lines. The scanning speed of the carbon dioxide gas laser is 700 mm / sec, and the output is 11 W. The weakening line is a straight line having a length of 30 mm. When the cross section of this weakening line was observed with a microscope, it could be confirmed that the substrate was melted to a depth of 10 μm from the surface of the substrate film. Therefore, the depth of the weakening line is about 62.5% of the thickness of the base film. Moreover, when the rupture strength of the weakening line was measured by pulling the packaging material at 5 points at a tensile speed of 100 mm / min, the maximum value was 4.9 N / 15 mm, the minimum value was 2.8 N / 15 mm, and the average value was 4 It was 0.0 N / 15 mm.

  Next, using this packaging material, the square packaging bag shown in FIG. 1 was manufactured. The size of the packaging bag was 160 mm × 160 mm, and the weakening line was arranged along one side thereof.

(Comparative Example 1)
In this example, a polyolefin resin film is used as the sealant layer.

  That is, a linear low-density polyethylene film having a thickness of 40 μm was used as a sealant layer, and a polyester resin film having a thickness of 16 μm was used as a base film, which were laminated together to produce a packaging material.

  Next, carbon dioxide laser light was irradiated from the side of the substrate film and scanning was performed to form weakened lines. The scanning speed of the carbon dioxide gas laser is 700 mm / sec, which is the same as that of the embodiment, the output is 11 W, which is the same as that of the embodiment, and the weakening line is a straight line having a length of 30 mm. The depth of this weakening line was 10 μm, the maximum value of the breaking strength was 8.7 N / 15 mm, the minimum value was 8.3 N / 15 mm, and the average value was 8.5 N / 15 mm.

  Then, using this packaging material, a packaging bag was manufactured in the same manner as in the example.

(Comparative example 2)
This example is an example in which the depth of the weakening line is deeper than 80% of the thickness of the substrate film, and other than that is the same as the example.

  That is, the scanning speed of carbon dioxide gas laser light was 700 mm / sec, and the output was 14 W. The formed weakening line penetrated the base film and reached the sealant layer. The depth of this weakening line was evaluated as 100% of the thickness of the base film. The depth of weakening line was 10 μm, the maximum value of the breaking strength was 1.2 N / 15 mm, the minimum value was 0.7 N / 15 mm, and the average value was 1.0 N / 15 mm.

(Comparative example 3)
This example is an example in which the depth of the weakening line is shallower than 40% of the thickness of the base film, and other than that is the same as the example.

  That is, the scanning speed of carbon dioxide gas laser light was 700 mm / sec, and the output was 7 W. When the cross section of the formed weakening line was observed with a microscope, it could be confirmed that the substrate was melted to a depth of 6 μm from the surface of the substrate film. Therefore, the depth of the weakening line is about 37.5% of the thickness of the base film. The maximum value of the breaking strength was 11.5 N / 15 mm, the minimum value was 7.7 N / 15 mm, and the average value was 10.2 N / 15 mm.

(Confirmation test)
The packaging bags of these Examples and Comparative Examples 1 to 3 were sealed with 80 ml of water and heated in a microwave oven. The output of the microwave oven is 600 W, and the heating time is the time until steam is released from the packaging bag.

  Then, first, it was confirmed whether the penetration point from which the water vapor was released was the position of the weakening line or another part. When water vapor is released by penetrating a portion other than this weakening line, it means that the packaging bag is broken.

  In addition, when the penetration point from which water vapor was released was a weakening line, it was confirmed whether it penetrated over the entire length or a part thereof. Penetration over the entire length of the penetration point means that the sealant layer is exposed over the entire length of the weakening line, and when the sealant layer is a nonwoven fabric (Examples and Comparative Examples 2, 3), it is easy to tear and open over the entire length of the weakening line to facilitate the formation of the opening for taking out the contents. On the other hand, in the case where the penetrating portion remains only in a part of the weakening line, a part of the base material film remains in this weakening line, and even if the sealant layer is a non-woven fabric, it follows the weakening line. It means that it is difficult to tear it.

  The results are shown in Table 1 together with the results of observing whether or not a burst sound was generated when the base film 11 was torn and penetrated.

(Discussion)
When the weakening line penetrates the base film (Comparative Example 2), the non-woven fabric sealant layer is exposed at the portion of the weakening line. In this case, it can be inferred that the breaking strength of the weakened line is substantially equal to the breaking strength of the nonwoven fabric sealant layer itself. According to the measured values, the breaking strength has a maximum value of 1.2 N / 15 mm, a minimum value of 0.7 N / 15 mm, and an average value of 1.0 N / 15 mm.

  When the processing depth of the weakening line is 40 to 80% of the thickness of the base film (Example), the weakening line does not penetrate the base film and the contents can be sealed. Instead, the microwave heating causes a crack to penetrate the base film over the entire length of the weakening line, and excess steam can be released from the crack. Moreover, the breaking strength before heating in the microwave oven was 4.9 N / 15 mm in the maximum value, 2.8 N / 15 mm in the minimum value, and 4.0 N / 15 mm in the average value. Since the sealant layer is exposed, the breaking strength thereof is substantially equal to the breaking strength of Comparative Example 2. Therefore, the sealant layer can be easily broken to form the opening for taking out the contents.

As can be seen from Comparative Example 3, when the processing depth of the weakening line is shallower than 40% of the base film, a part of the base film remains on the weakening line even after heating in a microwave oven. It is difficult to tear along.

100: packaging bag 10: packaging material 11: substrate film d ₁₁ : thickness of substrate film 12: sealant layer x: weakening line d _x : depth of weakening line

Claims (3)

A packaging bag formed by using a packaging material in which a base film and a sealant layer are laminated,
The sealant layer, a polyolefin-based resin fibers are deposited, and is composed of a nonwoven fabric in which the intersections of the resin fibers are joined,
A weakening line due to laser light irradiation is provided on the base film, and the weakening line has a depth of 40 to 80% of the thickness of the base film.
A packaging bag for heating a microwave oven, which is characterized in that   The packaging bag for heating a microwave oven according to claim 1, wherein the base film is made of a polyester resin film.   The packaging bag for heating a microwave oven according to claim 1 or 2, wherein the breaking line has a breaking strength of 2.8 to 4.9 N / 15 mm when pulled at a pulling speed of 100 mm / min.

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