JP6724365B2 - Laminated film and packaging container - Google Patents

Description

TECHNICAL FIELD The present invention relates to a technique of heating a content in a microwave oven while it is packaged, and discharging steam generated by heating to the outside of the package.

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

When the package is heated in a microwave oven without being opened, the moisture in the package becomes water vapor and the volume increases. Therefore, if there is no space for water vapor to escape, there is a risk of bag breakage. On the other hand, when the contents are in a semi-cooked state or the like, it may be necessary to steam not only by heating but also by steam generated. 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 container composed of a laminated film in both cases, and when the internal pressure increases, a crack is formed in a part of the laminated film, and the crack is broken by letting the steam escape through the crack as a steam vent hole. 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 packaging bodies described in Patent Documents 1 and 2 constitute 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 weak working line for vapor removal is formed so as 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 opens at the brittle working line and the inner layer film is thinly stretched, and thus the thinly stretched inner layer film is partially torn and a small penetration therethrough. A hole 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

By the way, many of these packages are stored and transported in a frozen state. When storing and transporting these packages in a frozen state, it is usual that a large number of packages are housed in a cardboard box as described later to protect the packages from external impact. That is, a large number of packages are packed in a cardboard box, and the cardboard boxes are frozen and stored/transported.

However, even when the package is protected by the cardboard box as described above, in the case of the package using the polyester film as the outer layer film, when the frozen cardboard box falls, the outer layer film of the package has pinholes. May occur.

Therefore, the present invention is based on the technique described in Patent Documents 1 and 2, and is a case where a target small hole is formed during heating in a microwave oven so that excess steam can be released and the product is frozen. Even so, it is an object of the present invention to provide a packaging container that is not damaged by dropping and the like, and a laminated film suitable for this packaging body.

That is, the invention according to claim 1 is composed of an inner layer film made of linear low-density polyethylene that is heat-sealable , and an outer layer film laminated on the inner layer film, and reaches the inside of the outer layer film, and In a laminated film having a weakened processing line that does not penetrate the inner layer film,
The outer layer film is a laminated film in which a stretched nylon film and a polyester film are laminated, and the polyester film is located on the inner layer film side,
It is a laminated film characterized by the above.

Next, the invention described in claim 2 is a packaging container using the laminated film according to claim 1 as a part of a packaging material.

The invention described in claim 3 is the packaging container according to claim 2, which is a packaging bag.

Further, the invention according to claim 4 has a container main body having an opening on the upper surface and having a flange around the opening, and a lid member which is heat-sealed to the flange of the container main body to close the opening. 3. The packaging container according to claim 2, further comprising: and the lid member made of the laminated film.

As can be seen from the examples described below, a laminated film in which a stretched nylon film and a polyester film are laminated is used as the outer layer film, and when both are arranged so that the polyester film is located on the inner layer film side, a microwave oven During heating, small holes are formed so that excess water vapor can be released, and even when frozen, it will not be damaged by impact such as dropping.

On the other hand, when the outer layer film is made of a polyester film alone, it may be broken and pinholes may be generated when an external impact is applied (Comparative Example 1). Further, when the outer layer film is composed of a stretched nylon film alone, small holes may not be formed during microwave heating, and the internal pressure of the package may be increased to rupture the package (Comparative Example 2). Further, even when using a laminated film in which a stretched nylon film and a polyester film are laminated as the outer layer film, when the stretched nylon film is arranged so as to be located on the inner layer film side, when it is composed of a stretched nylon film alone Similarly to, the small holes may not be formed during microwave heating and the package may burst (Comparative Example 3).

1A and 1B relate to a specific example of a laminated film with a fragile working line of the present invention, FIG. 1A is a cross-sectional explanatory view in the vicinity of the fragile working line, and FIG. 1B is a plan view thereof. 2 relates to a packaging bag using the laminated film with a weakened processing line of the present invention, FIG. 2(a) is a perspective view for explaining the packaging bag, and FIG. 2(b) is packaging when the packaging bag is heated in a microwave oven. It is a perspective view for explanation of a bag. FIG. 3 is a perspective view for explaining a packaging container using the laminated film with a weakened processing line of the present invention. FIG. 4 is an explanatory view showing an evaluation method of a laminated film with a weakened processing line of the present invention.

The laminated film of the present invention has a two-layer structure of an outer layer film and an inner layer film, the outer layer film is composed of a laminated film in which a stretched nylon film and a polyester film are laminated, and the polyester film is an inner layer film. It is located on the side. Then, this laminated film is provided with a brittle processing line which reaches the outer layer film and does not penetrate the inner layer film.

This laminated film is suitable for use as part of a microwave oven packaging container. A packaging container made using this laminated film can be cooked by heating it in a microwave oven while keeping the contents sealed inside. Water vapor is generated inside the packaging container as the microwave oven is heated, and at the same time, the internal pressure increases, and the packaging container expands outward. Therefore, the outer layer film is broken at the brittle working line, and the outer layer film ends on both sides of the outer layer film are pulled so as to spread, and the inner layer film adhered to the outer layer film is stretched. A large number of micropores are generated in the stretched inner layer film, and excess water vapor is released from the micropores to the outside of the packaging container, which suppresses an increase in internal pressure inside the packaging container and prevents the packaging container from bursting. Can be prevented. By the way, since the micropores generated in the stretched inner layer film are extremely small, the release rate of water vapor released through the micropores is also small. Therefore, the inside of the packaging container can maintain an appropriate internal pressure, and the contents can be sufficiently steamed for cooking.

The packaging container may be, for example, a packaging bag. It is also possible to use the laminated film of the present invention as a lid material for a rigid container. Hereinafter, the case where the laminated film of the present invention is used as a part of a packaging bag will be described as an example, and the roles of the laminated film of the present invention and the constituent elements of the laminated film will be described. FIG. 1 relates to the laminated film of the present invention, FIG. 1(a) is a sectional explanatory view thereof, and FIG. 1(b) is a plan explanatory view thereof. Further, FIG. 2 relates to a packaging bag using this laminated film, FIG. 2(a) is a perspective view for explaining the packaging bag, and FIG. 2(b) is for explaining the packaging bag when the packaging bag is heated in a microwave oven. It is a perspective view.

As shown in FIG. 1A, the laminated film 1 includes an outer layer film 11 and an inner layer film 13 as essential components, and both of them can be laminated by an adhesive layer 12, for example. Further, it is important that the outer layer film 11 is configured by laminating the stretched nylon film 112 and the polyester film 111, and that the polyester film 111 is located on the inner layer film 13 side. Therefore, in the case where the laminated film 1 constitutes a package, the stretched nylon film 112 is located on the outer surface side of the package. Usually the outer surface of the package.

The outer layer film 11 is preferably composed of two layers of the stretched nylon film 112 and the polyester film 111, but other layers can be laminated as long as the tensile breaking strength is not affected. For example, a printing ink film, a coating film of paint, a metal vapor deposition film such as an aluminum vapor deposition film, and an inorganic vapor deposition film such as an aluminum oxide vapor deposition film. The stretched nylon film has a certain oxygen barrier property, but by stacking a metal vapor deposition film or an inorganic vapor deposition film, the oxygen barrier property and the water vapor barrier property can be enhanced, and the content storability can be enhanced.

On the other hand, the inner layer film 13 plays a role as a heat seal layer at the time of manufacturing a package. In addition, when the package is heated in a microwave oven, it serves to properly expand at the position of the brittle working line to generate a large number of micropores. Further, when the weakened processing line is formed by laser irradiation, it is necessary not to absorb this laser light. As such an inner layer film 12, low density polyethylene, medium density polyethylene, unstretched polypropylene, linear low density polyethylene (LLDPE) and the like can be used, and among them, LLDPE can be preferably used.

The brittle processing line 11a forms a water vapor discharge hole in a part thereof when being heated in a microwave oven, and needs to be provided at a depth that does not reach the outer layer film 11 and penetrate the inner layer film 13. Desirably, the depth is such that the outer layer film 11 is penetrated and the inner layer film 13 is not penetrated. When the weakened line 11a is provided at a depth that penetrates the outer layer film 11, since it penetrates the stretched nylon film 112 included in the outer layer film 11, the oxygen barrier property of the stretched nylon film 112 is impaired, but it is fragile. Since the processing line 11x is provided in a thin line shape, its oxygen barrier property is slightly reduced. The length may be 40 mm or less.

Next, the fragile processing line 11a can be formed by laminating the outer layer film 11 and the inner layer film 13 to manufacture the laminated film 1, and then irradiating the laminated film 1 with a carbon dioxide laser. When irradiated with a carbon dioxide laser, the stretched nylon film 112 and the polyester film 111 constituting the outer layer film 11 absorb the laser beam and are melted, and the stretch is returned to form a brittle processed line 11a having a low tensile breaking strength. You can On the other hand, since the inner layer film 13 transmits the laser beam without absorbing it, the weakened processing line 11a does not penetrate the inner layer film 13.

Next, FIG. 2A is an explanatory perspective view showing a packaging bag 2 produced by using the laminated film 1. Further, FIG. 2B is an explanatory perspective view for explaining the role of the brittle processing line 11a when the packaging bag 2 is heated in a microwave oven.

When the packaging bag 2 is heated in a microwave oven, the internal pressure increases with the generation of water vapor, and the packaging bag 2 swells outward, so that the outer layer film 11 breaks at the brittle working line X, and this is broken. Both ends of the sandwiched outer layer film 11 are pulled so as to be separated from each other. Since the inner layer film 13 is adhered to the outer layer film 11, the inner layer film 13 is attached to both ends of the outer layer film 11 and is pulled in a direction orthogonal to the brittle working line X. Since it is not formed, it is thinly stretched between both ends of the outer layer film 11. Then, fine holes are regularly or irregularly formed in the inner layer film 13 in the thinly stretched region. In FIG. 2( b ), 13 a indicates the thinly stretched inner layer film 13, and 13 b indicates the fine holes opened in this inner layer film 13.

The laminated film of the present invention can also be used as a lid material. FIG. 3 shows such an example, and the packaging container 3 is composed of a container body 31 and a lid member. The container body 31 has an opening on the upper surface and a flange around the opening, and the lid member is heat-sealed to the flange to close the opening. For convenience of opening and taking out the contents, in the illustrated container 3, a tab is provided on the lid member.

The package thus obtained, whether it is distributed at room temperature, refrigerated distribution, or frozen distribution, is damaged during the distribution process, for example, when shock is applied during storage or transportation. There is no. Moreover, when heated by a microwave oven, a plurality of minute vapor discharge holes are opened along the brittle processing line X, so that the contents can be sufficiently steamed and excess water vapor can be discharged.

(Example)
As the outer layer film 11, a commercially available film obtained by laminating a stretched nylon film 112 and a polyester film 111 was used. That is, it is HEPTAX HBF (registered trademark) (thickness: 15 μm) manufactured by Gunze. Then, the inner layer film 13 was laminated on the surface of the polyester film 111 via the adhesive layer 12 to manufacture the laminated film 1. The inner layer film 13 is an LLDPE film.

The laminated film thus obtained was irradiated with carbon dioxide laser light from the outer layer film 11 side and scanned linearly to form a weakened line X having a length of 30 mm in the flow direction of the outer layer film 11. .. The wavelength of the laser light is 10.6 μm, the output is 25 W, and the scan speed is 700 mm/s.

The thus obtained laminated film with brittle working line X was stored in an environment of 40° C. and 90% RH for 3 days, and then a three-way sealed bag was made. The size of the bag is 140 mm×140 mm.

Next, 50 g of water was filled in the three-sided sealed bag and sealed with a heat sealer to manufacture the package of Example 1.

(Comparative Example 1)
A package was manufactured in the same manner as in the example except that a single 12 μm thick polyester film was used as the outer layer film.

(Comparative example 2)
A package was manufactured in the same manner as in Example except that a stretched nylon film having a thickness of 15 μm was used as the outer layer film.

(Comparative example 3)
As the outer layer film, HEPTAX HBF (15 μm in thickness) manufactured by Gunze Co. was used as in the example, but the inner layer film 13 was laminated on the stretched nylon film surface. Other than that, the package was manufactured similarly to the example.

(Evaluation)
With respect to the packaging bodies of these Examples and Comparative Examples 1 to 3, steamability and impact resistance were evaluated.

That is, if these packages are placed in a microwave oven and heated under the condition of 1000 W for 1 minute, whether or not a large number of micropores are generated in the region of the weakened processing line X, and whether or not this package is ruptured I confirmed whether or not. Then, the steaming suitability was evaluated as ◯ when a large number of micropores were not generated and the package was not ruptured, and as X when the predetermined micropores were not generated.

Further, as shown in FIG. 4( a ), the packaging body 3 is stacked on three trays and placed on the tray 4, and thus the trays 4 on which the packaging body 3 is placed are set as one set, and FIG. As shown in, the trays were housed in the cardboard box 5 in two rows and five stages. Note that FIG. 4C is a perspective view of the cardboard box package thus obtained.

Then, this cardboard box package is put in a freezing chamber to freeze the package 3, and then taken out from the freezing chamber and subjected to the integrated drop test of JIS Z0202 to obtain 0.8 m of one corner, three edges, and six sides. It was dropped from the height and examined for the occurrence of pinholes. Each of the packages of Examples and Comparative Examples 1 to 3 was subjected to an integrated drop test of 30 pieces, and the one having 0 pinholes had an impact resistance of ○ and even one had pinholes. The impact resistance was evaluated as x.

The results are shown in Table 1. In the table, “Ny/PET” is a film obtained by laminating a stretched nylon film and a polyester film, and indicates that the stretched nylon film is located on the outer surface side of the package. Further, “PET” and “Ny” represent a polyester film and a stretched nylon film, respectively, and “PET/Ny” is a film in which a stretched nylon film and a polyester film are laminated, and the polyester film is the outer surface of the package. It is located on the side.

As can be seen from these results, when the outer layer film is composed of a single polyester film, it may be broken when it is frozen and subjected to an impact from the outside to generate pinholes (Comparative Example 1). Further, the outer layer film is composed of a stretched nylon film alone (Comparative Example 2), or a stretched nylon film and a polyester film are laminated as the outer layer film, and the stretched nylon film is located on the inner layer film side. In such a case (Comparative Example 3), small holes may not be formed during microwave heating and the package may burst.

1: Laminated film with weakened wire 11: Outer layer film 111: Polyester film 112: Stretched nylon film 12: Adhesive layer 13: Inner layer film 13a: Stretched inner layer film 13b: Micropores 2: Packaging bag 2a: Seal line 3 : Packaging container 31: Container body 4: Tray 5: Cardboard box X: Weak working line

Claims (4)

A heat-sealable inner layer film made of linear low-density polyethylene , and an outer layer film laminated on the inner layer film, having a weakened processing line that reaches the inside of the outer layer film and does not penetrate the inner layer film. In laminated film,
The outer layer film is a laminated film in which a stretched nylon film and a polyester film are laminated, and the polyester film is located on the inner layer film side,
A laminated film characterized by the above. A packaging container using the laminated film according to claim 1 as a part of a packaging material. The packaging container according to claim 2, which is a packaging bag. The container body has an opening on the upper surface and has a flange around the opening, and a lid member that is heat-sealed to the flange of the container body to close the opening, and the lid member is the laminated film. The packaging container according to claim 2, which is composed of:

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