JP2017074965A - Laminated film and packaging container - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique for sufficiently steaming contents and discharging an excess of vapor by employing a stretched nylon film as an outer-layer film and forming small holes during microwave heating regardless of moisture absorption, in a laminated film composed of a laminate film formed from an outer-layer film 11 and an inner-layer film 12 arranged in layers and provided with a fragile processed line 11a with depth reaching the inside of the outer-layer film and not penetrating the inner-layer film, the laminated film being suitable for a packaging container for microwave heating.SOLUTION: As an inner-layer film, linear low-density polyethylene with a density of 0.93 g/cmor higher is used. During microwave heating, a large number of minute holes are opened in the inner-layer film along a fragile processed line, and an excess of vapor can be discharged. Meanwhile, since the minute holes are small in diameter, the speed at which vapor is released is low, making it possible to sufficiently steam and cook the contents.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technique for heating the contents in a microwave oven while packaging the contents and releasing the water vapor generated by the heating to the outside of the package.

  2. Description of the Related Art Conventionally, a package is known in which cooked or semi-cooked food is housed and sealed in a packaging container so that it can be stored at room temperature, low temperature, or frozen, and heated in a microwave oven without being opened to be ready for eating. .

  When the package is heated in a microwave oven without opening, the moisture in the package becomes water vapor and the volume increases. Therefore, if there is no gap through which water vapor can escape, there is a risk of bag breaking. On the other hand, when the contents are in a semi-cooked state, etc., not only heating but steaming with the generated steam may be required. In this case, if the hole through which the steam escapes is excessively large, steaming is not sufficiently performed, and there is a problem that the flavor is lowered.

  Several packages are known for this application. In any case, it is common to use a packaging container composed of a laminated film, and when the internal pressure increases, a tear is formed in a part of the laminated film, and the tear is broken by releasing water vapor as a steam vent. To prevent.

  As a package that can be steamed when heated by a microwave oven, for example, a package described in Patent Document 1 is known. The package described in Patent Document 1 is composed of a laminated film in which an inner layer film of a polyolefin-based resin is laminated on the inner side of an outer layer film, reaches the inside of the outer layer film on the lid member, and the inner layer film A fragile processing line for removing steam having a depth that does not penetrate through is formed by laser processing. In this package, when heated in a microwave oven, the fragile processed line is torn and a small through hole is formed. As a result, water vapor does not escape excessively, and steaming can be performed while preventing bag breakage.

International Publication No. 2014/061651

  By the way, in Patent Document 1, it is described that a biaxially stretched nylon film can be used as an outer layer film in addition to a polyethylene terephthalate film. I found out.

  That is, since nylon is a highly hygroscopic resin, the stretched nylon film may absorb moisture during storage when the stretched nylon film is used as the outer layer film and the polyolefin resin inner layer film is laminated.

  On the other hand, since the inner layer film is made of a polyolefin resin and has poor hygroscopicity, the laminate strength between the outer layer film and the inner layer film is lowered. Of course, the laminate strength of these inner and outer layers also decreases in the vicinity of the above-described weakly processed line for removing steam.

Thus, when the package body in which the laminate strength is reduced in the vicinity of the weakening line for steam venting is heated in a microwave oven, the inner layer film is broken across the entire weakening line for steam venting to form a large through hole.

  That is, when the outer layer nylon film absorbs moisture, a large through-hole is formed, and a large amount of water vapor is released to the outside, so that the contents are not sufficiently steamed and the flavor is lowered.

  Therefore, the present invention is based on the technique described in Patent Document 1, adopting a stretched nylon film as an outer layer film, and having a target small hole in microwave heating regardless of the presence or absence of moisture absorption. It is an object of the present invention to provide a technique that is formed so that the contents can be sufficiently steamed and excess water vapor can be released.

That is, the invention according to claim 1 is composed of an inner layer film that can be heat-sealed and an outer layer film laminated on the inner layer film, and reaches the inside of the outer layer film and does not penetrate the inner layer film. In a laminated film having a processing line,
The outer layer film comprises a stretched nylon film;
The inner layer film is made of linear low density polyethylene having a density of 0.930 g / cm ² or more,
It is the laminated film characterized by this.

  Next, in the invention according to claim 2, the inner layer film has a direction in which the tensile breaking strength is high and a direction in which the inner layer film is low, and the fragile work line is along a direction in which the tensile breaking strength is low. The laminated film according to claim 1, wherein the laminated film extends.

  The invention according to claim 3 is the laminated film according to claim 2, wherein the tensile breaking strength in the direction of lower tensile breaking strength is 30 MPa or less.

  Moreover, invention of Claim 4 is a packaging container which uses the laminated | multilayer film in any one of Claims 1-3 as a part of packaging material.

  Moreover, invention of Claim 5 is a packaging container of Claim 4 which is a packaging bag.

  The invention according to claim 6 is a container main body having an opening on the upper surface and having a flange around the opening, and a lid member that heat seals the flange of the container main body to close the opening. The packaging container according to claim 4, wherein the lid member is made of the laminated film.

As can be seen from the examples to be described later, when a stretched nylon film is used as the outer layer film, if a linear low density polyethylene having a density of 0.930 g / cm ² or more is employed as the inner layer film, it is subjected to brittle processing during microwave heating. A number of minute holes are opened in the inner layer film along the line. Excess water vapor can be released from the small holes. On the other hand, since these small holes have a small diameter, the water vapor release rate is low, and the contents can be sufficiently steamed and cooked.

FIG. 1 relates to a laminated film of the present invention, FIG. 1 (a) is a cross-sectional explanatory view thereof, and FIG. 1 (b) is a plan explanatory view thereof. 2 relates to a packaging bag using the laminated film of the present invention, 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. FIG. 3 is a perspective view for explaining a packaging container using the laminated film 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 laminated film is provided with a fragile processing line that reaches the outer layer film and does not penetrate the inner layer film.

  This laminated film is suitable for use as a part of a microwave heating packaging container. The packaging container created using this laminated film can be cooked by heating in a microwave oven while containing the contents inside and sealed. As the microwave oven is heated, water vapor is generated inside the packaging container, and at the same time, its internal pressure increases, and the packaging container expands outward. For this reason, the outer layer film is broken at the fragile processing line, and the outer layer film ends on both sides thereof are stretched so as to spread, and the inner layer film adhered to the outer layer film is stretched. In the stretched inner layer film, a large number of micropores are generated, and excess water vapor is released from the micropores to the outside of the packaging container. Can be prevented. By the way, since micropores generated in the stretched inner layer film are extremely small, the release rate of water vapor released through these micropores is also low. For this reason, the inside of a packaging container maintains a moderate internal pressure, and it is possible to cook by fully steaming the contents.

  The packaging container may be a packaging bag, for example. It is also possible to use the laminated film of the present invention as a lid for a rigid container. Hereinafter, taking the case where the laminated film of the present invention is used as a part of a packaging bag as an example, the role played by the laminated film of the present invention and components of the laminated film will be described. FIG. 1 relates to a laminated film of the present invention, FIG. 1 (a) is a cross-sectional explanatory view thereof, and FIG. 1 (b) is a plan explanatory view thereof. 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 12 as essential components.

  The outer layer film 11 is preferably composed of the stretched nylon film 111 alone, but other layers can be laminated as long as the tensile strength at break 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 laminating a metal vapor-deposited film or an inorganic vapor-deposited film, the oxygen barrier property and the water vapor barrier property can be enhanced, and the content preservability can be enhanced. FIG. 1A shows an example in which the outer layer film 11 is configured by laminating a printing ink film 112 on a stretched nylon film 111.

The inner layer film 12 needs to be composed of linear low density polyethylene having a density of 0.930 g / cm ² or more. As can be seen from Comparative Example 1 described later, when the inner layer film 12 is made of polypropylene, the inner layer film is broken across the entire area of the fragile processed line during microwave heating, and a large through hole is formed. For this reason, the contents cannot be fully steamed.

The same applies to the case where linear low density polyethylene having a density of less than 0.930 g / cm ² is adopted as the inner layer film 12. That is, the inner layer film is broken in the entire region of the fragile processed line during microwave heating, and a large through hole is formed. As a result, the contents cannot be sufficiently steamed. Desirably, it is a linear low density polyethylene having a density of 0.940 g / cm ² or more.

  The fragile processed line 11a forms a water vapor discharge hole in a part thereof when heated in a microwave oven, and needs to be provided at a depth that reaches the outer layer film 11 and does not penetrate the inner layer film 12. Since the fragile processed line 11a is provided through the stretched nylon film 111 in this way, the oxygen barrier property of the stretched nylon film 111 is impaired. However, the fragile processed line 11x is provided in a thin line shape, and therefore the oxygen barrier property thereof. The drop in is slight. Its length may be 40 mm or less.

  FIG. 2A is an explanatory perspective view showing a packaging bag 2 made using the laminated film 1. FIG. 2B is a perspective view for explaining the role played by the fragile processed wire 11a when the packaging bag 2 is heated in a microwave oven.

  As described above, when the microwave oven is heated, 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 fragile processing line 11a. The both end portions 11x and 11x of the sandwiched outer layer film 11 are pulled apart from each other. Since the inner layer film 12 is bonded to the outer layer film 11, the inner layer film 12 is pulled in a direction perpendicular to the fragile processing line 11 a along with both end portions 11 x and 11 x of the outer layer film 11. Since 11a does not penetrate, it is stretched thinly between both end portions 11x, 11x of the outer layer film 11. In the thinly stretched region, minute holes are opened in the inner layer film 12 regularly or irregularly. In FIG. 2 (b), 12a shows the inner layer film 12 stretched thinly, and 12b shows the micropores opened in the inner layer film 12.

  As will be described later, when the fragile processed line 11a is formed by laser irradiation, the fragile processed line 11a has a slightly high strength portion and a low strength portion based on the periodic output fluctuation of the laser beam. Therefore, the micropore 12b is formed in the low-strength portion. The micro holes 12b in this case are periodically and regularly arranged along the fragile processing line 11a.

  By the way, when the inner layer film 12 has a direction with a high tensile breaking strength and a direction with a low tensile breaking strength in the plane, if the fragile work line 11a extends along a direction with a high tensile breaking strength, it is accompanied by microwave heating. The inner layer film 12 is stretched in a direction perpendicular to the fragile processing line 11a, that is, in a direction having a low tensile breaking strength. For this reason, an inner layer film may fracture | rupture rapidly and a big hole may generate | occur | produce. And when such a big hole arises, the discharge | release rate of water vapor | steam becomes large and the content cannot be fully steamed. On the other hand, when the fragile processed line 11a extends along the direction where the tensile breaking strength is low, the inner layer film 12 is stretched in the direction where the tensile breaking strength is high during microwave heating. In this case, the inner layer film 12 is sufficiently stretched and is not broken, and generates minute holes 12b. For this reason, it is desirable that the fragile work line 11a extends along a direction in which the tensile breaking strength is low.

  For example, when the inner layer film 12 is a roll-up film and the tensile breaking strength in the flow direction (TD) is lower than the width direction (MD), the fragile processing line 11a is along the flow direction (TD). It is desirable to extend. FIG. 1 (b) shows the laminated film 1 having the fragile work line 11 a extending along the flow direction (TD) having a low tensile breaking strength.

The tensile breaking strength in the direction of low tensile breaking strength, in this example, the tensile breaking strength in the flow direction (TD) is desirably 30 MPa or less. On the other hand, the tensile breaking strength in the direction of high tensile breaking strength, in this example, the tensile breaking strength in the width direction (MD) is desirably 30 MPa or more.

  Next, after laminating the outer layer film 11 and the inner layer film 12, the laminated film 1 can be irradiated with a carbon dioxide gas laser to form a fragile processed line 11a. Lamination | stacking with the outer layer film 11 and the inner layer film 12 is possible using the adhesive agent 13, for example.

  Further, when irradiated with a carbon dioxide laser, the stretched nylon film 111 absorbs the laser beam and melts, and the stretching returns to form a fragile processed line 11a having a low tensile breaking strength. On the other hand, since the linear low density polyethylene is transmitted without absorbing the laser beam, the fragile processed line 11a does not penetrate the inner layer film 12.

  As mentioned above, although the case where the laminated film of this invention was used as a part of packaging bag was demonstrated as an example, the laminated film of this invention can also be used as a cover material. FIG. 3 shows such an example, and the packaging container 3 is composed of a container body 31 and a lid material. The container body 31 has an opening on the upper surface and a flange around the opening, and the lid member heat seals the flange to close the opening. In addition, for convenience at the time of opening and taking out the contents, the illustrated container 3 is provided with a tab on the lid.

  Hereinafter, the present invention will be described based on examples.

Example 1
The stretched nylon film 111 used in this example is Bonile RX (thickness: 15 μm) manufactured by Kojin Film and Chemicals. The stretched nylon film was provided with a printing ink coating 112 to obtain an outer layer film 11.

Further, as the inner layer film 12, linear low density polyethylene (trade name: HCE density: 0.935 g / cm ² , melting point: 123.6 ° C., thickness: 40 μm, moisture permeability: 10 g / m ² · day) manufactured by Tosero Co., Ltd. It was used. The inner layer film 12 has a tensile breaking strength in the flow direction (TD) of 26 MPa and a tensile breaking strength in the width direction (MD) of 47 MP.

  And after performing the corona discharge process on the one side of the inner layer film 12, the outer layer film 11 was adhere | attached and laminated | stacked on the process surface. The adhesive 13 used is A626 made by Mitsui Takeda Chemical.

  And the carbon dioxide laser was irradiated, and the weak processing line 11a which reached the outer layer film 11 and did not penetrate the inner layer film 12 was formed. The length of the fragile processing line 11a is 30 mm, and the extending direction is the flow direction (TD).

  Next, a three-side seal seal bag was prepared using the laminated film 1 thus obtained.

(Example 2)
A packaging bag was prepared in the same manner as in Example 1 except that the extending direction of the fragile processed line 11a was the width direction (MD).

(Example 3)
As the inner layer film 12, a linear low density polyethylene (trade name: HZ, density: 0.940 g / cm ² , melting point: 124.0 ° C., thickness: 40 μm, moisture permeability: 8 g / m ² · day) manufactured by Tosero Co., Ltd. A packaging bag was prepared in the same manner as in Example 1 except that it was used. The inner layer film has a tensile breaking strength in the flow direction (TD) of 25 MPa and a tensile breaking strength in the width direction (MD) of 44 MP.

Example 4
As the inner layer film 12, a linear low density polyethylene (trade name: HZR2, density: 0.950 g / cm ² , melting point: 128.0 ° C., thickness: 40 μm, moisture permeability: 8 g / m ² · day) manufactured by Tosero Co., Ltd. A packaging bag was prepared in the same manner as in Example 1 except that it was used. The inner layer film has a tensile breaking strength in the flow direction (TD) of 29 MPa and a tensile breaking strength in the width direction (MD) of 38 MP.

(Comparative Example 1)
Non-stretched polypropylene film (trade name: RXC-3, density: 0.890 g / cm ² , melting point: 140.0 ° C., thickness: 40 μm, moisture permeability: 10 g / m ² · day) manufactured by Tosero Co., Ltd. as the inner layer film 12 A packaging bag was prepared in the same manner as in Example 1 except that was used. The inner layer film has a tensile breaking strength in the flow direction (TD) of 34 MPa and a tensile breaking strength in the width direction (MD) of 43 MP.

(Comparative Example 2)
As the inner layer film 12, linear low density polyethylene (trade name: MCS, density: 0.920 g / cm ² , melting point: 116.0 ° C., thickness: 40 μm, moisture permeability: 14 g / m ² · day) manufactured by Tosero Co., Ltd. A packaging bag was prepared in the same manner as in Example 1 except that it was used. The inner layer film has a tensile breaking strength in the flow direction (TD) of 34 MPa and a tensile breaking strength in the width direction (MD) of 41 MP.

(Comparative Example 3)
As the inner layer film 12, linear low density polyethylene (trade name: XHT, density: 0.925 g / cm ² , melting point: 121.0 ° C., thickness: 40 μm, water vapor transmission rate: 12 g / m ² · day) manufactured by Futamura Co., Ltd. A packaging bag was prepared in the same manner as in Example 1 except that it was used. The inner layer film has a tensile breaking strength in the flow direction (TD) of 33 MPa and a tensile breaking strength in the width direction (MD) of 40 MP.

(Evaluation)
The packaging bags of Examples 1 to 4 and Comparative Examples 1 to 3 were stored in a constant temperature and humidity chamber at 40 ° C. and 90% RH for 6 hours, and the nylon film of the outer layer film was allowed to absorb moisture. 100 g of processed sugar beet was stored and sealed. Then, it was boiled and frozen. And this frozen packaging bag was mounted in the microwave oven, without opening, and it heated for 2 minutes with the output of 1900 watts. The packaging bag heated in this manner was evaluated by measuring the suitability for steaming and the size of the generated holes.

  In addition, steaming aptitude evaluated "*" when the laminated | multilayer film 1 was fractured | ruptured over the full length of the weak | frail processing line 11a or more, and evaluated as "(circle)" in this range.

  The hole size was evaluated as “◯” when the maximum dimension was less than 5 mm, and “x” when the maximum dimension was 5 mm or more. In addition, when the laminated | multilayer film 1 fractures | ruptures over the full length of the weak | frail processing line 11a or more, it is not measuring since it is meaningless to measure the size of a hole.

  The evaluation results are shown in Table 1. In the table, “LLDPE” means a linear low density polyethylene film. “CPP” is an unstretched polypropylene film.

(Discussion)
First, in Comparative Example 1 in which an unstretched polypropylene film was used as the inner layer film 12, the laminated film 1 was broken over the entire length of the fragile processed line 11a or more by microwave heating. For this reason, the release rate of water vapor is large, and the meat processing side dish is hardly steamed. Even when linear low density polyethylene is adopted as the inner layer film 12, the same applies to Comparative Examples 2 to 3 in which the density of the linear low density polyethylene is less than 0.930 g / cm ² .

On the other hand, in Examples 1 to 4 in which linear low density polyethylene having a density of 0.935 g / cm ² to a density of 0.950 g / cm ² or more is adopted as the inner layer film 12, a hole is opened in the fragile processed wire 11a. However, the whole length was not broken, and the meat processed side dish could be steamed and cooked.

From this result, when a nylon film is adopted as the outer layer film 11 and the inner layer film is composed of linear low density polyethylene having a density of 0.930 g / cm ² or more, even if the nylon film absorbs moisture, It can be understood that the contents can be steamed and cooked even when heated in a microwave oven.

  In particular, in the case of Examples 1 and 3-4 in which the fragile work line 11a extends along the TD direction having a low tensile breaking strength, the size of the hole 12b generated by microwave heating is small, and the contents are sufficient. You can steam and cook.

1: Laminated film 11: Outer layer film 111: Stretched nylon film 112: Printing ink coating 11a: Fragile processed line 11x: Both end portions sandwiching the fragile processed line 12: Inner layer film 12a: Stretched inner layer film 12b: Micropore 13: Adhesion Agent 2: Packaging bag 2a: Seal wire 3: Packaging container 31: Container body

Claims (6)

In the laminated film having a brittle work line that is composed of an inner layer film that can be heat-sealed and an outer layer film laminated to the inner layer film, reaches the inside of the outer layer film, and does not penetrate the inner layer film,
The outer layer film comprises a stretched nylon film;
The inner layer film is made of linear low density polyethylene having a density of 0.930 g / cm ² or more,
A laminated film characterized by that.   The inner layer film has a high direction and a low direction of tensile breaking strength in the plane thereof, and the fragile work line extends along a direction of low tensile breaking strength. A laminated film according to 1.   The laminated film according to claim 2, wherein the tensile breaking strength in the direction of lower tensile breaking strength is 30 MPa or less.   The packaging container which used the laminated | multilayer film in any one of Claims 1-3 as a part of packaging material.   The packaging container according to claim 4 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 material that heat-seals the flange of the container body to close the opening. The packaging container of Claim 4 comprised by these.