JP5006124B2 - Microwave heating container, inner lid used therefor, and food container containing food - Google Patents

Description

  The present invention relates to a container for partial heating in a microwave oven, an inner lid used therefor, and a food package containing foods therein.

Containers for performing partial heating in a microwave oven have been known for a long time.
For example, in Patent Document 1, the inside of a lunch box is partitioned into a plurality of storage portions, and a portion of the storage portions are covered with aluminum foil, thereby heating the food in the storage portion covered with aluminum foil. Techniques for preventing and heating food in other storage units are disclosed.
Since this technology is designed to unheat a part of the storage compartment that is partitioned in a plane in the lunch box, it can realize three-dimensional (two-dimensional) partial heating, but three-dimensional (tertiary) Inherently, it has the disadvantage that partial heating is not possible.

Therefore, Patent Document 2 discloses a container that includes a microwave-shielding container body and a microwave-permeable middle dish supported in the vicinity of the opening of the container body.
In the case of this container, since the container body shields microwaves, the portion below the middle dish, that is, the food stored directly in the container body is hardly heated, whereas the microwave-permeable middle dish The food placed on is heated.
For this reason, partial heating is realized three-dimensionally in the vertical direction of the container.

  In addition, a through-hole is provided in the bottom of the middle dish, and food that has been heated and melted on the middle dish dripped onto the non-heated food from the through-hole. It becomes possible to apply chocolate sauce, and the range of cooking methods using a microwave oven is expanded.

However, in the container of Patent Document 2, the microwave of the microwave oven passes through the middle dish from the opening of the container and penetrates into the lower part of the middle dish to some extent, so it is stored directly in the container body. Food cannot be prevented from being heated.
In particular, in a container with a large opening area or a container with a low height, the microwave intrudes into the part below the middle dish, so the food in the container body is heated to a level that cannot be ignored. End up.
Therefore, depending on the shape of the container, this technique is almost unusable, and there is a problem that the effect of non-heating cannot be expected even if it is forcibly used.
JP-A-11-299524 JP 2005-263319 A

  Therefore, the problem to be solved by the present invention is to enable three-dimensional partial heating to be realized with high accuracy without depending on the shape of the container in the microwave heating container.

In order to solve the above-described problems, in the microwave heating container of the present invention, the microwave cover is provided with an inner lid that covers the vicinity of the opening of the microwave-shielding container body, and has an aluminum foil layer laminated in the thickness direction and heat shrinkability. It has at least a heat-adhesive resin layer.
And, in the aluminum foil layer of the inner lid, a missing part is formed in the center in plan view, and the heat-adhesive resin layer is assumed to have heat shrinkability, at a position corresponding to the missing part of the aluminum foil layer, A cut was formed to define a flap-like portion that could be curled by heat shrinkage .

When the food is stored in the container body of the microwave heating container using such an inner lid, the food is placed on the inner lid and applied to the microwave oven, the food on the inner lid is heated, and the food in the container body Is not heated.
In particular, the food in the container body is not only shielded by the microwave from the surroundings but also from the opening by the inner lid having an aluminum foil layer, so that the heating of the food in the container body is higher than before. Is prevented.
Thus, by devising the structure of the inner lid, the food in the container body is almost completely unheated, so the unheated state does not depend on the shape of the container, Various shapes and sizes can be set.

Moreover, when this container is heated with a microwave oven, the thermoadhesive resin layer of the inner lid contracts, and the cut is curled to form an opening in the inner lid.
Therefore, when a heat-meltable food is placed on the inner lid, the melted food will drip from the opening onto the non-heated food in the container body, and a hot sauce or the like is applied to the cold food. The cooking state can be easily realized simply by heating with a microwave oven.
In particular, in this case, in the non-heated state of the inner lid, since the cut is not curled and no opening is formed, the food on the inner lid falls into the container body before cooking with a microwave oven, It is possible to prevent the food to be heated from becoming unheated.

  It is preferable that the missing portion has a substantially circular shape because the melted food on the inner lid is easy to flow in, and the diameter of the missing portion prevents the microwave from entering from the missing portion and heating the food in the container body. Is preferably 30.5 mm or less, which is about 1/4 of the microwave wavelength of 120 mm.

  When the thermal shrinkage rate of the heat-adhesive resin layer is less than 1%, the shrinkage force causing sufficient curling is poor, and when it exceeds 50%, the shrinkage force becomes too strong, and the cover material is wrinkled or cracked. Since it may generate | occur | produce, it is preferable that it is 1 to 50%.

In addition, before the inner lid is covered on the container body, the heat-adhesive resin layer may be contracted by heating to curl the flap-shaped portion defined by the cut.

  When food is stored in this container to form a food container, covering the upper lid on the inner lid seals the food placed on the inner lid, thereby improving the convenience of distribution.

  Since the inner lid that covers the microwave shielding container main body of the microwave heating container has a layer made of aluminum foil, microwaves can be prevented from entering the container main body from its opening, and the inside of the container main body Almost completely unheated state of the food stored in the container is realized.

1, a microwave oven heating container 1 (hereinafter abbreviated as a container 1) according to an embodiment includes a container main body 20, a sheet-like inner lid 10 heat-sealed on a flange of the container main body 20, and a container main body 20. And a dome-shaped upper lid 30 covering the opening.
As shown in the figure, the ice cream I is stored in the container body 20 of the container 1, and the solid chocolate C is placed on the inner lid 10.

  As shown in FIG. 2, the inner lid 10 of the container 1 is formed by laminating a heat-adhesive resin layer 12 having heat shrinkability on the inner surface (surface on the container body 20 side) of an aluminum foil layer 11 made of aluminum foil. It has a three-layer structure in which the resin film layer 13 is laminated on the surface opposite to the container body 20, and the outer shape is a circle with a tab.

As shown in FIG. 2, the aluminum foil layer 11 has a circular missing portion 11 a in plan view substantially at the center in plan view.
The diameter of the missing portion 11a is 30.5 mm or less so that microwaves in the microwave oven cannot pass through the missing portion 11a. In a more preferred aspect, the lower limit of the diameter is 2.0 mm.
Further, a missing portion 11b is also formed in a donut shape in the periphery of the inner lid 10, and this missing portion 11b extends from the end of the inner lid 10 (the end of the resin film or the heat-adhesive resin layer 12) to the inner lid 10. It is a range that extends about 2 to 10 mm in the radial direction.
This donut-shaped missing portion 11b has an effect of preventing sparking when heated in a microwave oven, and can be cooked more safely in the microwave oven.
Note that a plurality of missing portions 11a can be provided depending on the application, and the shape is not necessarily circular.

The circular missing portion 11a may be perforated by punching or the like, or may be formed by etching after laminating an aluminum foil and a resin film or a heat-adhesive resin layer 12.
Specifically, after laminating the aluminum foil and the resin film or the heat-adhesive resin layer 12, the aluminum foil is subjected to a donut-shaped resist film treatment, and the non-resist portion is dissolved and removed with an acid or alkali etching solution. The resist film may be peeled off as necessary.
The donut-shaped missing portion 11b may also be removed by etching similar to the above in the peripheral portion of the aluminum foil.
As another method, an aluminum foil cut into a donut shape in advance may be prepared and bonded to the resin film or the heat-adhesive resin layer 12.

Although the kind in particular of aluminum foil is not restrict | limited, For example, the well-known aluminum foil about 5-100 micrometers in thickness is employable.
The material can be appropriately selected from JISlN30, lN70, 3003, 3004, 8021, 8079 and the like, and the tempering can be appropriately selected from hard, semi-rigid, and soft.

As shown in FIG. 2, the heat-shrinkable heat-adhesive resin layer 12 has an arcuate shape near the center of the opening of the container body 20, that is, in a portion corresponding to the circular missing portion 11 a of the aluminum foil layer 11. A through cut 12a is provided.
As shown in FIG. 1, the inner lid 10 is heat-sealed with the heat-adhesive resin layer 12 facing the flange of the container body 20.
The cut line 12a may have any shape as long as it is formed of a bent line, a curve, or a combination of a line segment and a curve, in addition to an arc shape, but a U shape, a U shape, a V shape, and a U shape. , H-shape, X-shape, arc, corrugation, or a combination thereof is more preferable because the formation of the openings described later is favorable.
The length (size) of the cut may be a desired length (size), and the cut 12a is not limited to the through cut 12a, but may be a half cut or a perforation.

  As described above, the thermal adhesive resin layer 12 is provided with a cut 12a at a position corresponding to the missing portion 11a of the aluminum foil layer 11. Therefore, when the cut 12a is heated, the contraction force is increased. By opening and curling, an opening is created in the inner lid 10.

The kind of the heat-adhesive resin having heat shrinkability is not particularly limited, but for example, it is preferable to use at least one selected from unstretched polypropylene, stretched polypropylene, styrene, polyethylene, polyester, and the like. .
The heat shrink rate of the heat-shrinkable resin is desirably 1 to 50% (after holding at 120 ° C. atmosphere for 30 minutes) in a film state, and more preferably the heat shrink rate is 1.5 to 30%. It is good.
In the case of an unstretched film, the shrinkage rate differs between vertical (longitudinal direction during film production) and horizontal (width direction during film production), but it is sufficient that at least one of the thermal shrinkage rates is satisfied.
The heat shrinkage rate in the curl direction is preferably 1 to 50% (after holding at 120 ° C. for 30 minutes).
The heat-adhesive resin layer 12 is preferably made of a heat-shrinkable sealant film.
In the present invention, the thermal shrinkage rate of the film is calculated by the following equation.
Thermal shrinkage rate (%) = {(film length before heating−film length after heating) / film length before heating} × 100
The length before heating is 100 mm (in room temperature), held in an oven at 120 ° C. for 30 minutes, the film is taken out of the oven, cooled to room temperature, and then the length of the film may be measured with a scale, a comparator, etc. . For example, when the length after heating is 90 mm, the thermal shrinkage rate is 10%.
Other details may conform to JIS C2318.

As shown in FIGS. 1 and 2, the resin film layer 13 laminated on the outer surface of the aluminum foil layer 11 is for preventing the aluminum foil from sparking when the container 1 is placed in a microwave oven. Chocolate C is placed on it.
As shown in the figure, the resin film layer 13 is formed with cuts 13 a at positions corresponding to the cuts 12 a of the thermal adhesive resin layer 12.

This resin film is made of a polyethylene terephthalate film having a thickness of about 12 to 250 μm, a polyester film such as a polybutylene terephthalate film or a polyethylene naphthalate film, a nylon film, a polypropylene film, or a vinylidene chloride-acrylate copolymer resin film. At least one selected is preferred.
As these films, a biaxially stretched film, a uniaxially stretched film, and an unstretched film can be used suitably.

  Further, the inner lid 10 may be further printed, and a light shielding layer, an OP (overprint) layer, a primer layer, an anchor coat layer, a paper layer, or the like may be laminated as necessary. You may coat the surface with a cloudy agent, a lubricant, an anti-slip agent, and various coating agents.

As shown in FIG. 1, the container body 20 has a two-layer structure in which an inner container 21 molded with an aluminum foil is loaded into an outer container 22 molded with a synthetic resin.
The outer container 22 has a bottom wall, a peripheral wall that rises and rises from the bottom wall, and a flange 22a that projects substantially horizontally from the upper edge of the peripheral wall, and the inner container 21 rises and spreads from the bottom wall. The peripheral wall and the edge winding part 21a provided in the upper edge of the peripheral wall are provided.

Here, as shown in FIG. 1A, the dimensions of the edge winding portion 21 a of the inner container 21 are adjusted so as to slightly protrude from the opening of the outer container 22 with the inner container 21 loaded in the outer container 22. Has been.
Accordingly, as shown in FIG. 1B, when the inner lid 10 is heat sealed to the flange 22a of the outer container 22 and the opening of the container body 20 is sealed, the edge winding portion 21a of the inner container 21 is 10 is brought into contact with the heat-adhesive resin layer 12 and the bottom wall is bent, and is elastically pushed into the outer container 22.
Therefore, as shown in the drawing, the inner container 21 is biased toward the inner lid 10 with the edge winding portion 21a in contact with the inner lid 10, so that the inner container 21 and the inner lid 10 are urged. There is almost no gap between them.

Since the inner container 21 of the container body 20 is made of aluminum foil, the container body 20 shields microwaves so that the ice cream I stored in the container body 20 is not heated, and the outer container 22 is made of synthetic resin. Therefore, the container body 20 does not spark during heating by the microwave oven.
In particular, since there is no gap between the inner container 21 and the inner lid 10 as described above, microwaves are prevented from entering the container 1 from such a boundary portion.

  As the container body 20, in addition to this, a laminate film obtained by laminating an aluminum foil and a resin film is formed into a container shape with the aluminum foil inside, and an aluminum foil is formed into a container shape and then coated with resin or paper, etc. Can be adopted.

Moreover, as shown in FIG. 1, the dome-shaped upper lid 30 is for sealing the chocolate C placed on the inner lid 10 so that it does not fall during transport of the container 1, and is made of an appropriate synthetic resin. Is formed.
In addition to this, after laminating aluminum foil in a sandwich shape with two resin films, molded into a container, after laminating aluminum foil and resin film, molded into a container with a flange with the aluminum foil inside, Furthermore, what coated the resin on the surface of a flange can also be employ | adopted.

When the container 1 is put into a microwave oven with or without the top lid 30, the chocolate C on the inner lid 10 is heated and melted as shown in FIG. 3, and the ice cream I in the container body 20 is The container body 20 and the inner lid 10 are not heated because the microwaves are almost completely shielded.
Here, since the inner lid 10 also shields microwaves from the opening of the container body 20, the shielding state in the container body 20 is maintained almost completely.
Then, as shown in the figure, the cut 12a of the heat-adhesive resin layer 12 of the inner lid 10 and the cut 13a of the resin film 13 are curled to form an opening in the inner lid 10. It will drip and a hot chocolate sauce will be applied over Ice Cream I.
As described above, a food with a warm food on a cold food can be easily produced only by heating with a microwave oven, and can be eaten as it is when the inner lid 10 is opened with a tab.
Moreover, since the shielding state of the microwave in the container main body 20 does not depend on the shape of the container main body 20, the container main body 20 can have any shape and size.

In this embodiment, the inner lid 10 is formed in a flat sheet shape, but the shape of the inner lid 10 is not particularly limited to this, and is flat, mortar-shaped (inverted cone), inverted cone A trapezoidal shape, a drop-lid shape, or the like can be adopted, and a flange, an engaging groove or the like may be provided around the periphery if desired.
The shape of the container body 20 is not particularly limited, and may correspond to the shape of the inner lid 10.

Further, in the embodiment, the heating of the cut 12a portion of the inner lid 10 is performed simultaneously with the heating of the container 1 in the microwave oven. Of course, the heating of the portion of the cut 12a is performed on the inner lid 10 on the container body 20. It may be performed simultaneously with heat sealing.
However, as in the embodiment, as food such as chocolate C on the inner lid 10 is heated when the microwave oven is heated, the heat causes curling, and the process is simplified if the food falls from the opening. It becomes.

Of course, the food stored in the container 1 is not limited to the ice cream I and the chocolate C.
For example, it is possible to store noodles in the container body 20, place a soup hardened with gelatin on the inner lid 10, melt the soup by heating, and apply the warm soup on the cold noodles.

In order to further clarify the contents of the present invention, the container of the example and the comparative example (container body is the same) with different configurations of the inner lid were prepared as follows. Was done.
Example: outer layer base material / adhesive / aluminum foil / resist printing / adhesive / heat-shrinkable resin Comparative Example 1: outer layer base material / adhesive / aluminum foil / adhesive / heat-shrinkable resin Comparative Example 2: inner lid None Comparative Example 3: Outer layer base material / adhesive / heat-shrinkable resin

(Example)
Using a 12μm PET film with corona treatment on one side as the outer layer base material, LX500 made by Dainippon Ink & Chemicals, Inc. as the main agent, 10 parts, and 1 part of the company's KW75 as the curing agent, a two-part curable urethane This adhesive was diluted with ethyl acetate, and applied to the corona-treated surface of the previous PET film by a gravure method and dried so that the weight after drying was 3.5 g / m ² .
A 7 μm thick 1N30 soft aluminum foil was bonded with a heat roll at 60 ° C., followed by curing at 40 ° C. for 3 days.
Then, this aluminum foil was provided with a non-printing portion having a circular shape of φ90 mm larger than the opening of the aluminum foil molding container and a central portion of φ30 mm, and resist printing was performed on the donut shape. The material was etched to remove the aluminum foil other than the resist printing portion. Then, using the adhesive on the resist printing side of the base material in the same manner as before, a heat shrinkable resin made of J-film 30 μm XB-15FT (main component: blend resin film of polypropylene and polystyrene, heat shrinkage rate: vertical / Width: 19% / 7% at 120 ° C. for 30 minutes) and curing at 40 ° C. for 3 days.
This structure was used as an inner lid, and was punched out with a mold so as to form a substantially disk shape with a tab attached outer diameter φ100 mm. The center of the inner lid was cut into a circular arc shape (substantially C-shaped) with a diameter of 25 mm so that the center of the donut-shaped aluminum foil in plan view (a missing portion of the aluminum foil) did not contact the aluminum foil.
Similar to the container body of the embodiment, the outer container made of polypropylene (bottom surface φ55 mm, depth) so that the edge winding portion of the inner container (bottom surface φ50 mm, height 35 mm, opening φ80 mm) of the aluminum molding cup protrudes about 1 mm. 34 mm, opening φ82 mm, flange width 4 mm), and the peripheral edge of the inner lid and the flange of the polypropylene container were heat sealed at 200 ° C. × 80 kg / cup × 1 second.
At this time, a shrinkage force was imparted to the heat-shrinkable resin also by heat at the time of heat sealing at the center portion of the inner lid, and the portion partitioned by the cut was curled.
In addition, the edge winding part of the aluminum molding cup abuts on the lower surface of the heat-adhesive resin layer of the inner lid during heat sealing and is elastically pushed into the polypropylene container, so A gap is less likely to occur between the parts.

(Comparative Example 1)
A container was prepared by the same manufacturing method as in the examples except that the inner cover was not subjected to resist printing / etching.
(Comparative Example 2)
A container made of only the container body similar to the example without an inner lid was produced.
(Comparative Example 3)
From the configuration of the inner lid of Comparative Example 1, a container was produced from the inner lid from which the aluminum foil was removed and the same container body as in the example.

(Evaluation method 1)
Place 100 cc of water in the container body (aluminum cup), place a resin film small container (capacity about 50 ml) separately prepared on the inner lid, fill the small container with 30 cc of water, and use a microwave oven (Matsushita NE-M620 100V) manufactured by Denki Sangyo Co., Ltd. was heated at 600 W for 60 seconds, and the temperature rise of water in the container body (non-heated part) and water in the small container (heated part) was measured.
Since Comparative Example 2 does not have an inner lid, the small container was supported with disposable chopsticks.
The initial water temperature is 27 ° C. and the results are shown in Table 1.

(Evaluation method 2)
The container body (aluminum cup) is filled with 50 g of ice cream, 10 g of solid chocolate is placed on the inner lid, it is loaded into a microwave oven (NE-M620 100V manufactured by Matsushita Electric Industrial Co., Ltd.), heated at 600 W for 60 seconds, The state of time was observed.
The results are shown in Table 2.

From the above, in the examples, the inner lid was sufficiently curled, no spark was generated, and there was no temperature rise in the non-heated part.
On the other hand, in Comparative Example 1, the curl of the inner lid was not sufficient, sparking occurred, and there was a problem in safety.
In Comparative Example 2 and Comparative Example 3, it was found that the water temperature of the non-heated part increased and the non-heating effect was not sufficient.

Longitudinal sectional views of a microwave heating container containing food, in which (a) is in an exploded state and (b) is in a combined state. (A) is a plan view of the inner lid, (b) is a BB cross-sectional view of (a). In a state where the microwave heating container is heated, (a) is an overall longitudinal sectional view, and (b) is a partially enlarged longitudinal sectional view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Microwave heating container 10 Inner lid 11 Aluminum foil layer 11a Center missing part 11b Periphery missing part 12 Thermal adhesive resin layer 12a Cut 13 Resin film layer 13a Cut 20 Container main body 21 Inner container 21a Edge winding part 22 Outer container 22a Flange 30 Top lid I Ice cream C Chocolate

Claims (6)

An inner lid 10 having at least an aluminum foil layer 11 and a heat-adhesive resin layer 12 laminated in the thickness direction,
The aluminum foil layer 11 has a missing portion 11a, and the thermal adhesive resin layer 12 has heat shrinkability, and the thermal adhesive resin layer 12 has a missing portion 11a in the aluminum foil layer 11. An inner lid in which a cut 12a is formed at a corresponding position to define a flap-like portion that can be curled by heat shrinkage .   The inner lid according to claim 1, wherein the missing portion 11 a of the aluminum foil layer 11 is substantially circular and has a diameter of 30.5 mm or less.   The inner lid according to claim 1 or 2, wherein the thermal shrinkage rate of the thermal adhesive resin layer 12 is 1 to 50%. The inner lid according to any one of claims 1 to 3, wherein a shrinkage force is applied to the thermoadhesive resin layer 12 by heating to curl a flap-shaped portion defined by the cut line 12a.   A microwave shielding container main body 20 having a bottom wall and a peripheral wall rising from the peripheral edge of the bottom wall, and the inner lid 10 according to any one of claims 1 to 4 covered in the vicinity of the opening of the container main body 20 A microwave oven heating container.   The food packaging body of the microwave oven heating container according to claim 5, wherein the non-heating food is stored in the container body 20, the heating food is placed on the inner lid 10, and the upper lid 30 is placed thereon.

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