JPH0920373A - Retail container for retort food - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a retail container for retort food which, when the food therein is heated in a microwave oven, ingeniously enables avoiding unexpected burst of the container and scattering about of the contents resulting from the burst. SOLUTION: This retail container 1 for retort food is designed to be warmed in a microwave oven when served, the retail container being thermoplastic synthetic resin moldings which are a bowl-shaped vessel 1a for containing food prepared with seasonings 2, 3 and a lid 1b for the vessel attached to the bowl- shaped vessel and sealing it airtightly. To a part of the surface of the lid a heat-evolution seal 5 of a small size which when exposed to microwave radiation becomes heated to a high temperature is attached. In this instance the heat- evolution seal 5 in use is what is formed by laminating a thin plastic seal 5a with a thin metal layer consisting of a layer with a vaporization coating of aluminum and by coating the reverse surface with an adhesive agent 5c. When the retort food therein is warmed in a microwave oven 6, the heat evolved by the heat-evolution seal 5 opens a small hole in the lid to relieve the container so that the plastic container can be prevented safely from bursting unexpectedly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a container for retort food products which is heated in a microwave oven.

[0002]

2. Description of the Related Art Recently, various retort foods such as curry rice have become popular and are being marketed as products. As an automatic vending machine for such retort food, a microwave oven installed in the machine that heats and sells the retort food has been put into practical use. This retort food product is made by putting pre-cooked food in a plastic container (for example, an inexpensive and versatile polypropylene resin (thermoplastic resin) molded product) and sealing it with the same plastic lid. In order to enable long-term storage of food, an inert gas such as nitrogen is enclosed in the product container.

When selling such retort-packed food products in a vending machine, a vending machine having a built-in microwave oven is used, and the products paid out from the inside of the warehouse at the time of sale are transferred to the microwave oven on the way of the carry-out route. After loading and heating,
It is recommended to take it out to the product outlet for sale.

[0004]

By the way, when the retort food contained in the plastic closed-type product container is heated in the microwave oven as described above, the inert gas enclosed in the product container also rises as the temperature of the content food increases. Due to thermal expansion, the internal pressure of the container increases, which causes an accidental rupture of the entire plastic container, which often causes sales problems such as the food inside being scattered into the range.
In particular, the polypropylene resin, which is a material for the above-mentioned product container, has a relatively low heat distortion temperature and yield stress, and has a property of easily bursting when the internal pressure of the container increases when heating food. Moreover,
If food is scattered inside the microwave oven, it is not desirable in terms of hygiene. Therefore, a countermeasure is required.

Therefore, a mechanical container lid perforation mechanism is incorporated in the vending machine, a small hole is opened in the container lid of the product carried out from the product rack at the time of sales operation, and the container is opened during heating in the microwave oven. Some attempts have been made to prevent it from bursting, but there are drawbacks such as the complicated hole-piercing mechanism, and simpler countermeasures are desired. The present invention has been made in view of the above points, and an object thereof is to solve the above-mentioned problems, an unexpected rupture of a container when warming a retort food in a microwave oven, and scattering of the surrounding food due to the rupture of the container. (EN) It is an object to provide a product container for retort foods that can be skillfully avoided.

[0006]

According to the present invention, the above object is to provide a bowl container containing cooked food and a container lid which is attached to the bowl container and hermetically seals the thermoplastic plastic molded article. This is achieved by applying a small-sized heat-generating seal that heats to a high temperature by receiving microwave irradiation on a part of the surface of the lid.

The heat-generating seal is preferably formed by forming a thin metal layer on a thin plastic seal and applying an adhesive on the back surface thereof, and the metal layer is preferably formed by a vapor deposition layer of aluminum.

[0008]

[Function] As described above, when a product in which the retort food is contained in a thermoplastic closed container with a heat-sealing sticker attached to the lid of the bowl container is heated in a microwave oven, microwaves are concentrated on the metal layer of the heat-seal (electric field concentration). ), And the electromagnetic induction action causes eddy current loss in the metal layer of the seal to generate heat. As a result, the part of the container lid on which the heat-generating seal is attached is heated to a higher temperature and softens before the other parts, and the internal pressure rise due to the thermal expansion of the inert gas sealed in the container is also added to this part locally. A small hole opens, and before the entire container is ruptured, the enclosed gas is released through the small hole to reduce the internal pressure. Therefore, when warming the retort food in the microwave oven, it is possible to safely prevent the trouble that the product container is unexpectedly ruptured and the food contained therein is scattered around.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. First, in FIGS. 1 (a) and 1 (b), a product container 1 for retort food is composed of a bowl container 1a and a container lid 1b which is hermetically covered on the upper surface of the container 1a, and includes a bowl container 1a and a container lid 1b. Are made of thermoplastic plastic moldings such as polypropylene resin. Further, for example, a product container 1 for curry and rice has cooked rice 2 in one chamber of a bowl container 1a partitioned into two chambers A and B, and curry roux 3 in the other, and further long-term food An inert gas 4 such as nitrogen is sealed in the container for storage.

According to the present invention, a small-sized round-shaped heat-generating seal 5 is attached to the upper surface of the container lid 1 so as to extend over the above-mentioned two chambers A and B. As shown in FIG. 1C, the heat generating seal 5 is formed by laminating a thin metal layer 5b on a thin plastic layer 5a and applying an adhesive 5c on the back surface thereof. , Is formed by vapor-depositing aluminum on a plastic sheet to a thickness on the order of microns.

As shown in FIG. 1 (d), when the retort food product contained in the container 1 is heated in the microwave oven 6, the contents of the food are heated by the irradiation of microwaves and, at the same time, the container lid 1a is heated. Microwaves are concentrated (electric field concentration) on the metal layer 5b of the heat generation seal 5 attached to the surface of the container and heat is generated due to the eddy current loss, and the seal attachment portion of the container lid 1b made of thermoplastic is rapidly heated to a high temperature. Soften. In addition to the local heating and softening of the container lid 1b, the inert gas 4 enclosed in the product container 1 thermally expands to increase the internal pressure of the sealed container, which causes the entire product container 1 to be unexpected. Before it bursts, a small hole opens in the portion where the heat-sealing seal 5 is attached, allowing the internal pressure in the container to escape. That is, when the retort food is heated in a microwave oven, it is possible to safely prevent the product container 1 from unexpectedly rupturing and the food inside to be scattered into the microwave oven. In addition, in FIG.
Is a microwave oscillator such as a magnetron, 8 is a waveguide,
9 is a stirrer fan, 10 is a turntable, and MW is a microwave radiated in the range.

Further, the heat-generating seal 5 can be attached to each of the rooms partitioned by the bowl container 1a as shown in FIG. Further, the shape of the heat generating seal 5 is not limited to the round shape shown in FIG. 1, and any shape such as a ring shape having a circular hole 5d formed at the center of the circular heat generating seal 5 as shown in FIG. In addition to the above, depending on the situation, it is also possible to stack two heat generating seals 5 and attach them to the container lid.

[0013]

As described above, according to the present invention, when a reheatable food is heated in a microwave oven by simply attaching an inexpensive heat seal to the lid of the product container containing the retort food. Due to the heat generated by the heat-generating seal, a small hole can be opened in the container lid to allow the internal pressure to escape, so that it is possible to safely prevent a sales trouble in which the plastic container is unexpectedly ruptured and the food contents are scattered around.

[Brief description of drawings]

1 shows an embodiment of the present invention, (a) is an external view of a product container with a heat-generating seal for retort food, (b) is a cross-sectional view of the product container, (c) is a cross-sectional view of a heat-generating seal, (d) ) Is a diagram showing the state where the retort food is heated in the microwave

FIG. 2 is an external view of a product container showing an application example in which a heat-sealing sticking place is changed.

FIG. 3 is an external view of an application example in which the shape of a heat generation seal is different.

[Explanation of symbols]

 1 Product Container 1a Bowl Container 1b Container Lid 4 Inert Gas 5 Exothermic Seal 5a Plastic Layer 5b Metal Layer 5c Adhesive 6 Microwave

Claims (3)

[Claims] 1. A commercial product container for retort food that is heated in a microwave oven, wherein the container is a bowl container containing cooked food, and a container lid which is attached to the bowl container to seal the container is thermoplastic. A container for retort food products, comprising a molded product, wherein a small-sized heat-generating seal that heats to a high temperature by being irradiated with microwaves is attached to a part of the surface of the lid. 2. The container for retort food products according to claim 1, wherein the heat-generating seal is a thin plastic seal having a thin metal layer formed thereon and an adhesive applied to the back surface thereof. . 3. The container for retort food products according to claim 2, wherein the metal layer is a vapor-deposited layer of aluminum.