JP7524705B2 - Microwave heating container - Google Patents

Description

The present invention relates to a container that can be heated in a microwave oven and a method for manufacturing the same.

Containers that can be heated in a microwave oven include paper containers equipped with a heating sheet that generates heat when irradiated with microwaves.
For example, Patent Document 1 describes a microwave oven tray that includes a paper body having a polygonal bottom and side walls, and a heating sheet attached to the bottom that generates heat when irradiated with microwaves. The microwave oven tray has a body formed by folding a single sheet of paper, and the side walls are integrated by inserting an insertion part provided on the side walls into a notch provided on the side walls and engaging them with each other. This microwave oven tray makes it possible to cook food stored therein while browning it in the microwave oven.

JP 2013-255716 A

The microwave oven tray described in the above-mentioned Patent Document 1 has a stepped portion because the main body of the tray is made by folding paper alone, and the stepped portion cannot be sealed sufficiently, resulting in poor sealing performance.
It is also possible to cover the paper body with a resin film layer to seal it, but the tray body is equipped with a heat generating sheet that can brown the food placed inside, which would cause the resin film layer close to the heat generating sheet to melt.

Therefore, the present invention aims to provide a paper container for heating in a microwave oven, which has a high sealing property due to a resin film layer, and which allows the food contained therein to be browned without the resin film layer melting when heated in a microwave oven .

The present invention is characterized in that the blank sheet is formed from a laminated sheet in which a resin film layer, a paper layer, and a heat-generating base material layer that generates heat when irradiated with microwaves are laminated in this order,
A side panel is connected to each side of a polygonal bottom panel having equal interior angles via a valley fold line, and an edge piece is connected to an outer edge of the side panel opposite the bottom panel via a mountain fold line;
Only the resin film layer is provided continuously and without interruption between adjacent side panels and between adjacent edge pieces,
The resin film layer is a composite film in which a plurality of films are laminated via a sandwich resin layer, and the same material as a part of the films is used for the sandwich resin layer,
Adjacent side panels and adjacent edge pieces are not overlapped with each other, and are integrally joined to the resin film layer so that no gap consisting of only the resin film layer is formed.
The present invention relates to a container for microwave heating.

The invention described in claim 2 is the microwave oven container described in claim 1, characterized in that the bottom plate is an octagonal bottom plate with equal interior angles.

The invention described in claim 3 is a container for microwave heating described in claim 1 or 2, characterized in that the resin film layer is formed by extrusion molding and is made of polypropylene (PP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or polymethylpentene (TPX).

The invention described in claim 4 is the container for microwave heating described in any one of claims 1 to 3 , characterized in that the thickness of the resin film layer is 20 μm or more and 300 μm or less.

The container for microwave heating of the present invention is formed by molding a blank sheet made of a laminated sheet in which a resin film layer, a paper layer, and a heat-generating base layer that generates heat when irradiated with microwaves are laminated in this order, and only the resin film layer is provided continuously and seamlessly between adjacent side panels and between adjacent edge pieces. In addition, adjacent side panels and adjacent edge pieces are not overlapped with each other and are integrally joined to the resin film layer so that no gaps consisting only of the resin film layer are formed.
Therefore, there are no steps due to overlapping of the laminated sheets that make up the container for microwave heating, and the resin film layer provides high sealing performance despite being made of paper. Also, by providing a paper layer between the innermost heat-generating base material layer and the outermost resin film layer of the container for microwave heating, the heat insulating function of the paper layer prevents the resin film layer from melting when heated in a microwave oven, and the food contained therein can be browned.

FIG. 2 is a development view of a blank sheet for a container for microwave heating according to one embodiment. 2 is a schematic cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a plan view of a container for heating in a microwave oven formed from the blank sheet of FIG. 1. FIG. 2 is a perspective view of a container for heating in a microwave oven formed from the blank sheet of FIG. 1 . FIG. 2 is an explanatory diagram showing the state at the end of a hole punching process in the manufacturing process for a microwave oven heating container according to one embodiment.

Below, examples of embodiments of the present invention will be described, with reference to the drawings as necessary.

Figure 1 is a development view of a blank sheet 30 of a container 100 for microwave heating according to one embodiment. The container 100 for microwave heating according to one embodiment is formed from a blank sheet 30, which will be described next.

1, the blank sheet 30 has side panels 2, 3, 4, 5, 6, 7, 8, 9 connected to each side of the bottom panel 1, which has equal interior angles, via valley fold lines 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h, and edge pieces 10, 11, 12, 13, 14, 15, 16, 17 connected to the outer edges of the side panels 2, 3, 4, 5, 6, 7, 8, 9, opposite the bottom panel 1, via mountain fold lines 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a. In addition, only the resin film layer 51 is provided continuously without interruption between adjacent side panels and between adjacent edge pieces. In addition, between adjacent edge pieces, adhesive pieces are provided on the left and right ends of one of the edge pieces, so that when the blank sheet 30 is molded into a container, the adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b are joined to the edge pieces adjacent to the adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b, thereby improving the sealing performance of the container.

In this embodiment, the bottom plate 1 is an octagon with equal interior angles, but any polygon with equal interior angles may be used, such as a rectangle. In addition, the shape of each side plate 2, 3, 4, 5, 6, 7, 8, 9 may be, for example, an inverted trapezoid when each side of the bottom plate 1 is viewed from the bottom, so that when the blank sheet 30 is formed into the microwave oven heating container 100, each side plate 2, 3, 4, 5, 6, 7, 8, 9 is slightly inclined outward when viewed from the front, which gives it a good appearance, such as looking like tableware, when food is eaten as is after microwave heating.

Figure 2 is a schematic cross-sectional view taken along line A-A in Figure 1. The laminated sheet 40 constituting the blank sheet 30 is, for example, as shown in Figure 2, a resin film layer 51, a first adhesive layer 52, a paper layer 53, a second adhesive layer 54, and a heat-generating substrate layer 60 that generates heat when irradiated with microwaves, laminated in this order. The surface of the resin film layer 51 opposite the first adhesive layer 52 is the surface that will become the outside of the container, and the surface of the heat-generating substrate layer 60 opposite the second adhesive layer 54 is the surface that will become the inside of the container. Next, each layer will be described in detail.

(Resin film layer)
It is preferable that the resin film layer 51 be a thermoplastic resin layer, since it has heat resistance sufficient to withstand microwave heating and has the effect of enhancing sealing by being heat-sealed to adjacent side panels and adjacent edge pieces.

The resin film layer 51 is formed, for example, by extrusion molding, and is preferably made of polypropylene (PP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or polymethylpentene (TPX). The resin film layer 51 may be a single layer or a multilayer using these materials.

The resin film layer 51 may be a composite film in which a plurality of films are laminated via a sandwich resin layer. In this case, it is preferable that the same material as that of a part of the film is used for the sandwich resin layer. For example, when the film used for the resin film layer 51 as a composite film is made of polypropylene (PP) or polybutylene terephthalate (PBT), it is preferable to use a composite film with a sandwich resin layer made of polypropylene (PP). In addition, when the film used for the resin film layer 51 as a composite film is made of polyethylene terephthalate (PET), any resin may be used for the sandwich resin layer by performing an easy-adhesion treatment using polyethylene (PE) or polypropylene (PP).

In addition, in this embodiment, the resin film layer 51 also includes a barrier film layer to improve barrier properties.

The thickness of the resin film layer 51 is preferably 20 μm or more and 300 μm or less, and more preferably 100 μm or more and 200 μm or less, since there is a risk that the film layer 51 may be torn due to stress when the film layer 51 is folded toward the outside of the container during box making.

(Paper layer)
Paper layer 53 is made of, for example, coated cardboard, coated manila, ivory, or other paperboard. By providing paper layer 53 between heat generating base material layer 60 (described later) which is the innermost layer of container 100 for microwave heating and resin film layer 51 (described above) which is the outermost layer, food contained therein can be browned when heated in a microwave oven, for example to 200° C. or higher, without resin film layer 51 melting due to the insulating function of paper layer 53.

A printed layer may be formed on the surface of the paper layer 53 that faces the outside of the container.

(Heat-generating substrate layer that generates heat when irradiated with microwaves)
The heat-generating base material layer 60 is composed of, for example, a base material film layer 61 and a metal deposition layer 62. The surface of the base material film layer 61 opposite to the metal deposition layer 62 is the surface that becomes the inside of the container.

For example, polyethylene terephthalate, polypropylene, polymethylpentene, polyetherimide, etc. are used for the base film layer 61. The thickness of the base film layer 61 is preferably about 5 μm to 25 μm. Although it may be unstretched, a biaxially stretched film is preferred because it has high heat resistance.

The metal vapor deposition layer 62 can be made of, for example, aluminum, nickel, gold, silver, zinc, platinum, etc., but aluminum is preferred in terms of heat generation and sparks during heating. Aluminum is also preferred in terms of cost and productivity. The thickness is preferably 2 nm to 15 nm.

The metal deposition layer 62 can be deposited on the base film layer 61 by known methods such as vacuum deposition and sputtering. More specifically, metallic aluminum is used as a deposition source, and is heated and evaporated in a vacuum, and then condensed on the base film layer 61, such as a biaxially oriented polyethylene terephthalate film, to form a thin metal film.

(First adhesive layer, second adhesive layer)
The first adhesive layer 52 for bonding the resin film layer 51 and the paper layer 53, and the second adhesive layer 54 for bonding the paper layer 53 and the heat generating base material layer 60 are each made of a normal adhesive. Examples of the adhesives used include polypropylene resin, silicon resin, polyester resin, acrylic resin, vinyl acetate resin, and glue. In addition, in consideration of heat resistance, examples of the adhesives used include two-liquid curing urethane resin. can be done.

When the resin film layer 51 and the paper layer 53 are bonded together using the first adhesive layer 52, it is preferable to perform an easy-adhesion treatment before bonding the resin film layer 51 and the paper layer 53 together.

When the paper layer 53 and the heat-generating substrate layer 60 are bonded together using the second adhesive layer 54, it is preferable to perform an easy-adhesion treatment before bonding the paper layer 53 and the heat-generating substrate layer 60 together.

When the resin film layer 51 is laminated to the sheet 41 constituted by a laminate in which the paper layer 53 and the heat generating base material layer 60 are laminated in this order, for example, by a melt extrusion lamination method,
There is a method of laminating it to the sheet 41, but when the resin film layer 51 includes a barrier film layer as in this embodiment, a dry lamination method using an adhesive or the like is used.

Figure 3 is a plan view of a microwave oven heating container 100 formed from the blank sheet 30 of Figure 1. Figure 4 is a perspective view of a microwave oven heating container 100 formed from the blank sheet 30 of Figure 1.

The following describes the box-making process for forming the above blank sheet 30 into the microwave oven heating container 100 shown in Figures 3 and 4.

Each side panel 2, 3, 4, 5, 6, 7, 8, 9 is valley folded at each edge of the bottom panel 1, and each edge piece 10, 11, 12, 13, 14, 15, 16, 17 is mountain folded at the outer edge of the side panels 2, 3, 4, 5, 6, 7, 8, 9 opposite the bottom panel 1. The resin film layer 51 between adjacent side panels and between adjacent edge pieces is folded so as to be brought out to the outside of the container, and adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b are provided on the outer surfaces of the adjacent edge pieces on the container side. Adjacent side panels and adjacent edge pieces are joined together without overlapping each other and without leaving any gaps consisting only of the resin film layer 51.

The container 100 for microwave heating is completed by heat-sealing the resin film layer 51 to the side panels 2, 3, 4, 5, 6, 7, 8, 9, edge pieces 10, 11, 12, 13, 14, 15, 16, 17, and adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b. At this time, adjacent side panels and adjacent edge pieces are integrally joined with the resin film layer 51.

After the box is made, the food contents may be placed inside and a lid (not shown) may be attached to edge pieces 10, 11, 12, 13, 14, 15, 16, and 17, which are formed as so-called flanges, to seal the box.

As shown in FIG. 3, adjacent side panels and adjacent edge pieces are not overlapped, and are integrally joined to the resin film layer 51 so that no gaps consisting of only the resin film layer 51 are formed. Therefore, there are no steps due to overlapping of the laminated sheet 40, and the resin film layer 51 provides high sealing performance even though the product is made of paper.

As shown in Fig. 4, the microwave oven heating container 100 of this embodiment is a substantially rectangular container, but the bottom plate 1 is an octagon with equal interior angles. The reason for making the bottom plate 1 an octagon with equal interior angles is as follows.
Considering the case where a lid material is bonded to the flange formed by the edge pieces 10, 11, 12, 13, 14, 15, 16, and 17, the flange is preferably flat. By providing the film layer 51 folded toward the outside of the container at two corners of the flange, a flat flange can be formed without applying a tearing force to the folded portion of the film layer 51 when forming the flange surface. Therefore, when manufacturing a substantially rectangular container as in this embodiment, the bottom plate 1 becomes an octagon with equal interior angles.

In addition, by making each side panel 2, 3, 4, 5, 6, 7, 8, and 9 have an inverted trapezoid shape when each side of the bottom panel 1 is viewed from the bottom, when the blank sheet 30 is formed into the microwave oven heating container 100, each side panel 2, 3, 4, 5, 6, 7, 8, and 9 is slightly tilted outward when viewed from the front, which gives it a good appearance and looks like tableware when food is eaten as is after microwave heating.

The microwave heating container 100 of this embodiment has high sealing properties and can be stored at room temperature, refrigerated, or frozen. As described above, the microwave heating container 100 of this embodiment has a paper layer 53 between the innermost heat generating base material layer 60 and the outermost resin film layer 51, so that when heated in a microwave oven, the heat insulating function of the paper layer 53 prevents the resin film layer 51 from melting, and the food contained therein can be browned.

(Method of manufacturing the microwave oven heating container 100)
The manufacturing method of the microwave oven heating container 100 according to the present invention includes a hole punching step of punching notch holes 71 including the portions where the resin film layer 51 should be provided continuously without interruption between adjacent side panels and between adjacent edge pieces in the sheet 41 constituted by a laminate in which a paper layer 53 and a heat generating base layer 60 are laminated in this order, a resin film layer 51 lamination step of forming the resin film layer 51 on the surface of the paper layer 53 of the punched sheet 41 opposite to the heat generating base layer 60, a punching step of punching the laminated sheet 40 with the resin film layer 51 laminated thereon into blank sheets 30 one by one, and a box making step of forming the punched blank sheets 30 into the microwave oven heating container 100. Note that a printing step on the paper layer 53 may be included before the hole punching step. Next, an example of each step will be described in detail.

(Printing process)
First, printing is applied to the surface of the paper layer 53 that will become the outer surface of the container. The printing method may be a rotary gravure printing method, a flexographic printing method, an offset rotary printing method, or the like.

(Hole punching process)
Next, the process proceeds to a punching process in which notch holes 71 are made in sheet 41, which is a laminate formed by stacking printed paper layer 53 and heat-generating base material layer 60 in this order. Fig. 5 is an explanatory diagram showing the state at the end of the punching process in the manufacturing process of container 100 for heating in a microwave oven according to one embodiment. At the end of the punching process, this resin film layer 51 does not exist.

In this example, the width is such that one row of the final blank sheet 30 can be cut, and the cutout hole 71 is drilled in accordance with the position of the final blank sheet outline 72. The cutout hole 71 is shaped to include at least the portion of the final blank sheet 30 where the resin film layer 51 should be provided continuously, without interruption, between adjacent side panels and between adjacent edge pieces. For example, as shown in FIG. 5, holes are punched between adjacent side panels and between adjacent edge pieces, as well as in the area that extends slightly outward from between the adjacent edge pieces.

(Resin film layer lamination process)
Next, the process proceeds to a resin film layer 51 lamination process, in which a resin film layer 51 is formed on the surface of the perforated sheet 41 that will become the outer side of the container (the surface of the paper layer 53 opposite the heat-generating base material layer 60). By this resin film layer 51 lamination process, only the resin film layer 51 remains in the portion where the sheet 41, which is constituted by a laminate in which the paper layer 53 and the heat-generating base material layer 60 are laminated in this order as shown in Fig. 5, has been perforated and removed.

A preferred method for laminating the resin film layer 51 is, for example, a melt extrusion lamination method in which a thermoplastic resin such as molten polypropylene resin is extruded into a film shape by an extruder, and while the film is in a molten state, the sheet 41 composed of a laminate in which the paper layer 53 and the heat-generating base material layer 60 are laminated in this order is pressure-bonded to laminate it. When the resin film layer 51 includes a barrier film layer, a dry lamination method using an adhesive or the like is used.

(Punching process for blank sheets)
Next, the laminated sheets 40 on which the resin film layers 51 are laminated are separated into blank sheets 3 one by one.
The process then moves to a punching step in which the laminated sheet 40 is punched into blank sheets 30 one by one. Methods that can be used for punching the laminated sheet 40 into blank sheets 30 include a flat press using a punching die equipped with a Thompson blade, and a rotary cutter.

(Box making process)
Finally, the blank sheet 30 thus punched is moved to a box-making process in which it is shaped into a microwave oven heating container 100. The box-making process does not require special equipment and can be carried out using a normal box-making machine. The box-making machine or the like folds the resin film layers 51 between adjacent side panels and between adjacent edge pieces so that they are outside the container, and the adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b are provided on the outer surfaces of the adjacent edge pieces. The adjacent side panels and adjacent edge pieces are joined together without overlapping each other and without leaving any gaps consisting only of the resin film layers 51.

The resin film layer 51 is heat-sealed to the side panels 2, 3, 4, 5, 6, 7, 8, 9, edge pieces 10, 11, 12, 13, 14, 15, 16, 17, and adhesive pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b to complete the microwave oven heating container 100. At this time, adjacent side panels and adjacent edge pieces are integrally joined with the resin film layer 51.

After the box is made, the food contents may be placed inside and the lid may be glued to edge pieces 10, 11, 12, 13, 14, 15, 16, and 17 to seal the box.

The inventors of the present application conducted tests using the containers for microwave heating of Examples 1 to 4 and Comparative Examples 1 to 5 to confirm suitability for box making, browning of food after microwave heating, risk of burns when removing the container from the microwave after microwave cooking, risk of deterioration of the quality of the container, and sealing of the container. In Examples 1 to 4 and Comparative Examples 1 to 5, containers for microwave heating of the same shape as the container for microwave heating of the first embodiment shown in Figures 3 and 4, which were all made by the above-mentioned manufacturing method, were used. In addition, the laminated sheets constituting Examples 1 to 4 and Comparative Examples 1 to 5 were as shown in Figure 2, and the second adhesive layer and the heat-generating base material layer laminated in the laminated sheets were made of the same material and thickness. However, since the basis weight of the paper layer laminated in the laminated sheets constituting Examples 1 to 4 and Comparative Examples 1 to 5, the type of adhesive used in the first adhesive layer, and the thickness of the resin film layer are different, these layers will be described below.

Example 1
The basis weight of the paper layer is 200 g/ ^m2 , the adhesive used in the first adhesive layer is polypropylene (PP), and the thickness of the resin film layer is 60 μm.

Example 2
The basis weight of the paper layer is 250 g/ ^m2 , the adhesive used in the first adhesive layer is glue, and the thickness of the resin film layer is 42 μm.

Example 3
The basis weight of the paper layer is 300 g/ ^m2 , the adhesive used in the first adhesive layer is polypropylene (PP), and the thickness of the resin film layer is 60 μm.

Example 4
The basis weight of the paper layer is 300 g/ ^m2 , the adhesive used in the first adhesive layer is polypropylene (PP), and the thickness of the resin film layer is 70 μm.

(Comparative Example 1)
The basis weight of the paper layer is 150 g/ ^m2 , the adhesive used in the first adhesive layer is glue, and the thickness of the resin film layer is 42 μm.

(Comparative Example 2)
The basis weight of the paper layer is 200 g/ ^m2 , the adhesive used in the first adhesive layer is glue, and the thickness of the resin film layer is 42 μm.

(Comparative Example 3)
The basis weight of the paper layer is 350 g/ ^m2 , the adhesive used in the first adhesive layer is polypropylene (PP), and the thickness of the resin film layer is 60 μm.

(Comparative Example 4)
The basis weight of the paperboard is 350 g/ ^m2 , the adhesive used for the first adhesive layer is polypropylene (PP), and the thickness of the resin film layer is 70 μm.

(Comparative Example 5)
The basis weight of the paper layer is 300 g/ ^m2 , the adhesive used in the first adhesive layer is polyethylene (PE), and the thickness of the resin film layer is 60 μm.

(Test method)
The above-mentioned containers for microwave heating were visually inspected for distortion during box-making to determine suitability for box-making. After microwave cooking, the food was visually inspected for browning marks on the food, seepage of liquid substances from the food from the edge of the laminated sheet, and leakage of liquid substances from the food due to pinholes. The temperature of the edge of the container, which is the handle, was also checked.

(Test results and discussion)
The test results according to the above test methods are shown in Table 1.

In Examples 1 to 4, there was no distortion during box making, the food was well browned after cooking in a microwave oven, the temperature of the edge part (the handle) was 50°C, 60°C, or 70°C or higher, no liquid substances from the food seeped in through the edge of the laminated sheet, and no pinholes were formed.

On the other hand, in Comparative Examples 1 and 2, after microwave cooking, the food was well browned and no liquid substances from the food had seeped in through the edge of the laminated sheet, but there was distortion during box making and pinholes were formed after microwave cooking. In addition, the temperature of the edge of the handle of Comparative Example 2 after microwave cooking was 70°C or higher, while the temperature of the edge of the handle of Comparative Example 1 after microwave cooking was 80°C or higher.
In addition, in Comparative Examples 3 to 5, there was no distortion during box making, and after cooking in the microwave oven, the food was well browned, the temperature of the edge part (the handle) was 45°C or higher, and no pinholes were formed; however, liquid substances from the food had seeped in through the edge of the laminated sheet.

The above test results show that containers for microwave heating using laminated sheets with a combination of the basis weight of the paper layer, the type of adhesive used in the first adhesive layer, and the thickness of the resin film layer in Examples 1 to 4 not only provide good browning of food after microwave heating, but also have good suitability for box-making, reduce the risk of burns when removing the container from the microwave after microwave cooking, prevent deterioration of the quality of food, and provide stable sealing of the container.

As described above, the container for microwave heating of the present invention is formed by molding a blank sheet made of a laminated sheet in which a resin film layer, a paper layer, and a heat-generating base layer that generates heat when irradiated with microwaves are laminated in this order, and only the resin film layer is provided continuously and seamlessly between adjacent side panels and between adjacent edge pieces. In addition, adjacent side panels and adjacent edge pieces are not overlapped with each other and are integrally joined to the resin film layer so that no gaps consisting only of the resin film layer are formed.
Therefore, there are no steps due to overlapping of the laminated sheets that make up the container for microwave heating, and the resin film layer provides high sealing performance despite being made of paper. Also, by providing a paper layer between the innermost heat-generating base material layer and the outermost resin film layer of the container for microwave heating, the heat insulating function of the paper layer prevents the resin film layer from melting when heated in a microwave oven, and the food contained therein can be browned.

The manufacturing method of the container for microwave heating of the present invention includes a hole punching process, a resin film layer lamination process, a blank sheet punching process, and a box making process, and can efficiently manufacture the container for microwave heating described above without going through complicated processes.

1: Bottom plate 1a, 1b, 1c, 1d, 1e, 1f, 1g, 1h: Valley fold lines 2, 3, 4, 5, 6, 7, 8, 9: Side plate 2a, 3a, 4a, 5a, 6a, 7a, 8a, 9a: Mountain fold lines 10, 11, 12, 13, 14, 15, 16, 17: Edge pieces 10a, 10b, 12a, 12b, 14a, 14b, 16a, 16b: Adhesive pieces 30: Blank sheet 40: Laminated sheet 41: Sheet 51: Resin film layer 52: First adhesive layer 53: Paper layer 54: Second adhesive layer 60: Heat generating substrate layer 61: Substrate film layer 62: Metal vapor deposition layer 71: Notch hole 72: Blank sheet outline 100: Container for microwave heating

Claims (4)

The blank sheet is formed by laminating a resin film layer, a paper layer, and a heat-generating base material layer that generates heat when irradiated with microwaves in this order,
A side panel is connected to each side of a polygonal bottom panel having equal interior angles via a valley fold line, and an edge piece is connected to an outer edge of the side panel opposite the bottom panel via a mountain fold line;
Only the resin film layer is provided continuously and without interruption between adjacent side panels and between adjacent edge pieces,
The resin film layer is a composite film in which a plurality of films are laminated via a sandwich resin layer, and the same material as a part of the films is used for the sandwich resin layer,
Adjacent side panels and adjacent edge pieces are not overlapped with each other, and are integrally joined to the resin film layer so that no gap consisting of only the resin film layer is formed.
A container for microwave heating. The microwave oven heating container according to claim 1, characterized in that the bottom plate is an octagonal bottom plate with equal interior angles. 3. The container for microwave heating according to claim 1 or 2, wherein the resin film layer is formed by extrusion molding and is made of polypropylene (PP), polybutylene terephthalate (PBT), polyethylene terephthalate (PET), or polymethylpentene (TPX). The thickness of the resin film layer is 20 μm or more and 300 μm or less.
4. A container for microwave heating according to claim 1 .