JP7510050B2 - Microwave Containers - Google Patents

Description

The present invention relates to a microwave oven container.

As disclosed in the following Patent Document 1, for example, a microwave oven container has a flange portion that extends outward from the opening, and a ribbed heat-sealed portion is formed on the upper surface of this flange portion all around. This heat-sealed portion is used to heat-seal a film-like lid portion that covers the opening of the container. A steam exhaust portion for releasing steam is formed in part of the heat-sealed portion, and this steam exhaust portion is composed of a V-shaped portion with a pattern that expands outward. When the steam generated inside the container reaches a predetermined pressure, the steam exhaust portion configured in this way is designed so that stress is concentrated on the sharp tip on the inside of the V-shaped portion, causing the heat-sealed lid portion to break.

However, in a steam exhaust section configured in this way, the exhausted steam turns into water, causing the lid and steam exhaust section to stick together, blocking the steam exhaust port. In this case, as the container cools, the pressure inside is reduced, causing the container to deform.

JP 2008-290738 A

The present invention was made in consideration of these circumstances, and its purpose is to provide a microwave container that does not cause deformation of the container after steam is released.

According to the present invention, a microwave oven container is provided, which comprises a film-like lid, a container body having an opening at the top, formed in a concave shape and capable of accommodating contents, and a flange portion formed so as to extend outward from the opening, the upper surface of the flange portion is formed with a fusion portion which is fused to the rear surface of the lid portion, the fusion portion includes a steam exhaust portion for exhausting steam generated from inside the container body, and the lid portion is made of a shrink film.

Because the lid is made of shrink film, it shrinks when the container is heated, and rolls up near the steam outlet, so it does not block the steam outlet. This prevents the pressure inside the container from decreasing even when the container cools down, and makes it possible to prevent deformation of the container.

Preferably, the flange portion is formed around the periphery of the container body, and the steam exhaust portion is formed at a corner of the periphery.
Preferably, the fusion portion is formed in a convex rib shape on the upper surface side of the flange portion.

1 is a perspective view showing an entire microwave container 1 according to a first embodiment of the present invention. Fig. 2A is a plan view of the container body 2. Fig. 2B is a side view of the container body 2. 2B is a cross-sectional view taken along line III-III in FIG. 2A. Fig. 4A is a perspective view showing the lid opening portion 24 and the steam exhaust portion 25. Fig. 4B is a cross-sectional view taken along line IVb-IVb in Fig. 4A. 2 is a schematic diagram showing the vicinity of the wide portion 22A immediately after heating in a microwave oven. FIG. 3 of a microwave oven container 1 according to a second embodiment. FIG. Fig. 7A is a view of a microwave oven container 1 according to a second embodiment, which corresponds to Fig. 4A. Fig. 7B is a cross-sectional view taken along line VIIb-VIIb in Fig. 7A. FIG. 11 is a plan view of a microwave oven container 1 according to a third embodiment. FIG. 11 is a schematic diagram showing an example of a microwave container 1 in a third embodiment immediately after being heated in a microwave oven. Fig. 10A is a plan view of the container body 2 according to the fourth embodiment. Fig. 10B is a cross-sectional view taken along line Xb-Xb in Fig. 10A. Fig. 11A is a plan view of seal bar 30. Fig. 11B is an enlarged view of region D in Fig. 11A.

The following describes the embodiments of the present invention. The various features shown in the embodiments below can be combined with each other. In addition, each feature can be an invention independently.

1. First embodiment
1 is a perspective view showing the entire microwave oven container of the present invention. The microwave oven container 1 shown in FIG.

The container body 2 is formed of a single layer or multi-layer resin material containing, for example, polypropylene, and is generally rectangular in plan view with rounded corners, concave with an opening 21 at the top, and configured to accommodate contents. The container body 2 is formed with a flange portion 22 that extends outward from the opening 21. The flange portion 22 is generally rectangular in plan view, and has wide portions 22A at the corners that are wider than other portions. Note that a plan view means that the microwave container 1 is viewed vertically from above.

A rib-shaped heat-sealed portion 23 is formed on the upper surface of the flange portion 22. The heat-sealed portion 23 is formed around the entire circumference of the flange portion 22. In other words, the heat-sealed portion 23 is formed on the upper surface of the flange portion 22 so as to surround the opening 21 of the container body 2.

The lid portion 3 is a film having an outer periphery approximately the same size as the outer periphery of the flange portion 22, and includes a base layer and a sealant layer. The base layer is made of a shrink film (heat-shrinkable film). The shrink film is a resin film that has been given heat shrinkability by, for example, performing a stretching process (uniaxial stretching or biaxial stretching), and the material that can be used may be a polyester resin such as polyethylene terephthalate, a polyamide resin such as nylon 6, or an olefin resin such as polyethylene or polypropylene. The lid portion 3 may have an outer layer, such as a printed layer, laminated on the outside of the base layer.

The sealant layer can be formed of a polyolefin resin such as polyethylene, polypropylene, ethylene-vinyl acetate copolymer, or ethylene-propylene block copolymer, and more specifically, unstretched polypropylene or linear low-density polyethylene can be used. More preferably, an easy-peel sealant made by mixing polyethylene and polypropylene in a specified ratio can be used. This makes it easier to peel the lid 3 from the container body 2.

Here, it is also possible to adjust the peel strength by changing the ratio of the resins to be mixed. For example, if the container body 2 is made of polypropylene, the adhesive strength can be increased by increasing the proportion of polypropylene in the mixed resin, and conversely, the peelability can be increased by decreasing the proportion of polypropylene.

After the contents (not shown) are placed in the container body 2, the lid 3 is heat-sealed (sealed) to the heat-sealing portion 23 to close the opening 21 of the container body 2. Note that FIG. 1 shows the lid 3 partially peeled off from one of the wide portions 22A of the flange portion 22.

In addition, the wide portion 22A of the flange portion 22, which is the starting point for peeling off the lid portion 3, has a steam exhaust portion 25 formed in an 'M' shaped pattern of the heat-sealed portion 23.

Figure 2A is a plan view of the container body 2, and Figure 2B is a side view of the container body 2. As shown in Figure 2A, in the 'M'-shaped steam exhaust section 25 formed as part of the heat-sealed section 23, a 'V' pattern (a V-shaped portion that opens outward) is formed in the center, and the lid opening section 24 is formed by inverted 'V' patterns (V-shaped portions that open inward) on both sides of the 'M'-shaped steam exhaust section 25. The right side of the steam exhaust section 25 is integrated with a part of the lid opening section 24 adjacent to the right side, and the left side of the steam exhaust section 25 is integrated with a part of the lid opening section 24 adjacent to the left side.

When the lid 3 is peeled off from the wide portion 22A where the lid opening portion 24 of the flange portion 22 is formed, stress is concentrated at the sharp tip of the inverted 'V' shaped pattern of the lid opening portion 24, which has the effect of making it easy to peel off the lid 3. Also, when heating in a microwave, the steam pressure generated inside the container body 2 concentrates stress on the sharp tip of the 'V' shaped pattern of the steam exhaust portion 25, which has the effect of easily breaking the heat fusion with the lid 3 when the steam pressure reaches a predetermined pressure.

Figure 3 is a cross-sectional view taken along line III-III in Figure 2A. As shown in Figure 3, the heat-sealing portion 23 is formed so that its upper surface is nearly horizontal, ensuring the reliability of heat fusion with the lid portion 3. The heat-sealing portion 23 is formed so that its height t1 relative to the flange portion 22 on the inner periphery is smaller than its height t2 relative to the flange portion 22 on the outer periphery.

A step 27 is formed on the side of the container body 2 along the circumferential direction, with the diameter decreasing downward. The side surface 28 on the opening 21 side of the step 27 is formed so as to be inclined outward from the vertical direction (indicated by the dotted line P in the figure). Such a step 27 on the side of the container body 2 functions as a stopper that prevents the upper container body 2 from being stored too deeply into the lower container body 2 when multiple container bodies 2 are stacked, and by inclining the side surface 28 on the opening 21 side of the step 27 outward from the vertical direction, it has the effect of allowing the upper container body 2 to be easily removed from the lower container body 2.

Figure 4A is a perspective view showing the lid opening portion 24 and the steam exhaust portion 25 formed in the wide portion 22A of the flange portion 22. Figure 4B is a cross-sectional view taken along line IVb-IVb in Figure 4A. As shown in Figure 4B, the steam exhaust portion 25 is inclined so that the tip located on the inside of the V-shaped portion is lowered toward the opening.

In this way, by inclining the steam exhaust section 25 so that the tip located inside the V-shape is lower toward the opening 21, the seal strength on the opening 21 side of the steam exhaust section 25 can be weakened, making it easier to release steam. Therefore, it becomes possible to reliably control the heat fusion of the lid section 3 to break when the steam reaches a predetermined pressure.

Here, a preferred embodiment will be described in which the tip of steam exhaust portion 25 located inside the V-shape is inclined so that it is lower toward opening 21. In FIG. 4B, height t7 of the outer edge of the end portion (left end in the figure) of steam exhaust portion 25 on the expanding side from flange portion 22 is preferably set to 1 mm to 5 mm, and more preferably 1 mm to 3 mm, in order to ensure the thickness of the components to be provided as a microwave oven container. More specifically, height t7 can be any of the following values, or a value within the range of these values: 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, for example, 1.37 mm.

The heat-sealed portion 23, which is connected to the lid-opening portion 24, is formed so that its height t8 from the flange portion 22 is higher than the height t7 of the left outer edge. The height t8 is set to be 0.1 mm to 1.0 mm higher than the height t7, and can be set to, for example, 1.5 mm.

The height t6 of the right outer edge is preferably 40% to 90% of the height t7 of the left outer edge. The height t5 of the right inner edge is preferably 5% to 60% of the height t7, and can be, for example, 0.8 mm. It is more preferable that the height t5 is lower than the height t6.

Furthermore, it is preferable that the difference (t8-t7) between the height t8 of the heat-sealed portion 23 from the flange portion 22 and the height t7 of the left outer edge is smaller than the difference (t7-t5) between the height t7 of the left outer edge and the height t5 of the right inner edge.

By doing this, the tip of the V-shaped portion of the steam exhaust section 25 is lower than the expanding end, and at the same time, the inner edge of the tip itself is lower than its outer edge, so that the steam exhaust section 25 can change from a portion with relatively strong sealing strength to a portion with weak sealing strength as it moves from the side farther from the opening 21 of the container body 2 to the side closer to it.

Figure 5 is a schematic diagram showing the vicinity of the wide portion 22A immediately after heating in a microwave oven. As described above, in the microwave oven container 1, the lid portion 3 is made of a shrink film, so when steam generated inside the container by heating is discharged, the lid portion 3 shrinks and warps upward. This prevents the lid portion 3 from blocking the steam exhaust portion 25, preventing the container from being deformed due to reduced pressure inside the container. Furthermore, since the center portion of the lid portion 3 shrinks after heating, the lid portion 3 does not wrinkle or sag, improving the appearance. Here, since the steam exhaust portion 25 is formed at a corner around the container body 2, the container body 2 is also pulled by the lid portion 3 and warps. Therefore, the angle of the V-shaped portion of the steam exhaust portion 25 becomes steep, and the steam exhaust portion 25 is less likely to be blocked. In addition, since the steam exhaust portion 25 and the lid opening portion 24 are formed in a rib shape that is convex on the upper surface of the flange portion 22, the container body 2 is warped, which has the effect of making it easier to form a steam exhaust port.

<2. Second embodiment>

The microwave container 1 according to the second embodiment differs from the first embodiment in that the flange portion 22 of the container body 2 is formed at an angle. The following will focus on the differences.

As shown in FIG. 6, the flange portion 22 of the container body 2 is formed with its extending end facing downward and inclined at an angle θ (for example, 6° to 10°). This inclination of the flange portion 22 is almost the same around the entire circumference of the flange portion 22.

As shown in FIG. 7B, the flange portion 22 is formed with its extending end facing downward and inclined at an angle θ, so that the height t3 of the steam exhaust portion 25 relative to the outer horizontal plane Q is formed lower than the height t4 relative to the outer horizontal plane Q. In this case, the upper surface of the heat-sealed portion 23 other than the steam exhaust portion 25 is formed to be horizontal.

In FIG. 7B, the height t7 from the flange portion 22 of the outer edge of the end (left end in the figure) on the expanding side of the steam exhaust portion 25 is preferably set to 1 mm to 5 mm, and more preferably 1 mm to 3 mm, in order to ensure the thickness of the components that should be provided in the microwave oven container. More specifically, the height t7 can be any value of 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, or 5 mm, or a value within these numerical ranges, and can be, for example, 1.2 mm.

Furthermore, the height t6 of the right outer edge is preferably 40% to 90% of the height t7 of the left outer edge. The height t5 of the right inner edge is preferably 5% to 50% of the height t7. More preferably, the height t5 is lower than the height t6. Furthermore, the length t9 from the right inner edge of the steam exhaust portion 25 to the end of the opening 21 is preferably 10 mm or less, more preferably 5 mm or less, and more preferably 0 mm, and can be any value of 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, or 0 mm, or a value within these numerical ranges (this also applies to the above-mentioned embodiment 1). A microwave oven container 1 having a flange portion 22 of this type can also achieve the same effects as the first embodiment.

<3. Third embodiment>
In the above-mentioned embodiment, the microwave oven container 1 has a container body 2 that is substantially rectangular in plan view with rounded corners and has wide portions 22A at the corners. However, the present invention is not limited to this embodiment. For example, as shown in Fig. 8, the container body 2 may have a substantially elliptical shape in plan view and have a pair of wide portions 22A and steam exhaust portions 25 at both ends in the major axis direction. In this case, steam is basically exhausted from one of the steam exhaust portions 25, but depending on the amount of steam and the size of the steam port, steam may be exhausted from both ends in the major axis direction and the lid portion 3 may be warped upward as shown in Fig. 9.

<4. Fourth embodiment>
In the above-described embodiment, the rib-like heat-sealed portion 23 is formed in a convex shape on the flange portion 22 of the container body 2, but the fourth embodiment differs from the above-described embodiment in that the flange portion 22 is formed flat. The following mainly describes the differences.

As shown in Figures 10A and 10B, in the container body 2 in the fourth embodiment, the flange portion 22 is formed flat, and the flange portion 22 has a heat-sealing portion 23. The seal bar 30 that performs heat-sealing between the container body 2 and the lid portion 3 has a protrusion 31 formed on the flat flange portion 22 for forming the heat-sealing portion 23. In this embodiment, the heat-sealing portion 23 is formed by increasing the pressure during heat-sealing with the protrusion 31 formed on the seal bar 30.

As shown in Figures 11A and 11B, the protrusion 31 is formed in an annular shape on the seal bar 30 so as to face the flange portion 22 of the container body 2 when the container body 2 and the lid portion 3 are thermally welded. At a position facing the wide portion 22A of the container body 2, an opening portion forming portion 32A for forming the lid opening portion 24 and an exhaust portion forming portion 32B for forming the steam exhaust portion 25 are formed.

The height T11 of the opening portion forming portion 32A is formed to be greater than the height T12 of the steam exhaust portion 25. With this configuration, the pressure exerted by the opening portion forming portion 32A on the flat flange portion 22 during heat sealing can be made greater than the pressure exerted by the exhaust portion forming portion 32B. This makes it possible to weaken the seal strength of the steam exhaust portion 25 relative to the lid opening portion 24, making it easier to release steam.

Even in a microwave container 1 with such a configuration, the same effect as the above embodiment can be obtained by configuring the lid portion 3 with a shrink film.

5. Other embodiments
Although the embodiments have been described above, the technical ideas of the present disclosure can also be adopted in the following aspects.
In the above embodiment, the height t7 of the steam exhaust portion 25 from the flange portion 22 on the expanding side is different from the height t6 of the opposite side, but this is not limited to this. The height of the steam exhaust portion 25 (and the integrated lid opening portion 24) from the flange portion 22 may be constant.
In the above embodiment, the steam exhaust portion 25 is formed in an 'M' shape, but the shape is not limited to this.
In the steam embodiment, the lid opening portion 24 and the steam exhaust portion 25 are integrally formed, but the present invention is not limited to this embodiment and each of them may be provided separately.
The number of steam exhaust portions is not limited to the above embodiment.

1: Microwave oven container 2: Container body 3: Lid portion 21: Opening 22: Flange portion 22A: Wide portion 23: Heat-sealed portion 24: Lid opening portion 25: Steam exhaust portion 27: Step 28: Side 30: Seal bar 31: Convex portion 32A: Opening portion forming portion 32B: Exhaust portion forming portion

Claims (4)

A film-like lid portion;
A container body having an opening at an upper portion, formed in a concave shape, and capable of accommodating contents;
A flange portion is provided so as to extend outward from the opening,
A fusion portion is formed on an upper surface of the flange portion to be fused to a rear surface of the lid portion,
The fusion unit includes a steam exhaust unit for exhausting steam generated from inside the container body,
The steam exhaust portion has a V-shaped portion that expands outward,
The lid portion includes a base layer and a sealant layer,
A microwave container (excluding those having a glue-depleted portion in a layer provided between the base layer and the sealant layer) in which the base layer is made of shrink film . 2. The microwave container of claim 1,
The flange portion is formed around the periphery of the container body,
The steam exhaust is formed at a corner of the periphery. A microwave container according to claim 1 or 2,
A microwave oven container, wherein the fused portion is formed as a convex rib on an upper surface side of the flange portion. 3. A microwave container according to claim 1 or 2,
A microwave oven container, wherein the flange portion is formed flat.