JP2022095105A - Packaging container - Google Patents

Abstract

To provide a packaging container that can smoothly discharge a steam produced in microwave oven heating out of the container and also prevent foreign matter from entering the container, and can be manufactured at low cost while hardly causing a defect in molding even with a thin synthetic resin-made sheet.SOLUTION: A packaging container comprises a container body 1 molded out of a synthetic resin-made sheet and a lid body 2 fitted to the container body 1, and is adaptive to a microwave oven. A top surface part 20 of the lid body 2 is provided with a hemispherical concave surface part 29 which is curved downward along a first direction and also curved downward along a second direction orthogonal to the first direction, the hemispherical concave surface part 29 is provided with two slits 30 formed by cutting the sheet linearly along the first direction at an interval in the second direction, and deformation suppression ribs 34 are provided outside each of the slits 30 of the hemispherical concave surface part 29 in the second direction, respectively.SELECTED DRAWING: Figure 1

Description

The present invention relates to a microwave oven-compatible packaging container capable of heating the contained food in a microwave oven while the lid is closed. In particular, regarding packaging containers suitable for storing cooked foods such as microwave oven noodles, steam generated when heated in a microwave oven is smoothly released, foreign substances such as insects are prevented from being mixed in, and the cost is low. The present invention relates to a packaging container that can be manufactured from a thin synthetic resin sheet.

In recent years, cooked soups and microwave oven noodles have been packaged in packaging containers and displayed at convenience stores and the like. These packaging containers are required to be able to smoothly release steam generated when heated in a microwave oven and to prevent foreign substances such as insects from being mixed in. Furthermore, since this type of container is mass-produced at one time, inexpensive and high-quality products are required.

As such a container, in Patent Document 1 below, a concave surface curved in only one direction is provided on the bottom surface of a concave portion provided on the top plate of the lid, and the concave surface is provided with a concave surface in the curved direction of the concave surface. The ones in which a plurality of notches along the line are provided at predetermined intervals are described.

However, in this container, since the concave surface is curved in only one direction, the vertical dimension of the wall surface of the concave portion is maximum at the central portion in the bending direction and minimum at both ends in the bending direction. When the vertical dimension of the wall surface of the concave portion changes along the bending direction in this way, the synthetic resin sheet is stretched small at both ends in the bending direction when molded with a thin synthetic resin sheet. On the other hand, it will be greatly stretched in the central part in the bending direction. Therefore, the shape of the wall surface of the recess is difficult to stabilize, and further, the shape of the bottom surface of the recess is also difficult to stabilize, and molding defects are likely to occur. Further, if the thickness of the synthetic resin sheet is increased in order to improve the molding defect, the container becomes expensive.

Japanese Patent No. 6752539

INDUSTRIAL APPLICABILITY According to the present invention, steam generated when heated in a microwave oven can be smoothly released to the outside of the container, foreign matter can be prevented from entering the inside of the container, and even a thin synthetic resin sheet causes molding defects. An object of the present invention is to provide a packaging container that is difficult and can be manufactured at low cost.

The packaging container according to the present invention is a microwave-compatible packaging container provided with a container body formed from a synthetic resin sheet and a lid that fits into the container body, and is a top of the lid. The surface portion is provided with a hemispherical concave surface portion that curves downward along the first direction and curves downward along a second direction orthogonal to the first direction, and the hemispherical concave surface portion has a sheet. Two slits cut linearly along the first direction are provided at intervals in the second direction, and each of the outside of each slit in the hemispherical concave surface in the second direction is in the first direction. Deformation-suppressing ribs, which are ridges that extend longer than the slit and project upward or downward, are provided along the ribs.

According to this configuration, since the hemispherical concave surface portion is curved in two directions, the first direction and the second direction, molding defects are less likely to occur, and the hemispherical concave surface portion can be stably molded. The hemispherical concave surface portion is provided with two slits along the first direction. Since the sheet is cut linearly, these slits are formed from the slits before heating by a microwave oven. It is possible to prevent foreign matter from entering the inside of the container. The hemispherical concave surface portion is divided into a valve portion between the two slits and a pair of base portions located on both sides of the valve portion in the second direction by the two slits. When the internal pressure of the container rises due to the steam generated inside the container during heating in a microwave oven, the hemispherical concave surface tries to deform upward due to the internal pressure, but the pair of bases has convex deformation suppression. Since the ribs are provided, the pair of base portions are relatively difficult to deform upward, and the valve portions are relatively easy to deform. Therefore, when the microwave oven is heated, the pair of base portions are not deformed upward, and only the valve portion is deformed upward. By deforming the valve portion so as to float upward with respect to the pair of base portions, a gap is formed between the valve portion and the pair of base portions. The gap becomes a steam discharge passage, and the steam inside the container is discharged to the outside of the container through the gap. Therefore, it is possible to prevent the lid from coming off the container body due to an excessive increase in the internal pressure.

In particular, it is preferable that the deformation suppressing rib is provided close to the slit in the central portion of the hemispherical concave surface portion in the first direction. The central portion of the base portion in the first direction is the most easily deformable portion. If the deformation suppressing rib is provided close to the slit in the central portion of the base portion in the first direction, the deformation of the base portion can be effectively suppressed during heating in the microwave oven, and only the valve portion can be reliably suppressed. It can be deformed upward.

As described above, since the slit is provided in the hemispherical concave surface portion, molding defects are less likely to occur even with a thin synthetic resin sheet, and the lid can be manufactured at low cost. At the time of display at the store, the valve portion between the slits is in a closed state without being deformed upward, so that foreign matter such as dust and insects can be prevented from entering. When heating in a microwave oven, the valve portion floats and opens with respect to the outer base portion, and a gap serving as a steam discharge passage is formed between the valve portion and the base portion, so that it occurs inside the container. The steam can be reliably discharged to the outside of the container through the gap, and the lid can be prevented from coming off.

The perspective view which shows the opening state of the packaging container in one Embodiment of this invention. Top view of the lid of the packaging container. Enlarged plan view of the main part of the lid. FIG. 3A is a cross-sectional view taken along the line AA of FIG. BB sectional view of FIG. The perspective view which shows the state of the same packaging container at the time of heating in a microwave oven. The cross-sectional view corresponding to FIG. 4 which shows the state of the lid body of the packaging container at the time of heating in a microwave oven. FIG. 5 is a cross-sectional view corresponding to FIG. 5 showing a state of the lid of the packaging container when heated in a microwave oven. FIG. 3 is an enlarged plan view of a main part of a lid of a packaging container according to another embodiment of the present invention. FIG. 3 is an enlarged plan view of a main part of a lid of a packaging container according to another embodiment of the present invention. A lid of a packaging container as a comparative example, (a) is an enlarged plan view of a main part, and (b) is a sectional view taken along the line CC of (a). As a comparative example, it is a lid of a packaging container, (a) is an enlarged plan view of a main part, and (b) is a DD sectional view of (a). The first evaluation method of a lid is shown, (a) is a perspective view, (b) is a sectional view. A second evaluation method of the lid is shown, (a) is an enlarged bottom view of a main part of the lid, and (b) is an EE sectional view of (a).

Hereinafter, the packaging container according to the embodiment of the present invention will be described with reference to the drawings. The container in the present embodiment is for storing various foods, and is a microwave oven-compatible container that can be heated in a microwave oven with the lid closed without opening. Examples of foods include cooked soups and microwave oven noodles.

As shown in FIG. 1, the container includes a container body 1 and a lid 2. Both the container body 1 and the lid 2 are formed from a synthetic resin sheet by various thermoforming (sheet molding) such as vacuum forming and compressed air forming. The shape of the container in a plan view is arbitrary, and may be a round shape, an oval shape, a substantially square shape, a substantially polygonal shape, or the like, but a round shape is preferable. The container body 1 has an opening that opens upward. The lid 2 fits into the container body 1 and closes the opening of the container body 1. For the fitting between the container main body 1 and the lid body 2, an inner fitting structure is preferable in which the lid fitting portion 23 of the lid body 2 is brought into contact with the main body fitting portion 13 of the container main body 1 to be fitted. By adopting the inner fitting structure, it is possible to improve the sealing property so that the contained soup or the like does not leak when the lid is closed. An inner / outer fitting structure having both inner fitting and outer fitting is also preferable. Further, if necessary, a middle plate (not shown) may be accommodated between the container body 1 and the lid body 2.

The container body 1 and the lid 2 (middle plate if necessary) are synthetic resins such as polyethylene terephthalate and polyolefins such as polystyrene, polypropylene and polyethylene, and have heat resistance that can be used in a microwave oven. Resin sheets can be used. Further, as these sheet materials, a sheet in which the above-mentioned synthetic resin is filled with an inorganic substance, a foamed sheet in which the above-mentioned synthetic resin is foamed, a stretched sheet obtained by stretching the above-mentioned sheet, or the like can be used. Among these, heat-resistant foamed styrene resin sheet using heat-resistant styrene resin with excellent heat resistance as polystyrene, sheet in which polypropylene with excellent heat resistance is filled with or foamed with an inorganic substance, polyethylene terephthalate polystyrene, A heat-resistant sheet made by stretching a sheet such as polypropylene or polyethylene to improve heat resistance can be used and heat-molded. In particular, among these sheets, when a sheet having excellent transparency is used for the lid 2, it is preferable because the contained food can be visually recognized. Among these sheets, transparent polyethylene terephthalate, polystyrene, polypropylene and the like are uniaxially stretched. Alternatively, the biaxially stretched stretched sheet is particularly preferable because it also has the heat resistance required for microwave oven heating. On the other hand, a container using a heat-resistant foam material for the container body 1 is suitable because it does not get hot even when held with bare hands when heated in a microwave oven and has excellent heat retention.

The container body 1 can contain jelly-like soup, noodles, sardines, etc. as an container in advance so that it can be heated and eaten as it is in a microwave oven. The container body 1 can be obtained by thermoforming a sheet using a heat-resistant resin material. Since the container body 1 is heated in a microwave oven for use, it is particularly preferable to use a foamed heat-resistant resin material, which is not hot when taken out of the microwave oven after heating and suppresses burns. It is possible to efficiently transmit the electromagnetic waves of the microwave oven to the contained foodstuff, and to perform heating uniformly and in a short time.

The container main body 1 has a bottom surface portion 10, a main body side surface portion 11 extending upward from the outer edge of the bottom surface portion 10, and a main body flange portion 12 extending outward from the upper end of the main body side surface portion 11. I have. It is preferable that the main body fitting portion 13 into which the lid fitting portion 23 of the lid body 2 is fitted inward is formed on the upper portion of the main body side surface portion 11. The main body fitting portion 13 may have a reverse taper shape that gradually reduces in diameter toward the upper side, or is provided with a convex portion that protrudes inward in a vertical shape or a forward taper shape instead of the reverse taper shape. It may be a configuration. The main body flange portion 12 may be provided with a knob portion (not shown) for facilitating the opening of the lid. Legs (not shown) having various shapes may be provided on the bottom surface 10. The container body 1 may be transparent, but is preferably a foam material having heat insulating properties.

The lid 2 is preferably transparent, and the food contained in the container can be visually recognized from the outside through the lid 2. As shown in FIGS. 1 and 2, the lid 2 has a top surface portion 20, a lid side surface portion 21 extending downward from the outer edge of the top surface portion 20, and a lid side surface portion 21 extending outward from the lower end. The horizontal plane portion 22 extending substantially horizontally, the lid fitting portion 23 extending upward from the outer edge of the horizontal plane portion 22, and the lid extending outward from the upper end of the lid fitting portion 23. It is provided with a flange portion 24. The lid fitting portion 23 may have a reverse taper shape in which the diameter is gradually reduced toward the upper side, or may have a vertical shape or a forward taper shape in which a convex portion protruding outward is provided. .. The lid flange portion 24 may be provided with a knob portion 25 for facilitating the opening of the lid. In order to prevent a so-called blocking phenomenon in which the lid bodies 2 are tightly fitted to each other and cannot be removed when a large number of lid bodies 2 are stacked on the lid side surface portion 21 at the time of collection, a convex portion for blocking prevention (not shown). Omitted) may be provided. The convex portion for preventing blocking is arranged so that its position is shifted for each lid 2.

The upper surface of the top surface portion 20 is the outer surface of the lid body 2, and the lower surface of the top surface portion 20 is the inner surface of the lid body 2. It is preferable to form a stacking convex portion 26 on the peripheral edge portion of the upper surface of the top surface portion 20 in order to prevent misalignment between the containers when the containers in the closed state are stacked up and down. The stacking convex portion 26 is projected upward. The top surface portion 20 has a circular shape, but the stacking convex portion 26 extends long along the circumferential direction of the peripheral edge portion of the top surface portion 20 and has an arc shape. The stacking convex portion 26 is formed in a predetermined angle range of the entire circumference of the peripheral edge portion of the top surface portion 20. The stacking convex portions 26 are formed in pairs. The pair of stacking protrusions 26 may be symmetrical to each other and may be formed at positions facing each other by 180 degrees. As shown in FIG. 2, the pair of stacking convex portions 26 may be arranged so as to face each other in the X direction (second direction). The strip 3 may be wound around the position between the pair of stacking protrusions 26. The band-shaped body 3 orbits the closed container in the vertical direction. Of the peripheral edges of the top surface portion 20, two regions in the Y direction (first direction) are provided in which the stacking convex portions 26 are not formed. Since the two regions in which the stacking convex portion 26 is not formed are arranged so as to face each other in the Y direction, the winding of the strip-shaped body 3 becomes easy. The strip 3 passes above the two regions of the peripheral edge of the top surface portion 20 where the stacking convex portion 26 is not formed. The strip 3 is wound around the container along the Y direction.

An annular ridge 27 protruding upward is formed on the top surface portion 20. The ridges 27 are arranged inside the pair of stacking ridges 26 in a plan view. The ridge 27 is provided eccentrically on one side in the Y direction, for example. A recess 28 for discharging steam is formed inside the ridge 27 in a plan view. The bottom surface of the recess 28 may be lower than the flat portion of the top surface portion. It is preferable to project the ridges 27 all around the opening edge of the recess 28 so as to surround the periphery of the recess 28. However, the ridge 27 may be cut out in a part of the entire circumference of the recess 28. Further, a groove (not shown) may be provided on the upper surface of the ridge 27 from the inner side surface to the outer side surface of the ridge 27 over the entire width of the ridge 27.

The bottom surface of the recess 28 is a hemispherical concave surface portion 29. The hemispherical concave surface portion 29 is circular in a plan view. FIG. 3 shows an enlarged view of the hemispherical concave surface portion 29. The hemispherical concave surface portion 29 is a curved surface curved downward along the X direction and the Y direction, which are two directions orthogonal to each other. FIG. 4 is a cross-sectional view taken along the line AA of FIG. 3, which is a cross-sectional view of the hemispherical concave surface portion 29 cut along the Y direction at the center of the hemispherical concave surface portion 29, and FIG. -B cross-sectional view is a cross-sectional view in which the hemispherical concave surface portion 29 is cut along the X direction at the center of the hemispherical concave surface portion 29. The hemispherical concave surface portion 29 is curved downward along the Y direction and is curved downward along the X direction. The degree of curvature of the hemispherical concave surface portion 29 in the Y direction (radius of curvature) and the degree of curvature of the hemispherical concave surface portion 29 in the X direction (radius of curvature) may be the same, but may be different from each other. The hemispherical concave surface portion 29 has a spherical shape curved in all directions.

Two slits 30 are formed in the hemispherical concave surface portion 29. The slit 30 penetrates the front and back of the sheet constituting the lid 2. The slit 30 is formed by cutting the sheet linearly. There may be various methods for cutting the sheet. For example, the sheet can be cut with a blade or the sheet can be cut by laser processing. When the slit 30 is formed by laser processing, the width of the slit 30 (the dimension of the slit 30 in the direction orthogonal to the length direction of the slit 30) is set narrow. If the width of the slit 30 becomes too wide, steam is discharged from the slit 30 to the outside of the container before the pressure inside the container reaches a predetermined pressure, the pressure rise inside the container becomes insufficient, and the heating time becomes long. The upward floating deformation of the valve portion 31, which will be described later, is less likely to occur. Therefore, the width of the slit 30 is set to such a width that the pressure rise can be maintained and the valve portion 31 can be floated and deformed, for example, 0.2 mm or less.

Two slits 30 are formed. The slit 30 is linear and extends along the Y direction. The two slits 30 are preferably parallel to each other and preferably have the same length. The slit 30 has a length that occupies most of the total length of the hemispherical concave surface portion 29 in the Y direction. Both ends 30a of the slit 30 are separated from both ends of the hemispherical concave surface portion 29 in the Y direction by a predetermined distance. The pair of slits 30 are arranged line-symmetrically with the center line (Y-direction center line 29a) extending in the Y direction of the hemispherical concave surface portion 29 as the axis of symmetry. The positions of both ends 30a of the slits 30 in the Y direction are the same for both slits 30, but may be slightly misaligned. The slit 30 is not limited to a linear shape in a plan view, and may have a wave shape, an arc shape, or the like, or may be divided in the middle.

By forming a pair of slits 30 in the hemispherical concave surface portion 29, the hemispherical concave surface portion 29 is formed on both sides of the valve portion 31 between the pair of slits 30 and the valve portion 31 in the X direction along the X direction. It is partitioned into a pair of located base portions 32. FIG. 3 shows two virtual lines 33 connecting the ends 30a of both slits 30 with a straight line by a two-dot chain line. The virtual line 33 extends in the X direction. The pair of slits 30 and the two virtual lines 33 define a rectangular valve portion 31 long in the Y direction. Since the valve portion 31 is a part of the hemispherical concave surface portion 29, the valve portion 31 is curved downward along the Y direction and downward along the X direction. The valve portion 31 is a curved surface having no unevenness over the entire surface, and is continuously curved in the Y direction without a step, and is continuously curved in the X direction without a step.

Deformation suppressing ribs 34 are formed on each of the pair of base portions 32 of the hemispherical concave surface portions 29. The pair of deformation suppressing ribs 34 are located outside each slit 30 in the X direction. The shape of the deformation suppressing rib 34 may be various. The deformation suppressing rib 34 extends along the Y direction. The deformation suppressing rib 34 may be divided in the middle. The deformation suppressing rib 34 extends across the center line (X-direction center line 29b) extending in the X direction of the hemispherical concave surface portion 29. It is preferable that the deformation suppressing rib 34 has a length that occupies most of the total length of the base portion 32 in the Y direction. The length of the deformation suppressing rib 34 in the Y direction is longer than the length of the slit 30 in the Y direction. The longitudinal end 34a of the deformation suppressing rib 34 is closer to the ridge 27 than the end 30a of the slit 30. It is preferable that both ends 34a of the deformation suppressing rib 34 in the longitudinal direction reach the ridges 27.

An example of the deformation suppressing rib 34 is shown in FIG. In the present embodiment, the deformation suppressing rib 34 is curved in a plan view, and specifically, in a plan view, it is curved toward the outside in the X direction, that is, toward the direction away from the slit 30. However, as shown in FIG. 9, the deformation suppressing rib 34 may be curved inward in the X direction in a plan view, that is, in a direction approaching the slit 30. Further, as shown in FIG. 10, the deformation suppressing rib 34 may extend linearly in the Y direction without being curved in a plan view. The pair of deformation suppressing ribs 34 are preferably arranged line-symmetrically with each other with the center line 29a in the Y direction as the axis of symmetry. Each deformation suppressing rib 34 preferably has a line-symmetrical shape with the center line 29b in the X direction as the axis of symmetry. Although one deformation suppressing rib 34 is provided in each base portion 32, a plurality of deformation suppressing ribs 34 may be provided. The base portion 32 may be provided with a deformation suppressing rib other than the deformation suppressing rib 34. Further, the deformation suppressing rib 34 may be a downward ridge protruding downward, or may be an upward ridge protruding upward. In the present embodiment, the deformation suppressing rib 34 is a downward ridge. The cross-sectional shape of the deformation suppressing rib 34 is arbitrary, and in the present embodiment, it may be rectangular, but may be semicircular or the like.

It is preferable that the deformation suppressing rib 34 is close to the slit 30 at the center line 29b in the X direction. When the distance L1 between the deformation suppressing rib 34 and the slit 30 and the distance L2 between the deformation suppressing rib 34 and the ridge 27 are compared on the center line 29b in the X direction, there is a relationship of L1 <L2. Is preferable. It is preferable that the deformation suppressing rib 34 is provided eccentrically toward the slit 30 in the center line 29b in the X direction.

A storage recess 40 may be separately formed on the upper surface of the top surface portion 20 at a position adjacent to the recess 28 in the Y direction. For example, various sachets can be accommodated in the accommodating recess 40. The pouch can contain, for example, a seasoning for seasoning the food contained in the container.

A substantially horizontal edging portion 36 may be provided on the outer edge of the main body flange portion 12 of the container main body 1 or the outer edge of the lid flange portion 24 of the lid body 2. On the outer edge side of the edging portion 36, a large number of extra-fine irregularities may be formed to reinforce the edging portion 36, and the fingers or the like may not be cut even if they are hit by the fingers or the like. This unevenness has a wavy shape when viewed from the front, and the directions of many peaks and valleys are formed short in the width direction on each side, and the direction connecting the corners and the center at the corners (radiation). It may be formed parallel to the direction). Further, the unevenness is preferably formed by knurled eyes such as flat knurled eyes and knurled knurled eyes, and further preferably formed by knurled eyes to prevent slipping. Ribs may be appropriately provided on the side surface portion 11 of the main body, the side surface portion 21 of the lid, and the like.

In the container configured as described above, since the hemispherical concave surface portion 29 is not a curved surface curved in only one direction but a spherical curved surface, the hemispherical concave surface portion 29 can be accurately formed. Therefore, even if the sheet constituting the lid 2 is made thin, molding defects are less likely to occur and the sheet can be manufactured at low cost.

Food is stored in the container body 1, and the lid 2 is put on the container body 1 in which the food is stored. In the closing operation, the lid fitting portion 23 of the lid body 2 is fitted to the main body fitting portion 13 of the container main body 1, and the opening of the container main body 1 is closed by the lid body 2, but after that, the strip-shaped body is closed. 3 may or may not be wrapped around the container. Since the slit 30 is not a hole but a sheet cut linearly, it is possible to prevent foreign matter from entering through the slit 30 in the state of being displayed at the store.

When the contained food is heated in the microwave, it can be put in the microwave as it is without opening. When heated in a microwave oven, steam is generated from the food and the pressure inside the container rises. The pressure acts on the entire inner surface of the lid 2 and acts on the entire hemispherical concave surface portion 29, but the pair of base portions 32 are each provided with deformation suppressing ribs 34, and the deformation suppressing ribs 34 provide the base portion. The rigidity of 32 is increased. On the other hand, the valve portion 31 is not provided with the deformation suppressing rib 34, and the valve portion 31 has a smooth curved surface without unevenness over the entire surface. Therefore, as shown in FIG. 6, the pair of base portions 32 of the hemispherical concave surface portions 29 are not deformed upward, and only the valve portion 31 is deformed so as to float upward. In particular, since the deformation suppressing rib 34 extends along the Y direction, the deformation of the base portion 32 upward is efficiently suppressed. Further, since both ends 24a of the deformation suppressing rib 34 reach the ridges 27 and the deformation suppressing ribs 34 are connected to the ridges 27 at the both ends 34a, the ridges 27 and the deformation suppressing ribs 34 cooperate with each other. To prevent the base portion 32 from being deformed. Further, since the deformation suppressing rib 34 is close to the slit 30 in the center line 29b in the X direction, the deformation suppressing rib 34 efficiently prevents the deformation of the portion of the base portion 32 where the distance from the ridge 27 is large.

The valve portion 31 receives the pressure in the container and shifts from the normal state of FIGS. 4 and 5 to the upward deformation state of FIGS. 7 and 8. As the valve portion 31 rises upward, a gap 50 is formed between the valve portion 31 and the base portions 32 on both sides thereof. That is, gaps 50 are formed on both sides of the valve portion 31 that has risen to the upper side, and the gaps 50 serve as steam discharge passages. Then, the steam in the container is discharged to the outside of the container through the gaps 50 formed on both sides of the valve portion 31.

Three types of lids 2 shown in FIGS. 3, 9 and 10 were manufactured, and these were designated as Examples 1 to 3. Further, the lid bodies 2 shown in FIGS. 11 and 12, respectively, were manufactured and used as Comparative Examples 1 and 2. Comparative Examples 1 and 2 are the same lids 2 as in Examples 1 to 3, and have two slits 30 formed in the hemispherical concave surface portion 29 in the same manner. Unlike this, the base portion 32 is not provided with the deformation suppressing rib 34. Comparative Examples 1 and 2 have the same configuration as that of Examples 1 to 3 except that the deformation suppressing rib 34 is not provided on the base portion 32. The base portion 32 of Comparative Example 1 has no unevenness and has a continuous smooth curved surface. The base portion 32 of Comparative Example 2 is provided with a step 60 instead of the deformation suppressing ribs 34 of Examples 1 to 3. The step 60 extends linearly along the Y direction, and both end portions 60a reach the ridge 27. The step 60 is a step in which the center side of the hemispherical concave surface portion 29 is on the lower side. The steam discharge performance was evaluated for Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, as described below, as the first evaluation method, verification of whether or not the lid comes off when the internal pressure is increased, and as the second evaluation method, the valve portion 31 is easily deformed upward. The verification was done.

<First evaluation method (evaluation test 1)>
As the first evaluation method, it was verified whether or not the lid came off when the internal pressure was increased. As shown in FIG. 13, a jig 100 corresponding to the container body 1 to which the lid 2 can be internally fitted was manufactured. A through hole 101 is provided in the center of the bottom surface of the jig 100. The lid 2 is internally fitted to the jig 100, and a pressure of a saturated vapor pressure of 0.15 MPa is applied to the internal space from the through hole 101 of the jig 100, and at that time, whether or not the lid 2 is disengaged from the jig 100. The test was conducted. When the lid 2 did not come off from the jig 100, the valve portion 31 was deformed upward to generate a gap 50 with the base portion 32, and the pressure was released from the gap 50 to the outside. Become. On the other hand, when the lid 2 is detached from the jig 100, the valve portion 31 is not smoothly deformed upward, and the pressure is not released to the outside. The case where the lid did not come off was evaluated as "OK", and the case where the lid came off was evaluated as "NG".

<Second evaluation method (evaluation test 2)>
As a second evaluation method, a test was conducted on the ease of deformation of the valve portion 31 upward as a verification of whether or not the vapor removal by the valve portion 31 is sufficiently performed when the internal pressure is increased. As shown in FIG. 14, the lid 2 is turned upside down and placed so that the upper surface of the lid 2 faces downward, and the valve portion 31 and the base portion 32 are pressed downward from above to 4 mm downward. The load per square millimeter (unit: N) when deformed was measured. The pressing points of the valve portion 31 and the base portion 32 are indicated by reference numerals 110 and 111, respectively, in FIG. The pressing point 110 of the valve portion 31 is the center of the hemispherical concave surface portion 29 and is the intersection of the Y-direction center line 29a and the X-direction center line 29b. The pressing point 111 of the base portion 32 is located on the center line 29b in the X direction of the deformation suppressing rib 34. In Comparative Examples 1 and 2, since the deformation suppressing rib 34 does not exist, the portion corresponding to the deformation suppressing rib 34 in FIG. 3 is set as the pressing point 111 in the base portion 32 on the center line 29b in the X direction.

<Evaluation result>
The evaluation results are shown in Table 1. As a result of the evaluation test 1, the lid did not come off in any of Examples 1 to 3. That is, in Examples 1 to 3, the valve portion 31 is smoothly deformed upward and the pressure is released to the outside. On the other hand, in Comparative Example 1, the lid came off. From this, in Comparative Example 1, the valve portion 31 did not smoothly deform upward. This is because the valve portion 31 is not only deformed upward, but the valve portion 31 and the base portion 32 are integrated, that is, a hemispherical concave surface, as shown by the alternate long and short dash line in FIG. 11 (b). It is presumed that the entire part 29 was deformed upward. When the entire hemispherical concave surface portion 29 is deformed upward in this way, the gap 50 does not occur between the valve portion 31 and the base portion 32, so that the pressure cannot escape to the outside and the lid 2 becomes a jig. It is considered to be out of 100. Similarly, the lid came off in Comparative Example 2. In the case of Comparative Example 2, the step 60 is provided in the base portion 32, but the effect is small, and the entire hemispherical concave surface portion 29 is deformed upward as in the case of Comparative Example 1, and the valve portion 31. It is presumed that the gap 50 did not occur between the base portion 32 and the base portion 32.

The results of the evaluation test 2 show that in both Examples 1 to 3 and Comparative Examples 1 and 2, the load for deforming the valve portion 31 is relatively small, whereas the load for deforming the base portion 32 is deformed. The load became relatively large. However, when the load of the valve portion 31 and the load of the base portion 32 are compared and the ratio of the load of the base portion 32 when the load of the valve portion 31 is 1 is seen, Examples 1 to 3 and Comparative Examples 1 and 2 There was a significant difference between and. That is, in Examples 1 to 3, the ratio was 1: 9.6 to 1:14, and the load of the base portion 32 was about 10 times larger than the load of the valve portion 31. On the other hand, in Comparative Example 1, the ratio was 1: 1.9, and the difference between the load of the valve portion 31 and the load of the base portion 32 was extremely small. In Examples 1 to 3, since the base portion 32 is provided with the deformation suppressing rib 34, the base portion 32 is extremely difficult to be deformed with respect to the valve portion 31, so that only the valve portion 31 is smoothly heated in the microwave oven. It is thought that it can be transformed. On the other hand, in Comparative Example 1, the load of the base portion 32 is as small as 1.9 times the load of the valve portion 31, and there is no large difference in the degree of deformation between the valve portion 31 and the base portion 32. Therefore, it is considered that only the valve portion 31 cannot be deformed during microwave oven heating, and the valve portion 31 and the base portion 32 are integrally deformed. Further, in Comparative Example 2, since the base portion 32 is provided with the step 60, the load of the base portion 32 is larger than that in Comparative Example 1. However, since the load of the base portion 32 is only 5.8 times the load of the valve portion 31, it is difficult for only the valve portion 31 to be smoothly deformed during microwave oven heating, and there is a gap between the valve portion 31 and the base portion 32. It is considered that the steam cannot be smoothly discharged to the outside because it is difficult to form the steam, or even if a gap is formed, the gap is small. It was found that when the ratio of the deformation load of the valve portion 31 and the base portion 32 was 1: (6 or more), only the valve portion 31 was deformed upward and the steam was smoothly discharged to the outside.

1 Container body 2 Lid 3 Strip 10 Bottom 11 Main body side surface 12 Main body flange 13 Main body fitting 20 Top surface 21 Lid side surface 22 Horizontal surface 23 Lid fitting 24 Lid flange 25 Grip 26 For stacking Convex 27 Convex 28 Concave 29 Hemispherical concave 29a Y-direction center line 29b X-direction center line 30 Slit 30a End 31 Valve 32 Base 33 Virtual line 34 Deformation suppression rib 34a End 36 Border 40 Storage recess 50 Gap 60 Step 60a End 100 Jig 101 Through hole 110 Pressing point 111 Pressing point

Claims (2)

A microwave-compatible packaging container provided with a container body molded from a synthetic resin sheet and a lid that fits into the container body.
The top surface of the lid is provided with a hemispherical concave surface that curves downward along the first direction and curves downward along the second direction orthogonal to the first direction.
The hemispherical concave surface is provided with two slits in which the sheet is linearly cut along the first direction at intervals in the second direction.
On the outside of each slit in the hemispherical concave portion in the second direction, deformation suppressing ribs, which are protrusions extending upward or downward and extending longer than the slit along the first direction, are provided. Container for. The packaging container according to claim 1, wherein the deformation suppressing rib is provided close to the slit in the central portion of the hemispherical concave surface portion in the first direction.

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