Packaging containers

Abstract

The present invention provides a packaging container that improves load-bearing capacity from above, even when the sheet thickness is reduced, and prevents the lower container from being crushed or deformed when stacked in multiple layers. [Solution] A packaging container 100 is thermoformed from a synthetic resin sheet and comprises a container body 1 and a lid 2 that closes the opening of the container body 1. The lid 2 comprises a top surface portion 50 and a lid side portion extending downward from the peripheral edge of the top surface portion 50. The lid side portion 51 is provided with a plurality of high vertical ribs 81 extending in the vertical direction and having the same inward and outward height and circumferential width, and a plurality of low vertical ribs 82 extending in the vertical direction and having the same inward and outward height and circumferential width. The high vertical ribs 81 and low vertical ribs 82 have the same circumferential width, and the high vertical ribs 81 have a higher inward and outward height than the low vertical ribs 82.

Description

Technical Field

[0001] The present invention relates to a packaging container including a container body and a lid for closing an opening of the container body.

Background Art

[0002] Packaging containers formed by various thermoforming (sheet forming) such as vacuum forming or pressure air forming from a synthetic resin sheet are versatile because they are suitable for containing various foods in the field of food packaging, have excellent characteristics such as being light, inexpensive, easy to process, and capable of mass production.

[0003] The following Patent Document 1 describes a packaging container in which vertical concavo-convex ribs r, r' are formed over the entire circumference including the outer peripheral edge of the bottom surface 10 or the upper surface 20 from the side wall portions 11, 21 of the container body 1 and the lid body 2 formed of a synthetic resin sheet.

[0004] In stores such as supermarkets and convenience stores, packaging containers containing food are stacked in multiple stages vertically and displayed in the sales floor. According to the packaging container described in Patent Document 1, since it is reinforced by the concavo-convex ribs r, r', it will not be crushed or deformation will be suppressed even when stacked in multiple stages vertically.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, due to rising raw material prices and environmental concerns, there has been a demand for reducing plastic usage, specifically for developing packaging containers that use thinner sheets while maintaining the same strength as conventional containers. However, in thin-walled packaging containers made by molding thinner sheets, the rigidity and strength are reduced due to the thinning process. Therefore, the uneven ribs r and r' described in Patent Document 1 are insufficient for reinforcement, and stacking multiple containers vertically may result in them collapsing or deformation.

[0007] Generally, increasing the height of the ribs increases the second moment of area and the section modulus. In other words, it can increase the overall rigidity and strength of the packaging container. However, in vacuum forming and pressure forming, shapes with narrow openings and high heights result in molding defects, making high ribs unsuitable shapes. In particular, if the height of the ribs formed around the entire circumference of the side wall, such as the ribs r and r' of the packaging container described in Patent Document 1, is increased, the sheet may be excessively stretched and thinned during thermoforming, potentially reducing its strength. Also, if a thin sheet is used, there is a risk of holes forming during molding.

[0008] Increasing the width of the rib grooves can also increase the second moment of area and the section modulus. In other words, it can increase the overall rigidity and strength of the packaging container. However, when comparing the case where the width of the rib grooves is increased and the case where the height of the rib grooves is increased by the same ratio, as is clear from the second moment of area and section modulus, increasing the width of the rib grooves has a lower effect on increasing rigidity and strength. Therefore, in thin-walled packaging containers, even if the rigidity and strength are increased by increasing the width of the rib grooves, it may not reach the same level of rigidity and strength as conventional containers.

[0009] Therefore, the object of the present invention is to provide a packaging container that can be stacked in multiple layers vertically without being crushed or deforming. [Means for solving the problem]

[0010] The packaging container according to the present invention is a packaging container thermoformed from a synthetic resin sheet, comprising a container body and a lid that closes the opening of the container body, wherein the lid comprises a top surface and a lid side surface extending downward from the peripheral edge of the top surface, and the lid side surface is provided with a plurality of high longitudinal ribs extending in the vertical direction and having the same inward and outward height and circumferential width, and a plurality of low longitudinal ribs extending in the vertical direction and having the same inward and outward height and circumferential width, wherein the high longitudinal ribs and low longitudinal ribs have the same circumferential width, and the high longitudinal ribs have a greater inward and outward height than the low longitudinal ribs.

[0011] In this configuration, the high longitudinal ribs are made of relatively thin synthetic resin sheets formed by thermoforming, while the low longitudinal ribs are made of relatively thick synthetic resin sheets formed by thermoforming. Therefore, the decrease in rigidity and strength of the high longitudinal ribs due to the thinning of the synthetic resin sheet by thermoforming can be compensated for by the relatively thicker low longitudinal ribs. In addition, the high longitudinal ribs have a higher height of irregularities in the inward and outward directions on the side surface of the lid than the low longitudinal ribs, resulting in a larger second moment of area and section modulus, thus providing an effect of increasing rigidity and strength. As a result, a packaging container is provided that will not collapse and will not deform even when thin-walled packaging containers are stacked in multiple layers vertically.

[0012] In particular, it is preferable that at least one of multiple high longitudinal ribs and at least one of multiple low longitudinal ribs are alternately arranged in the circumferential direction of the side surface of the lid. By arranging it in this way, a balance of rigidity and strength in the vertical direction can be achieved throughout the circumferential direction.

[0013] In particular, it is preferable that the high longitudinal ribs are formed by a pair of outward-facing ribs that protrude outward from the side surface of the lid and are adjacent to each other, and a single inward-facing rib that protrudes inward from the side surface of the lid between the pair of outward-facing ribs, so that they protrude outward and inward from the side surface of the lid, respectively, and that the low longitudinal ribs are formed by a pair of outward-facing ribs that protrude outward from the side surface of the lid.

[0014] In particular, the top surface portion has a smooth central portion extending from the center of the top surface portion and a peripheral portion with irregularities surrounding the central portion of the top surface portion, and it is preferable that the peripheral portion of the top surface portion is provided with extension ribs that extend continuously from the upper end of the high vertical ribs. By providing such extension ribs, the area around the boundary between the peripheral portion of the top surface portion and the side portion of the lid is reinforced, and deformation of the lid due to load from above is suppressed. Therefore, even if a thin sheet is used for the lid, the necessary strength can be easily secured.

[0015] In particular, it is preferable to provide crossbeam ribs connecting adjacent extension ribs around the top surface. By providing such crossbeam ribs, the top surface is reinforced, and deformation of the lid due to upward load can be suppressed. Therefore, even if a thin sheet is used for the lid, the necessary strength can be easily ensured.

[0016] In particular, it is preferable that the lid has at least one corner in its plan view, and that at least one high longitudinal rib and an extension rib are provided in close proximity to the corner. This effectively reinforces the corner of the lid and prevents deformation of the corner due to upward load. Therefore, even if a thin sheet is used for the lid, the required strength can be easily ensured.

[0017] In particular, it is preferable that the top surface periphery is provided with corner-adjacent ribs that are connected to the extension ribs and extend toward at least one corner. With this configuration, the required strength can be more reliably ensured even when a thin sheet is used for the lid.

[0018] In particular, it is preferable to provide transverse ribs around the top surface that are connected to the corner-adjacent ribs and traverse the top surface periphery in an inward-outward direction. With this configuration, even if a thin sheet is used for the lid, the required strength can be more reliably ensured.

[0019] In particular, in the corner portion, it is preferable that a gate-shaped rib is provided which is connected to the transverse rib and extends across the top surface portion and the lid-side surface portions on both sides of the top surface portion. According to this configuration, the corner portion of the lid can be more effectively reinforced, and the load-bearing capacity in the vertical direction can be improved. Incidentally, the transverse rib, the corner-adjacent rib, and the gate-shaped rib may be concave ribs recessed toward the inner surface side or convex ribs protruding toward the outer surface side.

Advantages of the Invention

[0020] According to the packaging container of the present invention, even if the thickness of the sheet is made thinner than before, the necessary strength can be ensured, and deformation of the lower container when the containers are stacked vertically can be suppressed.

Brief Description of the Drawings

[0021] [Figure 1] Perspective view of the packaging container in the closed state in one embodiment of the present invention as viewed from the lid side. [Figure 2] Plan view showing the closed state of the packaging container. [Figure 3] Perspective view showing the open state of the packaging container. [Figure 4] Plan view showing the open state of the packaging container. [Figure 5] Enlarged perspective view of the main part showing the lid of the packaging container. [Figure 6] Enlarged plan view of the main part showing the lid of the packaging container from above. [Figure 7] Cross-sectional view taken along line VII-VII of FIG. 2 showing the closed state of the packaging container. [Figure 8] Enlarged perspective view of the main part showing the inner surface of the lid of the packaging container. [Figure 9] Cross-sectional view taken along line IX-IX of FIG. 8. [Figure 10] View showing a modification corresponding to FIG. 9.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, a packaging container according to one embodiment of the present invention will be described with reference to Figures 1 to 10. The packaging container 100 in this embodiment is a container with a lid that can hold various contents, and various foods are particularly suitable as the contents.

[0023] In the following description of the embodiments, the vertically upward direction when the container is placed with its bottom facing downwards is defined as "up," "upward," or "upper side," and the opposite vertically downward direction is defined as "down," "downward," or "lower side." Furthermore, the internal and external directions are defined as the direction towards the center of the container being "inside," "inward," or "inside," and the opposite direction being "outside," "outward," or "outside."

[0024] As shown in Figure 1, the packaging container 100 comprises a container body 1 with an opening at the top, and a lid 2 that is detachably attached to the container body 1 from above to close the opening at the top of the container body 1. In this embodiment, the container body 1 and the lid 2 are connected via a foldable hinge portion 3, which will be described later. In other words, this embodiment is a lid-integrated type in which the container body 1 and the lid 2 are integrally formed, and a hinge portion 3 is provided between the container body 1 and the lid 2 to connect them. Therefore, the lid 2 can rotate up and down around a horizontal axis relative to the container body 1 by the hinge portion 3. However, the container body 1 and the lid 2 may be formed as separate parts.

[0025] Both the container body 1 and the lid 2 are formed from synthetic resin sheets by various thermoforming (sheet molding) methods such as vacuum forming and pressure forming. Various synthetic resin sheets can be used for the container body 1 and the lid 2. These synthetic resin sheets are composed of, for example, polyester resins such as polyethylene terephthalate, styrene resins such as polystyrene, and polyolefin resins such as polypropylene. Stretched sheets obtained by uniaxially or biaxially stretching these sheets are also preferable. Among these sheets, using a sheet with excellent transparency for the lid 2 is preferable because it allows the contained food to be visually inspected.

[0026] The shape of the container in plan view can vary; for example, it may be a polygonal shape such as a rectangle, or a circular, semicircular, or elliptical shape. The container body 1 and the lid 2 correspond to each other in plan view. In this embodiment, a container with a roughly rectangular shape in plan view, specifically a roughly rectangular shape in plan view, will be described as an example.

[0027] <Container body 1> As shown in Figures 1, 3, and 4, the container body 1 in this embodiment is substantially rectangular in plan view, specifically, substantially rectangular in plan view. The container body 1 comprises a bottom portion 10, a body side portion 11 that rises upward while expanding outward from the peripheral edge (outer edge) of the bottom portion 10, and a body flange portion 12 that extends outward from the upper end (outer edge) of the body side portion 11. The bottom portion 10 is rectangular and has four sides 10a (two long sides and two short sides) and four corner portions 10b. The four sides 10a have two (a pair) long sides that extend in a direction parallel to the hinge portion 3 and two (a pair) short sides that extend in a direction perpendicular to the hinge portion 3. Corner portions 10b are provided between adjacent long sides and short sides. The shape of each corner portion 10b may vary; it may be a rounded corner curved in an arc shape when viewed from above, or a chamfered corner cut at an angle when viewed from above. The upper surface of the bottom portion 10 may be provided with protrusions or ridges as described later, or with partitions. Leg portions 13 may be provided projecting downwards from the lower surface of the bottom portion 10. The overall length of the main body side portion 11 in the vertical direction is approximately the same as the overall length of the lid side portion 51 in the vertical direction, as described later.

[0028] As shown in Figures 3 and 4, in this embodiment, the bottom surface 10 is provided with two types of ribs: narrow ribs 30 and wide ribs 31, which extend in a direction perpendicular to the hinge portion 3 (i.e., the long side) (i.e., the direction of the short side) and protrude upward. The narrow ribs 30 are formed to be narrower in the direction of the hinge portion 3 (long side) than the wide ribs 31, and extend along the entire length of the short side of the bottom surface 10, and are approximately parallel to each other at approximately equal intervals in the direction of the long side of the bottom surface 10. The wide ribs 31 are formed to be wider in the direction of the hinge portion 3 (long side) than the narrow ribs 30, and extend between adjacent narrow ribs 30. In this embodiment, five narrow ribs 30 are provided, and four wide ribs 31 are provided between the narrow ribs 30. The narrow ribs 30 and wide ribs 31 are arranged to be connected in a mesh-like manner. Furthermore, the narrow ribs 30 have a greater protrusion height (vertical height) than the wide ribs 31. In addition, the narrow ribs 30 located in the center of the long side have a greater protrusion height in the direction of the short side than the protrusion heights at both ends (see Figure 3 in particular). This setting of protrusion height improves the compressive strength of the bottom surface 10 when a load is applied inward to the side surface 11 of the main body.

[0029] Multiple recesses 15 are provided on the lower surface of the bottom portion 10, extending upward. These multiple recesses 15 are provided at predetermined intervals along a pair of long sides of the bottom portion 10. In this embodiment, the recesses 15 are formed at positions that connect to both ends of the three central narrow ribs 30 out of the five narrow ribs 30. The lower surface of the bottom portion 10 may also be provided with stacking recesses 32 to prevent horizontal misalignment of containers when they are stacked vertically in a closed state (hereinafter referred to as multi-layer stacking). In this embodiment, stacking recesses 32 are provided at two locations on the short side of the bottom portion 10.

[0030] The stacking recess 32 is recessed upward from the lower surface of the bottom portion 10. The stacking recess 32 is provided between the lower end of the main body side portion 11 and the narrow rib 30 located closest to the shortest side of the bottom portion 10. When stacking multiple containers, the top surface protrusion 55 of the top portion 50 fits into the stacking recess 32, effectively preventing misalignment of containers, especially in the short-side direction. At the boundary between the stacking recess 32 and the narrow rib 30, a bottom surface protrusion 33 is provided, extending downward from the lower surface of the bottom portion 10. When stacking multiple containers, the bottom surface protrusion 33 abuts against the top surface protrusion 55 and the bottom portion 10 in the long-side direction, effectively preventing misalignment of containers, especially in the long-side direction. The bottom surface protrusion 33 is formed so that its protrusion height from the lower surface of the bottom portion 10 is lower than that of the leg portion 13. A recessed rib 34 extending along the direction of the short side may be provided on the lower surface of the bottom protrusion 33. The recessed rib 34 has the effect of increasing the rigidity of the bottom protrusion 33 and preventing deformation.

[0031] The main body side portion 11 is provided with outward-facing ribs 16 that extend outward along substantially the entire length of the main body side portion 11 in the vertical direction (in other words, from the lower end to the upper end of the main body side portion 11), and inward-facing ribs 17 that extend inward between adjacent outward-facing ribs 16, extending along substantially the entire length of the main body side portion 11 in the vertical direction. Multiple outward-facing ribs 16 and inward-facing ribs 17 are provided in the circumferential direction. These outward-facing ribs 16 and inward-facing ribs 17 ensure the strength of the main body side portion 11 against stacking.

[0032] The circumferential width and inward / outward depth (projection height) of the outward-facing rib 16 and the inward-facing rib 17 may be constant over substantially the entire length in the vertical direction, or they may vary in the vertical direction. Furthermore, the circumferential width and inward / outward depth (projection height) of the outward-facing rib 16 and the inward-facing rib 17 may be the same or different. In this embodiment, the circumferential widths of the outward-facing rib 16 and the inward-facing rib 17 are different, with the outward-facing rib 16 being slightly narrower than the inward-facing rib 17. Also, the vertical lengths (formation positions) of the outward-facing rib 16 and the inward-facing rib 17 may be the same or different. In this embodiment, the lower end positions of the outward-facing rib 16 and the inward-facing rib 17 are different, with the inward-facing rib 17 being slightly higher than the outward-facing rib 16. Furthermore, the circumferential spacing between the outward-facing rib 16 and the inward-facing rib 17 may be constant over the entire circumference, or it may vary in the circumferential direction. Furthermore, the cross-sectional shapes of the outward-facing rib 16 and the inward-facing rib 17 may be various shapes such as polygonal shapes like rectangles, triangular shapes, semicircular shapes, or semi-elliptical shapes. In this embodiment, the cross-sectional shape of the outward-facing rib 16 is triangular, and a groove 16a is formed along the ridge. This groove 16a further strengthens the strength of the main body side portion 11 against stacking.

[0033] The outward-facing ribs 16 may extend to the periphery of the bottom surface 10. For example, the outward-facing ribs 16 provided on the long side may extend to the end of the wide rib 31 provided on the bottom surface 10, and the outward-facing ribs 16 provided on the short side may extend to the end of the narrow rib 30 provided on the bottom surface 10. In this case, the portion of the outward-facing rib 16 that extends to the periphery of the bottom surface 10 (i.e., the portion that protrudes downward from the periphery of the bottom surface 10) may function as a leg portion 13.

[0034] The inward-facing rib 17 may be tapered so as to become slightly narrower from the lower end to the upper end of the main body side portion 11. The inward-facing rib 17 may be connected to a narrow rib 30 provided on the bottom portion 10 via its lower end. The inward-facing rib 17 may be provided with an outward-facing concave groove portion 18. In this embodiment, the groove portion 18 is provided in the center of the width direction of the inward-facing rib 17 provided on the long side portion, extending from the main body side portion 11 to the periphery of the bottom portion 10. This groove portion 18 may extend to the narrow rib 30 connected to the inward-facing rib 17 (see Figures 3 and 4 in particular).

[0035] The inward-facing rib 17 may be provided adjacent to the corner portion 10b. The inward-facing rib 17 may be formed on both sides of the corner portion 10b, or on one side. In this embodiment, the inward-facing rib 17 is formed on both sides of the corner portion 10b. The upper surface of this inward-facing rib 17 can be an effective surface against loads from above. In addition, a slit rib 19 extending vertically and projecting inward (or outward) may be formed near the corner portion 10b of the inward-facing rib 17, in other words, between the inward-facing rib 17 and the corner portion 10b. In this embodiment, two slit ribs 19 are provided between each of the inward-facing rib 17 and the corner portion 10b.

[0036] The inward-facing rib 17 may be provided between the lower end of the outward-facing rib 16 and the peripheral portion of the bottom surface 10. In this embodiment, the inward-facing rib 17 provided between the outward-facing rib 16 and the peripheral portion of the bottom surface 10 is formed to be continuous with the lower end of the outward-facing rib 16 via a stepped surface 28.

[0037] The main body flange portion 12 is provided around the entire circumference of the upper end of the main body side portion 11. The main body flange portion 12 has a main body flange upper surface portion 20 extending outward from the upper end of the main body side portion 11, a main body skirt portion 21 extending downward (hanging down) from the outer edge of the main body flange upper surface portion 20, and a main body edging portion 22 extending outward from the lower end of the main body skirt portion 21.

[0038] The upper surface portion 20 of the main flange may have various shapes; it may be curved upwards, flat, or have decorative features such as indentations. The height of the upper surface portion 20 of the main flange may be constant around the entire circumference or may vary in the circumferential direction. The width of the upper surface portion 20 of the main flange may also be constant around the entire circumference or may vary in the circumferential direction.

[0039] In this embodiment, the upper surface 20 of the main flange has stepped surfaces 20a formed at the center of each side portion 10a in the long and short directions, with steps separating them. Of these stepped surfaces 20a, the stepped surface 20a provided at the center in the long direction is formed by lowering one step at both ends in the long direction. The stepped surface 20a provided at the center in the short direction is formed by lowering one step at the end opposite to the hinge portion 3 and lowering two steps in a step-like manner at the end on the hinge portion 3 side. When the lid 2 is closed, the stepped surfaces 20a fit into the stepped surface 60a of the lid flange portion 52 (the upper surface 60 of the lid flange), preventing misalignment of the lid 2 relative to the container body 1.

[0040] Furthermore, the upper flange portion 20 of the main body has flat surfaces 27 that widen in a planar manner at each corner portion 10b. The flat surfaces 27 receive the load acting on the lid 2 from above when the lid 2 (its flat surface 69) is superimposed on it in the closed state, and the flat surfaces 27 receive the load acting on the lid 2 from above. When the lid 2 is closed, the flat surfaces 27 are positioned below and opposite to the flat surface 69 of the lid 2, and as the lid 2 is pressed down from above, the flat surfaces 27 are superimposed on the flat surface 69 of the lid 2 and make planar contact.

[0041] The main body skirt portion 21 is provided with a main body fitting portion 23 that fits with the lid 2 (and its lid fitting portion 63) to maintain a closed lid state. In this embodiment, the main body fitting portion 23 is provided at the two corner portions 10b opposite to the hinge portion 3 side, and at the ends of the side portions 10a that are continuous with these two corner portions 10b. The main body fitting portion 23 protrudes outward at the corner portions 10b and the side portions 10a. At the corner portions 10b, the main body fitting portion 23 consists of a circumferentially extending convex ridge, and at the ends of the side portions 10a adjacent to the corner portions 10b, it consists of a plurality of convex portions arranged at predetermined intervals along the side portion 10a. The main body fitting portion 23 fits with the lid fitting portion 63 when the lid 2 is placed over the container body 1, maintaining a closed lid state.

[0042] Furthermore, the main body fitting portion 23 may be appropriately provided on the corner portion 10b or the edge portion 10a, and the position, number, and shape of the main body fitting portion 23 may vary. Also, the main body fitting portion 23 may be recessed inward, and the lid fitting portion 63 of the lid 2, which will be described later, may protrude inward. In addition, the corner portion 10b of the main body skirt portion 21 may be provided with a main body corner rib 24, which consists of a vertical groove that extends in the vertical direction and protrudes inward. The main body corner rib 24 can suppress deformation and cracking of the main body flange portion 12 when a downward force is applied, such as when fitting. The main body skirt portion 21 is also provided with a main body engaging portion 29 that engages with the lid 2 (the lid engaging portion 77) to prevent misalignment between the container body 1 and the lid 2 when the lid is closed. In this embodiment, the main body engaging portions 29 are recessed inward on both sides of the long side on the hinge portion 3 side, separated from each other. The main body engagement portion 29 consists of a groove that extends linearly along the long side, and a protrusion is provided at the bottom of the groove, extending along the long side to divide the inside of the groove into upper and lower sections.

[0043] The main body rim portion 22 is the outer edge of the main body flange portion 12 and extends substantially horizontally outward. The main body rim portion 22 is provided with a hinge portion 3 that connects to the lid 2 along one of its long sides, and various shapes of main body handles 25 are provided at both corner portions 10b of the long side on the opposite side of the hinge portion 3 (opening side), protruding outward more than the rest of the main body rim portion 22. The main body handles 25 may or may not be substantially horizontal. The main body handles 25 may be provided as appropriate at the corner portions 10b or the sides 10a, and the position, number, and shape of the main body handles 25 may vary. In addition, the main body rim portion 22 may be provided with stepped edge-rolling prevention ribs 26 to prevent the rim from rolling up due to the rise in internal pressure inside the container. In this embodiment, stepped edge-curling prevention ribs 26 are provided on the central part of the long side of the main body edging portion 22 on the side opposite to the hinge portion 3 (opening side) and on the central parts of each of the two short sides. When the lid is closed, these edge-curling prevention ribs 26 face the edge-curling prevention ribs 66 of the lid edging portion 62, which will be described later. Since the curling of the edges is particularly likely to occur on the long side, the edge-curling prevention ribs 26 may be provided only on the long side.

[0044] Furthermore, at the upper end of the main body side portion 11, in other words, at the boundary between the main body side portion 11 and the main body flange portion 12 (the upper surface portion 20 of the main body flange), a blocking prevention projection 14 may be provided to prevent the so-called blocking phenomenon, in which the container bodies 1 become stuck together and cannot be separated when many container bodies 1 are stacked together during collection. This blocking prevention projection 14 may be provided at multiple locations spaced apart in the circumferential direction.

[0045] <Lid 2> The lid 2 is formed in a plan view shape corresponding to the container body 1, and in this embodiment, it is approximately rectangular in plan view, specifically, approximately rectangular in plan view. The lid 2 comprises a top surface portion 50, a lid side portion 51 that expands downward from the peripheral edge (outer edge) of the top surface portion 50, and a lid flange portion 52 that extends outward from the lower end (outer edge) of the lid side portion 51. The top surface portion 50 is rectangular and has four sides 50a (two long sides and two short sides) and four corner portions 50b. The four sides 50a have two (a pair) long sides that extend in a direction parallel to the hinge portion 3 and two (a pair) short sides that extend in a direction perpendicular to the hinge portion 3. Corner portions 50b are provided between adjacent long sides and short sides. The shape of each corner portion 50b may vary; it may be a rounded corner curved in an arc shape when viewed from above, or a chamfered corner cut at an angle when viewed from above.

[0046] As mentioned above, the total length of the lid side portion 51 in the vertical direction is approximately the same as the total length of the main body side portion 11 in the vertical direction. Therefore, as shown in Figure 3, when the container is placed on a horizontal flat surface such as a table with the lid opened 180°, the bottom portion 10 of the container body 1 and the top portion 50 of the lid 2 can be placed parallel to the flat surface. In addition, the container body 1 of another packaging container 100 can be placed on top of the lid 2 in this open state. By stacking the lids 2 and container bodies 1 of multiple packaging containers 100 with the lids opened 180°, packaging can be done efficiently in a limited workspace.

[0047] The top surface portion 50 has a smooth surface portion (central top surface portion) 70 that extends in the center of the top surface portion, and a reinforcing surface portion (peripheral top surface portion) 71 that surrounds the periphery of the smooth surface portion 70. The smooth surface portion 70 is a region consisting of a flat surface that constitutes the central part of the top surface portion 50. The smooth surface portion 70 is a region consisting of a smooth surface (a surface without irregularities such as ribs). The smooth surface portion 70 is preferably a horizontal surface, but it may also be an inclined surface. The reinforcing surface portion 71 constitutes the periphery of the top surface portion 50 and is a frame-shaped region that encircles the outside of the smooth surface portion 70 in a plan view. The reinforcing surface portion 71 is a region in which irregularities such as ribs that protrude in the vertical direction are provided in order to increase the strength of the lid 2; in other words, it is a region that has been processed to have irregularities in the vertical direction. In other words, by providing a smooth surface portion 70 and a reinforcing surface portion 71 on the top surface portion 50 of the lid 2, it is possible to achieve both excellent visibility and the effect of preventing deformation of the top surface of the lid of the lower container when the containers are stacked one above the other in a closed state.

[0048] Between the smooth surface portion 70 and the reinforcing surface portion 71, there is a rectangular annular circumferential rib 72 that protrudes downward and encircles the space between the smooth surface portion 70 and the reinforcing surface portion 71. This circumferential rib 72 divides the top surface portion 50 into the central smooth surface portion 70 and the peripheral reinforcing surface portion 71. Furthermore, this circumferential rib 72 constitutes a frame surrounding the top surface portion 50 of the lid 2, thereby increasing the strength of the top surface portion 50 of the lid 2. The width in the inward and outward directions and the depth in the vertical direction (protrusion height) of the circumferential rib 72 may be constant around the entire circumference or may vary in the circumferential direction. In addition, the cross-sectional shape of the circumferential rib 72 may be various shapes such as a polygonal shape such as a rectangle, a triangular shape, a semicircular shape, or a semielliptical shape. It is preferable that the reinforcing surface portion 71 is higher in height than the smooth surface portion 70 via the circumferential rib 72.

[0049] A tapered surface may or may not be provided at the boundary between the top surface 50 and the side surface 51 of the lid (the peripheral edge of the top surface 50 and the upper end of the side surface 51 of the lid).

[0050] The peripheral edge (reinforcement surface 71) of the top surface 50 may be provided with top surface protrusions 55 for stacking, in order to prevent horizontal misalignment of containers when stacking multiple layers. In this embodiment, top surface protrusions 55 are provided at two locations on the short side of the top surface 50. The top surface protrusions 55 are projected upward from the upper surface of the reinforcement surface 71. The top surface protrusions 55 are provided in both the inward and outward directions of the reinforcement surface 71. The side surface of the protrusion located on the short side of the top surface 50 is formed flush and continuous with the lid side surface 51, and the outward-facing rib 56 is extended from the lid side surface 51 to the upper end of the protrusion side of the top surface protrusion 55. The top protrusion 55 is formed in a position corresponding to the stacking recess 32 of the bottom portion 10 in a plan view. When stacking multiple containers, it fits into the stacking recess 32 of the bottom portion 10 and comes into contact with the bottom protrusion 33 of the bottom portion 10, preventing horizontal displacement of the containers. The top protrusion 55 has outward-facing ribs 56 extending from the lid side portion 51 to the upper end of the protrusion side of the top protrusion 55, which is located on the short side of the top portion 50. This provides high rigidity against horizontal forces and prevents horizontal displacement of the containers when stacking multiple containers. Furthermore, since the top protrusion 55 is not provided on the long side of the top portion 50, labels can be attached, for example, around the long side portion 50a, which is easily visible when displayed. In other words, as in this embodiment, since the top surface protrusion 55 for stacking is provided only on the short side of the top surface 50, even if a label is attached to a highly visible position on the lid 2, such as extending from the long side of the top surface 50 to the long side of the lid side surface 51, the label will not interfere with the top surface protrusion 55 and the stacking recess 32. Therefore, when stacking multiple units, the top surface protrusion 55 of the top surface 50 and the stacking recess 32 can be reliably fitted together, preventing misalignment during stacking.

[0051] The side surface 51 of the lid is provided with a concave wall surface 51a that is offset inward for a predetermined length in the central part of the long side opposite to the hinge 3 (opening side). The concave wall surface 51a is formed with a step between it and the end wall surfaces 51b located at both ends in the direction of the long side, and in this embodiment, it is positioned to correspond to the stepped surface 60a of the upper surface 60 of the lid flange. The long side of the side surface 51 of the lid that is provided with the hinge 3 has high rigidity due to the hinge 3, so by providing the concave wall surface 51a on the long side of the side surface 51 of the lid that is opposite to the hinge 3, high rigidity is ensured and a balance of rigidity with the long side on the side where the hinge 3 is provided is achieved.

[0052] Figure 7 is a cross-sectional view showing the closed state of the packaging container, and is a cross-sectional view taken along line VII-VII in Figure 2. As shown in Figure 7, the concave wall surface 51a extends to a position where its lower end protrudes below the upper surface 60 of the lid flange portion 52, and is positioned inside the container body 1 in the closed state, protruding below the upper surface 20 of the body flange. This allows, for example, condensation adhering to the inner surface of the lid side portion 51 to be actively guided to the inner surface of the body side portion 11 when it flows down as water droplets. Therefore, it is possible to prevent water droplets from flowing outward from the overlapping portion between the upper surface 20 of the body flange portion 12 and the upper surface 60 of the lid flange portion 52, thereby preventing the outside of the packaging container 100 from getting wet.

[0053] The lid side portion 51 is provided with multiple outward-facing ribs 56 that extend vertically and project outward from the lid side portion 51, and multiple inward-facing ribs 57 that extend vertically and project inward between adjacent outward-facing ribs, each arranged circumferentially. Figure 8 is an enlarged perspective view of the main part showing the inner surface of the lid of the packaging container, and Figure 9 is a cross-sectional view taken along line IX-IX in Figure 8. In this embodiment, the outward-facing ribs 56 extend and project outward along substantially the entire length of the lid side portion 51 in the vertical direction (in other words, from the upper end to the lower end of the lid side portion 51). The inward-facing ribs 57 extend and project inward between adjacent outward-facing ribs 56 along substantially the entire length of the lid side portion 51 in the vertical direction (in the vertical direction). These outward-facing ribs 56 and inward-facing ribs 57 ensure the strength of the lid side portion 51 against stacking of containers.

[0054] The circumferential width and inward / outward depth (projection height) of the outward-facing rib 56 and the inward-facing rib 57 may be constant over substantially the entire length in the vertical direction, or they may vary in the vertical direction. Furthermore, the circumferential width and inward / outward depth (projection height) of the outward-facing rib 56 and the inward-facing rib 57 may be the same or different. In this embodiment, the circumferential widths of the outward-facing rib 56 and the inward-facing rib 57 are different, with the outward-facing rib 56 being wider than the inward-facing rib 57. The projection height ho of the outward-facing rib 56 from the side surface 51 of the lid and the projection height hi of the inward-facing rib 57 from the side surface 51 of the lid are also different, with the projection height ho of the outward-facing rib 56 being higher than the projection height hi of the inward-facing rib 57. Furthermore, the vertical lengths (formation positions) of the outward-facing rib 56 and the inward-facing rib 57 may be the same or different. In this embodiment, the lower end positions of the outward-facing rib 56 and the inward-facing rib 57 differ on the concave wall surface 51a and the rest of the lid side surface 51. On the concave wall surface 51a, the lower end positions of the outward-facing rib 56 and the inward-facing rib 57 are the same, while in the rest of the lid, the lower end position of the inward-facing rib 57 is slightly higher than that of the outward-facing rib 56.

[0055] Furthermore, the circumferential spacing between the outward-facing ribs 56 and the inward-facing ribs 57 may be constant over the entire circumference, or it may vary in the circumferential direction. As can be clearly seen by referring to Figure 9, in this embodiment, a plurality of outward-facing ribs 56 are provided continuously on the side surface 51 of the lid at equal intervals from one another. The ribs are arranged such that there are portions where inward-facing ribs 57 are arranged between adjacent outward-facing ribs 56, and portions where inward-facing ribs 57 are not arranged between adjacent outward-facing ribs 56.

[0056] The side surface 51 of the lid has multiple high longitudinal ribs 81 and multiple low longitudinal ribs 82 formed by the arrangement of outward-facing ribs 56 and inward-facing ribs 57. The multiple high longitudinal ribs 81 extend in the vertical direction of the side surface 51 of the lid and have the same inward-outward height and circumferential width. In this embodiment, the side surface of the high longitudinal rib 81 is formed by a pair of outward-facing ribs 56 that protrude outward from the side surface 51 and are adjacent to each other, and a single inward-facing rib 57 that protrudes inward from the side surface 51 between the pair of outward-facing ribs 56, thus protruding outward and inward from the side surface 51 of the lid. The multiple low longitudinal ribs 82 extend in the vertical direction of the side surface 51 of the lid and have the same inward-outward height and circumferential width. In this embodiment, the low longitudinal rib 82 is formed on its side by a pair of outward-facing ribs 56 that protrude outward from the lid side portion 51, and there are no inward-facing ribs 57 positioned between the pair of outward-facing ribs 56. The high longitudinal rib 81 and the low longitudinal rib 82 have the same circumferential width L, and the inward-outward height (ho + hi) of the high longitudinal rib 81 is higher than the inward-outward height (ho) of the low longitudinal rib 82.

[0057] The high longitudinal ribs 81 of the lid side portion 51, which have both outward-facing ribs 56 and inward-facing ribs 57, are stretched outward and inward during thermoforming, resulting in a relatively thin synthetic resin sheet. On the other hand, the low longitudinal ribs 82, which have only outward-facing ribs 56, are stretched only outward, resulting in a relatively thick synthetic resin sheet.

[0058] In this embodiment, both high longitudinal ribs 81 and low longitudinal ribs 82 are provided on the side surface 51 of the lid. This allows the low rigidity and strength of the high longitudinal ribs 81, which are relatively thin due to the thickness of the synthetic resin sheet, to be compensated for by the low longitudinal ribs 82, which are made of a relatively thick synthetic resin sheet. Furthermore, the high longitudinal ribs 81, which have both outward-facing ribs 56 and inward-facing ribs 57, have a higher total height of outward and inward irregularities (ho+hi) on the side surface 51 of the lid than the height of irregularities (ho) of the low longitudinal ribs 82, which have only outward-facing ribs 56. Therefore, the high longitudinal ribs 81 have a large second moment of area and section modulus, which can increase the rigidity and strength of the side surface 51 of the lid, and can compensate for the low rigidity and strength of the high longitudinal ribs 81, which are relatively thin due to the thickness of the synthetic resin sheet. As a result, even when the packaging containers 100 containing food are stacked in multiple layers, the lids 2 are less likely to deform, and a stable multi-layer stacking state can be ensured.

[0059] The high longitudinal ribs 81 and low longitudinal ribs 82 are arranged alternately in the circumferential direction of the lid side portion 51, with at least one of the multiple high longitudinal ribs 81 and at least one of the multiple low longitudinal ribs 82. As shown in Figure 9, in this embodiment, the lid side portion 51 has an arrangement in which three high longitudinal ribs 81 and two low longitudinal ribs 82 are arranged alternately in the circumferential direction, but is not limited to this. For example, there may be an arrangement in which two high longitudinal ribs 81 and two low longitudinal ribs 82 are arranged alternately, or an arrangement in which one high longitudinal rib 81 and one low longitudinal rib 82 are arranged alternately, or an arrangement in which three high longitudinal ribs 81 and three low longitudinal ribs 82 are arranged alternately.

[0060] The cross-sectional shapes of the outward-facing rib 56 and the inward-facing rib 57 may be various shapes such as polygonal shapes like rectangles, triangular shapes, semicircular shapes, or semi-elliptical shapes. In this embodiment, the cross-sectional shape of the outward-facing rib 56 is semicircular, and the cross-sectional shape of the inward-facing rib 57 is rectangular. The outward-facing rib 56 has a recessed groove 56a formed along the vertical direction. As shown in Figure 9, in this embodiment, the inward-facing rib 57 is provided between a pair of adjacent outward-facing ribs 56 via a step formed by the lid side surface portion 51, but this step may not be present. Figure 10 shows one modified example corresponding to Figure 9. In the modified example shown in Figure 10, there is no step formed by the lid side surface portion 51 between the outward-facing rib 56 and the inward-facing rib 57, and the outward-facing rib 56 and the inward-facing rib 57 are formed in an arc shape so that they connect smoothly.

[0061] Furthermore, the outward-facing rib 56 or the inward-facing rib 57 may extend to the peripheral edge (reinforcement surface 71) of the top surface 50 located above the side surface 51 of the lid. In this embodiment, the inward-facing rib 57, which is a part of the high vertical rib 81, extends to the reinforcement surface 71. In other words, the inward-facing rib 57 (high vertical rib 81) is provided with an extension rib 58 that extends from the side surface 51 of the lid (beyond the side surface 51 of the lid) to the reinforcement surface 71 of the top surface 50. That is, the reinforcement surface 71 is provided with an extension rib 58 that extends continuously from the upper end of the inward-facing rib 17 (high vertical rib 81). The extension rib 58 extends along the entire length of the reinforcement surface 71 of the top surface 50 in the inward-outward direction (from the outer end to the inner end of the reinforcement surface 71 of the top surface 50). The extended rib 58 reinforces the area around the boundary between the reinforcing surface 71 and the lid side surface 51, allowing it to more effectively withstand upward loads and suppress deformation of the lid 2.

[0062] As can be clearly seen by referring to Figure 6 along with Figure 1, the reinforcing surface 71 is provided with transverse beam ribs 59 that extend laterally along the circumferential rib 72 and connect adjacent extension ribs 58. Figure 6 is an enlarged plan view of the main part of the lid of the packaging container, shown from above. These transverse beam ribs 59 further reinforce the reinforcing surface 71, suppressing deformation of the lid 2 due to loads from above. Figure 8 is a perspective view of the main part of the lid side surface 51, seen from inside the lid 2. As shown in Figure 8, the inward rib 57 is formed to protrude inward from the lid side surface 51, and the extension rib 58 and transverse beam rib 59 are formed to protrude inward from the reinforcing surface 71. These extension rib 58 and transverse beam rib 59 can further increase the strength of the top surface 50 and corner portions 50b of the lid 2. The width and vertical depth (protrusion height) of the extension rib 58 and transverse beam rib 59 may be constant or may vary in the longitudinal direction. Furthermore, the cross-sectional shapes of the extension rib 58 and the crossbeam rib 59 may be various shapes such as polygonal shapes like rectangles, triangular shapes, semicircular shapes, or semi-elliptical shapes. In this embodiment, the cross-sectional shapes of the extension rib 58 and the crossbeam rib 59 are the same rectangular shape as the inward-facing rib 57.

[0063] Furthermore, in this embodiment, in order to further increase the strength of the top surface portion 50 of the lid 2, a connecting rib 73 is provided on the circumferential rib 72 located inside the reinforcing surface portion 71, so as to connect to the reinforcing surface portion 71 (its inner end). This connecting rib 73 extends along the entire length of the circumferential rib 72 in the inward and outward directions (from the outer end to the inner end of the circumferential rib 72), and in this embodiment, it has a roughly rectangular shape in plan view, specifically a roughly square shape in plan view. The circumferential width and vertical projection height of the connecting rib 73 may be constant along the entire length in the inward and outward directions, or they may vary in the inward and outward directions. For example, the circumferential width of the connecting rib 73 may be approximately the same as the distance between adjacent inward ribs 57, and the vertical projection height of the connecting rib 73 may be approximately the same as the height of the smooth surface portion 70 or the reinforcing surface portion 71 (that is, the connecting rib 73 may project upward to near the height of the smooth surface portion 70 or the reinforcing surface portion 71). Furthermore, the cross-sectional shape of the connecting rib 73 may be various shapes such as a polygonal shape like a rectangle, a triangular shape, a semicircular shape, or a semielliptical shape.

[0064] Furthermore, in this embodiment, in order to further increase the strength of the top surface 50 and corner portions 50b of the lid 2, as can be clearly seen by referring to Figures 5 and 6 along with Figure 1, a corner adjacent rib 74 is provided on the reinforcing surface 71, connected to the extension rib 58, extending substantially perpendicularly (i.e., in the direction of the edge) from near the center (in the inward and outward direction) of the extension rib 58 toward the corner portion and projecting downward, and a transverse rib 75 is provided, connected to the corner adjacent rib 74 extended at the corner portion, extending so as to traverse the reinforcing surface 71 in the inward and outward direction and projecting downward. In this embodiment, one corner adjacent rib 74 is extended (connected) from the extension rib 58 toward the reinforcing surface 71, but multiple corner adjacent ribs 74 may be provided. Also, the width in the inward and outward direction and the depth in the vertical direction of the corner adjacent rib 74 may be constant over the entire length in the circumferential direction, or they may vary in the circumferential direction. Furthermore, the cross-sectional shape of the corner-adjacent rib 74 may be various shapes such as a polygonal shape like a rectangle, a triangular shape, a semicircular shape, or a semielliptical shape. In this embodiment, each corner of the reinforcing surface 71 is provided with two transverse ribs 75 extending (connected) from the corner-adjacent ribs 74 provided on both sides of the corner, and one transverse rib 75 provided near the center of the two transverse ribs 75, approximately parallel to them (a total of three transverse ribs 75). However, the number of transverse ribs provided at each corner of the reinforcing surface 71 may be one, two, or four or more, and may be omitted depending on the strength. Furthermore, the circumferential width and vertical depth of the transverse rib 75 may be constant over the entire length in the inward and outward directions, or may vary in the inward and outward directions. Furthermore, the cross-sectional shape of the transverse rib 75 may be various shapes such as a polygonal shape like a rectangle, a triangular shape, a semicircular shape, or a semielliptical shape.

[0065] Furthermore, in this embodiment, in order to further increase the strength of the top surface 50 of the lid 2, particularly its corner portion 50b, a gate-shaped rib 76 may be provided at the corner portion 50b, connected to the transverse rib 75, and extending downward from the top surface 50 and the side portions 51 of the lid on both sides that constitute the corner portion 50b. The lower end of the gate-shaped rib 76 may or may not extend to the lower end of the side portion 51 of the lid. In addition, various shapes of ribs or other irregularities may be provided on the outside of the gate-shaped rib 76 for reinforcement. When such a gate-shaped rib 76 is provided, the corner portion 50b of the lid 2 can be reinforced more effectively, and the load-bearing capacity in the vertical direction can be improved.

[0066] In this embodiment, the reinforcing extension ribs 58, corner adjacent ribs 74, transverse ribs 75, and gate-shaped ribs 76 are all formed as concave ribs that are recessed downward (inward) when viewed from the outside of the container, but any or all of them may be formed as convex ribs that protrude upward (outward). Also, in this embodiment, the reinforcing extension ribs 58, corner adjacent ribs 74, transverse ribs 75, and gate-shaped ribs 76 are arranged on both sides of the corner portion in a manner approximately symmetrical with respect to a plane that extends inward and outward through the center of the corner portion, but they do not have to be arranged approximately symmetrically.

[0067] At the lower end of the side surface portion 51 of the lid, in other words, at the boundary between the side surface portion 51 of the lid and the flange portion 52 (the upper surface portion 60 of the flange of the lid), a blocking prevention projection 54 may be provided to prevent the phenomenon (blocking phenomenon) in which the lids 2 become tightly fitted together and cannot be separated when the lids 2 are placed on top of each other. In this embodiment, the blocking prevention projection 54 is provided at the lower end of the side surface portion 51 of the lid adjacent to the four corner portions (the lower end of the gate-shaped rib 76).

[0068] The shape of the lid flange portion 52 in plan view corresponds to the main body flange portion 12. The lid flange portion 52 is provided around the entire circumference of the lower end of the lid side portion 51. The lid flange portion 52 has a lid flange upper surface portion 60 extending outward from the lower end of the lid side portion 51, a lid skirt portion 61 extending downward (hanging) from the outer edge of the lid flange upper surface portion 60, and a lid edging portion 62 extending outward from the lower end of the lid skirt portion 61.

[0069] The upper surface 60 of the lid flange may be a flat surface. The height of the upper surface 60 of the lid flange may be constant around the entire circumference or may vary in the circumferential direction. The width of the upper surface 60 of the lid flange may also be constant around the entire circumference or may vary in the circumferential direction. The upper surface 60 of the lid flange may or may not have a tapered surface at the boundary with the side surface 51 of the lid (the lower end of the side surface 51 of the lid). The upper surface 60 of the lid flange may be a horizontal surface or an inclined surface.

[0070] In this embodiment, the upper surface 60 of the lid flange has stepped surfaces 60a formed at the center of the long and short sides of the edge portion 50a, with steps separating them. Of these stepped surfaces 60a, the stepped surface 60a provided at the center of the long side is formed by a step down at both ends in the long side. The stepped surface 60a provided at the center of the short side is formed by a step down at the end opposite to the hinge portion 3 and a step down in two steps at the end on the hinge portion 3 side. The stepped surfaces 60a fit into the stepped surface 20a of the main body flange portion 12 (the upper surface 20 of the main body flange) when the lid 2 is closed, preventing misalignment of the lid 2 relative to the container body 1.

[0071] Furthermore, the upper surface 60 of the lid flange has flat surfaces 69 that widen in a planar manner at each corner 50b. When the lid is closed, the flat surfaces 69 overlap with the flat surface 27 of the upper surface 20 of the main body flange and make planar contact, transmitting the load acting on the lid 2 to the container body 1 (and its flat surface 27). The flat surfaces 69 provided at each of the pair of corner 50b of the lid 2 that are furthest from the hinge 3 are positioned opposite each other on the flat surface 27 of the container body 1, and then pressed down from above, applying downward force, so that they overlap with the flat surface 27 of the container body 1. Because the flat surfaces 69 widen in a planar manner, it is possible to place your fingers on them when closing the lid 2, making it easier to apply downward force and close the lid 2.

[0072] The lid skirt portion 61 is provided with a lid fitting portion 63 that works in cooperation with the main body fitting portion 23 to maintain the closed lid state. In this embodiment, the lid fitting portion 63 is provided at the two corner portions 50b opposite to the hinge portion 3 side and at the end of the edge portion 50a that is continuous with these two corner portions 50b. The lid fitting portion 63 protrudes outward at the corner portions 50b and the edge portion 50a. At the corner portions 50b, the lid fitting portion 63 consists of a groove extending in the circumferential direction, and at the end of the edge portion 50a adjacent to the corner portion 50b, it consists of a plurality of recesses arranged at predetermined intervals along the edge portion 50a. The lid fitting portion 63 fits with the main body fitting portion 23 when the lid 2 is placed over the container body 1, maintaining the closed lid state.

[0073] Furthermore, the lid fitting portion 63 may be appropriately provided at corners, edges, etc., and the position, number, shape, etc. of the lid fitting portion 63 may vary. Also, the lid fitting portion 63 may protrude inward, and the main body fitting portion 23 of the container body 1 described above may be recessed inward. In addition, the corner portion of the lid skirt portion 61 may be provided with a lid corner rib 64 consisting of a vertical groove that extends vertically and protrudes inward. The lid corner rib 64 can suppress deformation and cracking of the lid flange portion 52 when a downward force is applied, such as when fitting. In addition, the lid skirt portion 61 is provided with a lid engaging portion 77 that engages with the container body 1 (the main body engaging portion 29) to prevent misalignment between the container body 1 and the lid 2 when the lid is closed. In this embodiment, the lid engaging portions 77 are provided on both sides in the long side direction on the hinge portion 3 side, spaced apart from each other and protruding inward. Each lid engagement portion 77 consists of two parallel convex grooves that extend linearly along the longer side.

[0074] The shape of the lid flange portion 52 can vary. In this embodiment, the lid flange portion 52 (or the lid skirt portion 61, etc.) is fitted to the outside of the main body flange portion 12 (or the main body skirt portion 21, etc.). However, it may also be an internal fitting configuration where the lid flange portion 52 (or the lid skirt portion 61, etc.) is fitted to the inside of the main body flange portion 12 (or the main body skirt portion 21, etc.), or an internal and external fitting configuration where it fits to both the outside and the inside. Furthermore, without using a fitting configuration, the main body flange portion 12 and the lid flange portion 52 may simply overlap vertically to close the opening, and the closed state may be maintained by various adhesive tapes or rubber bands. Therefore, the main body flange portion 12 and the lid flange portion 52 may consist only of flat surfaces (for example, a substantially horizontal surface).

[0075] The lid rim portion 62 is the outer edge of the lid flange portion 52 and extends substantially horizontally outward. A hinge portion 3 is provided along one of the long sides of the lid rim portion 62, connecting it to the container body 1. Various shapes of lid handles 65 are provided at both corners of the long side opposite to the hinge portion 3 (the opening side), protruding outward more than the rest of the lid rim portion 62. The lid handles 65 may or may not be substantially horizontal. The lid handles 65 may be provided as appropriate at corners, edges, etc., and the position, number, shape, etc., of the lid handles 65 may vary. In addition, the lid rim portion 62 may be provided with stepped edge-lifting prevention ribs 66 to prevent the edge from lifting due to the rise in internal pressure inside the container.

[0076] In this embodiment, a lid bottom surface portion 67 extending outward from the lower end of the lid skirt portion 61 and a lid vertical surface portion 68 rising upward while slightly widening outward from the peripheral edge of the lid bottom surface portion 67 are provided between the lid skirt portion 61 and the lid edging portion 62, and the lid edging portion 62 is provided extending outward from the upper end of this lid vertical surface portion 68. This lid vertical surface portion 68 allows the main body edging portion 22 and the lid edging portion 62 to be spaced apart in the vertical direction when the lid is closed. In addition, in this embodiment, stepped edge-curling prevention ribs 66 are provided on the central part of the long side of the lid bottom surface portion 67 on the side opposite to the hinge portion 3 (opening side) and on the central parts of each of the two short sides. When the lid is closed, these edge-curling prevention ribs 66 face the edge-curling prevention ribs 26 of the main body edging portion 22. Furthermore, since the curling of the edges is particularly likely to occur on the longer sides, the edge curling prevention ribs 66 may be provided only on the longer sides.

[0077] The upper and lower surfaces of the main body edging portion 22 and the lid edging portion 62 may be given a textured surface by applying fine indentations or embossing. By forming these indentations, the main body edging portion 22 and the lid edging portion 62 are reinforced, and it is possible to prevent damage from fingers or other objects touching them. When viewed magnified from the front, these indentations form a wave shape, with numerous peaks and valleys formed in the direction of the width along each side, and parallel to the direction connecting the corner and the center (radial direction) at the corners. Furthermore, these indentations may be formed by knurling, such as flat knurling or diagonal knurling, and it is preferable to form them with diagonal knurling to make them less slippery.

[0078] At the lower end of the side surface portion 51 of the lid, in other words, at the boundary between the side surface portion 51 of the lid and the flange portion 52 (the upper surface portion 60 of the flange of the lid), a blocking prevention projection 54 may be provided to prevent the so-called blocking phenomenon, in which the lids 2 become stuck together and cannot be separated when many lids 2 are stacked on top of each other during collection. Multiple blocking prevention projections 54 may be provided at intervals in the circumferential direction.

[0079] The container body 1 and lid 2 are formed by so-called sheet molding. Sheet molding methods include, for example, vacuum forming, pressure forming, vacuum pressure forming, double-sided vacuum forming, and hot plate forming, and in any case, they are formed by thermoforming a synthetic resin sheet. The synthetic resin sheet is made of, for example, styrene-based resins such as polyethylene terephthalate and polystyrene, or olefin-based resins such as polypropylene and polyethylene, and transparent sheets are used in particular for the lid 2. Transparent sheets may also be used for the container body 1. Furthermore, stretched sheets, which are obtained by appropriately stretching these sheets, are a more preferable sheet material because they can improve heat resistance and strength while maintaining transparency.

[0080] Furthermore, in addition to these materials, the container body 1 can also be made of non-transparent materials, such as sheets made by filling the aforementioned synthetic resin with inorganic substances, or foamed sheets made by foaming these sheet materials. It may also be a foamed polystyrene sheet made by foaming polystyrene, or a heat-resistant foamed styrene resin sheet using a styrene-based resin with improved heat resistance, such as polyphenylene ether, which has excellent heat resistance as polystyrene. Furthermore, a laminated sheet can be used, which is a foamed sheet with printing applied to it, or a plain resin film laminated on one or both sides. If the container body 1 is formed from a foamed sheet, the container can be made lighter. If the lid 2 is formed from a non-foamed sheet, the strength of the lid 2 can be easily ensured, resulting in excellent load-bearing capacity when stacked, and making it easier to thin the wall thickness.

[0081] As described above, in the packaging container 100 according to this embodiment, the lid side surface 51 is provided with a plurality of outward-facing ribs 56 that extend vertically and protrude outward, and a plurality of inward-facing ribs 57 that extend vertically between adjacent outward-facing ribs 56 and protrude inward, each in the circumferential direction. The lid side surface 51 is provided with a plurality of high vertical ribs 81 that extend vertically and have the same inward-outward height and circumferential width, and a plurality of low vertical ribs 82 that extend vertically and have the same inward-outward height and circumferential width. The high vertical ribs 81 and low vertical ribs 82 have the same circumferential width, and the high vertical ribs 81 have a higher inward-outward height than the low vertical ribs 82.

[0082] The high longitudinal ribs 81 on the side surface 51 of the lid are made of a relatively thin synthetic resin sheet produced by thermoforming, while the low longitudinal ribs 82 are made of a relatively thick synthetic resin sheet produced by thermoforming. Therefore, the decrease in rigidity and strength of the high longitudinal ribs 81 due to the thinning of the synthetic resin sheet by thermoforming can be compensated for by the relatively thicker low longitudinal ribs 82. In addition, the high longitudinal ribs 81 have a higher height of irregularities in the inward and outward directions of the side surface 51 of the lid than the low longitudinal ribs 82, resulting in a larger second moment of area and section modulus, thus providing an effect of increasing rigidity and strength. Therefore, even when stacking multiple thinned packaging containers 100 vertically, the lid 2 will not be crushed and deformation will be suppressed. As a result, even when stacking multiple closed packaging containers 100 containing food vertically, the lid 2 is less likely to deform, and a stable stacking state can be ensured.

[0083] In this embodiment, the high vertical rib 81 is formed by a pair of outward-facing ribs 56 that protrude outward from the lid side surface 51 and are adjacent to each other, and a single inward-facing rib 57 that protrudes inward from the lid side surface 51 between the pair of outward-facing ribs 56, and has been described as an example where the ribs protrude outward and inward from the lid side surface 51, respectively. However, the multiple high vertical ribs referred to in the present invention are not limited to this, and any ribs that extend in the vertical direction and have the same inward and outward height and circumferential width may be used.

[0084] Furthermore, in this embodiment, the low longitudinal rib 82 is described as having a side surface formed by a pair of outward-facing ribs 56 that protrude outward from the lid side surface 51, but the multiple low longitudinal ribs referred to in the present invention are not limited to this, and any ribs that extend in the vertical direction and have the same inward and outward height and circumferential width may be used.

[0085] Furthermore, since at least one of the multiple high longitudinal ribs 81 and at least one of the multiple low longitudinal ribs 82 are alternately arranged in the circumferential direction of the side surface of the lid, a balance of rigidity and strength in the vertical direction can be achieved throughout the entire circumferential direction.

[0086] Furthermore, the reinforcing surface 71 is provided with extension ribs 58 that extend continuously from the upper ends of the inward-facing ribs 57 (high longitudinal ribs 81). This reinforces the area around the boundary between the reinforcing surface 71 and the lid side surface 51, allowing it to more effectively withstand loads from above and suppress deformation of the lid 2. Therefore, even if a thin sheet is used for the lid 2, the required strength can be easily ensured.

[0087] Furthermore, the reinforcing surface 71 is provided with crossbeam ribs 59 that connect adjacent extension ribs 58, so the reinforcing surface 71 is further reinforced, and deformation of the lid 2 due to load from above can be suppressed. Therefore, even if a thin sheet is used for the lid, the necessary strength of the lid 2 can be easily ensured.

[0088] Furthermore, the lid 2 has at least one corner portion 50b in its plan view, and at least one inward rib 57 (high longitudinal rib 81) and an extension rib 58 are provided in close proximity to the corner portion 50b. This effectively reinforces the corner portion 50b of the lid 2, preventing deformation of the corner portion 50b due to an upward load. Therefore, even if a thin sheet is used for the lid 2, the required strength can be easily ensured.

[0089] Furthermore, since the reinforcing surface portion 71 is provided with corner-adjacent ribs 74 that are connected to the extension ribs 58 and extend toward at least one corner portion 50b, the required strength can be more reliably ensured even when a thin sheet is used for the lid 2.

[0090] Furthermore, since the reinforcing surface 71 is provided with transverse ribs 75 that are connected to the corner adjacent ribs 74 and traverse the reinforcing surface 71 in the inward and outward directions, the required strength can be more reliably ensured even when a thin sheet is used for the lid 2.

[0091] In this embodiment, the container body 1 and lid 2, which are commonly referred to as a food pack, are integrally connected via a foldable hinge portion 3, but the container body 1 and lid 2 may be separate components (without the hinge portion). [Explanation of Symbols]

[0092] 1...Container body, 2...Lid, 3...Hinge, 10...Bottom, 10a...Edge, 10b...Corner, 11...Body side, 12...Body flange, 13...Legs, 14...Blocking prevention protrusion, 16...Outward rib, 16a...Recessed groove, 17...Inward rib, 18...Groove, 19...Slit rib, 20...Body flange top, 20a...Step 21...Main body skirt section, 22...Main body edging section, 23...Main body fitting section, 24...Main body corner rib, 25...Main body knob section, 26...Rib for preventing edge curling, 27...Flat surface, 30...Narrow rib, 31...Wide rib, 32...Stacking recess, 33...Bottom protrusion, 34...Recessed rib, 50...Top surface, 50a...Edge section, 50b...Corner section, 51...Lid Side section, 51a...concave wall surface, 51b...end wall surface, 52...lid flange section, 54...blocking prevention protrusion, 55...top protrusion, 56...outward rib, 57...inward rib, 58...extension rib, 59...cross beam rib, 60...lid flange top surface, 60a...stepped surface, 61...lid skirt section, 62...lid edging section, 63...lid fitting section, 64...lid corner Ribs, 65... Lid handle, 66... ​​Ribs to prevent edge curling, 67... Lid bottom, 68... Lid vertical, 69... Flat surface, 70... Smooth surface (center of top), 71... Reinforcement surface (periphery of top), 72... Circumferential ribs, 73... Connecting ribs, 74... Corner adjacent ribs, 75... Transverse ribs, 76... Gate-shaped ribs, 81... High longitudinal ribs, 82... Low longitudinal ribs, 100... Packaging container

Claims

1. A packaging container thermoformed from a synthetic resin sheet, comprising a container body and a lid that closes the opening of the container body, The lid comprises a top surface and a side surface extending downward from the peripheral edge of the top surface. The side surface of the lid is provided with a plurality of high longitudinal ribs extending in the vertical direction and having the same inward and outward height and circumferential width, and a plurality of low longitudinal ribs extending in the vertical direction and having the same inward and outward height and circumferential width. The high longitudinal ribs and the low longitudinal ribs have the same circumferential width, and the high longitudinal ribs have a greater height in the inward and outward directions than the low longitudinal ribs. A packaging container characterized by the following features.

2. The packaging container according to claim 1, characterized in that the high longitudinal ribs and low longitudinal ribs are arranged alternately in the circumferential direction of the side surface of the lid, with at least one of the plurality of high longitudinal ribs and at least one of the plurality of low longitudinal ribs being arranged alternately.

3. The aforementioned high longitudinal rib is formed by a pair of outward-facing ribs that protrude outward from the side surface of the lid and are adjacent to each other, and a single inward-facing rib that protrudes inward from the side surface of the lid between the pair of outward-facing ribs, so that it protrudes outward and inward from the side surface of the lid, respectively. The packaging container according to claim 1 or 2, characterized in that the low longitudinal rib has a side surface formed by the pair of outward-facing ribs and protrudes outward from the side surface of the lid.

4. The top surface portion has a smooth central portion extending in the middle of the top surface portion, and a peripheral portion of the top surface portion surrounded by the central portion, which has irregularities. The packaging container according to claim 1, characterized in that the top surface periphery is provided with extension ribs that extend continuously from the upper end of the high vertical ribs.

5. The packaging container according to claim 4, characterized in that the top surface periphery is provided with transverse beam ribs connecting adjacent extension ribs.

Images