Lids for packaging containers and packaging containers using the same

Abstract

The present invention provides a packaging container lid made of a synthetic resin sheet that resists deformation at the corners even when the containers are stacked or lifted. [Solution] The lid 1 of the packaging container is made of a synthetic resin sheet and has a top surface portion 11 that is rectangular in plan view and side wall portions 12 that extend downward from each side of the top surface portion 11. The lid 1 has raised portions 14 formed by expanding the top surface portion 11 at least one pair of diagonal corners, and groove portions 15 formed on two consecutive sides of the side wall portions 12 and on the top surface portion 11. The groove portions 15 extend upward from the lower end of one side wall portion 12 and are formed continuously along the periphery of the raised portion 14 to the lower end of the other side wall portion 12.

Description

Technical Field

[0006] ,

[0001] The present invention relates to a lid for a packaging container made of a synthetic resin sheet.

Background Art

[0002] It is often seen that bento boxes, prepared foods, etc. are packaged in packaging containers formed from thin synthetic resin sheets and displayed at stores. Lids for such packaging containers are often transparent so that the contents can be viewed, and are being made thinner in consideration of the environment and resource conservation.

[0003] As the lid of the packaging container becomes thinner, its strength and rigidity decrease, increasing the risk of it being crushed when stacked or deformed when lifted. In particular, lids for packaging containers that are rectangular in plan view, such as square or rectangular ones, are likely to have their corners crushed and deformed when the containers are stacked or lifted, and if deformed, there is a risk of problems such as a decrease in the willingness to purchase or difficulty in viewing the contents inside.

[0004] Therefore, in the lid of a packaging container made of a thin synthetic resin sheet, not only are raised portions or the like provided at the corners of the top surface portion to prevent displacement of the placed containers, but also measures are taken to increase strength, rigidity, etc.

[0005] For example, Patent Document 1 below discloses a lid provided with displacement-preventing protrusions for suppressing lateral displacement between containers when food packaging containers are stacked vertically (see paragraph

[0036] , FIG. 1, etc.). Patent Document 2 below (see FIG. 1, etc.) and Patent Document 3 below (see FIG. 1, etc.) also disclose that protrusion portions are provided at each corner of the lid of a packaging container that is rectangular in plan view.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] As synthetic resin sheets are becoming thinner in packaging container lids, the lids are prone to deformation when the containers are stacked, especially at the corners where the load is concentrated. Therefore, research and development is being conducted to ensure the strength and rigidity of the corners in order to prevent lid deformation. The inventors have diligently studied the shape of the corners of the lid and have developed a lid for a packaging container that is less prone to deformation of the corners.

[0008] Therefore, the object of the present invention is to provide a packaging container lid made of a synthetic resin sheet that is less prone to deformation at the corners even when the containers are stacked or lifted. [Means for solving the problem]

[0009] A lid for a packaging container according to one embodiment of the present invention is a lid for a packaging container made of a synthetic resin sheet having a top surface that is rectangular in plan view and side wall surfaces that extend downward from each side of the top surface, wherein at least a pair of diagonal corners of the lid are provided with raised portions formed by expanding the top surface, and grooves formed on two consecutive sides of the side wall surfaces and on the top surface, wherein the grooves extend upward from the lower end of one of the side wall surfaces, pass along the periphery of the raised portion, and are formed continuously to the lower end of the other side wall surface.

[0010] In the above-described packaging container, the groove can be formed at a certain distance from the raised portion.

[0011] In the above-described packaging container, the raised portion can be formed to have a constant width in a plan view, and can also be shaped to curve or bend along the corners of the top surface.

[0012] In the above-described packaging container, a recessed portion extending in the vertical direction, formed by indenting the lid, can be provided within the area surrounded by the groove.

[0013] In the above-described packaging container, in the portion formed on the side wall surface of the groove and / or recess, the bottom of the groove and / or recess can be formed from two inclined surfaces of different angles, and the inclined surface can be formed from an upper inclined surface located at the top and a lower inclined surface located at or below half the height of the side wall surface and having a gentler slope than the upper inclined surface.

[0014] The lid of the packaging container described above can be made less susceptible to deformation such as crushing by providing raised and grooved portions at the corners, which creates an uneven shape at the corners and reinforces that area. Furthermore, by forming the bottom of grooves and recesses located on the side walls from two inclined surfaces with different angles, deformation can be made even more difficult to induce. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing the lid of a packaging container according to one embodiment of the present invention. [Figure 2] Figure 1 is a plan view of the lid of the packaging container. [Figure 3] Figure 1 is a cross-sectional view of the lid of the packaging container. [Figure 4] This is an enlarged end view showing the area near the groove provided in the lid of the packaging container shown in Figure 1. [Figure 5] This is a perspective view showing an example of a container body that can be applied to the lid of the packaging container shown in Figure 1. [Figure 6] This is a front view showing a stack of packaging containers using the lids of the packaging containers shown in Figure 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0016] Hereinafter, the lid of the packaging container according to an embodiment of the present invention will be described based on the drawings.

[0017] As shown in FIG. 1, the lid 1 of the packaging container according to an embodiment of the present invention is formed in a trapezoidal truncated shape, and includes a top surface portion 11 having a rectangular shape in plan view, a side wall portion 12 extending downward from the periphery of the top surface portion 11, a flange portion 13 protruding outward from the lower end portion of the side wall portion 12, and a raised portion 14 that bulges outward from the vicinity of the corners of the top surface portion 11 and the side wall portion 12.

[0018] As shown in FIG. 2, the top surface portion 11 has a horizontal plane shape that is rectangular in plan view, more specifically, a rectangular shape with chamfered corners. The top surface portion 11 may be formed in an inclined plane shape, a dome shape, etc., but it is preferably formed in a horizontal plane shape so that other packaging containers can be easily stacked.

[0019] As shown in FIG. 1 or FIG. 3, the side wall portion 12 is formed in an inclined plane shape that slopes downward from each side of the periphery of the top surface portion 11. The side wall portion 12 may be formed in a concave curved surface shape in cross section, a convex curved surface shape in cross section, etc., but it is preferably formed in an inclined plane shape in order to make the lid 1 difficult to be crushed.

[0020] As shown in FIG. 1 or FIG. 3, the flange portion 13 is formed to protrude outward from the lower end portion of the side wall portion 12 and is formed in a stepped shape. At each corner of the lid 1, a grip portion 13a is formed by further extending the flange portion 13 outward to form an obtuse-angled isosceles triangle shape in plan view. In the present invention, the flange portion 13 may not be provided, but it is preferably provided in order to maintain the rigidity and strength of the lid 1.

[0021] As shown in FIG. 3, a fitting portion 16 is formed in the circumferential direction of the lid 1 near the side wall portion 12 of the flange portion 13. The fitting portion 16 is provided around the entire circumference of the lid 1 and is formed in the shape of a rectangular groove. The surfaces on the outer side of the lid on a pair of opposing sides are tapered, allowing it to be fitted into the container body 2, which will be described later, for internal fitting. In this embodiment, the lid 1 is fitted to the inside of the container body 2, but it is not limited to this, and any fitting structure such as an external fitting structure or an internal-external fitting structure may be adopted. Alternatively, the lid 1 may be placed on the container body 2 without fitting and secured with staples or adhesive tape.

[0022] As shown in Figure 1 or Figure 2, the raised portions 14 are provided at least one pair of diagonally opposite corners of the top surface 11, forming an upward bulge in the top surface 11, which prevents other packaging containers from shifting when placed on top of the top surface 11. Preferably, the raised portions 14 are provided at all four corners of the top surface 11. By providing the raised portions 14 at all four corners, the top surface 11 becomes a cross-shaped plane in plan view, as shown in Figure 2. This provides functions such as indicating the direction in which to wrap the shrink film after closing the lid, and making it easier to place chopsticks on top. The raised portion 14 is preferably formed along the periphery of the top surface portion 11 with a constant width in plan view, and it is also preferable that it has a curved or bent shape, such as an L-shape in plan view, along the corners of the top surface portion 11. In this invention, "constant width" means that a range of ±10% is permitted. The raised portion 14 is not particularly limited, but it can be formed by raising it to a height of 2 to 10 mm, preferably 3 to 7 mm, relative to the top surface portion 11.

[0023] As shown in Figure 1 or Figure 2, grooves 15 are continuously formed on two of the side wall surfaces 12 and on the top surface 11. The groove 15 is formed by recessing the lid 1 inward, extending from the lower end of one side wall surface 12, passing through the top surface 11, and continuing to the lower end of the other side wall surface 12. More specifically, it extends linearly upward from the lower end of one side wall surface 12 to the top surface 11, where it is formed in a bent shape along the periphery of the raised portion 14, and then descends linearly down the other side wall surface 12, continuing to its lower end. In this embodiment, the groove 15 formed on the top surface 11 is formed to exhibit a deformed M-shape in plan view. In addition, if the lower end of the side wall portion 12 is not clearly continuous with the fitting portion 16, as in this embodiment, the lower end of the side wall portion 12 can be defined as the point where the horizontal line extending from the upper surface of the flange portion 13 (or the horizontal line extending from the highest point if the upper surface is not a horizontal plane) intersects with the side wall portion 12.

[0024] The grooves 15 along the perimeter of the raised portion 14 are formed to extend parallel to the edges of the raised portion 14. Note that "along the perimeter of the raised portion 14" includes both providing the grooves adjacent to the raised portion 14 without any gaps, and providing them at a certain distance from the raised portion 14. By providing the grooves 15 at a certain distance from the raised portion 14, the corners of the top surface 11 are reinforced in a stepped manner, increasing strength and making it less susceptible to deformation from stresses from above when stacked, or from multi-directional stresses due to vibrations during transportation. Furthermore, by providing the grooves 15 along the perimeter of the raised portion 14, they appear as a unified whole, resulting in a superior appearance and not hindering the visibility of the contents inside when displayed. It also makes the top surface 11 less susceptible to crushing when other packaging containers 3 are placed on it. The distance from the raised portion 14 is not particularly limited, but is preferably about 1 mm to 5 mm.

[0025] The groove 15 is not particularly limited, but can be formed in the shape of a square groove, a circular groove, a V-shaped groove, etc. However, it is preferable to make it a square groove in order to increase the strength of the corners of the lid 1.

[0026] It is preferable that the area surrounded by the groove 15 includes a recessed portion 17 extending in the vertical direction, formed by indenting the lid 1, as shown in Figure 1 or Figure 2. The recessed portion 17 may be formed across both the side wall portion 12 and the raised portion 14, or it may be formed on only one of either the side wall portion 12 or the raised portion 14. In this embodiment, one recessed portion 17 is provided on the chamfered portion of each corner of the lid 1, and one recessed portion 17 is provided on each of its left and right sides. However, it is sufficient to provide at least one recessed portion within each range, and it is preferable to provide at least one recessed portion on each of the two side wall portions 12 within each range. The recessed portion 17 is not particularly limited, but can be formed in the shape of a square groove, a circular groove, a V-shaped groove, etc. However, it is preferable to make it a square groove in order to increase the strength of the corners of the lid 1. Furthermore, the recessed portion 17 may be the same width as the groove portion 15, but it is preferable to form it wider than the groove portion 15.

[0027] In the groove portion 15, as shown in Figure 4, the bottom portion 15a of the part located on the side wall portion 12 can be formed from two inclined surfaces with different angles. Preferably, it is formed from an upper inclined surface 15b located at the top and a lower inclined surface 15c located at less than half the height of the side wall portion 12 and having a gentler slope than the upper inclined surface 15b. In this invention, the height of the side wall portion 12 refers to the height in the vertical direction from the lower end of the side wall portion 12.

[0028] The lower inclined surface 15c is preferably provided at a position from the lower end of the side wall surface 12 at a position of about half the height of the side wall surface 12, preferably at a position of about one-third the height of the side wall surface 12, and more preferably at a position of about one-quarter the height of the side wall surface 12.

[0029] The difference in inclination angle between the upper inclined surface 15b and the lower inclined surface 15c is not particularly limited, but is preferably 5° or more and 50° or less, more preferably 10° or more and 40° or less, and even more preferably 20° or more and 35° or less. It is preferable that the recessed portion 17, like the groove portion 15, be formed from two inclined surfaces with different angles.

[0030] The lid 1 can be used as a packaging container 3 by, for example, placing it over the container body 2 in the form shown in Figure 5. The following describes the container body 2, but the container body 2 is not limited to the following forms. The container body 2 is shaped like an inverted trapezoidal base with rounded corners in a rectangular shape when viewed from above. More specifically, as shown in Figure 5, it comprises a bottom portion 21, a peripheral wall portion 22 rising upward from the periphery of the bottom portion 21, and a flange portion 23 extending outward from the upper end of the peripheral wall portion 22.

[0031] The bottom portion 21 includes a rectangular horizontal surface portion 21a on which the contents can be placed, and a recessed groove portion 21b provided around the surface portion 21a.

[0032] The circumferential groove 21b is formed by recessing the outer circumference of the bottom surface 21 and also serves as the legs 24 of the container body 2. The circumferential groove 21b may be formed to the same depth all around, or the depth may be varied, making a part of the bottom shallower.

[0033] The peripheral wall portion 22 is formed in a curved cross-sectional shape that curves upward from the bottom portion 21 and widens outward from the main body, and a flange portion 23 that protrudes outward from the main body is provided at its upper end. The upper side of the peripheral wall portion 22 is formed in a reverse taper shape on each of the opposing sides, and is a fitting portion 22a into which the lid 1 can be fitted.

[0034] In this embodiment, the flange portion 23, as shown in Figure 6, comprises a flat portion 23a that extends horizontally with a constant width, a skirt portion 23b that extends downward in a stepped manner from the leading edge of the flat portion 23a, and a minute projection 23c that protrudes outward from the lower end of the skirt portion 23b with a minute width.

[0035] Furthermore, each corner of the container body 2 is provided with a knob 25 that is obtuse isosceles triangular in plan view, formed by further extending the flange portion 23 outward.

[0036] The container body 2 can be used as a packaging container 3 by placing the lid 1 over it. In this embodiment, the container body 2 is formed to be a horizontally elongated rectangular parallelepiped when the lid 1 is placed over it. The packaging container 3 is not particularly limited, but can be approximately 30mm to 70mm in height, 200mm to 300mm in length, and 70mm to 150mm in width, and is suitable for storing food and beverages such as bento boxes, rice, bread, fruits and vegetables, fresh fish, prepared foods, desserts, and sushi.

[0037] As shown in Figure 6, the packaging containers 3 can be stacked. For example, the legs 24 of the container body 2 of another packaging container 3 can be placed on the top surface 11 for stacking. In this case, the legs 24 of the upper packaging container 3 are surrounded by the raised portion 14 of the lower packaging container 3, making it less likely to shift or move. Furthermore, in this embodiment, since the legs 24 rest on the groove 15, any moisture or oil adhering to the legs 24 of the upper stacked container body 2 can be guided downwards through the groove 15 of the lower lid 1, preventing moisture or oil from adhering to the container and causing it to become dirty when picked up.

[0038] The following describes an example of a manufacturing method for the lid 1 and the container body 2. The lid 1 and the container body 2 are not particularly limited, but can be manufactured by thermoforming a synthetic resin sheet. The synthetic resin sheet may be either a non-foamed resin sheet or a foamed resin sheet, but it is preferable to mold the container body 2 and the lid 1 from a thin-walled non-foamed resin sheet.

[0039] In the case of non-foamed resin sheets, it is preferable to use sheets with a thickness in the range of 0.1 mm to 2.0 mm, and particularly in the range of 0.2 mm to 1.2 mm. In the case of foamed resin sheets, it is preferable to use sheets with a thickness in the range of 0.5 mm to 4.0 mm, and especially in the range of 0.7 mm to 2.2 mm. Furthermore, in the case of foamed resin sheets, it is preferable to have a foaming ratio of 1.05 to 20.0 times, and especially in the range of 1.5 to 15.0 times.

[0040] As non-foamed resin sheets, thermoplastic resin sheets such as polyolefin resin sheets (e.g., polyethylene resin sheets, polypropylene resin sheets), polystyrene resin sheets, polyester resin sheets (e.g., polyethylene terephthalate resin sheets, modified polyethylene terephthalate resin sheets with heat resistance), etc., can be used. Alternatively, materials that can withstand microwave heating, such as heat-resistant polystyrene resin sheets, polypropylene resin sheets, or modified polyethylene terephthalate resin sheets with heat resistance, may be used.

[0041] As the foamed resin sheet, for example, foamed polyolefin resin sheets, foamed polystyrene resin sheets, and foamed polyester resin sheets such as foamed polyethylene terephthalate can be used. Laminated sheets made by laminating synthetic resin sheets can also be used. Examples of laminated sheets include laminated sheets made by heat-laminating a resin film onto a non-foamed resin sheet or a foamed resin sheet, laminated sheets made by co-extrusion, and laminated sheets made by extrusion lamination.

[0042] Biomass plastics such as biodegradable resins may be used as the non-foamed resin sheet, foamed resin sheet, and laminated sheet mentioned above. Biomass plastics are polymer materials obtained by chemical or biological synthesis using materials derived from renewable organic resources as raw materials. Compared to petroleum-derived resins, biomass plastics can reduce carbon dioxide emissions into the atmosphere and thus reduce the burden on the environment. Examples of biomass plastics include polylactic acid resin, biomass polyethylene, and biomass polyethylene terephthalate.

[0043] Examples of thermoforming include vacuum forming, pressure forming, vacuum pressure forming, and hot plate forming.

[0044] The lid 1 and container body 2 may be colored, such as black or white, but it is preferable that they be transparent or semi-transparent so that the contents can be seen. In addition, if the lid 1 and container body 2 are transparent or semi-transparent, letters, pictures, or other designs may be printed or engraved on their surfaces to the extent that they do not impede visibility. Furthermore, the flange portions 13, 23, etc., may be given a textured finish to prevent slipping. In addition, stacking protrusions, such as cubes or rectangular parallelepipeds, can be provided at appropriate positions on the lid 1 and the container body 2.

[0045] The following describes an example of how to use a packaging container 3 when the container body 2 described above is applied to the lid 1. By placing the contents, such as food items, on the mounting surface 21a of the container body 2, placing the lid 1 over the container body 2, and pressing down from above the lid 1, the fitting portion 16 fits into the fitting portion 22a of the container body 2, allowing the contents to be packaged in the packaging container 3. To open the packaging container 3, for example, grasp the tab 15 on the lid 1 with your left hand and the tab 25 on the container body 2 with your right hand, and pull in opposite directions to release the engagement of the fitting portion 16 and the fitted portion 22a, and then lift the lid 1.

[0046] As shown in Figure 1, the lid 1 has raised portions 14 and grooves 15 at its corners, creating an uneven shape at the corners of the top surface 11. The grooves 15 on the side walls 12 support the top surface 11. This reinforces the corners of the lid 1, making it less susceptible to deformation such as crushing. Therefore, even when stacking packaging containers 3, the lid 1 is less likely to deform.

[0047] By forming the groove 15 at a certain width interval from the raised portion 14, the corners of the top surface 11 are formed in a stepped shape, further reinforcing them and making them less susceptible to deformation. Furthermore, by forming the raised portion 14 with a certain width in a plan view and shaping it to curve or bend along the corners of the top surface 11, the upper packaging container 3 is less likely to shift when stacked, and the groove 15 located on the top surface 11 is formed in a bent shape, making the corners of the top surface 11 less susceptible to deformation.

[0048] By providing a vertically extending recessed portion 17 formed by indenting the lid 1 within the area surrounded by the groove portion 15, the corners of the lid 1 can be reinforced and made less susceptible to deformation.

[0049] Furthermore, in the groove 15 located on the side wall surface 12, the bottom 15a of the groove 15 is formed from two inclined surfaces 15b and 15c with different angles, which can also make it less likely for deformation to occur at the corners of the lid 1.

[0050] The configurations of the embodiments described above are not intended to limit the present invention, and modifications are possible as long as the technical objectives remain the same, and the present invention includes such modifications. [Explanation of symbols]

[0051] 1. Lid of a packaging container 11 Top section 12 Side wall section 13 Flange section 13a Thumb part 14 Ridge 15 groove 15a bottom 15b Upper slope 15c lower slope 16 Fitting part 17 Recessed area 2. Container body 21 Bottom part 21a Placement surface section 21b Peripheral groove 22 Side wall section Fitted portion 22a Flange portion 23 Flat portion 23a Skirt portion 23b Minute protrusion 23c Leg portion 24 Grip portion 25 Packaging container 3

Claims

1. A lid for a packaging container made of a synthetic resin sheet, having a top surface that is rectangular in plan view and side wall surfaces that extend downward from each side of the top surface, The lid is provided with a raised portion formed by expanding the top surface at at least one pair of diagonal corners, and grooves formed on two consecutive sides of the side wall and on the top surface. The groove extends upward from the lower end of one of the side wall surfaces and is formed continuously along the periphery of the raised portion to the lower end of the other side wall surface, in the lid of a packaging container.

2. The lid of a packaging container according to claim 1, wherein the groove is formed at a distance of a certain width from the raised portion.

3. The lid for a packaging container according to claim 1 or 2, wherein the raised portion is formed to have a constant width in a plan view and is shaped to curve or bend along the corner of the top surface.

4. The lid of a packaging container according to claim 1, wherein the area surrounded by the groove portion is provided with a vertically extending recess formed by indenting the lid.

5. In the portion formed on the side wall surface of the groove and / or recess, the bottom of the groove and / or recess is formed from two inclined surfaces with different angles. The lid of a packaging container according to claim 1, 2, or 4, wherein the inclined surface is formed from an upper inclined surface located at the top and a lower inclined surface located at or below half the height of the side wall portion and having a gentler slope than the upper inclined surface.

6. A packaging container using the lid of the packaging container according to claim 1 or 2.

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