container

Abstract

To provide a container for food packaging which can improve openability while appropriately joining a lid body and a container body.SOLUTION: A container 1 includes a container body 2 having an opening M, a lid boy 3 closing the opening M, and a joint area Aa where the lid body 3 and the container body 2 are joined to each other in the state where the opening M is closed, wherein the container body 2 includes a body side flange 5 provided along a peripheral edge Ma of the opening M, the lid body 3 includes a lid body flange 6 stacked on the body side flange 5, the body side flange 5 includes a body side stacked surface 5a facing the lid body flange 6, the lid side flange 6 includes a lid side stacked surface 6a facing the body side flange 5, the body side stacked surface 5a and the lid side stacked surface 6a are provided with a second groove part 92 or a fourth groove part 12, and the joint area Aa includes a main joint part 13 for joining the body side flange 5 and the lid side flange 6 while avoiding the second groove part 92 and the fourth groove part, and a low joint part 14 overlapping the second groove part 92 or the fourth groove part 12.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a container for containing contents such as food. [Background technology]

[0002] Known containers for containing and packaging contents such as food include, for example, containers made of foamed resin and containers molded from resin sheets. These containers include a container body with an opening for putting in and taking out food, and a lid that is attached to the container body to close the opening. The lid and container body have overlapping flanges. The flanges basically have surfaces that face each other and come into contact when the lid is closed (hereinafter, for convenience, referred to as "facing contact surfaces"). The facing contact surfaces overlap and are fused and joined by heating using, for example, ultrasonic vibrations (see Patent Documents 1 to 4). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-185752 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-199292 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-199293 [Patent Document 4] Japanese Patent Application Laid-Open No. 2013-199294 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned container, the flat opposing surfaces are basically melt-bonded together, which makes the bonding strength strong and makes it difficult to open. As a result, when trying to forcefully peel the flanges apart to open the lid, the flanges tend to tear, which can lead to further damage.

[0005] The present invention aims to solve the above-mentioned problems and to provide a food packaging container that can improve the ease of opening while ensuring an appropriate joint between the lid and the container body. [Means for solving the problem]

[0006] The present invention provides a container comprising a container body having an opening, a lid body that closes the opening, and a joint region that joins the lid body and the container body when the opening is closed, wherein the container body comprises a body-side flange provided along the periphery of the opening, the lid body comprises a lid-side flange that is laminated on the body-side flange, the body-side flange having a body-side lamination surface facing the lid-side flange, and the lid-side flange having a lid-side lamination surface facing the body-side flange, and at least one of the body-side lamination surface and the lid-side lamination surface has a recessed portion, and the joint region comprises a main joint portion that joins the body-side flange and the lid-side flange while avoiding the recessed portion, and a low joint portion that overlaps the recessed portion. Note that the "low joint portion" includes both a form in which the body-side flange and the lid-side flange are not joined and a form in which the joint is weaker than the main joint portion.

[0007] In the above-described container, a recess is provided on at least one of the body-side lamination surface of the body-side flange and the lid-side lamination surface of the lid-side flange, and the main bond in the bonding region is located away from the recess. The recess is shaped to separate the body-side lamination surface and the lid-side lamination surface. Therefore, the recess is not bonded and becomes a gap, or even if bonded, the density is low and the bond strength is weaker than the main bond. As a result, a low bond is formed where the recess overlaps, and the presence of the low bond makes it easier to open the container when peeling the lid from the container body. Furthermore, the provision of the recess makes it easier to control the locations where the main bond and low bond are formed, enabling proper bonding. As a result, this container improves openability while ensuring proper bonding between the lid and container body.

[0008] In the container, the recessed portion may be provided on the lid-side laminated surface. By providing the recessed portion on the lid-side laminated surface, it becomes easier to reduce the bonding strength when peeling the lid from the container body.

[0009] In the container described above, the recessed portions may be provided on both the lid-side laminated surface and the body-side laminated surface. By providing recessed portions on both the lid-side laminated surface and the body-side laminated surface, unevenness in the location where the low-bonding portion is formed is reduced compared to when a recessed portion is provided on only one of the surfaces, thereby improving ease of opening.

[0010] In the container described above, the recessed portions may be a plurality of grooves provided along the periphery of the opening, and the grooves may be elongated grooves having a longitudinal direction. By changing the longitudinal direction of the plurality of elongated grooves provided along the periphery of the opening, it becomes easier to adjust the ease of opening.

[0011] In the container, the longitudinal direction of the groove may be inclined with respect to a reference direction along the periphery of the opening. For example, when multiple grooves with the same longitudinal direction are arranged along the periphery of the opening, it becomes easier to arrange more grooves, and it becomes easier to expand the area where the low-bonding portion is formed.

[0012] In the container described above, the plurality of grooves may be provided on the lid-side lamination surface and the body-side lamination surface, and the longitudinal direction of the grooves provided on the lid-side lamination surface may intersect with the longitudinal direction of the grooves provided on the body-side lamination surface. By intersecting the grooves on the lid-side lamination surface and the grooves on the body-side lamination surface, it becomes easier to form low-bonding portions evenly over a wide area, improving ease of opening.

[0013] The present invention also provides a container having a lid body that closes the opening of the container body, wherein the container body has a body-side flange arranged along the periphery of the opening, the lid body has a lid-side flange that is laminated on the body-side flange, the body-side flange has a body-side stacking surface that faces the lid-side flange in the closed state, and the lid-side flange has a lid-side stacking surface that faces the body-side flange in the closed state, at least a portion of the body-side stacking surface and the lid-side stacking surface are intended joining areas, and at least one of the body-side stacking surface and the lid-side stacking surface has a recess formed in the intended joining area.

[0014] In the above-described container, at least a portion of the body-side lamination surface of the body-side flange and the lid-side lamination surface of the lid-side flange are intended to be joined, and a recess is formed in at least one of the body-side lamination surface and the lid-side lamination surface. For example, when the body-side flange and the lid-side flange are joined by ultrasonic welding, a main joint portion joining the body-side flange and the lid-side flange is formed in the intended joining area. Here, the recess is shaped to separate the body-side lamination surface and the lid-side lamination surface. Therefore, the main joint portion is formed to avoid the recess, and a weak joint portion with a lower joint strength than the main joint portion is formed in the area overlapping the recess. The formation of the weak joint portion facilitates opening when peeling the lid body from the container body. Furthermore, the provision of the recess makes it easier to control the locations where the main joint portion and the weak joint portion are formed, enabling proper joining. As a result, this container improves openability while ensuring proper joining between the lid body and the container body. [Effects of the Invention]

[0015] According to the present invention, it is possible to improve the ease of opening while ensuring appropriate joining between the lid and the container body. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing a container in which a lid is joined to a container body according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing a container in which a lid is joined to a container body. [Figure 3] FIG. 3 is an enlarged plan view of a portion of the container shown in FIG. 2, with a portion of the lid cut away. [Figure 4] 4A is a cross-sectional view taken along line IVa-IVa in FIG. 3, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG. [Figure 5] 10A and 10B show an enlarged view of a portion of the recess structure when the lid is closed, where FIG. 10A is a cross-sectional view showing the recess structure of the flange on the main body side, and FIG. 10B is a cross-sectional view showing the recess structure of the flange on the lid side. [Figure 6]FIG. 2 is a perspective view showing the container with the lid open. [Figure 7] FIG. 2 is a plan view showing the container with the lid open. [Figure 8] 1A and 1B are schematic views showing the shapes of the bonding surfaces, where FIG. 1A is a plan view showing the bonding surface according to a first embodiment, FIG. 1B is a plan view showing the bonding surface according to a first modified example, and FIG. 1C is a plan view showing the bonding surface according to a second modified example. [Figure 9] 10A and 10B show a container according to a second embodiment, in which FIG. 10A is a plan view with the lid closed, and FIG. 10B is a cross-sectional view taken along line bb in FIG. 10A. [Figure 10] 10A and 10B show a container according to a third embodiment, in which FIG. 10A is a plan view with the lid closed, and FIG. 10B is a cross-sectional view taken along line bb in FIG. 10A. [Figure 11] 10A and 10B show a container according to a fourth embodiment, in which FIG. 10A is a plan view of the container with the lid open, and FIG. 10B is a side view of the container with the lid open. [Figure 12] FIG. 1 is an explanatory diagram schematically illustrating an example of an ultrasonic sealing machine. [Figure 13] 1A and 1B are diagrams illustrating the shapes and dimensions of recesses according to the embodiments, in which (a) is a plan view of the recesses according to Example 1, (b) is a cross-sectional view of the recesses according to Example 1, (c) is a plan view of the recesses according to Example 2, and (d) is a cross-sectional view of the recesses according to Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, a container according to an embodiment of the present invention will be described with reference to the drawings, however, the container of the present invention is not limited to only this embodiment.

[0018] The container 1 of the first embodiment (see FIG. 1) is a food packaging container that mainly contains and packages food. However, the contents of the container 1 are not limited to food but also include utensils used when eating, such as chopsticks and spoons, and other objects. This also applies to containers 1A to 1C of the second to fourth embodiments described below, in which the contents are not limited to food but also include other objects.

[0019] 1 and 6, container 1 comprises a container body 2, a lid 3, and a hinge 4 that connects container body 2 and lid 3 in an openable and closable manner. Container body 2 has an opening M for inserting and removing contents. Lid 3 is connected to container body 2 via hinge 4 so that opening M can be opened and closed. In other words, container 1 is a resin food pack in which lid 3 and container body 2 are integrally sheet-molded via hinge 4.

[0020] In this embodiment, the depth of the lid 3 is shallower than the depth of the container body 2, and the lid 3 cannot actually hold the contents. Therefore, the container body 2 and the lid 3 can be clearly distinguished. However, it is also possible to configure the container body 2 and the lid 3 so that the contents can be held by both, in which case one can be understood as the container body 2 and the other as the lid 3.

[0021] The container 1 is made of a synthetic resin sheet and is manufactured by vacuum forming using a predetermined mold. The synthetic resin from which the container 1 is made is preferably transparent so that the contents inside the container 1 can be visually confirmed. Examples of transparent synthetic resins include polystyrene-based, polyethylene-based, polypropylene-based, and polyester-based synthetic resins. The container 1 may be translucent or opaque.

[0022] Furthermore, in terms of the mechanical strength of the molded container 1, it is preferable that the synthetic resin sheet used for the container 1 is a stretched sheet manufactured by stretching the synthetic resin so that its molecules are oriented. Furthermore, biaxially stretched sheets are more preferable than uniaxially stretched sheets because they have a better balance of physical properties. In particular, biaxially stretched sheets of polystyrene-based resins have a well-balanced performance in terms of rigidity, heat resistance, transparency, environmental friendliness, and processability, making them suitable as materials for the container 1. In this embodiment, for example, a biaxially stretched sheet of polystyrene-based resin is used.

[0023] As shown in Figures 6 and 7, the container body 2 in an open state has a rough shape of a horizontally elongated rectangle in a plan view. The top of the container body 2 is open, forming an opening M. The container body 2 has a bottom 21 provided at the bottom opposite the opening M, and a side wall 22 erected from the periphery of the bottom 21. The bottom 21 is provided with an uneven surface, which supports the contents, such as food, contained therein in a slightly elevated state. The side wall 22 is provided with a plurality of vertical ribs 22a.

[0024] The container body 2 has a body-side flange 5 joined to the lid 3. The body-side flange 5 is bent from the upper end of the side wall 22 and is provided so as to protrude outward. Here, "outward" refers to the outward direction that is opposite to the inside (inner side) where the contents are accommodated, based on the opening M. The body-side flange 5 is provided along a part of the periphery Ma of the opening M, avoiding the hinge portion 4. For example, the periphery Ma of the opening M according to this embodiment is substantially rectangular. The hinge portion 4 is provided along one of the four sides of the periphery Ma of the opening M, and the body-side flange 5 is provided along the other sides.

[0025] The lid body 3 includes a cover portion 31 and a lid-side flange 6 provided to protrude from a peripheral edge 31a of the cover portion 31. The cover portion 31 covers and closes the opening M when the lid body 3 is folded back at the hinge portion 4 and attached to the container body 2. The lid-side flange 6 is layered on the body-side flange 5 when the lid body 3 closes the opening M.

[0026] The cover portion 31 has a shape that follows the shape of the opening M in a plan view, and in this embodiment, has a substantially rectangular shape that follows the substantially rectangular shape of the opening M. The cover portion 31 is formed into a three-dimensional shape that has a depth (bulge) on the opposite side to the container body 2 when the opening M is closed.

[0027] The lid-side flange 66 is provided so as to fit along part of the peripheral edge 31a of the cover part 31, avoiding the hinge part 4. The peripheral edge 31a of the cover part 31 is roughly rectangular, following the shape of the peripheral edge Ma of the opening M, and the hinge part 4 is connected to one of the four sides. The lid-side flange 6 is layered on the body-side flange 5 when the cover part 31 covers the opening M. In other words, the lid-side flange 66 is provided so as to fit along part of the peripheral edge 31a when the opening M is closed with the lid body 3.

[0028] Next, the structures of the body-side flange 5 and the lid-side flange 6 and the joining area Aa will be described with reference to Figures 1, 2, 3, and 4. When the opening M is closed with the lid 3, the body-side flange 5 and the lid-side flange 6 are stacked on top of each other. The body-side flange 5 has an inner surface (body-side stacking surface 5a) that faces the lid-side flange 6, and an outer surface 5b that is opposite the body-side stacking surface 5a (see Figures 3 and 4). The lid-side flange 6 has an inner surface (lid-side stacking surface 6a) that faces the body-side flange 5, and an outer surface 6b that is opposite the lid-side stacking surface 6a.

[0029] The area where the body-side lamination surface 5a and the lid-side lamination surface 6a overlap is the lamination area A. Within the lamination area A, the area where the body-side flange 5 and the lid-side flange 6 are scheduled to be joined is the planned joining area Ab. Furthermore, when the body-side flange 5 and the lid-side flange 6 are joined in at least a portion of the planned joining area Ab, the planned joining area Ab becomes the joining area Aa.

[0030] The body-side flange 5 has a rib structure 7 that protrudes from the outer surface 5b. The rib structure 7 has a first rib 71 that is provided along the periphery Ma of the opening M, and a plurality of second ribs 72 that are provided so as to be connected to the first rib 71. The second ribs 72 are provided so as to branch off from the first rib 71. The first ribs 71 are blocking ribs that prevent the propagation of a tear in the event that the tear occurs.

[0031] The lid flange 6 has a rib structure 8 that protrudes from the outer surface 6b. The rib structure 8 has a third rib 81 that is provided along the periphery Ma of the opening M when the lid 3 is closed, and a plurality of fourth ribs 82 that are provided so as to be connected to the third rib 81. The fourth ribs 82 are provided so as to branch off from the third rib 81. The third ribs 81 are blocking ribs that prevent the propagation of a tear in the event that the tear occurs.

[0032] The container 1 is formed by vacuum molding a synthetic resin sheet, and has a recessed structure 9 formed on the main body side stacking surface 5a, corresponding to the rib structure 7 formed on the outer surface 5b of the main body side flange 5 (see FIG. 4). In other words, the back surface of the rib structure 7 is the recessed structure 9. The recessed structure 9 includes a first groove portion 91 with a bottom corresponding to the first rib 71 and a second groove portion 92 with a bottom corresponding to the second rib 72. The first groove portion 91 is located close to the periphery Ma of the opening M and is provided along the periphery Ma of the opening M. A plurality of second groove portions 92 are provided, and are provided so as to be connected to the first groove portion 91. The first groove portion 91 and the second groove portion 92 are provided in the stacking region A. The first groove portion 91 is provided so as to avoid the intended joining region Ab (joining region Aa), and the second groove portion 92 is provided in the intended joining region Ab (joining region Aa). The second grooves 92 correspond to recesses provided on the main body side stacking surface 5a.

[0033] The second grooves 92 provided on the main body-side stacking surface 5a are elongated grooves, and the longitudinal direction Db of the second grooves 92 is inclined with respect to a reference direction Da along the periphery Ma of the opening M (see FIG. 5). The concept of the reference direction Da along the periphery Ma of the opening M will be described. The second grooves 92 have two ends 92a, 92b, one end 92a being connected to the first groove 91 and the other end 92b being spaced apart from the first groove 91. The position on the periphery Ma of the opening M that is closest to one end 92a of the second groove 92 is identified, and the tangent direction of this closest position is the reference direction Da along the periphery Ma of the opening M relative to the second groove 92. Note that in this embodiment, one end 92a of each of adjacent second grooves 92 is aligned along the periphery Ma of the opening M, which is substantially linear, and the reference direction Da is common to both.

[0034] As a supplementary note, in this embodiment, the reference direction Da is described assuming a rectangular perimeter Ma. However, based on the concept of the reference direction Da described above, even if the perimeter Ma is circular or has another curved shape, the reference direction Da can be determined by identifying the position closest to one end 92a and identifying the tangent direction of this closest position.

[0035] Because the second groove portion 92 according to this embodiment extends linearly, the longitudinal direction Db can also be understood as a linear direction. When the smaller intersection angle α, which is the intersection angle between a first virtual line along this linear direction and a second virtual line along the reference direction Da, is greater than 0° and less than 90°, the longitudinal direction Db of the second groove portion 92 is inclined with respect to the reference direction Da along the periphery Ma of the opening M. This intersection angle α is preferably 30° or greater and 70° or less, and more preferably 40° or greater and 50° or less. If the second groove portion 92 is not linear but bent along the way, the linear direction of the portion of the second groove portion 92 to which one end 92a belongs can be determined as the longitudinal direction Db. If the second groove portion 92 is curved, the tangent direction of the portion to which one end 92a belongs can be determined as the longitudinal direction Db.

[0036] Corresponding to the rib structure 8 formed on the outer surface 6b of the lid flange 6, a recessed structure 10 is formed on the lid-side stacking surface 6a (see FIG. 4). In other words, the back surface of the rib structure 8 is the recessed structure 10. The recessed structure 10 includes a third groove portion 11 with a bottom corresponding to the third rib 81 and a fourth groove portion 12 with a bottom corresponding to the fourth rib 82. In other words, the third groove portion 11 is provided so as to be close to and along the periphery Ma of the opening M when the opening M is closed by the lid 3. In the following explanation, the relationship between the third groove portion 11 and the fourth groove portion 12 and the opening M will be explained based on the state in which the opening M is closed by the lid 3.

[0037] A plurality of fourth groove portions 12 are provided. The plurality of fourth groove portions 12 are provided so as to be connected to the third groove portions 11. The third groove portions 11 and the fourth groove portions 12 are provided in the lamination area A (see FIG. 5). The third groove portions 11 are provided so as to avoid the intended joining area Ab (joining area Aa), and the fourth groove portions 12 are provided in the intended joining area Ab (joining area Aa). The fourth groove portions 12 correspond to recessed portions provided in the lid-side lamination surface 6a.

[0038] The fourth groove 12 provided on the main body-side stacking surface 5a is a long groove, and the longitudinal direction Dc of the fourth groove 12 is inclined with respect to a reference direction Da along the periphery Ma of the opening M. Regarding the fourth groove 12, the reference direction Da along the periphery Ma of the opening M will be described. The fourth groove 12 has two ends 12a, 12b, one end 12a is connected to the third groove 11, and the other end 12b is separated from the third groove 11. The position on the periphery Ma of the opening M that is closest to one end 12a of the fourth groove 12 is identified, and the tangent direction of this closest position becomes the reference direction Da along the periphery Ma of the opening M with respect to the fourth groove 12. Note that in this embodiment, one end 12a of each of multiple adjacent fourth grooves 12 is aligned along the periphery Ma of the opening M, which is substantially linear, and shares the same reference direction Da.

[0039] Because the fourth groove portion 12 according to this embodiment extends linearly, the longitudinal direction Dc can also be considered a linear direction. When the smaller intersection angle β between a third virtual line along this linear direction and a fourth virtual line along the reference direction Da is greater than 0° and less than 90°, the longitudinal direction Dc of the fourth groove portion 12 is inclined with respect to the reference direction Da along the periphery Ma of the opening M. This intersection angle β is preferably 30° or greater and 70° or less, and more preferably 40° or greater and 50° or less. If the fourth groove portion 12 is not linear but bent along the way, the linear direction of the portion to which one end 12a of the fourth groove portion 12 belongs can be determined as the longitudinal direction Dc. If the fourth groove portion 12 is curved, the tangent direction of the portion to which one end 12a belongs can be determined as the longitudinal direction Dc.

[0040] When the lid 3 is closed, the body-side stacking surface 5a of the body-side flange 5 and the lid-side stacking surface 6a of the lid-side flange 6 overlap. Here, the second groove portion 92 of the body-side flange 5 and the fourth groove portion 12 of the lid-side flange 6 are arranged to intersect, for example, in an X-shape in plan view.

[0041] When the lid 3 is closed, the body flange 5 and the lid flange 6 are joined. As shown in Figures 3 and 4, a plurality of main joints 13 are provided in spots in the joining area Aa of the body flange 5 and the lid flange 6. The main joints 13 are provided so as to avoid the second groove 92 and the fourth groove 12. The main joints 13 join the body flange 5 and the lid flange 6 together by, for example, melting.

[0042] Low-bonding portions 14 are provided in the joining region Aa at positions overlapping the second groove portions 92 and the fourth groove portions 12. The second groove portions 92 and the fourth groove portions 12 are shaped so that the body-side stacking surface 5a and the lid-side stacking surface 6a are spaced apart (see FIG. 4(a)). Therefore, gaps are generated between the second groove portions 92 and the fourth groove portions 12, and the second groove portions 92 and the fourth groove portions 12 are not joined, or even if they are joined, the density is low. As a result, low-bonding portions 14, which have a weaker joining strength than the main joining portions 13, are formed in the areas overlapping the second groove portions 92 and the fourth groove portions 12.

[0043] Next, a method for joining the body flange 5 and the lid flange 6 will be described with reference to Figure 12. Figure 12 is an explanatory diagram that schematically shows an ultrasonic sealing machine 100. The ultrasonic sealing machine 100 includes a conveyor unit 101, a pressure roller 102, and an ultrasonic horn 103. The container 1, with the lid 3 attached to the container body 2 so as to close the opening M, is transported in one direction by the conveyor unit 101. The pressure roller 102 and the ultrasonic horn 103 are arranged on the movement trajectory of the body flange 5 and the lid flange 6 of the container 1. The pressure roller 102 and the ultrasonic horn 103 are arranged so as to face each other with the overlapping body flange 5 and lid flange 6 sandwiched between them.

[0044] The ultrasonic horn 103 has a vibration surface 103a that vibrates in contact with the lid-side flange 6. The pressure roller 102 has a gear portion 102a that rotates while in contact with the body-side flange 5. The gear portion 102a and the vibration surface 103a hold the lid-side flange 6 and the body-side flange 5 together. The ultrasonic vibrations applied from the vibration surface 103a to the lid-side flange 6 and the body-side flange 5 propagate into the lid-side flange 6 and the body-side flange 5, causing the joining surfaces to heat up and a softening and melting phenomenon to occur, joining the lid-side flange 6 and the body-side flange 5.

[0045] The shape of the joining surfaces of the body flange 5 and the cover flange 6 depends on, for example, the shape of the gear portion 102a of the pressure roller 102, and can be formed in various ways. For example, the size and area of ​​the joining surfaces depend on the size and shape of the convex portion of the gear portion 102a facing the vibration surface 103a. Furthermore, the spacing between the multiple joining surfaces depends on the pitch of the gear portion 102a. A specific description will be given below with reference to FIG. 8. FIG. 8 is an enlarged view schematically showing the shape of the joining surfaces, and FIG. 8(a) shows the joining surface 15 according to this embodiment. FIG. 8(b) shows the joining surface 15A according to a first modified example, and FIG. 8(c) shows the joining surface 15B according to a second modified example.

[0046] As shown in (a) of Figure 8, the bonding surface 15 according to this embodiment includes a plurality of bonding spots 16a. For example, two bonding spots 16a aligned in a direction away from the periphery Ma of the opening M form a pair to form one bonding unit 16. The plurality of bonding units 16 are arranged side by side along the periphery Ma of the opening M. A lower bonding portion 14 is formed in the portion of the bonding spot 16a that overlaps with the second groove portion 92 and the fourth groove portion 12, and a main bonding portion 13 is formed in the portion that avoids the second groove portion 92 and the fourth groove portion 12 (see Figure 3).

[0047] 8(b), the joint surface 15A according to the first modified example includes a plurality of joint units 16A arranged at equal intervals along the periphery Ma of the opening M. In the joint units 16A, low joint portions 14 are formed in the portions that overlap the second groove portion 92 and the fourth groove portion 12, and main joint portions 13 are formed in the portions that avoid the second groove portion 92 and the fourth groove portion 12.

[0048] 8(c), the joint surface 15B according to the second modification includes a first joint unit 16B extending along the periphery Ma of the opening M, and a second joint unit 16C located farther from the opening M than the first joint unit 16B and extending along the first joint unit 16B. In the first joint unit 16B and the second joint unit 16C, a low joint portion 14 is formed in the portion that overlaps with the second groove portion 92 and the fourth groove portion 12, and a main joint portion 13 is formed in the portion that avoids the second groove portion 92 and the fourth groove portion 12.

[0049] Next, a container 1A according to a second embodiment will be described with reference to Fig. 9. The container 1A has a structure common to the container 1. Therefore, the following description will focus on the differences, and the structures common to the container 1 will be assigned the same reference numerals and will not be described in detail.

[0050] The container 1A comprises a container body 2A having an opening M, a lid 3 that closes the opening M, and a hinge portion 4 that connects the container body 2A and the lid 3. The container body 2A is provided with a body-side flange 5A, and the lid 3 is provided with a lid-side flange 6. The body-side flange 5A comprises a body-side stacking surface 5a, and the lid-side flange 6 comprises a lid-side stacking surface 6a. In the container 1A, a recessed structure 10 is provided on the lid-side stacking surface 6a, but no recessed structure 9 is provided on the body-side stacking surface 5a. The recessed structure 10 comprises a third groove portion 11 and a fourth groove portion 12. The main joint portion 13 is provided so as to avoid the fourth groove portion 12, and the lower joint portion 14 is provided so as to overlap the fourth groove portion 12.

[0051] Next, a container 1B according to a third embodiment will be described with reference to Fig. 10. The container 1B has a structure common to the containers 1 and 1A. Therefore, the following description will focus on the differences, and the same reference numerals will be used to designate the same structures as the containers 1 and 1A, and detailed description thereof will be omitted.

[0052] Container 1B comprises a container body 2 having an opening M, a lid 3B that closes the opening M, and a hinge portion 4 that connects the container body 2 and the lid 3B. A body-side flange 5 is provided on the container body 2, and a lid-side flange 6B is provided on the lid 3B. The body-side flange 5 comprises a body-side stacking surface 5a, and the lid-side flange 6 comprises a lid-side stacking surface 6a. In container 1B, a recessed structure 9 is provided on the body-side stacking surface 5a, but no recessed structure 10 is provided on the lid-side stacking surface 6a. The recessed structure 9 comprises a first groove portion 91 and a second groove portion 92. A main joint portion 13 is provided so as to avoid the second groove portion 92, and a lower joint portion 14 is provided so as to overlap the second groove portion 92.

[0053] Next, a container 1C according to a fourth embodiment will be described with reference to Fig. 11. The container 1C has a structure common to the containers 1, 1A, and 1B. Therefore, the following description will focus on the differences, and the structures common to the containers 1, 1A, and 1B will be assigned the same reference numerals and will not be described in detail.

[0054] Container 1C comprises a container body 2C having an opening M, a lid 3C that closes the opening M, and a hinge portion 4 that connects the container body 2C and the lid 3C. The container body 2C and the lid 3C are substantially identical in shape. That is, the container can be considered to comprise two container portions of the same shape, in which case one container portion that contains food or the like is the container body 2C, and the other is the lid 3C. Note that even when no food or the like is contained, if one portion can be conveniently designated as the container body 2C, the other portion is the lid 3C. In this embodiment, the container portion on the left side shown in FIG. 11 is the container body 2C, and the container portion on the right side is the lid 3C.

[0055] The container body 2C is provided with a body-side flange 5C, and the lid 3C is provided with a lid-side flange 6C. The body-side flange 5C has a body-side stacking surface 5a, and the lid flange 6 has a lid-side stacking surface 6a. The container 1C has recessed structures 9, 10 on both the body-side stacking surface 5a and the lid-side stacking surface 6a. Therefore, like the container 1 according to the first embodiment, a first groove 91, a second groove 92, a third groove 11, and a fourth groove 12 are provided. When the lid 3C is closed and joined, the main joint 13 is provided so as to avoid the second groove 92 and the fourth groove 12, and the low joint 14 is provided so as to overlap the second groove 92 or the fourth groove 12.

[0056] Next, a description will be given of the actions and effects of the containers 1, 1A to 1C. Since the containers 1, 1A to 1C have substantially the same actions and effects, the container 1 will be described as a representative, and the actions and effects specific to each of the containers 1, 1A to 1C will be described later.

[0057] The container 1 includes a body-side flange 5 and a lid-side flange 6 joined to each other by a joining region Aa. The main joining portion 13 in the joining region Aa is provided to avoid the second groove portion 92 and the fourth groove portion 12. The second groove portion 92 or the fourth groove portion 12 is shaped to separate the body-side stacking surface 5a and the lid-side stacking surface 6a. Therefore, the second groove portion 92 or the fourth groove portion 12 is not joined and forms a gap, or even if joined, the density is low and the joining strength is weaker than the main joining portion 13. As a result, the area overlapping the second groove portion 92 or the fourth groove portion 12 becomes a low joining portion 14. The presence of the low joining portion 14 facilitates opening when peeling the lid body 3 from the container body 2. Furthermore, the provision of the second groove portion 92 or the fourth groove portion 12 makes it easier to manage the locations where the main joining portion 13 and the low joining portion 14 are formed, enabling appropriate joining. As a result, according to this container 1, the lid 3 and the container body 2 can be appropriately joined together, while improving the ease of opening.

[0058] The second grooves 92 and the fourth grooves 12 formed in the container 1 are provided along the periphery Ma of the opening M, and the second grooves 92 and the fourth grooves 12 are elongated grooves. In other words, by changing the orientation of the second grooves 92 or the fourth grooves 12 in the longitudinal directions Db and Dc, the ease of opening can be easily adjusted.

[0059] Furthermore, the multiple second groove portions 92 or multiple fourth groove portions 12 are arranged so as to be aligned along the periphery Ma of the opening M. Furthermore, the longitudinal directions Db, Dc of the multiple second groove portions 92 face the same direction, and these longitudinal directions Db, Dc are inclined with respect to the reference direction Da along the periphery Ma of the opening M. Therefore, compared to when the longitudinal directions Db, Dc are along the reference direction Da, it is easier to arrange more second groove portions 92 or fourth groove portions 12, and it is easier to expand the area where the low joint portion 14 is formed.

[0060] As shown in FIGS. 6 and 7 , the container 1 with the lid 3 open, i.e., the container 1 before joining, includes a body-side flange 5 and a lid-side flange 6. The body-side flange 5 includes a body-side stacking surface 5a, and the lid-side flange 6 includes a lid-side stacking surface 6a. At least a portion of the body-side stacking surface 5a and the lid-side stacking surface 6a constitutes a joining region Ab. A second groove 92 and a fourth groove 12 are formed in the joining region Ab. When the body-side flange 5 and the lid-side flange 6 are joined, a main joining region 13 is formed in the joining region Ab, avoiding the second groove 92 and the fourth groove 12. A weak joining region 14, which has a lower joining strength than the main joining region 13, is formed in the area overlapping the second groove 92 and the fourth groove 12. The formation of the weak joining region 14 makes it easier to peel the lid 3 from the container body 2 when opening. Furthermore, the provision of the second groove 92 and the fourth groove 12 makes it easier to manage the locations where the main bond portion 13 and the low bond portion 14 are formed, enabling appropriate bonding. As a result, this container 1 can improve openability while ensuring appropriate bonding between the lid 3 and the container body 2.

[0061] Furthermore, in the containers 1, 1A, and 1C, the fourth groove portion 12 is provided in the lid-side lamination surface 6a, which makes it easier to reduce the bonding strength when peeling the lid body 3 from the container body 2. For example, even in cases where the lid body 3 is peeled off from the container body 2 while being pulled while holding the container body 2 to prevent the contents from spilling, the provision of the fourth groove portion 12 in the lid-side lamination surface 6a can improve the ease of opening when peeling the lid body 3 off from the container body 2.

[0062] Furthermore, in the containers 1 and 1C, the second groove portion 92 is provided on the body-side lamination surface 5a, and the fourth groove portion 12 is provided on the lid-side lamination surface 6a. Therefore, compared to when the second groove portion 92 or the fourth groove portion 12 is provided on either one side, the location where the low-bonding portion 14 is formed is less uneven, improving the ease of opening.

[0063] Furthermore, in the containers 1 and 1C, the second grooves 92 and the fourth grooves 12 are arranged to intersect when the lid 3 is closed. If the second grooves 92 and the fourth grooves 12 overlap, this means that the low-bonding portions 14 overlap, narrowing the area where the low-bonding portions 14 are formed. When the second grooves 92 and the fourth grooves 12 intersect, the overlapping area is reduced, and the area where the low-bonding portions 14 are formed is expanded. In other words, it becomes easier to form the low-bonding portions 14 evenly over a wide area, improving the ease of opening.

[0064] In particular, containers 1, 1C are resin food packs in which lid body 3, 3C and container body 2, 2C are integrally sheet-molded via hinge portion 4, and because container 1 as a whole is flexible, there is a possibility that the lid flange 6 and container body flange 5 may become misaligned on the side opposite hinge portion 4 when lid body 3, 3C is closed. Even in this case, because second groove portion 92 and fourth groove portion 12 intersect, low joint portion 14 can be easily formed evenly over a wide area, improving openability.

[0065] Furthermore, the above-described containers 1, 1A to 1C can be formed from, for example, a stretched polystyrene sheet. When a polystyrene sheet is used, the balance of properties such as transparency, rigidity, and heat resistance is good. However, because stretched polystyrene sheets have rigidity, they tend to break easily, so there is a significant benefit in improving the ease of opening them. [Example]

[0066] EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In each example and comparative example, a container sample was prepared and the ease of opening was evaluated.

[0067] Example 1 The container according to Example 1 was formed based on the container according to the first embodiment. The container according to Example 1 was formed by vacuum forming a polystyrene sheet. The container comprises a container body having an opening, a lid that closes the opening, and a hinge portion that connects the container body and the lid. The container body comprises a body-side flange, and the lid comprises a lid-side flange. A second groove portion is provided on the body-side stacking surface of the body-side flange, and a fourth groove portion is provided on the lid-side stacking surface. The second groove portion and the fourth groove portion are formed to have substantially the same shape and dimensions. The second groove portion and the fourth groove portion are arranged to intersect when the lid is closed.

[0068] 13(a) is a plan view showing the second groove portion 92 of the container according to Example 1, and FIG. 13(b) is a cross-sectional view taken along line bb in FIG. 13(a). The spacing L between adjacent second groove portions 92 is 3.5 mm, and the inclination angle (intersection angle α) of the second groove portion 92 relative to the reference direction is 45°. The distance W in the width direction perpendicular to the longitudinal direction of the second groove portion 92 is 1.2 mm. The depth D of the second groove portion 92 is 0.3 mm. In cross-sectional view, the second groove portion 92 is formed in an arc shape, and the radius of curvature of the arc is 0.75 mm.

[0069] Example 2 The container according to Example 2 was formed based on the container according to the first embodiment. The container according to Example 2 was formed by vacuum forming a polystyrene sheet. The container comprises a container body having an opening, a lid that closes the opening, and a hinge portion that connects the container body and the lid. The container body comprises a body-side flange, and the lid comprises a lid-side flange. A second groove portion is provided on the body-side stacking surface of the body-side flange, and a fourth groove portion is provided on the lid-side stacking surface. The second groove portion and the fourth groove portion are formed to have substantially the same shape and dimensions. The second groove portion and the fourth groove portion are arranged to intersect when the lid is closed.

[0070] FIG. 13(c) is a plan view showing the second groove portion 92 of the container according to Example 2, and FIG. 13(d) is a cross-sectional view taken along line dd in FIG. 13(c). The spacing L between adjacent second groove portions 92 is 3.5 mm, and the inclination angle (intersection angle α) of the second groove portion 92 relative to the reference direction is 45°. The distance W in the width direction perpendicular to the longitudinal direction of the second groove portion 92 is 0.77 mm. The depth D of the second groove portion is 0.3 mm. In cross-sectional view, the second groove portion 92 is formed in an arc shape, and the radius of curvature of the arc is 0.4 mm. As will be described later, Example 2 also has a joint surface similar to that of Example 1, but for convenience, the joint surface is omitted in FIG. 13(c).

[0071] (Comparative Example 1) The container according to Comparative Example 1 had the same structure as Example 1, except that the second and fourth grooves were not formed.

[0072] The body flange and the lid flange of the containers according to Examples 1 and 2 and Comparative Example 1 were joined using an ultrasonic sealing machine. The body flange and the lid flange were joined so as to form a spot-like joining surface. Multiple joining spots 16a were formed on the joining surface, and two joining spots 16a aligned in a direction away from the periphery Ma of the opening M formed a pair to form one joining unit 16. In plan view, the joining spots 16a were approximately square with sides measuring 1 mm. The two joining spots 16a forming the joining unit 16 were spaced 1.5 mm apart. The multiple joining units 16 were arranged side by side, 1.5 mm apart, along the periphery Ma of the opening M. In Examples 1 and 2, the lower joining portion 14 was formed in the joining spot 16a in the portion overlapping the second groove portion 92 and the fourth groove portion, and the main joining portion 13 was formed in the portion avoiding the second groove portion 92 and the fourth groove portion. On the other hand, in Comparative Example 1, the second groove portion 92 and the fourth groove portion are not formed, and therefore the low joint portion 14 is not formed.

[0073] A plurality of containers according to Example 1 were prepared, and the lids were opened by peeling them off from the container body. A plurality of containers according to Example 2 were prepared, and the lids were opened by peeling them off from the container body. A plurality of containers according to Comparative Example 1 were prepared, and the lids were opened by peeling them off from the container body. As a result, the containers according to Example 1 and Example 2 could be opened without tearing or the like. In contrast, the container according to Comparative Example 1 was difficult to open, and some of them were torn. When the container according to Example 1 and the container according to Example 2 were compared, the container according to Example 1 was easier to open.

[0074] Although the present invention has been described above based on the embodiments and examples, the present invention is not limited to the above embodiments and examples, and other configurations are also possible. For example, in the above embodiments, the second groove portion, which is a recessed portion, is connected to the first groove portion, and the fourth groove portion is connected to the third groove portion. However, the second groove portion may not be connected to the first groove portion, and the fourth groove portion may not be connected to the third groove portion, or the first groove portion and the third groove portion may be omitted. Furthermore, the hinge portion may be omitted. [Explanation of symbols]

[0075] 1, 1A, 1B, 1C...container, 2, 2A, 2C...container body, 3, 3B, 3C...lid body, M...opening, Ma...periphery, 5, 5A, 5C...body side flange, 5a...body side stacking surface, 6, 6B, 6C...lid side flange, 6a...lid side stacking surface, 12...fourth groove portion, Dc...longitudinal direction of fourth groove portion, 13...main joint portion, 14...low joint portion, 92...second groove portion (recessed portion), Db...longitudinal direction of second groove portion, Da...reference direction, Aa...joining area, Ab...planned joining area.

Claims

1. a container body having an opening; a lid that closes the opening; a joining region that joins the lid body and the container body together when the opening is closed, the container body includes a body-side flange provided along the periphery of the opening, the lid body includes a lid-side flange that is laminated on the body-side flange, the body-side flange has a body-side stacking surface facing the lid-side flange, the lid-side flange has a lid-side lamination surface facing the body-side flange, a recessed portion is provided on at least one of the body-side stacking surface and the lid-side stacking surface, The joining region includes a main joining portion that joins the body-side flange and the lid-side flange while avoiding the recessed portion, and a lower joining portion that overlaps the recessed portion, The container, wherein the recessed portion has a long groove having a longitudinal direction, and at least one of both ends of the long groove in the longitudinal direction is closed.

2. A container as described in claim 1, wherein the recessed portion has a groove portion extending along the periphery of the opening when the lid body is closed, and the other of the two ends of the long groove is connected to the groove portion.

3. The container according to claim 1 or 2, wherein the recessed portion is provided on the lid-side stacking surface and the body-side stacking surface.

4. 4. The container according to claim 1, wherein the recessed portion comprises a plurality of the long grooves arranged side by side along the periphery of the opening.

5. 5. The container according to claim 1, wherein the longitudinal direction of the long groove is inclined with respect to a reference direction along the periphery of the opening.

6. A container body having an opening; a lid that closes the opening; a joining region that joins the lid body and the container body together when the opening is closed, the container body includes a body-side flange provided along the periphery of the opening, the lid body includes a lid-side flange that is laminated on the body-side flange, the body-side flange has a body-side stacking surface facing the lid-side flange, the lid-side flange has a lid-side lamination surface facing the body-side flange, a recessed portion is provided on at least one of the body-side stacking surface and the lid-side stacking surface, The joining region includes a main joining portion that joins the body-side flange and the lid-side flange while avoiding the recessed portion, and a lower joining portion that overlaps the recessed portion, the recessed portion is a plurality of grooves provided along the periphery of the opening, The groove portion is a long groove having a longitudinal direction. a longitudinal direction of the groove portion is inclined with respect to a reference direction along a periphery of the opening, the plurality of grooves are provided on the cover-side stacking surface and the body-side stacking surface, A container, wherein the longitudinal direction of the groove provided on the lid-side stacking surface and the longitudinal direction of the groove provided on the body-side stacking surface are arranged to intersect.

7. A container provided with a lid that closes an opening of a container body, the container body includes a body-side flange provided along the periphery of the opening, the lid body includes a lid-side flange that is laminated on the body-side flange, the body-side flange has a body-side stacking surface that faces the lid-side flange in a closed state, the lid-side flange has a lid-side stacking surface that faces the body-side flange in a closed state, At least a portion of the body-side lamination surface and the lid-side lamination surface is a planned joining area, a recessed portion is formed in each of the intended joining region of the main body side lamination surface and the intended joining region of the lid side lamination surface, the recessed portion is a long groove having a longitudinal direction, A container, wherein the long groove provided on the body side stacking surface and the long groove provided on the lid side stacking surface are arranged to intersect.

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