Lids for packaging containers

Abstract

To provide a lid body of a packaging container which prevents visibility of a storage article from being hindered from any angle and has excellent transparent feeling as a whole.SOLUTION: A lid body, which is fitted to a container body for storing a storage article and is obtained by molding a thermoplastic resin sheet material, includes a top plate part that has at least a pair of regions between opposite sides composed of planes and has a polygonal shape in plan view, and side wall parts that are continuously provided in a periphery of the top plate part and have fixed heights. The top plate part and the side wall part, and the adjacent side wall parts in a circumferential direction are continuously provided by an angular lateral leading-out corner part and a vertical leading-out corner part forming linear ridge lines in a horizontal direction and a height direction, chamfers obtained by cutting the vertical leading-out corner part into an inverse triangular shape and a triangular shape are provided on upper and lower parts of the ridge line in the height direction, and at least one of the upper and lower parts of the chamfers is chamfered into a spherical triangle.SELECTED DRAWING: Figure 20

Description

[Technical Field]

[0001] The present invention relates to a transparent lid for a packaging container formed from a thermoplastic resin sheet material, and relates to a configuration that enhances the visibility of the contents contained therein. [Background technology]

[0002] BACKGROUND ART Packaging containers for boxed lunches, sushi, prepared foods, and the like that are displayed and sold in supermarkets and convenience stores are well known. The container body and lid are molded from thermoplastic resin sheet material, and these are fitted together to close the lid. The lid is transparent, ensuring visibility of the food or other contents inside.

[0003] It is important for this type of packaging container to appeal to the eye and stimulate purchasing desire, but in the lid of Patent Document 1, the presence of anti-slip protrusions on the corners of the top plate makes it difficult to see from angles that pass through these protrusions, and even in the lid of Patent Document 2, there is an issue in that the recesses on the corners make the contents appear distorted. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-14370 [Patent Document 2] Japanese Patent Application Publication No. 2018-135111 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, when the part of the lid that protects the contents is made up of a top plate and a side wall, these parts have a significant impact on the visibility of the contents. Therefore, if the top plate and the side wall are each made up of a smooth surface without any irregularities, visibility will be good on a surface-by-surface basis through the top plate when the product is viewed from directly above, and through the side wall when the product is viewed from directly to the side.

[0006] On the other hand, when consumers choose a product, they often look at it from diagonally above rather than directly above or to the side, to observe the contents in three dimensions. In response to this, stores sometimes display products so that the consumer's line of sight is diagonally above. In any case, the angle from which consumers view products is not constant. Therefore, it is ideal to be able to see the contents as they are from any angle.

[0007] However, in conventional lids, the corners between the top plate and side wall where the surface direction changes, and the corners between adjacent side wall sections, are often rounded. In other words, each corner is narrow but forms a kind of curved surface. For this reason, even if the top plate and side wall sections are made of smooth surfaces, when the product is viewed from above at an angle, the contents appear distorted or blurred at each corner, hindering visibility, and the lid as a whole lacks transparency.

[0008] The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a lid for a packaging container that does not impede the visibility of the contents from any angle and has excellent overall transparency. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention uses a lid body that fits onto a container body that stores contents and is made by molding a thermoplastic resin sheet material, and that has a top plate portion that is polygonal in plan view, with at least one pair of opposite side regions formed as a flat surface, and side wall portions of a constant height that are connected to the periphery of the top plate portion, and the top plate portion and the side wall portions, and the side wall portions adjacent in the circumferential direction, are connected by angular horizontal and vertical corner portions that form linear ridges in the horizontal and vertical directions, respectively, and above and below the ridge line in the vertical direction, chamfered portions are formed by cutting the corners of the vertical corner portions into an inverted triangle and a triangle, respectively, and at least one of the top and bottom of the chamfered portion is chamfered into a spherical triangle.

[0010] According to the above means, the lid body has a flat top plate portion, and the connecting portions between the top plate portion and the side wall portions and the connecting portions between the side wall portions are composed of angular horizontal and vertical corner portions.Therefore, even when observed from above at an angle, the visibility of the contents is not hindered by the horizontal and vertical corner portions, and the lid body can be made to have excellent transparency, like that of glass.

[0011] In addition, the upper and lower chamfered portions may have a ridge line formed in the height direction between their respective vertex angles, and may be spaced apart vertically by the length of the ridge line. By concentrating the chamfered portions at the four corners of the side wall portion in this manner, the strength of the lid body can also be improved.

[0012] Regarding the top plate, the phrase "at least one area between two opposite sides is flat" means that the area ratio of the top plate that is flat is higher than the area ratio of the top plate that is not flat, and does not mean that the entire surface must be flat. Furthermore, the lid is preferably transparent. However, it does not only mean a completely transparent body in the sense of the word, but also includes translucency as long as the objective of improving visibility of the present invention can be achieved.

[0013] Furthermore, the following is added as a means for solving the problems of the present invention. (Appendix 1A) A packaging container comprising a lid body and a container body formed by sheet molding, wherein a plurality of container bodies can be stacked by placing the container body on the lid body, The lid body is A top plate portion that is entirely flat, a side wall portion that is downwardly connected to the periphery of the top plate portion via a linear connecting portion, and at least a portion that is continuous with the connecting portion is configured as a flat surface; The radius of curvature on the surface side of the connecting portion is 0.6 mm or less, The container body is A bottom plate portion; and legs projecting downward from the periphery of the bottom plate portion, The bottom plate portion and the leg portions form a loading recess with a cross-sectional recessed shape and an open bottom surface in the lid body. A packaging container characterized by: (Appendix 2A) A packaging container in which the radius of curvature of the inner corner formed by the bottom plate and the leg in the loading recess is 0.6 mm or less. (Appendix 3A) A packaging container in which the protruding length of the legs that defines the depth of the loading recess is 5 mm or less. (Appendix 4A) A packaging container in which the loading recess has multiple legs formed around the periphery of the bottom plate, avoiding the corners, so that the corners corresponding to the corners of the bottom plate are open. (Appendix 5A) The container body further comprises a body peripheral wall portion rising upward on the outer periphery of the bottom plate portion, a body flange portion extending outward from the body peripheral wall portion, and a skirt portion extending downward from the body flange portion, the lower edge of which is at the same level as the lower end of the leg formed between the bottom plate portion and the body peripheral wall portion, or extends below that level. (Appendix 6A) The bottom plate portion of the packaging container comprises a raised bottom portion and a base bottom portion formed one step lower around the raised bottom portion with a step portion interposed therebetween, and a rib is provided near the step portion of the raised bottom portion and protrudes downward from the raised bottom portion with a protruding length equal to or less than the height of the step portion. (Appendix 7A) The rib is a straight line in plan view that crosses the corner of the raised bottom in a corner-cutting manner and connects both ends to two adjacent sides of the base of the packaging container. (Appendix 1B) A lid for a packaging container formed by molding a thermoplastic resin sheet material, A top plate portion having a polygonal shape in plan view; a side wall portion of a constant height provided adjacent to the periphery of the top plate portion, The top plate portion is formed of a flat surface, the side wall portion has a flat portion connected to the top plate portion and an adjacent side wall portion via a linear connecting portion, a dihedral angle θ between the top plate portion and the side wall portion is θ>90°; The radius of curvature R on the surface side of the connecting portion is R≦0.6 mm A lid for a packaging container characterized by: (Appendix 2B) A lid for a packaging container, wherein the dihedral angle θ formed between the top plate and the side wall is 90°<θ≦105°. (Appendix 3B) The sheet material is made of PET resin. The IV value of the PET resin (based on JIS K7367-1) is 0.70 to 0.85, The moisture content of the sheet material (as determined by Karl Fischer coulometric titration in accordance with JIS K0113) is less than 1500 ppm; The sheet material has a thickness of 0.10 to 0.80 mm. (Appendix 4B) The lid for a packaging container is made of a sheet material having a thickness of 0.20 to 0.50 mm. (Appendix 5B) A method for forming a lid for a packaging container, comprising: A method for forming a lid for a packaging container using a vacuum forming method in which a sheet material is vacuumed against the male mold side. [Effects of the Invention]

[0014] According to the present invention, the connecting portion where the surfaces of the top plate and side wall that make up the lid change significantly is composed of angular corners indicated by linear ridges, so that the visibility of the contents stored in the container body is not hindered regardless of the line of sight. Furthermore, the vertical corners are chamfered above and below the ridge in the height direction, with the corners cut into an inverted triangle and a triangle, respectively, so that the chamfers are concentrated at the four corners of the side wall, improving the strength of the lid without hindering the visibility of the contents. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a perspective view of a packaging container according to an embodiment of the present invention; [Figure 2] FIG. 1 is a plan view of the lid body. [Figure 3] FIG. 1 is a side view of the lid. [Figure 4] End view of line AA in Figure 2 [Figure 5] End view of line BB in Figure 2 [Figure 6]Process diagram showing the molding method of the present invention [Figure 7] FIG. 1 is a plan view of the container body. [Figure 8] FIG. 1 is a side view of the container body. [Figure 9] End view of CC line in Figure 7 [Figure 10] 1 is an explanatory diagram showing the relationship between the lid and the container body when the packaging containers are stacked. [Figure 11] 1. An explanatory diagram showing the state in which the container body is tilted due to misalignment. [Figure 12] An explanatory diagram showing the procedure for correcting the tilted container body to its original position. [Figure 13] FIG. 10 is a plan view of a container body according to another embodiment; [Figure 14] DD line end view in Figure 13 [Figure 15] An explanatory diagram showing the procedure for correcting the tilted container body to its original position. [Figure 16] FIG. 10 is a plan view of the main part of the container body showing a modified example of the rib; [Figure 17] 1 is a perspective view of a cover according to a first embodiment of the present invention; [Figure 18] 10 is a perspective view of a cover according to the second embodiment of the present invention. [Figure 19] 10 is a perspective view of a cover according to the third embodiment. [Figure 20] 10 is a perspective view of a cover according to the fourth embodiment. [Figure 21] 10 is a perspective view of a cover according to the fifth embodiment. [Figure 22] 10 is a perspective view of a lid according to the sixth embodiment. [Figure 23] 10 is a perspective view of a cover according to the seventh embodiment of the present invention. [Figure 24] 10 is a perspective view of a cover according to the eighth embodiment of the present invention. [Figure 25] 10 is a perspective view of a cover according to the ninth embodiment. [Figure 26] 10 is a perspective view of a cover according to the first embodiment. [Figure 27] FIG. 1 is an explanatory perspective view of a lid according to the molding method of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0016] Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Fig. 1 is a perspective view of a packaging container according to one embodiment of the present invention, showing a lid 10 and a container body 20 separated from each other. The configurations of the lid 10 and the container body 20 will be described in detail below.

[0017] First, to explain the structure of the lid 10 in detail, the lid 10 is transparent. Figures 2 and 3 are a plan view and a side view showing only the lid 10, which has a flange 11 that is attached from the outside to the opening edge of the container body 20, and further has a concave lid fitting portion 12 on the side of the flange 11 that fits into the body fitting portion 21. The portion that protects the contents stored in the container body 20 is made up of a top plate 1 and a side wall 2 of a fixed height that is connected to the periphery of the top plate.

[0018] The top panel 1 is a rectangle in plan view, with the entire surface being flat. Side wall portions 2 are connected to each of the four sides of the top panel 1 via connecting portions 3. Each connecting portion 3 is made up of an angular, horizontally projecting corner that forms a linear ridge in the horizontal direction along the four sides of the top panel 1, and when viewed as a whole, it forms the same rectangular shape in plan view as the top panel 1. Note that in this embodiment, the top panel 1 is illustrated as having a rectangular shape in plan view, and its entire surface is described as being flat. However, if the top panel 1 has another polygonal shape in plan view, the object of the present invention regarding visibility can be achieved by making at least one region between two opposite sides flat, as long as the area proportion of the top panel 1 that is flat is higher than the area proportion of the top panel 1 that is not flat.

[0019] In this embodiment, as shown in Figure 3, the side wall 2 has a two-tiered structure with an upper flat surface 4 and a lower flat surface 5 separated by a boundary 6. The upper flat surface 4 is connected to the top plate 1 via the horizontal connecting portion 3 described above, while adjacent upper flat surfaces 4 on the left and right are connected by a connecting portion 7 that is linear in the vertical direction. In other words, this connecting portion 7 is composed of an angular vertical corner that forms a linear ridge in the height direction. Meanwhile, the lower flat surface 5 is connected to the upper flat surface 4 via the boundary 6, while adjacent lower flat surfaces 5 on the left and right are connected by a triangular chamfered portion 8. Here, the upper and lower flat plane portions 4 and 5 have the same rising angle from the flange portion 11 side toward the top plate portion 1 side, and are flush, so that in reality there is no linear boundary portion 6 as shown in the figure, but because the connecting configuration between adjacent flat plane portions is different, with the upper flat plane portion 4 having a linear connecting portion 7 and the lower flat plane portion 5 having a triangular chamfered portion 8, for the sake of convenience of explanation they are referred to as boundary portion 6. Therefore, like the connecting portion 7, the oblique side toward the vertex angle of the chamfered portion 8 is also configured with an angular vertical corner portion that forms a linear ridge in the height direction.

[0020] The side wall 2 is formed with a stacking protrusion 9 that bulges outward from the container, spanning the lower flat surface 5 and the flange 11. This prevents the lids 10 from fitting completely together when stacked on top of each other, making it easier to remove the lids 10 one by one when closing the container body 20 containing contents (foodstuffs, etc.). Apart from this stacking protrusion 9, the side wall 2 can be said to be entirely flat, just like the top plate 1, and this is one of the characteristic features of the present invention.

[0021] Further characteristic features of the lid 10 will be described with reference to Figures 4 and 5. First, the dihedral angle between the top panel 1 and the side wall 2 (upper flat surface 4) is set to greater than 90° and less than 105° on both the long and short sides of the lid 10, as a preferred example for ensuring rigidity. Specifically, the dihedral angle θ1 on the long side is set to 97.0°, as shown in Figure 4. The dihedral angle θ2 on the short side, not shown, is also set to greater than 90° and less than 105°. Furthermore, the angle θ2 between the top panel 1 and the connecting portion 7 at the corner of the lid 10 is set to 100.0°, as shown in Figure 5. The two sets of dihedral angles on the long and short sides can be set to different angles as long as they are within the above-mentioned range. By setting different angles in this way, the display appearance of containers containing contents can be varied compared to containers with the same angle, thereby increasing customer appeal.

[0022] Furthermore, the radius of curvature R on the front surface of the connecting portion 3 between the top panel 1 and the side wall 2 (upper flat portion 4), and the connecting portion 7 between the side wall portions 2 (upper flat portions 4) are all set to 0.4 mm. This value is also one example, and it is preferable to set it smaller, but the object of the present invention can be achieved if it is 0.6 mm or less. In short, what is important in the present invention is that the connecting portions 3 and 7 are composed of angular horizontal and vertical corners that form linear ridges in the horizontal and vertical directions.

[0023] By configuring the top plate 1 and side wall 2 as described above, the lid 10 maintains rigidity while providing good visibility. In other words, in terms of rigidity, the top plate 1 is supported almost vertically by the side wall 2, which increases the load-bearing capacity, and by forming the connecting portions 3 and 7 into angular shapes with extremely small radii of curvature, the resistance to bending and twisting is increased.

[0024] Regarding visibility, the top panel 1 is entirely flat, and the side wall 2 is also entirely flat at the upper flat section 4 and flat at the lower flat section 5 except for the stacking protrusion 9. Furthermore, the connecting sections 3·7 are composed of angular horizontal and vertical corners that form linear ridges in the horizontal and vertical directions, so that the contents can be clearly seen without distortion not only from directly above or directly to the side but also from diagonally above. Furthermore, in this embodiment, the vertices formed by the three surfaces of the top panel 1 and the two adjacent side walls 2, i.e., the four corners F of the top panel 1, are composed of pin-angle shapes (ridge angles) whose tips coincide with the intersections of the connecting sections 3·7. Therefore, even when viewed obliquely toward one of the four corners F of the top panel 1, visibility at that corner is not impaired, and the transparency of the entire lid 10 is enhanced.

[0025] The lid 10 is most easily visible when it is colorless and transparent, but there are no limitations on color or transparency. The molding material, i.e., the sheet material, can be selected from conventionally known thermoplastic resins, with thermoplastic polyester resins such as PBT resin, PEN resin, PET resin, PETG resin, and SPG resin being preferred. It is particularly preferable to select PET resin, which offers excellent workability, moldability, and cost.

[0026] Furthermore, when molding the lid 10 using a PET resin sheet material, it is preferable to use a sheet material made of PET resin with an IV value (based on JIS K7367-1) of 0.70 to 0.85, a moisture content (based on Karl Fischer coulometric titration method based on JIS K0113) of less than 1500 PPM, and a thickness of 0.10 to 0.80 mm. Note that if the sheet thickness is in the range of 0.20 to 0.50 mm, it is possible to achieve both the above-mentioned rigidity and visibility at a higher level.

[0027] Next, a method for molding the lid 10 will be described with reference to FIG. 6. (a) to (e) in the figure are conceptual diagrams showing the molding process for the lid 10. First, the thermoplastic resin sheet material 30 is heated and softened by a double-sided heater 31 (FIG. 6(a)). The softened sheet material 30 is then transported between a mold (male mold) 32 and a plug 33 (FIG. 6(b)). The mold 32 is then raised and its molding surface is pressed against the sheet material 30 (FIG. 6(c)). In this state, the plug 33 is actuated to seal the sheet material 30 between the mold 32, and a vacuum is drawn through multiple suction holes 32a formed through the mold 32 (FIG. 6(d)). The mold 32 and plug 33 are then returned to their original positions and released (FIG. 6(e)). After that, the excess portion is cut off and trimmed to obtain the lid 10.

[0028] Here, vacuum forming has been described as the molding method for lid 10, but pressure forming, in which softened sheet material is tightly attached to a mold using compressed air, may also be used, and vacuum forming and pressure forming may be used simultaneously. While vacuum forming can be used to mold lid 10 having connecting portions 3·7 with the angular horizontal and vertical corners described above, the arrangement of suction holes 32a for molding top plate 1 more smoothly while maintaining transparency will be described in detail at the end.

[0029] Next, the configuration of the container body 20 will be described in detail. As shown in Figures 7 and 8 as well as Figure 1, the container body 20 in this embodiment comprises a bottom plate 22, a body peripheral wall 23 rising upward from the outer periphery of the bottom plate 22, a body flange 24 extending outward from the body peripheral wall 23, and a skirt 25 extending downward from the body flange 24 via the body fitting portion 21 described above. The bottom plate 22 is rectangular in plan view and has approximately the same area as the top plate 1 of the lid 10. After placing foodstuffs or other contents on the bottom plate 22, the lid 10 is placed over the container and the lid fitting portion 12 and the body fitting portion 21 of the two are fitted together to complete the lid closing operation. The rigidity and visibility of the packaging container closed in this manner have been described in detail above.

[0030] In this embodiment, the bottom plate portion 22 has a raised bottom. That is, the inner side of the bottom plate portion 22 has a raised bottom portion 22a, and a lower base portion 22c is formed around the raised bottom portion 22a via a stepped portion 22b. Of these, the raised bottom portion 22a is the main portion on which the contents are placed, and the surrounding base portion 22c catches drips and excess oil from ingredients and also functions as a portion for placing small items such as soy sauce and wasabi that are added as needed.

[0031] A plurality of legs 26 are provided intermittently on the outer periphery of the bottom plate 22 (base portion 22c) and inside the main body peripheral wall 23. In this embodiment, the legs 26 are linear in plan view and provided at eight locations in total, two on each of the long and short sides of the container body 20. One of the features of this embodiment is that the legs 26 are intentionally provided to avoid the corners 22d of the bottom plate 22. Note that the legs 26 do not necessarily literally serve as parts that support the container body 20 (packaging container); if the extension length of the above-mentioned skirt portion 25 is sufficiently long, the skirt portion 25 may actually function as a leg of the container body 20.

[0032] As shown in FIG. 9 , the legs 26 protrude downward from the bottom plate 22, and the legs 26 and the bottom plate 22 define a loading recess 27 with a cross-sectionally concave shape and an open bottom. In this embodiment, the legs 26 are provided intermittently, so that the loading recess 27 is concave only in the cross section passing through the legs 26. However, as described below, the loading recess 27 still functions to fit the lid 10. In addition, since the bottom plate 22 has a raised bottom, the top surface of the loading recess 27 has a two-tiered structure. In this embodiment, the base 22c is used as the reference plane to define the top surface. Furthermore, the radius of curvature R1 of the inner corner 27a of the loading recess 27 formed by the legs 26 and the base 22c is set to 0.6 mm or less, corresponding to the radius of curvature R of the surface side of the connecting portion 3 of the lid 10. Although the angle of the interior corner portion 27a is not limited, it is effective to make it correspond to the dihedral angle formed by the top plate portion 1 and the side wall portion 2 (upper flat surface portion 4) of the lid body 10 in terms of ease of fitting and prevention of horizontal misalignment.

[0033] When packaging containers containing contents and equipped with the above-described container bodies 20 are stacked flat in several tiers, the container body 20 of the upper container is placed on top of the lid 10 of the lower container by fitting the loading recess 27 into the lid 10, as shown in Figure 10. When stacked in this manner, in the present invention, the three-dimensional shapes of the upper part into which the lid 10 is fitted and the inner surface of the loading recess 27 of the container body 20 are nearly identical, and in particular, the range of curvature R on the surface side of the connecting portion 3 of the lid 10 and the radius of curvature R1 of the inner corner of the loading recess 27 of the container body 20 are identical or have a similar corresponding relationship, so that the stacked state can be maintained firmly.

[0034] The depth of stacking recess 27 is determined by the protruding length of leg 26, and the deeper the depth, the stronger the retention of the fitted state, but in the present invention, as described above, the top plate 1 and side wall 2 of lid 10 are configured as flat surfaces, and the range of curvature R on the surface side of connecting portion 3 in lid 10 and the radius of curvature R1 of inner corner 27a of stacking recess 27 in container body 20 are made to match or approximate each other, thereby enabling a firm stacking state to be maintained, and the depth of stacking recess 26 can be made as small as possible. Specifically, a protruding length of 5 mm from base 22c is sufficient for leg 26, and making it shorter improves the formability of container body 20 and contributes to improved productivity.

[0035] Furthermore, in this embodiment, as described above, the legs 26 are avoided from being disposed at the corners 22d of the bottom plate 22, and the corners (corners) of the loading recess 27 are intentionally opened (i.e., no corners are present). This configuration is more preferable because it increases the design freedom of the lid 10 and prioritizes visibility. In contrast, if, for example, L-shaped legs 26 are provided along the corners 22d of the bottom plate 22 to form corners of the loading recess, the top plate 1 of the lid 10 must also be shaped to precisely fit the corners of the loading recess, which restricts the formability of the lid 10. However, the present invention does not intend to completely eliminate such configurations and may adopt them as desired.

[0036] In this way, in the present invention, the stacked packaging containers remain firmly stacked (engaged in the stacking recesses) even when a lateral external force or slight vibration is applied to the stacked packaging containers. However, for example, after a consumer picks up a container, the containers may shift from the correct position, causing the loading recesses 27 to come loose and the container body 20 of the upper container to become tilted relative to the lid 10 of the lower container. Figure 11 shows a state in which the loading recesses 27 have come loose for some reason, causing the container body 20 of the upper container to become tilted relative to the lid 10 of the lower container. When the upper container tilts in this way, the conventional configuration has no way to prevent it, and there is a risk that the upper container will avalanche. However, according to the present invention, the extension length of the skirt portion 25 of the container body 20 is sufficiently long so that even if the container body 20 tilts, the lower edge 25a of the skirt portion 25 catches on the upper corners (side wall portions 2) of the lid 10 of the lower container, preventing the upper container from collapsing. In particular, the connecting portions 3 and 7 of the lid 1 are formed into angular shapes with extremely small radii of curvature, making it easy for the lower edge 25a of the skirt portion 4 to catch on these portions as well. In this case, the extension length of the skirt portion 25, although depending on the size of the lid 10 and other factors, is at least at the same level as the lower ends 26a of the legs 26, and more preferably, it extends downward beyond the lower ends 26a of the legs 26.

[0037] On the other hand, to return the upper container to its original position after it has tilted as described above, it is sufficient to slide the container body 20 little by little in the direction that corrects the tilt, as shown in Figure 12 (Figures 12(a) and 12(b)). However, depending on the weight of the contents of the container body 20, the step portion 22b of the upper container may get caught on the upper corner portion (corresponding to the connecting portion 3) of the lid body 10 of the lower container midway, making it difficult to slide the upper container any further.

[0038] 13 and 14, another embodiment of container body 40 that improves on this point will be described. Container body 40 has the same configuration as the above embodiment, with bottom plate portion 41 having a raised bottom portion 42 on the inner side and a lower base portion 44 formed around the periphery via a stepped portion 43. However, in this embodiment, ribs 45 that are rectangular in plan view and protrude downward from raised bottom portion 42 are provided near stepped portion 43. More specifically, ribs 45 are provided at the four corners of raised bottom portion 42 (FIG. 13), and their protruding length H1 is set to be approximately the same as height H0 of stepped portion 43.

[0039] With a container body 40 provided with such ribs 45, even if the upper container tilts, the ribs 45 will ride up onto the upper corners of the lid body 10 of the lower container (Figure 15(a)), and while the upper container is sliding in a direction to eliminate the tilt, the ribs 45 act as a guide, sliding against the top plate portion 1 of the lid body 10 of the lower container (Figure 15(b)), so that the step portion 43 located outside of this will never get caught on the upper corners of the lid body 10, allowing the upper container to be smoothly returned to its original position (Figure 15(c)).

[0040] In addition to the above-mentioned guide function, rib 45 also functions to reinforce bottom plate portion 41, but if protruding length H1 is made too large, a new step will be created in addition to the original step 43, onto which the upper corner of lid 10 of the lower container may become caught, and this will also affect the formability of container body 40. For this reason, in the present invention, protruding length H1 of rib 45 is set to be equal to or less than height H0 of step 43.

[0041] In this regard, in the modified example shown in Figure 16, rib 50 is formed linearly in plan view, cutting across corner 52 of raised bottom 51 and connecting both ends to adjacent base 53a on the long side and base 53b on the short side via step 53. Therefore, even though rib 50 has a relatively small protruding length, it still exhibits a reinforcing function that more reliably prevents bending or twisting of raised bottom 51. Of course, rib 50's guiding function as described above allows an upper container that is beginning to collapse to return to its original position smoothly.

[0042] Next, Examples 1 to 10 in which the configuration of the lid 10 according to the above embodiment is modified while maintaining high visibility and transparency will be described with reference to Figs. 17 to 26. Note that the same components as those in the lid 10 of the above embodiment are denoted by the same reference numerals. Furthermore, the same components will be described with the same reference numerals between Examples. [Example]

[0043] 17 is a perspective view of a lid 100 according to Example 1. In Example 1, as in the above embodiment, a planar chamfered portion 8 is formed on the lower side of the vertical corner portion that constitutes the connecting portion 7 between the side wall portions 2, and an additional planar chamfered portion 101 having an inverted triangle shape is also formed on the upper side of the connecting portion 7. In other words, in Example 1, the pin-shaped (ridged) corners of the four corners of the top plate portion 1 in the above embodiment are chamfered into an inverted triangle to form the chamfered portion 101. Therefore, the same effects as those of the above embodiment can be obtained in terms of visibility of the contents and overall transparency.

[0044] In addition, in this Example 1, the connecting portion 7 is formed between the vertices of the upper and lower chamfered portions 101 and 8. In other words, the upper and lower chamfered portions 101 and 8 are spaced apart vertically by the height of the connecting portion 7. Therefore, by concentrating the chamfered portions 101 and 8 at the four corners of the side wall portion 2, the strength of the lid body 100 is improved. [Example]

[0045] 18 is a perspective view of a lid 200 according to Example 2. In Example 2, as in Example 1, a pair of upper and lower chamfered portions 101 and 108 are formed at the four corners of the side wall 2. However, in Example 2, the connecting portion 201 of the side wall 2 is formed in an X-shape, and the chamfered portions 101 and 108 are not spaced apart but have a common apex angle. Thus, in Example 2, the same visibility and transparency as in the embodiment can be obtained, and the same strength as in Example 1 can be ensured. [Example]

[0046] 19 is a perspective view of a lid 300 according to Example 3. Example 3 is different from the above-described embodiment in that the connecting portion 301 between the side wall portions 2 is configured as a vertically rounded corner portion with a curved outer shape. In the lid 300 according to Example 3, the connecting portion 3 around the top plate portion 1 is also configured as an angular horizontally rounded corner portion that forms a linear ridge in the horizontal direction. Therefore, when observed from diagonally above, which is a more common observation method, the connecting portion 3 does not impede visibility, and a higher transparency is obtained than in conventional lids in which the connecting portion 3 is formed at a rounded angle. [Example]

[0047] FIG. 20 is a perspective view of a lid 400 according to a fourth embodiment, which corresponds to the invention described in the claims of the present application. This fourth embodiment is similar to the first embodiment in that chamfered portions 401 and 408 are formed above and below the connecting portion 7 between the side wall portions 2, spaced apart by the length of the connecting portion 7 and rounded at the corners. However, in this fourth embodiment, the upper chamfered portion 401 is a spherical triangle, which differs from the flat chamfered portion 101 in the first embodiment. It is optional whether either the upper or lower chamfered portion is a spherical triangle, and both the upper and lower chamfered portions may be spherical triangles. Alternatively, the upper and lower chamfered portions may each have an inwardly bulging inner spherical surface. Alternatively, only one of the lower chamfered portions 8 may have an inwardly bulging inner spherical surface. In this fourth embodiment, as in the first embodiment, the chamfered portions 401 and 408 are concentrated at the four corners of the side wall portion 2, thereby improving the strength of the lid 400.

[0048] So far, in the lid bodies according to the embodiments and Examples 1 to 4, at least the connecting portion between the top plate and the side wall portion is composed of angular horizontal corner portions that form a horizontal linear ridge. Therefore, when the lid body is placed on a serving table or a shelf with the top plate as the bottom, the angular connecting portion creates a sharp edge, preventing tilting and improving stability.

[0049] In addition, the edge effect described above makes it easier for fingers to hook and grasp the lid, and since the contact area of ​​the fingers with the connecting portion when grasping the lid in this manner is small, fingerprints and the like are less likely to be left on the lid, and the impact of fingerprints and the like on visibility can be minimized.

[0050] Furthermore, when the lid body is used as the container body, the effect of increasing the storage capacity can be expected because the connecting portion is configured as an angular protruding portion. [Example]

[0051] Although the lids described so far have been rectangular, they may also be dome-shaped, as in the lid 500 according to Example 5 shown in FIG. 21 . In Example 5, the top panel 501 has a rectangular shape in plan view with a semicircular cross section, and includes a pair of semicircular side walls 502 on both sides. The top panel 501 and the side walls 502 are connected by an angular semicircular corner 503 that forms a semicircular ridge. In Example 5, the angular semicircular corner 503 that forms the connecting portion does not impede visibility when observed from diagonally above. Although the top panel 501 has a curved surface throughout, the object of the present invention regarding visibility can be achieved as long as the area ratio of the top panel 501 that is formed by the curved surface is higher than the area ratio of the top panel 501 that is not formed by the curved surface. [Example]

[0052] 22 is a perspective view of a lid 600 according to Example 6, which is similar to Example 5 in that the top plate 601 is dome-shaped. However, in Example 5, the top plate 501 is semicircular and does not have front and rear side plates. In contrast, in Example 6, the top plate 601 has an arc-shaped cross section that is less than a semicircle, and a pair of rectangular side walls 602 are provided at the front and rear of the top plate 601. Furthermore, a pair of mountain-shaped side walls 603 with arc-shaped upper edges are provided at both left and right ends of the top plate 601. The front and rear rectangular side walls 602 are connected to the front and rear of the top plate 601 by angular horizontal corners 604 that form horizontally linear ridgelines, and the left and right mountain-shaped side walls 603 are connected to the left and right of the top plate 601 by angular arc-shaped corners 605 that form arc-shaped ridgelines. The rectangular side wall portion 602 and the mountain-shaped side wall portion 603 are connected by an angular vertical corner 606 that forms a linear ridgeline in the height direction. Therefore, in the lid 601 according to Example 6, as in Example 5, visibility is not hindered by the arc-shaped corner 605, and visibility at the vertical corner 606 is also good. Furthermore, the four corners F of the top plate 601 are configured as pin-angle shapes whose tips coincide with the intersections of the arc-shaped ridgeline (arc-shaped corner 605), the horizontal ridgeline (horizontal corner 604), and the height ridgeline (vertical corner 606). Therefore, even when viewed obliquely toward one of the four corners F of the top plate 601, visibility at that corner is not hindered, and the transparency of the entire lid 600 is improved. In the sixth embodiment, the connecting portion between the rectangular side wall portion 602 and the mountain-shaped side wall portion 603 is chamfered into a triangle with two vertical corner portions 606 forming the hypotenuse, but this portion may be formed without the corner chamfering and with a single vertical corner portion 606. Alternatively, the vertical corner portion 606 may have a different angle of the hypotenuse to form a connecting portion (connecting portion 7 in the first embodiment) in the same manner as in the first embodiment, and a flat chamfered portion 8 may be formed below the connecting portion. [Example]

[0053] 23 is a perspective view of a lid 700 according to Example 7, which is the lid according to the embodiment of FIG. 1, but with an area for affixing a label bearing information such as price, ingredient names, place of production, and expiration date. That is, like the above-described embodiment, the connecting portion 3 on the long side of the top plate 1 and side plate 2 is configured with a sharp, horizontally projecting corner that forms a linear horizontal ridge. However, in Example 7, the connecting portion 3 is divided midway without forming a horizontally projecting corner, forming a curved surface 701. Therefore, when a label is affixed across this curved surface 701 to the top plate 1 and side plate 2, the label will not be torn by the sharp corners. Furthermore, in this example, as in the embodiment of Figure 1, the vertices formed by the top panel 1 and the three surfaces of the two adjacent side wall portions 2, i.e., the four corners F of the top panel 1, are configured as pin-angles (edge ​​angles) whose tips coincide with the intersections of the connecting portions 3 and 7. Therefore, even when viewed obliquely toward one of the four corners F of the top panel 1, the visibility at that portion is not hindered, and the transparency of the entire lid 10 is enhanced. In other words, in this Example 7, except for the label affixed portion, the same effects as those of the above-mentioned embodiments can be obtained in terms of visibility and transparency. [Example]

[0054] FIG. 24 is a perspective view of a lid 800 according to Example 8. As with Example 7, a label-attachable area is provided. However, in Example 8, the horizontal corners of the connecting portion 3 are changed to inclined surfaces 801, which are flatly rounded corners. However, this does not change the effect of Example 7, and the same effects as Example 7 are obtained in terms of visibility and transparency. What is necessary in the present invention is to eliminate the angularity of the horizontal corners around the top panel when securing a label-attachable area. While Examples 7 and 8 describe the curved surface 701 and inclined surface 801 as the label-attachable area, wrapping strips or the like can also be wrapped around this area. In this invention, this area is broadly considered an accessory area. [Example]

[0055] 25 is a perspective view of a lid 900 according to Example 9. Example 9 is characterized in that the side wall portions 2 are connected to each other at the four corners of the top panel 1 via vertical recessed corner portions 901 that are concavely curved and recessed inward. That is, in Examples 1 to 8, these portions basically protruded outward due to vertical recessed corner portions or the like, but in Example 9, they are recessed inward. However, the connecting portions 3 between the top panel 1 and the side panel portions 2 are formed by angular horizontal recessed corner portions that form a linear ridge in the horizontal direction, and the connecting portions 902 between the side wall portions 2 formed on both sides of the vertical recessed corner portions 901 are also formed by angular vertical recessed corner portions that form linear ridges in the height direction. Therefore, the visibility of the line of sight passing through these connecting portions 3 and 902 is not obstructed, and the vertical recessed corner portions 901 not only add a new aesthetic change to the lid 900 but also increase the rigidity of the lid 900 in the compression direction. [Example]

[0056] FIG. 26 is a perspective view of a lid 1000 according to Example 10. A feature of Example 10 is that the top panel 1 and the side wall 2 are connected via a horizontal recessed corner 1001 that is concave and curved inward. That is, in Examples 11 through 8 except for Example 6, this portion basically protrudes outward due to a horizontal recessed corner or the like, but in Example 10, it is recessed inward. However, the connecting portion 7 between the side panel portions 2 is formed by an angular horizontal recessed corner that forms a linear ridge line in the height direction, and the connecting portions 1002 between the top panel 1 and the side wall 2 formed above and below the horizontal recessed corner 1001 are also formed by angular horizontal recessed corners that form linear ridge lines in the horizontal direction. Therefore, visibility through these connecting portions 7 and 1002 is not obstructed, and the horizontal recessed corner 1001 adds an unprecedented change to the aesthetics of the lid 1000.

[0057] The gist of the lid according to the present invention is that the connecting portions of the top plate and side plate, which constitute the main surfaces, where the direction of these surfaces changes significantly are configured with angular corners that form linear ridges, thereby enhancing the overall transparency without impeding the visibility of the connecting portions. As a method for molding such angular connecting portions, vacuum molding has been described with reference to Figure 6. However, even if the connecting portions can be molded in an angular state, if the top plate itself has irregularities, the transparency of the top plate will be significantly reduced. Therefore, the conditions for the mold (male mold) required to mold the top plate into a smooth surface without irregularities using the vacuum molding method will be described below.

[0058] First, the male mold 32 shown in Fig. 6 is premised on the assumption that the top surface, which forms the top plate portion of the lid body, is finished as smoothly as possible, and the suction holes 32a for vacuuming must be arranged as follows: That is, the first condition is that the suction holes 32a should not be provided near the center of the top plate portion 1, but should be provided as close as possible to the outer periphery of the top plate portion 1 (connected portion 3), as shown by the suction marks m1 to m4 on the molded lid body in Fig. 27. In other words, it is necessary to provide the suction holes slightly offset from the ridge line of the top plate portion toward the center.

[0059] In the case of a concave mold, if the mold has suction holes in the area corresponding to the center of the top plate 1, the center of the softened sheet material is first sucked toward the suction holes by vacuuming. Then, the peripheral areas try to adhere to the mold, but because the center of the sheet material adheres to the mold first, the center begins to harden and blocks the suction holes. This delays the subsequent vacuuming of the peripheral areas, and this time difference can result in the top plate being molded with a "bumpy" shape.

[0060] In contrast, if a mold is provided with suction holes near the outer periphery of the top plate 1, vacuum holes can be provided near each side to suck out the air trapped between the top surface of the mold and the sheet material, speeding up molding, and further suction causes the area around the vacuum holes to adhere to the sheet material, preventing further suction, and the small amount of remaining air prevents the top mold and the sheet from adhering to each other, allowing molding to be performed while maintaining the transparency of the sheet. In other words, if the sheet material adheres to the mold, no matter how smooth the top surface of the mold may be, any minute irregularities will be reflected in the molded product, causing a loss of transparency.

[0061] As a condition other than arranging the suction holes near the outer periphery of the top plate portion 1 as described above, the diameter of the suction holes is preferably 1 mm or less, and more preferably 0.5 mm or less.

[0062] In addition, the fewer the number of suction holes, the better. Specifically, the suction holes must be spaced at least 5 mm apart, and in the applicant's implementation, they are sometimes spaced at least 40 mm apart.

[0063] In this regard, if the top plate is polygonal, it is not necessary to provide one suction hole on each side, but if the top plate is rectangular, if one suction hole is provided on the short side, it is a condition that one suction hole must also be provided on the long side.

[0064] On the other hand, if the top plate is circular, the suction holes should be arranged at approximately equal intervals, and if it is polygonal, the suction holes should be arranged so that they are approximately evenly spaced along each side. In other words, it is not desirable to arrange the suction holes so that they are densely packed together.

[0065] Furthermore, if the top plate is polygonal, it is possible to provide suction holes near the corners (or the four corners if the top plate is square). However, providing suction holes only at the corners is not effective, and it is essential that they be located near the outer periphery. [Explanation of symbols]

[0066] 1, 501, 601 Top plate 2, 502 Side wall 3 Continuous part (side corner part) 4 Upper plane part 5 Lower plane part 6 Boundary 7 Connecting section (vertical corner section) 8, 101, 401 Chamfered part 9 Stacking protrusion 10, 100, 200, 300, 400, 500, 600, 700, 800, 900, 100 lid 20, 40 Container body 21 Main body fitting part 22, 41 Bottom plate part 22a, 42, 51 False bottom 22b, 43, 53 Step part 22c, 44, 53a・53b base 23 Main body peripheral wall 24 Main body flange 25 Skirt Club 26 Legs 27 Loading recess 30 Sheet material 31 Heater 32 Mold (male mold) 32a Suction hole 33 Plug 45, 50 ribs 301 Connecting section (R-shaped vertical corner section) 503 Semicircular corner 602 Rectangular side wall part 603 Chevron-shaped side wall part 604 Horizontal corner 605 Circular arc corner 606 Horizontal corner 701 Curved Surface 801 Slope 901 Vertical corner 902 Connecting section (vertical corner section) 1001 Horizontal corner 1002 Continuous part (side corner part) m1~m4 Suction trace

Claims

[Claim 1] A transparent or semi-transparent lid that fits onto a container body that contains an object and is made by molding a thermoplastic resin sheet material, and allows the object to be seen, The lid body is a top panel portion having a polygonal shape in a plan view, in which at least one region between opposite sides is formed by a flat surface; a side wall portion of a constant height provided adjacent to the periphery of the top plate portion, The top plate portion and the side wall portion, and the circumferentially adjacent side wall portions are connected by angular horizontal corner portions and vertical corner portions that form linear ridges in the horizontal and height directions, respectively; Chamfered portions are formed above and below the ridge line in the height direction by cutting the corners of the vertical corner portion into an inverted triangle shape and a triangle shape, respectively; the upper and lower chamfered portions have a ridge line formed between their vertices in the height direction, are spaced apart vertically by the length of the ridge line, and at least one of the upper and lower chamfered portions is chamfered into a spherical triangle, the side wall portion has a flat portion that is connected to the top plate portion and the adjacent side wall portion via the horizontal corner portion and the vertical corner portion, The planar portion is upper flat surface portions each having the inverted triangular chamfered portion at an upper corner thereof and connected via the vertical corner portion; adjacent lower flat surfaces are connected to each other via the triangular chamfered portion whose apex is continuous with the lower end of the vertical corner portion of the upper flat surface portion; The plane has a two-stage structure, a boundary line between the flat chamfered portion with the triangular corners and the flange portion attached to the opening edge portion of the container body from the outside is parallel to a side surface of the corner of the flange portion in a plan view; a gripping area protruding from a position lower than the flat chamfered portion with the triangular corners and lower than the flange portion to an outer side of the lid body beyond the boundary line; A lid body characterized by:

Images