Paper container and method of manufacturing the same

Abstract

To provide a paper container which is thinly foldable even though being made of paper.SOLUTION: The paper container is a container for storing food. A tray 100 has a bottom 10 and a plurality of walls 20 surrounding the periphery of the bottom 10. The bottom 10 and the plurality of walls 20 define a space for storing food, and the bottom 10 and each wall 20 are formed by folding a paper sheet. The wall 20 has a flat surface 22 at its upper end, and the width of the flat surface 22 is 5 mm or less on average.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present disclosure relates to a paper box container, and more particularly to a tray-type paper container for storing small portions of food, such as boxed lunches and New Year's dishes. [Background technology]

[0002] Conventionally, containers for storing food, such as lunch boxes and containers for New Year's dishes, have often been made of plastic or other resins (see, for example, Patent Document 1). In recent years, the movement away from plastic has accelerated due to the impact of marine pollution caused by microplastics. In addition, in light of the SDGs and other factors, there is a demand for a positive list system and for the abolition of the use of plastic containers for food containers, and paper containers are attracting attention. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Registered Utility Model No. 3208520 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0004] However, although a paper container has a high-class appearance, if the cut edge of the paper is visible, it looks flimsy. Therefore, in order to hide the cut edge of the paper and to give it an even more luxurious appearance, it is conceivable to fold the paper container to make it thicker. That is, it is a paper container with a flat surface provided on the upper end of the wall, that is, a so-called frame added. Moreover, by adding a frame to such a paper container, in addition to simply folding it, it is possible to give it an even higher-class appearance and strength.

[0005] Generally, paper containers are assembled automatically using a box-making machine, but there is a limit to how much the box-making machine can fold, and the box-making machine can only fold the container to a certain width, such as about 7 mm. On the other hand, if the paper container is too thick, the storage volume inside the container decreases.

[0006] The present disclosure has been made in view of the above background, and one of its objects is to provide a paper container that is thin and foldable while being a paper container, and a manufacturing method thereof.

[0007] The paper container according to the first embodiment of the present disclosure is a paper container for storing food, comprising a bottom and a plurality of walls surrounding the bottom, the bottom and the plurality of walls defining a food storage space, the bottom and the walls being constructed by folding a paper sheet, the walls having flat surfaces at their upper ends, the width of the flat surfaces being 5 mm or less on average. With the above configuration, a paper container can be realized that is compatible with automatic box making by a box making machine, while the upper ends of the walls are folded back to provide flat surfaces.

[0008] In addition, in the paper container according to the second embodiment of the present disclosure, in the above embodiment, when the paper sheet is unfolded, each of the walls includes an inner surface forming the storage space, a flat surface joined to a second side of the inner surface that faces the first side joined to the bottom, and an outer surface joined to a third side of the flat surface that faces the second side, and the second side and the third side are each mountain-folded to form the flat surface. With the above configuration, one side of the paper sheet can be exposed to both the storage space of the paper container and the outer surface of the wall, and the appearance can be improved by using only one side of the sheet as a decorative surface.

[0009] Furthermore, in the paper container according to the third embodiment of the present disclosure, in any of the above embodiments, at least some of the walls have recesses formed at the boundaries with the flat surface at the corners of the inner surface, and the flat surface of the adjacent wall is disposed in the recesses. With the above configuration, the walls can be joined without gaps by avoiding interference at the interfaces between them while providing flat surfaces on the walls.

[0010] Furthermore, in the paper container according to a fourth embodiment of the present disclosure, in any of the above embodiments, the plurality of walls have folds between adjacent walls, and the folds extend from the corners on both sides of the inner surface, separating the recesses. With the above configuration, it is possible to fold the folds between the walls without causing interference at the interface between the walls.

[0011] Furthermore, in a paper container according to a fifth embodiment of the present disclosure, in any one of the above-mentioned embodiments, the folded portion has a V-shaped depression in the middle, and the angle of the V-shape is 130° to 160°.

[0012] Furthermore, in the paper container of form 6 of the present disclosure, in any of the above forms, the multiple wall portions are inclined relative to the bottom so that the food storage space becomes wider toward the opening end, and adjacent wall portions of the multiple wall portions have different inclination angles.

[0013] Furthermore, in the paper container according to a seventh embodiment of the present disclosure, in any one of the above embodiments, the width of the flat surface is 2 mm to 3 mm.

[0014] Furthermore, in a paper container according to an eighth embodiment of the present disclosure, in any one of the above-mentioned embodiments, the paper sheet is waterproofed.

[0015] Furthermore, in a paper container according to a ninth embodiment of the present disclosure, in any one of the above-mentioned embodiments, the paper container is configured so that a plurality of the paper containers can be stacked.

[0016] Furthermore, in a paper container according to a tenth embodiment of the present disclosure, in any one of the above embodiments, the paper container is a tray, one or more of which are stored in a food storage container.

[0017] Furthermore, a method for manufacturing a paper container according to form 11 of the present disclosure includes a step of setting a base paper in a mold having a first plate with a Thomson blade and a second plate opposite the first plate, the second plate having a groove in a portion corresponding to the cutting edge of the Thomson blade, and forming a half cut in the fold portion having a width of 5 mm or less, and a step of forming a box out of the paper sheet with the half cut formed therein using a box making machine. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view showing a food storage container including a paper container according to embodiment 1. FIG. [Diagram 2] 2 is an exploded perspective view of the food storage container of FIG. 1 with the tray removed. [Diagram 3] FIG. 3 is a perspective view showing one of the trays in FIG. 2. [Figure 4] FIG. 4 is a development view of the tray in FIG. 3. [Diagram 5] FIG. 11 is a cross-sectional view showing a state in which a plurality of trays are stacked. [Figure 6] 6 is a cross-sectional view of the tray taken along line VI-VI in FIG. [Figure 7] 7 is a cross-sectional view of the tray taken along line VII-VII in FIG. 3. [Figure 8] FIG. 2 is an exploded perspective view showing a wooden die for a Thompson blade. [Figure 9] FIG. 9 is a schematic cross-sectional view showing how a half cut is made in the base paper by the Thomson blade in FIG. 8. [Figure 10] FIG. 4 is a perspective view with an enlarged view of a main part, showing the assembled state of the tray in FIG. 3. [Figure 11] FIG. 4 is a perspective view with an enlarged view of a main part, showing the assembled state of the tray in FIG. 3. [Figure 12] FIG. 4 is a perspective view with an enlarged view of a main part, showing the assembled state of the tray in FIG. 3. [Figure 13] FIG. 4 is a perspective view with an enlarged view of a main part, showing the assembled state of the tray in FIG. 3. [Figure 14] FIG. 11 is a cross-sectional view showing a tray according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, the embodiments of the present disclosure will be described based on the drawings. However, the embodiments shown below are examples for embodying the technical ideas of the present disclosure, and the present disclosure does not specify the paper container as follows. In addition, this specification never specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, and relative positions of the components described in the embodiments are not intended to limit the scope of the present disclosure to those alone, and are merely explanatory examples, unless otherwise specified. Note that the size and positional relationship of the members shown in each drawing may be exaggerated to clarify the explanation. Furthermore, in the following explanation, the same name and symbol indicate the same or similar members, and detailed explanation will be omitted as appropriate. Furthermore, each element constituting the present disclosure may be configured as a form in which multiple elements are composed of the same member and one member serves multiple elements, or conversely, the function of one member can be shared by multiple members.

[0020] Plastic and other resin products have traditionally been widely used for food containers, such as lunch boxes sold at convenience stores and supermarkets, and New Year's meal boxes sold at department stores. However, the movement to eliminate plastic is gaining momentum in light of the environmental burden caused by such plastic products, such as soil pollution and marine pollution, and the depletion of oil resources. In this situation, the movement to eliminate plastic has accelerated with the "Positive List System for Food Containers, Utensils, and Containers and Packaging" that came into effect on June 1, 2020, and there is an even greater demand to avoid using plastic small bowls and trays in lunch containers as much as possible. This is why paper small bowls are in demand.

[0021] Most plastic small bowls currently on the market have frames. In other words, the upper end of the plastic wall is formed into a horizontal surface. In contrast, most paper small bowls currently on the market do not have frames. This is because if a box-making machine is used to automatically make a container with a frame, the frame must be made to a certain width or the container must be folded without a frame, since the creases must be made by machine. In particular, it is difficult to make a small container such as a small bowl with a thin frame using a box-making machine. Also, if a paper small bowl is to be framed by hand folding without using a box-making machine, it is difficult to manufacture domestically due to the cost. Also, even if it is manufactured overseas, such as in China, the fold lines are not neatly aligned and there are problems with the quality of the paper material, so there are concerns about its use as food.

[0022] In addition to the spread of the new coronavirus, international situations such as the Ukrainian conflict have caused logistics to stop, and the rising prices of raw materials have combined to reveal the unstable factors of a structure that relies on imports. On the other hand, the movement to eliminate plastic is accelerating due to concerns about marine pollution caused by resin products such as plastic. In this situation, a stable supply of paper small bowls is urgently needed. In addition, it is also necessary to increase the added value of paper small bowls, which are expensive compared to plastic small bowls, in order to be accepted by the market. Adding a frame to a paper small bowl can also lead to a luxurious appearance. In light of this background, the inventor has conducted extensive research and has come up with an invention that makes it possible to automatically produce paper small bowls with frames, which have not been available on the market before, by machine, so as to give a sense of volume to paper containers and create a sense of luxury. [Embodiment 1]

[0023] A storage container 1000 according to a first embodiment of the present disclosure is shown in a perspective view in FIG. 1. The storage container 1000 shown in this figure shows an example of a container for storing food, and can be used as, for example, a stacked box for New Year's dishes or a lunch box. Here, an example with a lid LD is shown, but the container may be a container without a lid. In addition, although the following example describes a container for food, the present disclosure can also be applied to other uses, such as containers and trays for medicines, small items, gifts, etc. In particular, the present disclosure can be suitably applied as a storage container or tray for luxury items that require good appearance.

[0024] The storage container 1000 stores a plurality of trays 100 as shown in the exploded perspective view of FIG. 2. In the example of FIG. 2, six trays 100 of the same small bowl shape are stored in the storage container 1000, but the present disclosure is not limited to this configuration, and the shape of each tray and the number of trays stored in the storage container can be set arbitrarily. In addition, it is preferable that each wall portion 20 of each tray 100 is inclined from a vertical position with respect to the bottom portion 10 so that the width becomes wider toward the opening portion. In particular, by providing a tapered wall portion 20 in an inverted isosceles trapezoid shape or an inverted V-shape, it is possible to stack trays 100 of the same shape as shown in the cross-sectional view of FIG. 5.

[0025] As shown in the perspective view of Fig. 3, each tray 100 is formed in a box shape with an open top and a bottom. The tray 100 in Fig. 3 includes a bottom 10 and a plurality of walls surrounding the periphery of the bottom 10. The bottom 10 is formed in a rectangular shape. In this example, the bottom 10 is formed in a square shape, but it goes without saying that the bottom 10 may be formed in a rectangular shape depending on the required capacity, external shape, etc.

[0026] The bottom 10 and the multiple walls 20 define a food storage space. The bottom 10 and the walls 20 are formed by folding a paper sheet, as shown in the development view of FIG. 4. Any paper that meets food hygiene standards can be used as the paper sheet, such as a bowl laminated with PP or PE on one side, or paper coated with food varnish. Waterproofing the sheet makes it possible to store foods with a lot of juice. It is preferable to waterproof or color the sheet on only one side (for example, the paper side in FIG. 4). This eliminates the need for processing the back side, making processing easier and reducing costs. (Wall part 20)

[0027] Each of the multiple wall portions 20 is composed of an inner surface portion 21, a flat surface 22, and an outer surface portion 23. The inner surface portion 21 is joined to a first side 1, which is one of the four sides that constitute the periphery of the bottom portion 10. In this example, four wall portions 20 are provided. Each wall portion 20 is formed in an inverted isosceles trapezoid shape as shown in FIG. 3 and other figures. As a result, each wall portion 20 is inclined in a manner that spreads out toward the opening surface, and multiple trays 100 can be stacked as shown in FIG. 5. In the example shown in the development view of FIG. 4, the angle θ1 of the left and right corners of the inner surface portion 21 of the wall portion 20 on the front side is 95°. On the other hand, the angle θ2 of the corners of the inner surface portion 21 of the left and right wall portions 20b and 20c is 97° (the reason for making the inclination angles of the wall portions 20 different will be described later). (Inner surface portion 21)

[0028] The multiple inner surface portions 21, together with the bottom portion 10, form a storage space for food and the like. Each inner surface portion 21 has a first side 1 on the long side, a second side 2 opposite the first side 1, a fourth side 4 on the short side, and a fifth side 5 opposite the fourth side 4. The first side 1 is joined to the bottom portion 10. The second side 2 is joined to the flat surface 22. The fourth side 4 and the fifth side 5 are each connected to the folded portion 30. (Flat surface 22)

[0029] The flat surface 22 is formed between the inner surface 21 and the outer surface 23 of the wall portion 20. This flat surface 22 functions as the periphery of the storage space, i.e., as a frame. Each flat surface 22 has a second side 2 and a third side 3, and is joined to the inner surface 21 at the second side 2 and to the outer surface 23 at the third side 3. The width between the second side 2 and the third side 3 is 5 mm or less. (External part 23)

[0030] The outer surface portion 23 is folded back from the inner surface portion 21 via the flat surface 22 to form the outer surface of the wall portion 20. The outer surface portion 23 is joined to the flat surface 22 via the third side 3. The outer surface portion 23 folded back from the inner surface portion 21 via the flat surface 22 is bonded so that its tip is in contact with the inner surface portion 21, as shown in the cross-sectional view of FIG. 6 and the like. In other words, the folded outer surface portion 23 forms a triangle in cross-sectional view with the flat surface 22 and a part of the inner surface portion 21. In the example of FIG. 5, the tip of the outer surface portion 23 is joined to the middle of the inner surface portion 21, but the present disclosure is not limited to this configuration, and for example, the length of the outer surface portion may be extended to be approximately equal to that of the inner surface portion. This allows the side surface of the tray to be formed by the outer surface portion, eliminating seams on the side surface of the tray and improving the appearance. In addition, hot melt is used to bond the outer surface portion 23 to the inner surface portion 21. (Flap part 24)

[0031] Of the outer surface portions 23, a pair of opposing outer surface portions 23, i.e., the outer surface portions 23 located on the left and right in Fig. 4, are provided with flap portions 24 on both sides. The flap portions 24 are mountain-folded and sandwiched between the inner surface portion 21 and the outer surface portion 23 of the adjacent wall portion 20 when the tray 100 is assembled, and are glued. (Fold 30)

[0032] A folding portion 30 is provided at a portion where the wall portions 20 are adjacent to each other when the tray 100 is assembled. The folding portions 30 are provided at the fourth side 4 and the fifth side 5 of the side surface of the wall portion 20, respectively. Each folding portion 30 is formed in a V-shape, and a sixth side 6 is provided in the center of the V-shape for folding. Like the flap portion 24, the folding portion 30 is also sandwiched between the inner surface portion 21 and the outer surface portion 23 of the adjacent wall portion 20 and glued.

[0033] The folding portion 30 is folded around the sixth side 6. As described above, the angle θ3 at the edge of the sixth side 6 of the folding portion 30 is not a straight line of 180°, but a V-shape. If the angle θ3 of the edge of the sixth side 6, which is the fold of the folding portion 30, is too small, it is difficult to pass through a box-making machine. If it is too large, it causes problems in stacking the trays. In addition, it has been found that when the size of the tray is small, the repulsive force against the folding of the paper sheet becomes large, causing the glue of the folding portion 30 adhered to the inner surface portion 21 to peel off. Therefore, taking into consideration the above-mentioned box-making machine, stacking, etc., the angle θ3 of the V-shape is set to 130° to 160°, preferably 140° to 150°, and most preferably 145°. (Recess 25)

[0034] The front and rear wall portions 20 are formed with recesses 25 at the end of the boundary between the flat surface 22 and the inner surface portion 21. As shown in the enlarged views of the main portion in Fig. 10 and Fig. 11, the recesses 25 are portions for fitting the ends of the left and right wall portions 20 where the flat surfaces 22 are provided. By forming the recesses 25, the walls 20 can be joined together smoothly without interference. For this reason, it is preferable that the depth of the recesses 25, i.e., the length d5 ​​from the end face of the flat surface 22 to the cut-out portion of the inner surface portion 21, is formed to be approximately equal to the widths d3 and d1 of the left and right flat surfaces 22 as shown in Fig. 11.

[0035] Moreover, the folding portion 30 extends from the corners on both sides of the inner surface portion 21 across the recess 25. With this configuration, the folding portion 30 provided between the wall portions 20 can be folded with less interference of the folding portion 30 at the interface between the wall portions 20. Specifically, it is preferable that the length d6 of the bottom of the recess 25, i.e., the length d6 from the edge of the inner surface portion 21 to the position where the folding portion 30 protrudes, coincides with the length d7 from the edge of the inner surface portion 21 to the position where the folding portion 30 protrudes in the adjacent inner surface portion 21 (the inner surface portions 21 on the left and right sides of the bottom portion 10 in FIG. 4) when the tray 100 is assembled.

[0036] In the development view of Fig. 4, the first side 1 is made into a valley fold, and the second side 2 and the third side 3 are made into mountain folds, so that the surface of the paper sheet is exposed to the storage space of the paper container and the outer surface of the paper container, as shown in the cross-sectional views of Fig. 6 and Fig. 7. This makes it possible to apply coloring and waterproofing only to the surface side of the paper sheet, while leaving these treated surfaces exposed as the exterior of the paper container, improving its appearance.

[0037] In addition, by providing the flat surface 22 between the inner surface 21 and the outer surface 23, the wall 20 is made thick to represent the frame of the food container, or a picture frame, so to speak, and it is possible to increase the sense of volume and luxury in appearance. In particular, containers made of paper sheets are weaker in strength than containers made of plastic or the like, and trays made of thin paper can give a flimsy impression. In contrast, in the tray 100 according to this embodiment, the flat surface 22 is provided in the part where the paper is folded back between the inner surface 21 and the outer surface 23, which increases the strength by expressing thickness, and also gives an impression of toughness in appearance, and adds a sense of volume and luxury that does not feel like it is made of paper.

[0038] On the other hand, if such a frame, i.e., flat surface, is too large, the food storage space will be narrowed accordingly. However, in order to narrow the flat surface, since the flat surface is formed by folding a paper sheet, it is necessary to set the fold lines close together, but there is a problem in that it is difficult to make the fold lines close together. In particular, when folding a paper sheet automatically using a box-making machine, the limit is about 7 mm in width. Thus, it has been difficult to neatly form a narrow flat surface in the past.

[0039] In contrast, in the tray 100 according to the first embodiment, the mold 50 used for punching the paper sheet ST is devised to realize the tray 100 that can be made into a box by a box-making machine. Specifically, as shown in the exploded perspective view of FIG. 8, the mold 50 is composed of a first plate 51 that serves as a wooden mold provided with a Thomson blade 53, and a second plate 52 that serves as a receiving plate or face plate facing the first plate 51. The Thomson blade 53 forms a pattern on the first plate 51 for cutting the paper sheet ST from the paper base paper as shown in the development diagram of FIG. 4. In addition, the Thomson blade 53 with a short cutting edge is provided along the folds so that half cuts are provided at each fold of the development diagram. The Thomson blade 53 is provided close to the second side 2 and the third side 3 in the development diagram, which correspond to the flat surface 22 of the tray 100.

[0040] On the other hand, as shown in the cross-sectional view of Fig. 9, the second plate 52 has a groove 54 in a portion corresponding to the tip of the Thomson blade 53 of the first plate 51, particularly in the area where the Thomson blades 53 are close to each other. This allows a neat half cut even in close areas on the paper sheet ST, and makes it possible to assemble the boxes by a box-making machine along the fold lines. As a result, it is possible to obtain a tray 100 having a narrow flat surface 22.

[0041] The width d of the flat surface 22 is 5 mm or less. Preferably, the width of the flat surface 22 is 1 mm to 4 mm, more preferably 2 mm to 3 mm. As shown in FIG. 4, it is preferable that the widths d1 to d4 of the flat surface 22 of each wall portion 20 are equal. However, the width of the flat surface 22 may be changed for each wall portion 20. For example, as shown in the cross-sectional view of FIG. 6, the widths d2 and d4 of the flat surface 22 of the wall portion 20 where the folded piece is interposed between the inner surface portion 21 and the outer surface portion 23 may be larger than the widths d1 and d3 of the flat surface 22 of the wall portion 20 where the space is formed between the inner surface portion 21 and the outer surface portion 23, as shown in the cross-sectional view of FIG. 7.

[0042] In this manner, a paper container having a frame can be obtained. In particular, as shown in Fig. 5, by folding back the outer surface 23 constituting the wall 20 to provide a flat surface 22, a paper small bowl having a good appearance can be obtained by inclining the wall 20 in a tapered shape.

[0043] According to the inventor's tests, it was found that there are various technical problems in manufacturing a small paper bowl with a picture frame. First, when folding back both ends of the flat surface 22 at the top of the wall portion 20 to form a picture frame, it is necessary to fold the die-cut paper sheet, but there is a problem that the creases are distorted or wobbly due to the repulsion caused by the grain of the paper, and the box shape is not finished neatly. Specifically, in the development view of FIG. 4, when folding the lines of the second side 2 and the third side 3, the interval between these lines is narrow, so that the repulsion when folding the paper sheet is large, making it difficult to make a box with a box-making machine. Therefore, a high-pressure (e.g., 400t) punching machine is used so that the creases and the lines of the picture frame are neatly produced when punching the sheet.

[0044] In this embodiment, the second side 2 and the third side 3 are both folded in opposite directions to create creases during box making. This suppresses rebound at the crease, making it easier to fold along the intended crease when folding in the normal direction. [Manufacturing method of tray 100]

[0045] Here, the manufacturing method of the tray 100 will be described. First, the base paper is set in a mold and cut out. At this time, half cuts are made in each fold. Here, the width between the second side 2 and the third side 3, which are the two folds that make up the flat surface 22, is 5 mm or less.

[0046] Next, the paper sheet on which the half cuts are formed is made into a box by a box-making machine. Here, the details of making the tray 100 into a box will be described with reference to Fig. 4 and Figs. 10 to 14. In the development view of Fig. 4, the second side 2 and the third side 3 of each wall portion 20 are each mountain-folded as shown in the cross-sectional view of Fig. 6 to form a flat surface 22 and an outer surface portion 23. In addition, the first side 1 is valley-folded to make the inner surface portion 21 around the bottom portion 10 stand upright. Meanwhile, the fold portion 30 is folded between the adjacent wall portions 20. Specifically, the fourth side 4 and the fifth side 5 are each mountain-folded, and the sixth side 6 is valley-folded.

[0047] Here, for the sake of explanation, the first side 1 of the front wall 20a (the lower part of the bottom 10 in FIG. 4) is valley-folded, and the second side 2 and the third side 3 of the left and right wall 20b, 20c are mountain-folded, as shown in the perspective view of FIG. 10. Folds 30 are folded on both sides of the back side of the inner surface 21 on the front side. In the example of FIG. 10, in order to make the folds 30 easier to see, the flap 24 provided on the outer surface 23 of the left and right wall 20b, 20c is intentionally valley-folded at the seventh side 7 and the eighth side 8 to open it. The left and right wall 20b, 20c are brought close to the front wall 20a in FIG. 10.

[0048] Then, as shown in FIG. 11, the edges of the flat surfaces 22 of the left and right wall portions 20b, 20c are abutted so as to enter the grooves 54 formed under both sides of the flat surface 22 of the front wall portion 20a. In this state, the angles of the left and right wall portions 20b, 20c are determined. Then, the left and right folding portions 30 of the front wall portion 20a are folded so as to contact the back surface of the inner surface portion 21, respectively. Furthermore, as shown in the perspective view of FIG. 12, the flap portions 24 provided on the left and right wall portions 20b, 20c are folded in a mountain fold so as to overlap the folding portions 30, respectively. In this state, as shown in FIG. 13, the outer surface portion 23 of the front wall portion 20a is folded in a mountain fold via the flat surface 22 and overlapped on the back side of the inner surface portion 21. In this state, the folding portions 30, the flap portions 24, and the outer surface portion 23 are fixed to the inner surface portion 21. For fixing, known fixing devices such as glue, adhesive, double-sided tape, and cellophane tape can be appropriately used. In this manner, the tray 100 as shown in the perspective view of FIG. 3 is assembled.

[0049] By overlapping the flap portion 24 on the folding portion 30 in this manner, the folding portion 30 is hidden by the flap portion 24, and even if the outer surface portion 23 is peeled off, it is not noticeable. In the example of Fig. 13, the folding portion 30 is fixed to the inner surface portion 21 of the wall portion 20a on the front side in the figure, among the wall portions 20. However, the present disclosure is not limited to this configuration, and the folding portion 30 may be fixed to the inner surface portions 21 of the left and right wall portions 20b, 20c, instead of the wall portion 20a on the front side.

[0050] Furthermore, the wall portion on the side where the folding portion 30 is fixed (the wall portion 20a on the front side in FIG. 13, etc.) is thicker than the other wall portions (the left and right wall portions 20b, 20c in the example of FIG. 13, etc.) by the amount of the folding portion 30 and the flap portion 24 sandwiched between the inner surface portion 21 and the outer surface portion 23. In consideration of such a difference in thickness, the angle at which the wall portion 20 is inclined may not be constant for each wall portion 20, but may be different between the front side and the side side. In the example shown in the development view of FIG. 4, the angle θ2 of the front side wall portion 20a that is folded from the bottom portion 10 to a vertical position is set to 97°. On the other hand, the angle θ1 of the left and right wall portions 20b, 20c is set to 95°. In this way, the angle of the wall portion 20a on which the folding portion 30 and the flap portion 24 are overlapped is set to be larger than the other wall portions 20b, 20c, so that the tray 100 can be easily assembled without any strain. In other words, the difference in thickness of the paper when folded is absorbed by the different angles. This difference in angle allows the boxes to be made into boxes through a box-making machine and also allows the storage containers to be stacked. [Embodiment 2]

[0051] In the tray 100 according to the first embodiment shown in Figures 3, 6, etc., the outer surface portion 23 is formed shorter than the inner surface portion 21. In particular, in a mode in which the tray 100 is used by being packed in a storage container 1000 as shown in Figures 1 and 2, the outer periphery of the tray 100 is not exposed, so there is no need to be so concerned about appearance. In such a case, the outer surface portion 23 can be shortened to reduce material costs.

[0052] However, in applications where the appearance is important, such as when the trays are spaced apart and the periphery of the trays is visible, the outer surface portion 23 may be extended to the same extent as the inner surface portion 21. Such an example is shown as a tray 200 according to embodiment 2 in the cross-sectional view of Fig. 14. By extending the outer surface portion 23B up to the bottom portion 10 of the tray 200 in this manner, the side surface of the tray 200 is covered with the outer surface portion 23B having a processed surface, thereby improving the appearance. [Industrial Applicability]

[0053] The paper container and its manufacturing method disclosed herein can be suitably used as small food bowls for portioning, such as lunch boxes, stacked boxes for New Year's dishes, and confectionery boxes.

[0054] In addition, by using small bowls and trays made from natural paper instead of plastic trays, we can reduce the amount of petroleum-based plastic used and reduce the environmental impact by preventing soil and ocean pollution caused by plastic dumping. As a result, we have achieved the following of the 17 goals and 169 targets set out in the international goals SDGs (Sustainable Development Goals) adopted at the United Nations Summit in September 2015: "8. Decent work and economic growth", "8.4 By 2030, improve progressively global resource efficiency in consumption and production and endeavour to decouple economic growth from environmental degradation, in accordance with the 10-year framework of programmes on sustainable consumption and production, with developed countries taking the lead." "9. Build inclusive and sustainable industrial and technological infrastructure", "9.4 By 2030, improve infrastructure and industry to ensure sustainability, including by increasing resource efficiency and expanding the adoption of clean and environmentally friendly technologies and industrial processes. All countries will take action in accordance with their respective capabilities", "11. Sustainable cities and towns", "11.6 By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management", - The technology contributes to the following targets: "12. Responsible Consumption and Production", "12.4 By 2020, achieve the environmentally sound management of chemicals and all wastes throughout their life cycle, in accordance with agreed international frameworks, and significantly reduce their release to air, water and soil in order to minimize their adverse impacts on human health and the environment", and "12.5 By 2030, substantially reduce waste generation through prevention, reduction, recycling and reuse". [Explanation of symbols]

[0055] 1000…Storage container 100, 200…tray 1...First side 2...Second side 3...Third side 4...Fourth side 5…fifth side 6...Sixth side 7...Seventh side 8...Eighth side 10...bottom 20...Wall part 21…Inner surface 22…Flat surface 23, 23B...External part 24…Flap section 25…Recess 30…Folding section 50…type 51…First plate 52…Second board 53…Thomson blade 54...Groove LD…Lid ST...Paper sheet; ST2...Die-cut paper sheet

Claims

1. A paper container for storing food, The bottom and A plurality of walls surrounding the bottom portion; Equipped with The bottom portion and the plurality of walls define a food storage space, The bottom and each wall are constructed by folding a sheet of paper, The wall portion has a flat surface at an upper end thereof, A paper container, wherein the flat surface has an average width of 5 mm or less.

2. The paper container according to claim 1, In a state where the paper sheet is unfolded, the plurality of walls each have: An inner surface portion that constitutes the storage space; The flat surface is joined to a second side of the inner surface portion, the second side being opposed to a first side joined to the bottom portion; an outer surface portion joined to a third side of the flat surface opposite to the second side; Equipped with The second side and the third side are each folded in a mountain fold to form the flat surface.

3. The paper container according to claim 2, At least some of the wall portions form recesses at the boundaries between the corners of the inner surface and the flat surface, A paper container configured so that the flat surface of an adjacent wall portion is placed in the recess.

4. The paper container according to claim 3, The plurality of wall portions each have a folding portion between adjacent wall portions, The folded portions extend from the corners on both sides of the inner surface, separating the recesses.

5. The paper container according to claim 4, The folded portion has a V-shaped recess in the middle, The paper container has a V-shaped angle of 130° to 160°.

6. The paper container according to any one of claims 1 to 5, The walls are inclined with respect to the bottom so that the food storage space becomes wider toward the open end, The paper container has adjacent wall portions of the plurality of walls each having a different inclination angle.

7. The paper container according to any one of claims 1 to 5, The width of the flat surface is 2 mm to 3 mm.

8. The paper container according to any one of claims 1 to 5, The paper sheet is waterproofed to form a paper container.

9. The paper container according to any one of claims 1 to 5, The paper container is configured so that a plurality of the paper containers can be stacked.

10. The paper container according to any one of claims 1 to 5, The paper container is a tray, one or more of which are stored in a food storage container.

11. a step of setting the base paper in a mold having a first plate with a Thomson blade and a second plate facing the first plate, the second plate having a groove in a portion corresponding to the cutting edge of the Thomson blade, and forming a half cut in a fold portion having a width of 5 mm or less; a step of forming the paper sheet having the half cut into a box using a box-making machine; A method for producing a paper container comprising the steps of:

Images