Paper container, blank sheet and manufacturing method

Abstract

To provide a paper container in which a film sheet is properly pressed onto a container body. [Solution] A paper container 1A includes a paper container body 10A whose top surface forms an opening 11A, and which has a polygonal bottom portion 12A with multiple side portions 13 extending from each side folded along the sides of the bottom portion 12A, with the side edges 14 of adjacent side portions 13 butting together to form corners, forming a truncated pyramid shape, and a film layer 20 formed by pressing a film sheet laminated on the inner surface of the container body 1A by vacuum suction. The container body 10A has a gap 50 formed by separating the side edges 14 that butt together at the corners, extending linearly between the bottom portion and the opening and set to a dimension longer than the dimension of a straight line connecting the bottom portion and the opening.

Description

[Technical Field]

[0001] The present invention relates to a paper container having a film layer formed by pressing a film sheet onto the inner surface of a paper container body. [Background technology]

[0002] BACKGROUND ART Conventionally, as a container for storing food or the like, a paper container in which a plastic film sheet is crimped onto the inner surface of a paper container body is known. This paper container is manufactured by folding a blank sheet into the shape of the container, and then crimping a film sheet onto the inner surface of the container body. Specifically, the air between the container body formed by folding the blank sheet and the film sheet laminated on its top surface is vacuum-suctioned, crimping the film sheet onto the container body.

[0003] As one of such paper containers, a tray-type container in the shape of a truncated quadrangular pyramid has been proposed. For example, in the container body used in the paper container of Patent Document 1, at the corners of the four side surfaces connecting the upper and lower bases of the truncated quadrangular pyramid, the side edges of the adjacent side surfaces are butted together, and the side edges are spaced apart to form linear gaps along the corners. Furthermore, it is also disclosed that by providing intake openings at the connection points between each corner and the bottom of the paper container, it is possible to ensure the suction ability of the film sheet against the paper container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2013-545675 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the case of a truncated pyramidal container such as that described above, if the only air passage for sucking air between the container body in which the blank sheet is folded and the film sheet is the straight gap provided at each corner, there is a risk that the film sheet will not be sucked in sufficiently and will not be properly crimped. Furthermore, even if an air intake opening is provided as described above, the absence of a container body structure causes the suction load to be concentrated, which could result in damage to the film sheet during suction. Therefore, there is room for improvement in providing a paper container in which a film sheet is properly crimped onto the container body.

[0006] The present invention was invented in consideration of the above-mentioned problems, and one of its objectives is to provide a paper container in which a film sheet is appropriately crimped to a container body. However, other objectives of the present invention are not limited to this objective, but also include the effects and advantages derived from the various configurations shown in the "Mode for Carrying Out the Invention" below, which cannot be obtained with conventional technology. [Means for solving the problem]

[0007] (1) The paper container disclosed herein comprises a paper container body formed into a truncated pyramid shape with an opening on the top surface, a plurality of side portions extending from each side of a polygonal bottom portion folded along the creases of the sides of the bottom portion, and side edges of adjacent side portions extending from the bottom portion toward the opening butting together to form corners; and a film layer formed by pressing a film sheet laminated on the inner surface of the container body, wherein the container body is characterized in that the side edges butting together at the corners are formed apart from each other, and the container body has a gap portion extending linearly between the bottom portion and the opening, the gap portion being set to a dimension longer than the dimension of a straight line connecting the bottom portion and the opening.

[0008] (2) It is preferable that the gap portion has a bent portion formed by bending the gap portion at an intermediate position between the bottom surface portion and the opening. (3) The container body has an octagonal opening and an octagonal bottom surface, and the side surface is formed by a first region having a trapezoidal shape that narrows from the bottom surface toward the intermediate position, and a second region connected to the first region and having a trapezoidal shape that widens toward the opening, and is provided with a first side surface having a side edge bent in a dogleg shape, and a second side surface adjacent to the first side surface and having a side edge bent in a shape that fits the side edge of the first side surface, and it is preferable that the gap portion has the side edge bent in a dogleg shape at the bend. (4) Preferably, a fold is provided between the first region and the second region in the first side portion, and a plurality of notches are intermittently formed along the fold between the first region and the second region.

[0009] (5) The container body has a rectangular opening and an octagonal bottom surface, and the side surface has a first side surface and a second side surface whose side edges are butted together in the region from the opening to the intermediate position, and a triangular third side surface that is sandwiched between the first side surface and the second side surface and extends from the bottom surface to the intermediate position, and it is preferable that the gap is branched into two at the bend from the opening toward the bottom surface along both side edges of the third side surface.

[0010] (6) It is preferable that a plurality of cuts are formed intermittently along the folds between the sides of the bottom surface portion and the side surface portions. (7) It is preferable that each of the plurality of side portions has a flange portion extending from an edge on the opening side to a side opposite the opening, and that the side edges of the flange portions abut against each other. (8) Additionally, the present disclosure provides a blank sheet used to form the container body of the paper container described in any one of (1) to (7). [Effects of the Invention]

[0011] According to the present invention, it is possible to provide a paper container in which a film sheet is appropriately crimped onto the container body. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a paper container according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing the paper container of FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the cross section AA of FIG. 2. [Figure 4] FIG. 2 is a plan view of a blank sheet for the container body of FIG. 1. [Figure 5] FIG. 2 is a perspective view of a mold (forming die) for producing the paper container of FIG. [Figure 6] FIG. 2 is an explanatory diagram of a method for manufacturing the paper container of FIG. [Figure 7] FIG. 3 is a perspective view of a paper container according to a second embodiment of the present invention. [Figure 8] FIG. 8 is a plan view showing the paper container of FIG. [Figure 9] FIG. 8 is a plan view of a blank sheet for the container body of FIG. 7. [Figure 10] 10(a) to 10(d) are explanatory diagrams of modified paper containers. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a paper container as an embodiment will be described. In this embodiment, the paper container is placed on a horizontal surface. The paper container of this embodiment is symmetrical in the front-rear and left-right directions. The vertical direction in which gravity acts is referred to as downward (indicated by "D" in the figure), and the opposite direction of downward is referred to as upward (indicated by "U" in the figure). Furthermore, the side of the storage space in the container body where the items are stored is referred to as the inside, and the side opposite the inside is referred to as the outside.

[0014] [I. First embodiment] In the first embodiment below, the configuration of the paper container is described in item [1]. Next, the configuration of the mold used to manufacture the paper container of item [1] is described in item [2]. Then, the effects of the configurations of items [1] and [2] are described in item [3]. [1. Composition of paper containers] [1-1. Overview] A paper container 1A according to a first embodiment will be described with reference to FIGS. As shown in Figure 1, paper container 1A is a bowl-shaped or rice bowl-shaped paper tray container. An example of paper container 1A is a food packaging container for containing food. However, paper container 1A can also contain a variety of items other than food. The paper container 1A includes a paper container body 10A and a film layer 20 formed by pressing a film sheet laminated on the inner surface of the container body 10A by vacuum suction.

[0015] <Container body> The container body 10A is a package having an octagonal opening 11A on the top surface and an internal storage space. The container body 10A has an octagonal (polygonal) bottom surface 12A and eight side surfaces 13 extending from each side of the bottom surface 12A. Folds 17 extend between each side of the bottom surface 12A and the side surfaces 13.

[0016] The container body 10A is formed into a truncated pyramidal shape by folding eight side surfaces 13 along fold lines 17. The material used for the container body 10A is not particularly limited as long as it is a commonly used paper, and is preferably paper whose main component is plant-derived pulp, and more preferably paper whose main component is wood pulp. Specific examples include kraft paper, fine paper, (white) paperboard, base paper for paper containers, milk carton base paper, cup base paper, liner paper, coated paper, one-side glazed paper, glassine paper, graphene paper, etc. Among these, kraft paper, fine paper, (white) paperboard, base paper for paper containers, cup base paper, and one-side glazed paper are preferred. From the viewpoint of rigidity, high-quality paperboard, special paperboard, cup base paper, and kraft paper are more preferred among (white) paperboards. Examples of kraft paper include bleached kraft paper, unbleached kraft paper, and one-side glazed bleached kraft paper, and from the viewpoint of printability and hygiene, bleached kraft paper and one-side glazed bleached kraft paper are preferred.

[0017] Alternatively, a corrugated cardboard consisting of three layers of a liner, a core and another liner may be used, and in particular, from the viewpoint of achieving both strength and moldability of the container body 10A, a microflute cardboard having a small thickness is preferred. The basis weight of the paper is preferably 200 to 800 g / m 2 and more preferably 200 to 700 g / m 2 and more preferably 200 to 500 g / m 2 and even more preferably 300 to 500 g / m 2 is. From the viewpoint of formability, the density of the paper is preferably 0.5 to 1.2 g / cm 3 and more preferably 0.6 to 1.0 g / cm 3 and more preferably 0.7 to 0.9 g / cm 3 and even more preferably 0.8 to 0.9 g / cm 3 is.

[0018] The thickness of the paper is preferably 200 to 1000 μm, more preferably 250 to 1000 μm, even more preferably 300 to 700 μm, and even more preferably 300 to 500 μm. Paper may contain various additives, and examples of internal sizing agents include rosin-based, alkyl ketene dimer-based, alkenyl succinic anhydride-based, styrene-acrylic, higher fatty acid-based, and petroleum resin-based agents. In addition to internal sizing agents, other known internal additives may also be added. Examples of internal additives include fillers, paper strength agents, retention aids, pH adjusters, drainage aids, water-resistant agents, softeners, antistatic agents, antifoaming agents, slime control agents, dyes, and pigments.

[0019] Examples of fillers include titanium dioxide, kaolin, talc, and calcium carbonate. In the paper making process, any known wet paper machine can be appropriately selected and used. Examples of paper machines include Fourdrinier paper machines, gap former paper machines, cylinder paper machines, and short wire paper machines. The paper layer formed by the paper machine is preferably conveyed on a felt and dried in a dryer. A multi-stage cylinder dryer may be used as a pre-dryer before drying in the dryer. The paper obtained as described above may be subjected to a surface treatment using a calendar to make the thickness and profile uniform. For the calendar treatment, a known calendaring machine can be appropriately selected and used. The material used for the container body 10A is not limited to the above, and various paper materials can be used.

[0020] As shown in Figures 1 to 3, when the side portions 13 are folded to form a truncated pyramid shape, the side edges 14 of adjacent side portions 13 extending from the bottom portion 12A toward the opening 11A butt against each other to form corners of the truncated pyramid. The container body 10A is formed into an octagonal truncated pyramid shape, having eight corners formed by butting the side edges of the eight side portions 13 against each other. Note that the "corner" referred to here refers to the corners of the side portions 13 connecting the upper and lower bases of the truncated pyramid, and does not include the corners formed between the side portions 13 and the bottom portion 12A.

[0021] A gap 50A is provided at the corner where the side edges 14 butt against each other. The gap 50A is formed by separating the side edges 14, and extends linearly between the bottom surface 12A and the opening 11A. The gap portion 50A is a corner portion that connects the inner side (inside the storage space) and outer side (outside the storage space) of the container body 10A, and serves as a passage (flow passage) for air to pass from the inner side to the outer side of the container body 10A during vacuum suction in the manufacturing process of the paper container 1A described below. The distance between the side edges 14 at the gap 50A is set in consideration of both the breathability during suction and the moldability of the container body 10A.

[0022] In this embodiment, gap 50A is set to a dimension longer than the dimension of a straight line connecting bottom surface 12A and opening 11A. The "straight line" here means a straight line connecting a corner of bottom surface 12A to the upper end of side edge 14 of side surface 13 (the intersection of upper edge 16 and side edge 14). This gap 50A has a bent portion 51A formed by bending the gap 50A at an intermediate position M between the bottom surface portion 12A and the opening 11A. In this embodiment, an example is given in which the gap 50A is bent into a dogleg shape by the bent portion 51A. The detailed configuration of the gap 50A will be described later.

[0023] Additionally, the container body 10A has flanges 15 that extend from the upper edge 16 (on the opening 11A side) of each side surface 13 to the opposite side of the opening 11A. The flanges 15 are brim-shaped portions that are provided along the outer periphery of the opening 11A. The side edges of the flanges 15 extending from adjacent side surfaces 13 are abutted against each other and are spaced apart to form gaps. In other words, the gaps 50A extend to the flanges 15.

[0024] <Film layer> The film layer 20 is a layer in which the inner surface of the paper container body 10A is covered (interiorly) with a film sheet. The film layer 20 is a functional layer that not only maintains the folded state of each side surface portion 13 of the container body 10A, but also provides functions such as water resistance and heat resistance to the inner surface of the paper container body 10A. A sheet material having properties according to the function to be imparted is used for the film sheet used in the film layer 20. For example, a plastic sheet having properties such as stretchability, which takes into account the film stretching when adhering to the container body, water resistance, heat resistance, and heat fusion properties is used for the film sheet.

[0025] The film sheet is preferably a resin laminate having extensibility and barrier properties. The resin laminate is more preferably a resin laminate including a barrier layer as an intermediate layer, and a layer made of a thermoplastic resin, since the layer in contact with the inner surface of the container body 10A needs to be heat-sealed to the container body 10A. That is, the resin laminate is more preferably a film layer 20 including a barrier layer as an intermediate layer, and a layer made of a thermoplastic resin, which is the layer in contact with the inner surface of the container body 10A.

[0026] The barrier layer is not limited to resin and may be made of metal foil or the like. However, from the viewpoint of making the printed surface of the paper base layer visible and enhancing the design, it is preferably made of resin, and more preferably made of transparent resin. The resin constituting the barrier layer is preferably at least one selected from the group consisting of polyamide resins, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, and polyvinylidene chloride resins, and more preferably at least one selected from the group consisting of polyamide resins, polyvinyl alcohol, and ethylene-vinyl alcohol copolymers. As the polyamide-based resin, aromatic polyamide is preferred, and polyamide MXD6 is more preferred.

[0027] Resins constituting the layer in contact with the inner surface of the container body 10A of the resin laminate include polyolefin resins such as polyethylene and polypropylene, aliphatic polyamide resins such as nylon 6, and polyester resins such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). The layer facing the inside of the storage space is made of, for example, polypropylene (PP) resin, specifically, homopolypropylene, random polypropylene copolymer, or block polypropylene copolymer, and it is particularly preferable to use a random polypropylene copolymer.

[0028] Examples of polyamide resins include aliphatic polyamide polymers such as nylon 6, nylon 66, nylon 69, nylon 610, nylon 612, nylon 11, and nylon 12, and aliphatic polyamide copolymers such as nylon 6-66 (a copolymer of nylon 6 and nylon 66; the same notation applies hereinafter), nylon 6-10, nylon 6-12, nylon 6-69, nylon 6-610, and nylon 66-69. Of these, aliphatic polyamide copolymers are preferred, with nylon 6-66, nylon 6-10, or nylon 6-12 being particularly preferred. These may be used alone or in combination.

[0029] Representative examples of polyester resins include poly(ethylene terephthalate), poly(butylene terephthalate), poly(ethylene terephthalate / isophthalate), poly(ethylene glycol / cyclohexanedimethanol / terephthalate), etc. Furthermore, these polymers may contain, as copolymerization components, diols such as ethylene glycol, butylene glycol, cyclohexanedimethanol, neopentyl glycol, and pentanediol, or dicarboxylic acids such as isophthals, benzophenone dicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenylmethane dicarboxylic acid, propylene bis(phenylcarboxylic acid), diphenyloxide dicarboxylic acid, oxalic acid, maleic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sabatic acid, and diethylsuccinic acid.

[0030] Examples of polyolefin resins include polyethylene resins such as linear low-density polyethylene, low-density polyethylene, medium-density polyethylene, and high-density polyethylene; polypropylene resins such as polypropylene; and various copolymers such as propylene-ethylene copolymers, ethylene-vinyl acetate copolymers, ionomer resins, ethylene-(meth)acrylic acid copolymers, and ethylene-(meth)acrylic acid-unsaturated carboxylic acid ester copolymers. Polyethylene resins are preferred, and linear low-density polyethylene is particularly preferred. These may be used alone or in combination. The film sheet used for the film layer 20 may have the above-mentioned structure or may have a multi-layer structure that combines various structures.

[0031] Furthermore, from the viewpoint of reducing the environmental load, it is also preferable to use a biodegradable resin such as polylactic acid (PLA), polyglycolic acid (PGA), or polybutylene succinate (PBS) as the film sheet used for the film layer 20. The thickness of the film layer 20 is preferably 10 to 300 μm, more preferably 15 to 200 μm, more preferably 20 to 100 μm, and even more preferably 30 to 50 μm. The film sheets used for the film layer 20 may be laminated by dry lamination, but a film formed by co-extrusion, in which the sheets are simultaneously melt-extruded, is preferred.

[0032] [1-2.Details] The detailed configuration of the container body 10A according to the first embodiment will be described. In the following description, one of the adjacent side surface portions 13 of the container body 10A will be referred to as a first side surface portion 31A, and the other will be referred to as a second side surface portion 32A. The first side surface portion 31A is formed by a first region 130 and a second region 131 connected to each other via a fold 18. The fold 18 is a folded line that extends parallel to the edge of the bottom surface portion 12A along the surface of the first side surface portion 31A at an intermediate position M. In the first side surface portion 31A, the first region 130 is folded toward the inside of the container body 10A relative to the second region 131 via the fold 18.

[0033] The first region 130 has a trapezoidal shape that narrows from the bottom surface portion 12A toward the intermediate position M. The second region 131 has a trapezoidal shape that widens from the fold 18 corresponding to the upper base of the first region 130 toward the opening 11A. That is, the first side surface portion 31A is an hourglass-shaped surface portion that is narrowed at a middle position M when viewed from the side, and both side edges 41A thereof are bent at the middle position M into a dogleg shape.

[0034] The second side portion 32A has a side edge 42A bent into a shape that fits the side edge 41A of the first side portion 31A, and is a hexagonal side portion having a portion that widens from the bottom portion 12A toward the intermediate position M. Specifically, the side edge 42A of the second side surface portion 32A is bent along the side edge 41A of the adjacent first side surface portion 31 A to form a dogleg shape. Therefore, a dogleg-shaped gap 50A is formed between the side edge 41A of the first side surface portion 31A and the side edge 42A of the second side surface portion 32A, and this gap 50A is bent into a dogleg shape at a bend 51A at an intermediate position M.

[0035] In addition, in the container body 10A of this first embodiment, multiple notches are formed intermittently along the folds 17 extending between each side of the bottom portion 12A and the first side portion 31A and the second side portion 32A (side portion 13). Furthermore, a plurality of cuts are formed intermittently along the fold 18 extending between the first region 130 and the second region 131 on the first side surface portion 31A.

[0036] The multiple cuts formed along the folds 17, 18 form gaps (slits that penetrate the thickness of the container body 10A) that extend intermittently in a linear manner in the folds 17, 18 (container body 10A), and serve as a flow path for air to pass from the inner surface to the outer surface of the container body 10A during suction, as described below. The dimensions of the cuts along the extending direction of the folds 17, 18 and the number of cuts are set in consideration of both the breathability during suction and the moldability of the container body 10A.

[0037] In addition, if the four first side portions 31A of the paper container 1A shown in Figures 1 to 3 are considered to be "corner surfaces forming the corners of a quadrangular pyramid," the paper container 1A can also be viewed as a quadrangular pyramid-shaped container having four main side surfaces (second side portions 32A) and four corner surfaces (first side portions 31A) located between these side surfaces. When the paper container 1A is considered to have a truncated quadrangular pyramid shape, it can be said to have gaps 50A bent in a dogleg shape along both side edges of the corners (first side surface 31A) that form the corners of the truncated quadrangular pyramid shape. The first region 130 of the first side surface 31A can also be said to form a chamfered surface on the bottom surface 12A side of the corners that form the corners of the truncated quadrangular pyramid shape.

[0038] [1-3. Blank sheet for container body] As shown in Fig. 4, the blank sheet 10A' used for the container body 10A includes an octagonal bottom sheet piece 12A' and side sheet pieces 13' extending from each side of the bottom sheet piece 12A'. In the explanation of Fig. 4, the direction in which the side sheet pieces 13' extend from each side of the bottom sheet piece 12A' is referred to as the "extending direction," and the side of the side sheet piece 13' that faces the bottom sheet piece 12A' along the extending direction is referred to as the "inside" of the extending direction, and the opposite side is referred to as the "outside" of the extending direction.

[0039] A fold line 17' is provided between the bottom sheet piece 12A' and the side sheet piece 13' along the edge of the bottom sheet piece 12A'. In each side sheet piece 13', a parallel fold line 16' is provided along the edge of the bottom sheet piece 12A' at the outer edge in the extension direction, and a flange sheet piece 15' extends outward in the extension direction from the fold line 16'.

[0040] Of each side surface sheet piece 13', the first side surface sheet piece 31A' has a first region 130' which is trapezoidal in shape and narrows in width from the edge of the bottom surface sheet piece 12A' toward the outside in the extension direction, and a second region 131' which is connected to the first region 130' and is trapezoidal in shape and widens in width toward the outside in the extension direction toward the opening 11A. The side edge 41A' (side edge 14') of the first side surface portion sheet piece 31A' is bent in a dogleg shape.

[0041] Of each side surface sheet piece 13', the second side surface sheet piece 32A' has a hexagonal shape with a portion that widens outward in the extension direction from the side of the bottom surface sheet piece 12A'. The side edge 42A' (side edge 14') of the second side surface sheet piece 32A' is bent in a dogleg shape to fit the side edge 41A' of the adjacent first side surface sheet piece 31A'.

[0042] [2. Configuration of the molding die] Next, the structure of the mold 150 used to manufacture the paper container 1A using the blank sheet 10A' of FIG. 4 will be described with reference to FIGS. FIG. 5 is a perspective view of a forming die 150 used to manufacture the paper container 1A using the blank sheet 10A'. The forming die 150 is a die (cavity, female die) for forming the blank sheet 10A' into the truncated pyramidal container body 10A and for pressing the film layer 20 onto the inner surface of the container body 10A by vacuum suction.

[0043] The forming die 150 has a recess 52 recessed into the upper surface side of a base portion 151. The base portion 151 is a base portion that supports the recess 52. The recess 52 is formed in a shape corresponding to the container body 10A (see FIGS. 1 to 3) to be formed, and forms a recess into which the blank sheet 10A′ is pressed. In order to perform suction processing, a plurality of air holes (reference numeral 58 in FIG. 6 described later) that communicate between the inside and outside of the recess 52 are provided on the inner surface of the recess 52. These air holes are scattered and spaced apart from one another.

[0044] The recess 52 has on its inner surface a plurality of surface portions 53 that correspond to the surface shape of the container body 10A (see FIGS. 1 to 3) when the container body 10A (see FIGS. 1 to 3) is placed thereon. The multiple surface portions 53 specifically include one first surface portion 54 corresponding to the bottom surface portion 12A (see Figures 1 to 3) of the container body 10A (see Figures 1 to 3) when the container body 10A (see Figures 1 to 3) is placed in the recess 52, and eight second surface portions 55 corresponding to the side surface portions 13 (see Figures 1 to 3) of the container body 10A.

[0045] The mold 150 has a flange surface portion 56 that extends from the upper edge of the recess 52 toward the outside of the recess 52. The flange surface portion 56 can be subdivided along the outer periphery of the recess 52 into eight portions corresponding to the eight second surface portions 55, respectively. Furthermore, a stepped portion 57 is provided along the outer periphery of each flange surface portion 56. The stepped portion 57 forms a step that rises outward relative to the surface portion of each flange surface portion 56.

[0046] A groove 60 is provided on the inner surface of the recess 52, extending along a linear region corresponding to the linearly extending gap in the container body 10A (see Figures 1 to 3) when the container body 10A is placed in the recess 52. The grooves 60 are provided in communication with at least two of the scattered air holes, and form air passages that extend linearly on the inner surface of the recess 52 during suction processing. The grooves 60 of this embodiment extend linearly along the boundaries between the plurality of surface portions 53 on the inner surface of the recess 52. The boundaries between the plurality of surface portions 53 are recessed facing the locations where each side of the bottom portion 12A meets the side portion 13 in the container body 10A (see FIGS. 1 to 3) and where adjacent side portions 13 butt against each other. The groove portion 60 illustrated here includes a side groove portion 61 extending along the boundary between the second surface portions 55 among the boundaries between the multiple surface portions 53, a bottom groove portion 62 extending along the boundary between the first surface portion 54 and the second surface portion 55, an upper groove portion 63 extending along the boundary between the flange surface portions 56, and a middle groove portion 64 extending along a linear region corresponding to the fold 18.

[0047] The side grooves 61 are provided between the side edges of the second surface 55 that correspond to the side surfaces 13 (see FIGS. 1 to 3) when the container body 10A (see FIGS. 1 to 3) is placed in the recess 52. The bottom grooves 62 face between the bottom surface 12A and the side surfaces 13 of the container body 10A when the container body 10A (see FIGS. 1 to 3) is placed in the recess 52. When the container body 10A (see FIGS. 1 to 3) is placed in the recess 52, the upper groove 63 faces the gap between the side edges of the flange 15 of the container body 10A. When the container body 10A (see FIGS. 1 to 3) is placed in the recess 52, the middle groove 64 faces between the first region 130 and the second region 131 of the first side surface portion 31A.

[0048] Next, with reference to FIG. 6, a manufacturing apparatus 100 for manufacturing the paper container 1A using the forming mold 150 will be described. The manufacturing apparatus 100 includes a first preparation section 101 that folds and arranges the blank sheet 10A' of the container body 10A along the recess 52 of the forming mold 150, a second preparation section 102 that arranges a film sheet 20' above the blank sheet 10A' folded in the first preparation section 101, a press section 103 that heats and presses the film sheet 20' arranged in the second preparation section 102 toward the blank sheet 10A' arranged in the first preparation section 101, and a suction section 104 that presses the film sheet 20' pressed by the press section 103 against the blank sheet 10A' by vacuum suction.

[0049] The suction section 104 is provided with a suction device (not shown) that sucks air through the air hole 58 . The press section 103 is equipped with a heating device (not shown) that heats and softens the film sheet 20′, and a protrusion 70 for pressing the film sheet 20′. The protrusion 70 is a mold (plug, male mold) with a convex shape that corresponds to the recess 52, and is urged downward by a urging device (not shown). The convex shape of the protrusion 70 is set to have dimensions smaller than those of the recess 52.

[0050] The method for manufacturing the paper container 1A using the manufacturing apparatus 100 includes the following steps S1 to S4. Step S1: The blank sheet 10 of the container body 10A is placed along the recess 52 of the mold 150. The first preparation step is to fold and arrange A'. Step S2: A film is placed above the blank sheet 10A′ folded in the first preparation step. Second preparation step of placing the sheet 20' Step S3: A second preparation step for the blank sheet 10A' arranged in the first preparation step a pressing step in which the film sheet 20' placed in the Step S4: The film sheet 20' pressed in the pressing step is vacuum-suctioned. Suction process to press the rank sheet 10A'

[0051] In the above-mentioned manufacturing apparatus 100, when the film sheet 20' arranged in the second preparation section 102 is heated and pressed toward the blank sheet 10A' arranged in the first preparation section 101, the blank sheet 10A' pressed into the recess 52 has the side portion 13 folded against the bottom portion 12A to form the container body 10A.

[0052] In this state, when air is sucked in through air holes 58 by suction section 104, the air between container body 10A and film sheet 20' is sucked out through gap 50A in container body 10A and the cuts in folds 17 and 18. This creates a vacuum between container body 10A and film sheet 20', causing film sheet 20' to adhere tightly to bottom portion 12A, side portions 13, and flange portion 15, forming (vacuum forming) paper container 1A with film layer 20 crimped onto the inner surface of container body 10A.

[0053] In the paper container 1A formed as described above, when an object such as food is contained in the storage space of the container body 10A, the storage space of the container body 10A is replaced with gas, and the opening 11B is closed with a sealing material (film sheet) attached to the flange portion 15.

[0054] [3. Actions and Effects] The paper container 1A of the first embodiment has the above-mentioned configuration, and therefore can achieve the following actions and effects. (1) Because the gap 50A is set to a dimension longer than the dimension of a straight line connecting the bottom surface 12A and the opening 11A, the cross-sectional area of ​​the air flow path (the dimension of the gap 50A when viewed from the front) can be secured in the gap at the corner, compared to a conventional structure in which a straight gap along the corner forms an air flow path. Therefore, air is reliably sucked between the container body 10A and the film sheet, and the film sheet can be reliably pressed against the container body 10A. Furthermore, because air is more easily sucked in uniformly through the linear gap 50A, the suction load is distributed and the film sheet is less likely to be damaged compared to conventional structures that use suction openings, which also allows the film sheet to be securely crimped to the inner surface of the container body 10A. Therefore, it is possible to provide a paper container 1A in which the film sheet is properly pressure-bonded to the container body.

[0055] (2) By bending the gap portion 50A at the bending portion 51A, the dimension of the gap through which air can pass can be increased with a simple configuration compared to a straight gap portion. (3) The gap portion 50A is bent in a dogleg shape along the dogleg shape of the side edges 41A, 42A of the first side portion 31A and the second side portion 32A, respectively, and the structure for ensuring the length of the pair of gap portions 50A is simple.

[0056] Furthermore, first side surface portion 31A is formed by trapezoidal first region 130 and second region 131, and the number of planar portions increases at the corners of container body 10A, making container body 10A less likely to bend and making it easier to ensure the strength of container body 10A. Increasing the number of planar portions at the corners of container body 10A makes the shape of the inner surface of the storage space of container body 10A closer to a spherical shape, improving heat circulation efficiency when paper container 1A is cooked in a microwave oven.

[0057] (4) Multiple notches are formed along the folds 17 between each side of the bottom portion 12A and the side portion 13, creating linear gaps in addition to the gap portion 50A, making it easier to pull the film sheet toward the bottom portion 12A, and more reliably forming the film layer 20. (5) By forming multiple cuts along the fold 18 between the first region 130 and the second region 131 in the first side surface portion 31A, it is possible to further increase the linear gap in addition to the gap portion 50A. This makes it easier to draw the film sheet toward the first side surface portion 31A, and the film layer 20 can be formed more reliably.

[0058] (6) The flange portions 15 extend from each side portion 13, and the side edges of adjacent flange portions 15 are butted together, which reduces the likelihood of partial overlap between the flange portions 15 and the resulting step. This makes it easier to form the upper surface of the flange portion 15 into a flat shape, and therefore the film layer 20 can be reliably formed on the upper surface of the flange portion 15 as well. In addition, the blank sheet used for the container body 10A of the paper container 1A has the same effects as those (1) to (6) above.

[0059] Furthermore, since the molding die 150 of the first embodiment has the configuration described above, it is possible to obtain the following actions and effects. (7) The grooves 60 are provided in the recess 52 of the mold 150, communicated with at least two air holes 58, and extend along linear regions corresponding to the linear gaps in the container body 10A, allowing the film sheet on the upper surface of the container body 10A to be sucked evenly in a line. This distributes the suction load and ensures the adhesiveness of the film sheet. (8) The forming die 150 is used to manufacture a paper container 1A having a paper container body 10A formed into a truncated pyramidal shape with a top surface forming an opening 11A, multiple side surfaces 13 folded at creases 17 along each side of a polygonal bottom surface 12A, and side edges 14 of adjacent side surfaces 13 butting against each other to form corners, and a film layer 20 formed by pressing a film sheet laminated on the inner surface of the container body 10A. The forming die 150 is suitable for the truncated pyramidal paper container 1A configured as described above, because it can suck the film sheet uniformly and linearly along a linear region corresponding to the linearly extending gap in the container body 10A.

[0060] (9) The grooves 60 extend linearly along the boundaries between the surface portions 53 corresponding to the surface shape of the container body 10A, allowing uniform suction along the line where each side of the bottom portion 12A of the container body 10A meets the side portion 13 and where adjacent side portions 13 meet. This distributes the suction load, ensuring the adhesiveness of the film sheet. (10) The side grooves 61 allow the film sheet on the upper surface of the container body 10A to be sucked evenly along the gaps between the butted portions of the side surfaces 13. This ensures a more reliable suction of the film sheet. Furthermore, since the side grooves 61 function as clearances for the side edges 14 at the butt joints of the side surface portions 13, gaps can be reliably secured between the side edges 14 of the side surface portions 13 at the butt joints. Also, the side surface portions 13 are less likely to be arranged overlapping each other, ensuring the moldability of the container body 10A.

[0061] (11) The bottom groove 62 allows suction along the boundary between the bottom surface 12A and the side surface 13 of the container body 10A, so that the film sheet can be reliably drawn into the bottom side of the recess 52. (12) The upper groove 63 ensures a clearance at the butted portion of the flanges 15, making it difficult for the flanges 15 to be arranged overlapping each other, ensuring moldability of the container body 10A. Furthermore, the stepped portion 57 provided along the outer periphery of the flange surface portion 56 makes it easier to peel the film sheet from the forming mold 150 after the paper container 1A has been formed. In addition, the manufacturing apparatus 100 and manufacturing method using the molding die 150 have the same effects as those (7) to (11) above.

[0062] [II. Second Embodiment] Next, in this section [1], a paper container 1B according to a second embodiment will be described with reference to FIGS. Fig. 7 is a perspective view of a paper container 1B, and Fig. 8 is a view of the paper container 1B as seen from above. Fig. 9 is a plan view of a blank sheet 10B' used for a container body 10B. The paper container 1B in Figs. 7 to 9 differs from the paper container 1A in Figs. 1 to 4 mainly in the side portions 31B, 32B, and 33B adjacent to each other at the corners of the container, and in the gap portion 50B and bent portion 51B provided at the corners, but the other configurations are the same. In the following explanation, the same components as those in Figs. 1 to 4 are designated by the same reference numerals, and duplicate explanations will be omitted.

[0063] [1. Configuration] As shown in Figures 7 and 8, the paper container 1B has a container body 10B with a rectangular opening 11B and an octagonal bottom portion 12B, and eight side portions 13 extending from each side of the bottom portion 12B are folded to form a truncated pyramid shape. The container body 10B has three types of side surface portions 13: a first side surface portion 31B, a second side surface portion 32B, and a third side surface portion 33B.

[0064] The first side surface portion 31B and the second side surface portion 32B have their respective side edges 41B, 42B abutting against each other in a region from the opening 11B to the intermediate position M. Each of the first side surface portion 31B and the second side surface portion 32B is formed in a hexagonal shape that widens from the bottom surface portion 12B toward the opening 11B, and an upper edge 16 (on the opening 11B side) forms one side of the opening 11B. The third side surface portion 33B is disposed between the first side surface portion 31B and the second side surface portion 32B, and is formed in a triangular shape extending from the bottom surface portion 12B to the intermediate position M.

[0065] The gap 50B of the container body 10B is formed by the side edge 41B of the first side surface portion 31B, the side edge 42B of the second side surface portion 32B, and the side edge 43B of the third side surface portion 33B. Specifically, the gap portion 50B is linear along the side edges 41B, 42B from the opening 11B to the intermediate position M, and from the bend portion 51B at the intermediate position M toward the bottom surface portion 12B, it branches into two gaps: one gap along the side edge 41B of the first side surface portion 31B and one side edge 43B of the third side surface portion 33B, and one gap along the side edge 42B of the second side surface portion 32B and the other side edge 43B of the third side surface portion 33B.

[0066] 7 and 8, the third side surface portion 33B of the paper container 1B can be said to form a surface portion that is chamfered on the bottom surface 12B side of the four corners of the truncated quadrangular pyramid. Also, the gap portion 50B can be said to be a "Y-shaped gap" that branches along the surface portion that is chamfered on the bottom surface 12B side of the four corners of the truncated quadrangular pyramid.

[0067] As shown in Figure 9, the blank sheet 10B' used for the container body 10B has an octagonal bottom sheet piece 12B' and side sheet pieces 13' extending from each side thereof, which include a first side sheet piece 31B', a second side sheet piece 32B', and a third side sheet piece 33B'. Each of the first side surface sheet piece 31B' and the second side surface sheet piece 32B' has a hexagonal shape that widens from one side of the bottom surface sheet piece 12B' toward the outside in the extension direction. Each of the side edges 41B', 42B' of the first side surface sheet piece 31B' and the second side surface sheet piece 32B' has a bent, dogleg shape.

[0068] The third side surface sheet piece 33B' has a triangular shape extending outward from one side of the bottom surface sheet piece 12B'. More specifically, the third side surface sheet piece 33B' has an isosceles triangle shape with both side edges 43B' of equal length. The dimension along the extension direction of the third side surface portion sheet piece 33B' (height of the triangle) is set smaller than the dimensions along the extension direction of the first side surface portion sheet piece 31B' and the second side surface portion sheet piece 32B', so that the gap portion 50B in the container body 10B molded using the blank sheet 10B' branches into two at the intermediate position M.

[0069] The mold used to manufacture the paper container 1B using the blank sheet 10B' in Figure 9 has a recess formed in a shape corresponding to the container body 10B to be molded (see Figures 7 and 8), and differs from the mold 150 in Figure 5 in that it has a groove portion corresponding to the container body 10B, but the other configurations are the same. The inner surface of the mold recess used to manufacture the paper container 1B is provided with grooves, including a side groove facing the point where the first side portion 31B, the second side portion 32B and the third side portion 33B are butted together when the container body 10B is placed on it, a bottom groove facing between the bottom portion 12B and the side portion 13, and an upper groove facing the gap between the side edges of the flange portion 15.

[0070] [2. Actions and Effects] The paper container 1B of the second embodiment has the above-mentioned configuration, and therefore can achieve the following actions and effects. (13) Because the gap portion 50B is branched into two, the gap can have a longer dimension for ventilation compared to a straight gap portion. This makes it easier to ensure the suction properties of the film sheet, and the film layer 20 can be reliably formed. In addition, compared to a conventional structure with an additional suction opening, the suction load is more easily distributed, making the film sheet less likely to tear and ensuring the film layer 20 to be reliably formed. Therefore, the paper container 1B can be manufactured appropriately. Furthermore, triangular third side surface portions 33B are formed on the bottom surface portion 12B side at the corners of container body 10B, and the number of planar portions at the corners of container body 10B increases, making container body 10B less likely to bend and making it easier to ensure the strength of container body 10B. The increased number of planar portions at the corners of container body 10B makes the shape of the inner surface of the storage space of container body 10B closer to a spherical shape, improving the heat circulation efficiency when cooking with the paper container 1B in a microwave oven. Additionally, the same effects as those of the first embodiment can be obtained from the same configuration as the first embodiment.

[0071] [III. Modifications] The above-described embodiments are merely examples, and are not intended to exclude various modifications and applications of techniques not explicitly described in these embodiments. The configurations of the present embodiments can be modified in various ways without departing from the spirit of the invention. Furthermore, they can be selected and combined as needed.

[0072] For example, the gap is not limited to a bent shape at a bent portion, and may be a curved gap. The shape of the paper container is not limited to the bowl-shaped or bowl-shaped (deep dish-shaped) described above, but may be, for example, a shallow tray-shaped container, and may be any polygonal truncated pyramid shape, not limited to the octagonal or square truncated pyramid shapes described above. The cuts provided at the folds (at the locations indicated by the reference numerals 17 and 18) in the paper container may be omitted.

[0073] The mold is not limited to a structure in which grooves extend along all boundaries of the multiple surface portions, but may have a structure in which grooves extend along boundaries of only some of the multiple surface portions. For example, the upper groove 63 of the flange surface portion may be omitted. The manufacturing apparatus is not limited to one that performs only vacuum forming in the suction step (suction unit 104) described above, but may also perform vacuum / pressure forming that uses both vacuum suction and compressed air.

[0074] In addition, as shown in FIGS. 10(a) to 10(d), holding pieces 80A, 80B, 80C, and 80D may be provided extending from one side edge of the side surface portion. FIG. 10(a) shows an M-shaped pressing piece 80A that extends from the side edge 42A of the second side surface portion 32A toward the first side surface portion 31A of the paper container 1A. FIG. 10(b) shows triangular pressing pieces 80B extending from both side edges 43B of the third side surface portion 33B of the paper container 1B toward the first side surface portion 31B and the second side surface portion 32B. FIG. 10(c) shows a paper container 1B that, in addition to the holding piece 80B of (b), has a trapezoidal holding piece 80C extending from the side edge 42B of the second side surface portion 32B toward the first side surface portion 31B. FIG. 10(d) shows triangular pressing pieces 80D extending from both side edges 43B of the third side surface portion 33B of the paper container 1B toward the first side surface portion 31B and the second side surface portion 32B. The holding pieces 80A, 80B, 80C, and 80D can improve the strength of the connection between adjacent side surface portions. [Explanation of symbols]

[0075] 1A, 1B Paper containers 10A, 10B Container body 11A,11B opening 12A,12B Bottom part 13 Side part 14 Side edges 15 Flange 17 folds 18 folds 20 film layers 31A, 31B First side part 32A, 32B Second side part 33B Third side part 41A,41B side edge 42A,42B side edge 43B Side edge 50A, 50B Gap 51A,51B Bend part 150 mold 52 recess 53 area 54 First side 55 Second surface part 56 Flange surface 57 Step 58 Air vent 60 Groove 61 Gutter section 62 Bottom groove 63 Upper Mizobe 64 Middle groove part 70 Convex part

Claims

1. a paper container body having an opening on the top surface and a plurality of side surfaces extending from a bottom surface and folded up from the bottom surface; a film layer formed by pressing a film sheet laminated on the inner surface of the container body, The container body has side edges of the side surfaces spaced apart from each other, and has a linear gap between the bottom surface and the opening, the gap is bent in a dogleg shape between the bottom surface and the opening to form an air passage during vacuum suction; The plurality of side surfaces include a first side surface portion having the side edge bent in a dogleg shape and a second side surface portion adjacent to the first side surface portion, the second side surface portion has a side edge bent into a shape that matches the side edge of the first side surface portion, The first side surface portion has a fold, The second side surface portion does not have a fold, A plurality of cuts are intermittently formed along the fold in the first side surface portion. A paper container characterized by:

2. a paper container body having an opening on the top surface and a plurality of side surfaces extending from a bottom surface and folded up from the bottom surface; a film layer formed by pressing a film sheet laminated on the inner surface of the container body, The container body has side edges of the side surfaces spaced apart from each other, and has a linear gap between the bottom surface and the opening, The gap is bent in a Y-shape between the bottom surface and the opening to form an air passage during vacuum suction. A paper container characterized by:

3. the gap portion has a bent portion formed by bending the gap portion at an intermediate position between the bottom surface portion and the opening, The plurality of side surfaces include a first side surface portion and a second side surface portion whose side edges abut against each other in a region from the opening to the intermediate position, and a third side surface portion that is sandwiched between the first side surface portion and the second side surface portion and has a triangular shape extending from the bottom surface portion to the intermediate position, The gap portion is branched into two at the bent portion along both side edges of the third side surface portion from the opening toward the bottom surface portion.

3. The paper container according to claim 2.

4. A plurality of cuts are intermittently formed along the fold provided between the bottom surface portion and the side surface portion. The paper container according to any one of claims 1 to 3.

5. Each of the side surfaces has a flange extending from an edge on the opening side to a side opposite the opening, The side edges of the flange portions are butted against each other. The paper container according to any one of claims 1 to 4.

6. A method for forming a container body of the paper container according to any one of claims 1 to 5. A blank sheet characterized by:

7. A manufacturing method for manufacturing the paper container according to any one of claims 1 to 5 using the blank sheet according to claim 6, a first preparation step of folding and arranging the blank sheet of the container body along a recess of a forming mold having a plurality of surface portions on its inner surface corresponding to the surface shape of the container body while the container body is placed thereon; a second preparation step of arranging the film sheet above the blank sheet folded in the first preparation step; a pressing step of pressing the film sheet arranged in the second preparation step toward the blank sheet arranged in the first preparation step while heating the film sheet; a suction step in which, when air is sucked into the film sheet pressed in the pressing step by vacuum suction, the gap is used as an air flow path, and air is sucked out from between the container body and the film sheet through the flow path, drawing in the film sheet and pressing it against the blank sheet. A manufacturing method characterized by:

Images