Paper container and method for manufacturing the same

Abstract

To provide a method for manufacturing a tray type paper container which can cope with small lot production, and a tray type paper container having a layer constitution suitable for the same.SOLUTION: A method for manufacturing a tray type paper container 10 subjects paperboard 2 to necessary punching 11, coats an adhesive 3 with a thickness of 1 μm or more and 10 μm or less on the surface and dries the adhesive, mounts an inner face synthetic resin film 4 thereon, tightly fastens the paperboard with a plane press device, forms a laminate 1, and then punches the laminate into a predetermined blank sheet BL.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a tray-shaped paper container, and more particularly to a tray-shaped paper container having excellent sealability of a lid material and suitable for small-lot production, and a method for manufacturing the same.

Background Art

[0002] Tray-shaped or box-shaped paper containers with a waterproof treatment on the inner surface are widely used. In a simple case, a laminate obtained by performing a waterproof treatment such as laminating a resin film on the inner surface of cardboard is simply assembled into a box shape and used as a container for storing bento or snacks with little juice. In these containers, since a certain degree of water resistance is not required and use in a horizontal state is assumed, there are also examples where a simple cover is used as the lid.

[0003] When trying to use a tray-shaped paper container as a sealed container, it is necessary to consider not only the sealing performance of the container body but also the sealing performance with the lid material. For this purpose, a method is adopted in which a horizontal flange portion is provided at the upper edge of the paper container, and the lid material is closely sealed to this flange portion.

[0004] The blank for a tray container described in Patent Document 1 has side plates raised on four sides of a square bottom plate, and edge pieces are extended at the tips of the respective side plates so that four edge pieces form a flange portion. A tray-shaped paper container with a flange portion can be used as a sealed container by sealing a lid material.

[0005] In this invention, a problem that there are sometimes fine holes at the intersection of the conventional intersection of the side plates and the edge pieces and juice leaks out is solved by providing small protrusions at the edge of the tongue piece at the tip of the flange portion.

[0006] However, in the case of a container assembled from the blank for a tray container described in Patent Document 1, it was inevitable that a step in the laminate occurred in the flange portion due to the structure. When there was a step on the upper surface of the flange portion, there was a risk of pinholes occurring in the step portion when the lid material was sealed.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] In order to solve this problem, we have developed a new tray-shaped paper container in which the laminates do not overlap in the flange portion, and thus no step is formed in the flange portion. (Japanese Patent Application No. 2020-059941)

[0009] This paper container is a paper tray made of paper blanks. The paper blanks consist of a base paper and a thermoplastic resin layer formed on both the front and back surfaces of the base paper or on the inner surface of the tray. The paper tray is composed of a bottom surface, side plates, and edge pieces. The side plates rise up surrounding the bottom surface to form the tray. The edge pieces are continuous with the upper ends of the side plates and surround the perimeter of the tray parallel to the bottom surface to form a flange. In the base paper that constitutes the blanks, at the corners of the tray, the areas between the side plates and adjacent side plates are cut away so that they do not overlap when the side plates are raised. Also, the areas between the edge pieces and adjacent edge pieces are cut away so that they do not overlap when the entire edge piece is formed. The thermoplastic resin layer is laminated from both the front and back surfaces of the base paper or from the inner surface of the tray, including the areas where the base paper has been cut away. The side plates that rise up surrounding the bottom surface are sealed and connected between the side plates and adjacent side plates by the thermoplastic resin layer in the areas where the base paper has been cut away. Similarly, between the edge pieces and adjacent edge pieces, they are sealed and connected by the thermoplastic resin layer in the areas where the base paper has been cut away, and a tray is formed. This is a paper tray characterized by the above.

[0010] This paper tray was able to obtain a flat flange without steps by previously cutting it so that adjacent edge pieces do not overlap and then forming a thermoplastic resin layer. As a means of efficiently and inexpensively manufacturing such a paper tray, as described in its embodiment, a method of providing a window cutout in the cup base paper and then extruding and laminating a thermoplastic resin on the front and back surfaces was adopted.

[0011] However, according to this method, it is necessary to perform all three processes of the window cutting process, the extrusion lamination process, and the blank punching process by winding. For this reason, in the case of large lot production, it is possible to produce inexpensively and efficiently, but it is completely unsuitable for small lot production.

[0012] The problem to be solved by the present invention is to propose a manufacturing method for a tray-type paper container that can also handle small lot production, and a tray-type paper container having a layer configuration suitable for it.

Means for Solving the Problems

[0013] As a means for solving the above problems, the invention according to claim 1 punches necessary holes in cardboard cut into a predetermined shape, applies an adhesive to the surface of the cardboard other than the punched part, dries it, places a synthetic resin film having a size larger than the size of the cardboard on the adhesive surface, presses the whole with a flat press machine to bond the cardboard and the synthetic resin film, creates a laminate having a cardboard layer and an inner synthetic resin film layer, and then punches it into a predetermined blank sheet shape, which is a manufacturing method of a tray-shaped paper container characterized in that the blank sheet has a bottom plate in a shape obtained by stretching a regular octagon in the vertical and horizontal directions, and rectangular corner plates are continuously provided on the four non-stretched sides of the bottom plate via mountain fold lines, trapezoidal side plates are continuously provided on the other sides of the bottom plate via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, there are parts where the cardboard layer is punched out and only the inner synthetic resin film layer exists between each corner plate and the side plate and between each corner plate and the edge piece, in forming, the tip parts of each side plate and the edge pieces are folded inside each corner plate so that their respective tips do not overlap, the edge piece continuously forms a horizontal and flat flange part that surrounds the periphery of the opening of the paper container in parallel with the bottom surface at the upper end of the side plate, and the cardboard layer and the inner synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less, which is a manufacturing method of a tray-shaped paper container.

[0014] According to the manufacturing method of the tray-shaped paper container according to the present invention, since the cardboard layer and the inner synthetic resin film layer can be bonded using a flat press machine generally called a PP laminating machine, it can also cope with small-lot production.

[0015] Also, the invention according to claim 2 is a method for manufacturing a tray-type paper container, which comprises punching a cardboard cut into a predetermined shape as required, placing a synthetic resin film having a size larger than that of the cardboard, on which an adhesive has been previously applied over the entire surface, compressing the whole with a flat press machine to bond the cardboard and the synthetic resin film, and then punching into a predetermined blank sheet shape, characterized in that the blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided via mountain fold lines on the four non-stretched sides of the bottom plate, on the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, there are portions where the cardboard layer is punched out and only the inner surface synthetic resin film layer and the adhesive layer exist between each corner plate and the side plate and between each corner plate and the edge piece, in the forming process, the tip portions of each side plate and the edge pieces are folded inside each corner plate so that their respective tips do not overlap, the edge piece is continuous with the upper end of the side plate and forms a horizontal, stepped-free, flat flange portion that surrounds the periphery of the opening of the paper container in parallel with the bottom surface, and the cardboard layer and the inner surface synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less, which is a method for manufacturing a tray-type paper container.

[0016] Also, the invention according to claim 3 is a tray-type paper container formed by shaping a blank sheet obtained by punching a laminate having a cardboard layer and an inner surface synthetic resin film layer into a predetermined shape, the blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided via mountain fold lines on the four non-stretched sides of the bottom plate, on the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, There is a part where the paperboard layer is punched out and the inner surface synthetic resin film layer exists between each corner plate and the side plate and between each corner plate and the edge piece. In molding, the tip portions of each side plate and the edge piece are folded inside each corner plate so that their respective tips do not overlap. The edge piece continuously forms a flat flange portion that is parallel to the bottom surface and surrounds the periphery of the opening of the paper container at the upper end of the side plate, without steps and being horizontal. The tray - type paper container is characterized in that the paperboard layer and the inner surface synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less.

[0017] Further, the invention according to claim 4 is the tray - type paper container according to claim 3, characterized in that the thickness of the adhesive layer is 2 μm or more and 6 μm or less.

[0018] Further, the invention according to claim 5 is the tray - type paper container according to claim 3 or 4, characterized in that the adhesive for forming the adhesive layer is an aqueous dispersion having the same composition as the inner surface synthetic resin film layer.

Effect of the Invention

[0019] According to the manufacturing method of the tray - type paper container described in claim 1 or 2, compared with the conventional manufacturing method by a winding method that requires three steps, production in a much smaller lot is possible. Therefore, it can be said that it is a manufacturing method suitable for multi - variety and small - quantity production, which has been on the increase in recent years.

[0020] Whether to apply the adhesive on the paperboard side as in the manufacturing method described in claim 1 or to apply the adhesive on the inner surface synthetic resin film side as in the manufacturing method described in claim 2 can be selected according to the existing manufacturing equipment. Therefore, the introduction of new production equipment can be minimized. 。

[0021] When an aqueous dispersion having the same composition as the inner surface synthetic resin film layer is used as the adhesive as in the invention described in claim 5, unlike the solvent type adhesive, it does not have an adverse effect on the indoor environment, and a general-purpose synthetic resin film such as a polyethylene resin film can be used as the inner surface synthetic resin film layer, so it is also economically advantageous.

Brief Description of the Drawings

[0022]

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Figure 12

DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, with reference to the drawings, the tray-type paper container 10 according to the present invention and its manufacturing method will be described in detail. FIG. 1 is a perspective view showing an example of the tray-type paper container 10 according to the present invention. FIG. 2 is a plan schematic view of the blank sheet BL of the tray-type paper container 10 shown in FIG. 1. FIG. 3 is a cross-sectional schematic view showing the layer structure of the blank sheet BL manufactured by the manufacturing method according to claim 1, corresponding to the A-A' cross-section of FIG. 2. FIG. 4 is a cross-sectional schematic view showing a state in which the blank sheet of FIG. 3 is molded, corresponding to the B cross-section of FIG. 1. Hereinafter With reference to these drawings, the manufacturing method of the tray-type paper container according to the present invention and the tray-type paper container manufactured thereby will be described.

[0024] As an embodiment of the manufacturing method of the tray-type paper container 10 according to the present invention, as described in claim 1, The paperboard 2 cut into a predetermined shape is punched with necessary punching 11, the adhesive 3 is applied to the surface of the paperboard other than the punched portion and dried, and then a synthetic resin film having a size larger than the size of the paperboard is placed on the adhesive surface, and the whole is pressed by a flat press machine to bond the paperboard and the synthetic resin film, and the paperboard layer 2 and the inner surface synthetic resin film layer 4 are laminated via an adhesive layer 3 having a thickness of 1 μm or more and 10 μm or less. After creating the laminate 1, it is characterized by punching into a predetermined blank sheet BL shape, which is a manufacturing method of the tray-type paper container 10.

[0025] As shown in FIG. 2, the blank sheet BL has a bottom plate 5 in the shape of a regular octagon stretched in the vertical and horizontal directions. Rectangular corner plates 6, 6, 6, 6 are successively connected to the four non-stretched sides of the bottom plate 5 via mountain fold lines e, f, g, h, respectively. Trapezoidal side plates 7, 7, 7, 7 are successively connected to the other sides of the bottom plate 5 via mountain fold lines a, b, c, d, respectively. Edge pieces 8 are successively connected to each side plate 7 via valley fold lines i, j, k, l. A punched portion 11 where only the inner synthetic resin film layer 4 exists, that is, the paperboard layer 2 is punched out, exists between each corner plate 6 and the side plate 7, and between each corner plate 6 and the edge piece 8.

[0026] In the forming process, the tip of each side plate 7 and the edge piece 8 are folded inside each corner plate 6 so that their respective tips do not overlap, and the edge piece 8 continuously forms a horizontal, stepped-free, flat flange portion 9 that surrounds the periphery of the opening of the paper container 10 in parallel with the bottom surface 5 at the upper end of the side plate 7.

[0027] As another embodiment of the method for manufacturing the tray-type paper container 10 according to the present invention, as described in claim 2, A synthetic resin film 4 having a size larger than that of the paperboard 2, on which an adhesive 3 is previously applied over the entire surface, is placed, and the whole is pressed with a flat press machine to create a laminate 1 in which the paperboard 2 and the synthetic resin film 4 are laminated via an adhesive layer 3 having a thickness of 1 μm or more and 10 μm or less, and then punched into a predetermined blank sheet BL shape. This is a method for manufacturing the tray-type paper container 10.

[0028] The blank sheet BL obtained by this method is the same as that shown in FIG. 2 in a plan view. However, it is different in that not only the inner synthetic resin film layer 4 but also the adhesive layer 3 exists in the punched portion 11 where the paperboard layer 2 between each corner plate 6 and the side plate 7 and between each corner plate 6 and the edge piece 8 is punched out.

[0029] A printed display is made on the cardboard layer 2 that contacts the outside of the general container, which becomes the surface side of the laminate 1. Therefore, the crease line where the cardboard layer 2 side becomes a mountain is the mountain crease line, and the crease line where the cardboard layer 2 side becomes a valley is the valley crease line. In FIG. 2, the mountain crease line is shown by a dotted line, and the valley crease line is shown by a dashed-dotted line. Note that FIG. 2 shows the state of the blank sheet BL as seen from the surface side.

[0030] On the other sides of the bottom plate 5, trapezoidal side plates 7 are continuously provided via mountain crease lines a, b, c, and d, respectively, and edge pieces 8 are continuously provided on each side plate via valley crease lines i, j, k, and l.

[0031] The cardboard layer 2 is punched out between each corner plate 6, the side plate 7, and the edge piece 8, and only the part of the inner synthetic resin film layer 4 exists. In molding, the tip of each side plate 7 and the flange part 8 are folded inside each corner plate 6 so that the respective tips do not overlap and are molded.

[0032] Since the four-sided edge pieces 8 do not overlap each other, the flange part 9 after molding becomes a flat finish with no steps. Therefore, when sealing the lid material, there is no occurrence of pinholes, etc., and the sealing performance is enhanced.

[0033] Also, after punching the necessary holes in the cardboard layer 2, the inner synthetic resin film layer 4 is formed on the entire surface, and then a blank sheet punched into a predetermined shape is used. Therefore, in the molded tray-shaped paper container, the inner synthetic resin film layer 4 continuously exists from the bottom surface to the flange part, so there is no worry about water leakage.

[0034] FIG. 3 is a schematic cross-sectional view showing the layer structure of the blank sheet BL manufactured by the manufacturing method according to claim 1, and corresponds to the A-A' cross-section of FIG. 2. Since the adhesive layer 3 is applied on the cardboard layer 2, there is no adhesive layer on the inner synthetic resin film layer 4 of the punched part 11. FIG. 4 is a schematic cross-sectional view showing the state of the blank sheet of FIG. 3 after molding, and corresponds to the B cross-section of FIG. 1.

[0035] FIG. 5 is a schematic cross-sectional view showing the layer structure of the blank sheet BL manufactured by the manufacturing method according to claim 2, corresponding to the A-A' cross-section of FIG. 2. FIG. 6 is a schematic cross-sectional view showing the state where the blank sheet of FIG. 5 is molded, corresponding to the B cross-section of FIG. 1.

[0036] In any case of FIGS. 4 and 6, at the time of molding, since heating and pressurization are applied, the inner synthetic resin film layers 4 are heat-sealed and integrated with each other.

[0037] Regarding the adhesive for bonding the paperboard layer 2 and the inner synthetic resin film layer 4, as the thickness of the adhesive layer 3, it is necessary to be 1 μm or more and 10 μm or less. If the thickness is less than 1 μm, the amount of the adhesive is insufficient and the adhesive strength may be insufficient. If the thickness exceeds 10 μm, not only is the amount of the adhesive too much and uneconomical, but also there may be adverse effects due to poor drying or the like. A more desirable thickness of the adhesive layer 3 is 2 μm or more and 6 μm or less.

[0038] As the adhesive, it can be appropriately selected according to the material of the inner synthetic resin film, but desirable results can be obtained by using an aqueous dispersion having the same composition as the inner synthetic resin film. For example, if a polyethylene resin film is used as the inner synthetic resin film, a polyethylene resin dispersion is optimal as the adhesive, and if a polypropylene resin film is used as the inner synthetic resin film, a polypropylene resin dispersion is optimal as the adhesive.

[0039] FIG. 7 is an explanatory cross-sectional view showing a state where the inner synthetic resin film 4 is placed on the paperboard 2 having the adhesive layer 3 formed thereon with the hot plate 21 of the flat press 20 open in the manufacturing method according to claim 1. FIG. 8 is an explanatory cross-sectional view showing a state where the hot plate 21 is clamped from the state of FIG. 7 in the manufacturing method according to claim 1.

[0040] In Figures 7 and 8, only one set is compressed, but there may be cases where multiple sets are stacked via a release film or the like, compressed, and adhered. Also, in the figures, cushions, release films, etc. are omitted.

[0041] Figures 9 to 12 illustrate the manufacturing method of the tray-type paper container according to the present invention in accordance with the steps. Figure 9 is a plan explanatory view showing a state in which the necessary punching 11 is performed on the paperboard layer 2 in the manufacturing method of the tray-type paper container according to Claim 1. Figure 10 is a plan explanatory view showing the inner surface synthetic resin film 4 cut to a predetermined size. Figure 11 is the paperboard on which the punching shown in Figure 9 is performed and the inner surface synthetic resin film shown in Figure 10 are bonded together to form a laminate 1, and is a plan explanatory view showing the state. Figure 12 is a plan explanatory view showing a state in which the laminate 1 shown in Figure 11 is punched to form a blank sheet BL.

[0042] According to the manufacturing method of the tray-type paper container according to the present invention, in manufacturing the blank sheet BL, since all processes can be completed in a single-sheet manner, production is possible even in small lots, and it can be said that it is a method suitable for multi-variety and small-quantity production. Hereinafter, the tray-type paper container according to the present invention will be specifically described based on examples.

[0043] <Example 1> After punching the paperboard (Pearl Card manufactured by Mitsubishi Paper Mills, basis weight 260 g / m 2 ), a polypropylene resin dispersion (Baron manufactured by Daiichi Paint Co., Ltd.) as an adhesive was applied so that the dried thickness would be 1.0 μm, and then a polypropylene resin film (thickness 40 μm) as an inner surface synthetic resin film was placed on the adhesive surface and compression-bonded at a thermocompression bonding temperature of 140 to 150 °C using a flat press machine to adhere. After punching the obtained laminate into a predetermined blank shape, it was formed into a tray-type paper container having the shape shown in Figure 1.

[0044] The formability during molding, the odor after molding, and the heat resistance in a microwave oven were evaluated.

[0045] <Example 2> A blank sheet was prepared in the same manner as in Example 1, except that the adhesive was applied to the surface of the PP film instead of the cardboard surface, and it was molded into a tray-type paper container in the same manner. Evaluation was carried out in the same manner as in Example 1.

[0046] <Example 3> A laminate was prepared in the same manner as in Example 1, except that a polyethylene resin dispersion (Arrow Base PE, manufactured by Unitika Ltd.) was used as the adhesive, a polyethylene resin film was used as the inner synthetic resin film, and the thermocompression bonding temperature was set to 90 to 100°C. It was molded into a tray-type paper container in the same manner and evaluated in the same manner.

[0047] <Example 4> A laminate was prepared in the same manner as in Example 2, except that a polyethylene resin dispersion (Arrow Base PE, manufactured by Unitika Ltd.) was used as the adhesive, a polyethylene resin film was used as the inner synthetic resin film, and the thermocompression bonding temperature was set to 90 to 100°C. It was molded into a tray-type paper container in the same manner and evaluated in the same manner.

[0048] <Comparative Example 1> A laminate was prepared in the same manner as in Example 2, except that a maleic acid-modified polypropylene resin adhesive (solvent type) (Arrow Base PP DB5010, manufactured by Unitika Ltd.) was used as the adhesive and the thermocompression bonding temperature was set to 60 to 70°C. It was molded into a tray-type paper container in the same manner and evaluated in the same manner.

[0049] <Comparative Example 2> A laminate was prepared in the same manner as in Example 2, except that a urethane resin-based adhesive (solvent type) (Takelac A969V, manufactured by Mitsui Chemicals, Inc.) was used as the adhesive and the thermocompression bonding temperature was set to 60 to 70°C. It was molded into a tray-type paper container in the same manner and evaluated in the same manner.

[0050] <Comparative Example 3> A laminate was prepared in the same manner as in Example 4, except that a urethane resin-based adhesive (solvent type) (Takelac A969V, manufactured by Mitsui Chemicals, Inc.) was used as the adhesive and the thermocompression bonding temperature was set to 60 to 70°C. It was molded into a tray-type paper container in the same manner and evaluated in the same manner.

[0051] <Comparative Example 4> As the inner synthetic resin film, a polyethylene terephthalate resin film (thickness 20 μm) was used. As the adhesive, a urethane resin-based adhesive (solvent type) (Take lac A969V, manufactured by Mitsui Chemicals, Inc.) was used. A laminate was prepared in the same manner as in Example 4 except that the thermocompression bonding temperature was set to 60 to 70°C, and it was similarly formed into a tray-shaped paper container and evaluated in the same manner.

[0052] <Comparative Example 5> As the inner synthetic resin film, a polybutylene terephthalate resin film (thickness 20 μm) was used. As the adhesive, a urethane resin-based adhesive (solvent type) (Take lac A969V, manufactured by Mitsui Chemicals, Inc.) was used. A laminate was prepared in the same manner as in Example 4 except that the thermocompression bonding temperature was set to 60 to 70°C, and it was similarly formed into a tray-shaped paper container and evaluated in the same manner.

[0053] <Comparative Example 6> As the inner synthetic resin film, a polymethylpentene resin film (thickness 20 μm) was used. As the adhesive, a urethane resin-based adhesive (solvent type) (Take lac A969V, manufactured by Mitsui Chemicals, Inc.) was used. A laminate was prepared in the same manner as in Example 4 except that the thermocompression bonding temperature was set to 60 to 70°C, and it was similarly formed into a tray-shaped paper container and evaluated in the same manner.

[0054] The above results are summarized in Table 1.

[0055]

Table 1

[0056] From the results in Table 1, it was found that the tray-shaped paper container manufactured by the manufacturing method of the tray-shaped paper container according to the present invention has performance no inferior to that of the tray-shaped paper container manufactured by the conventional continuous winding method.

Explanation of Signs

[0057] 1 ··· Laminate 2 ··· Paperboard layer 3 ··· Adhesive layer 4 ··· Inner synthetic resin film layer BL ··· Blank sheet 5 ··· Bottom panel 6 ··· Corner board 7 ··· Side panel 8 ··· Edge piece 9 ··· Flange part 10 ··· Tray-shaped paper container 11 ··· Punched part a~l ··· Score lines 20 ··· Plane press 21 ··· Hot plate

Claims

1. The cardboard cut into a predetermined shape is punched as necessary, and after applying an adhesive to the surface of the cardboard other than the punched portion and drying it, a synthetic resin film having a size larger than the size of the cardboard is placed on the adhesive surface, the whole is compressed by a flat press machine to bond the cardboard and the synthetic resin film, after creating a laminate having a cardboard layer and an inner synthetic resin film layer, A method for manufacturing a tray-shaped paper container, characterized in that it is punched into a predetermined blank sheet shape, The blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided on the four non-stretched sides of the bottom plate via mountain fold lines, On the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, There are portions between each corner plate and the side plate and between each corner plate and the edge piece where the cardboard layer is punched out and only the inner synthetic resin film layer exists, In forming, the tip portions and edge pieces of each side plate are folded inside each corner plate so that their respective tips do not overlap, The edge piece continuously forms a horizontal and flat flange portion that surrounds the periphery of the opening of the paper container parallel to the bottom surface at the upper end of the side plate, The method for manufacturing a tray-shaped paper container, characterized in that the cardboard layer and the inner synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less.

2. After punching the cardboard cut into a predetermined shape as necessary, a synthetic resin film having a size larger than the size of the cardboard, which has been previously coated with an adhesive on the entire surface, is placed, the whole is compressed by a flat press machine to bond the cardboard and the synthetic resin film, Thereafter, a method for manufacturing a tray-shaped paper container, characterized in that it is punched into a predetermined blank sheet shape, The blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided on the four non-stretched sides of the bottom plate via mountain fold lines, On the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, There are portions between each corner plate and the side plate and between each corner plate and the edge piece where the cardboard layer is punched out and only the inner synthetic resin film layer and the adhesive layer exist, In the forming process, the tip portions of each side plate and the edge pieces are folded inside each corner plate so that their respective tips do not overlap, The edge piece continuously forms a horizontal and flat flange portion that surrounds the periphery of the opening of the paper container in parallel with the bottom surface at the upper end of the side plate, The method for manufacturing a tray-type paper container, characterized in that the paperboard layer and the inner synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less.

3. A tray-type paper container formed by shaping a blank sheet obtained by punching a laminate having a paperboard layer and an inner synthetic resin film layer into a predetermined shape, The blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided via mountain fold lines on the four non-stretched sides of the bottom plate, On the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, There are portions where the paperboard layer is punched out and the inner synthetic resin film layer exists between each corner plate and the side plate and between each corner plate and the edge piece, In the forming process, the tip portions of each side plate and the edge pieces are folded inside each corner plate so that their respective tips do not overlap, The edge piece continuously forms a horizontal and flat flange portion that surrounds the periphery of the opening of the paper container in parallel with the bottom surface at the upper end of the side plate, The paperboard layer and the inner synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less, The paperboard layer is in contact with one surface of the adhesive layer, and the other surface of the adhesive layer is in contact with the inner synthetic resin film layer, characterized in that it is a tray-type paper container.

4. A tray-type paper container formed by shaping a blank sheet obtained by punching a laminate having a paperboard layer and an inner synthetic resin film layer into a predetermined shape, The blank sheet has a bottom plate in the shape of a regular octagon stretched in the vertical and horizontal directions, and rectangular corner plates are continuously provided via mountain fold lines on the four non-stretched sides of the bottom plate, On the other sides of the bottom plate, trapezoidal side plates are continuously provided via mountain fold lines, and edge pieces are continuously provided on each side plate via valley fold lines, There are portions where the paperboard layer is punched out and the inner synthetic resin film layer exists between each corner plate and the side plate and between each corner plate and the edge piece, In forming, the tip portions and edge pieces of each side plate are folded inside each corner plate so that their respective tips do not overlap, The edge piece continuously forms a flat flange portion that surrounds the periphery of the opening of the paper container parallel to the bottom surface at the upper end of the side plate, without steps and horizontally. The paperboard layer and the inner synthetic resin film layer are laminated via an adhesive layer having a thickness of 1 μm or more and 10 μm or less. The adhesive for forming the adhesive layer is a dried product of an aqueous dispersion having the same composition as the inner synthetic resin film layer, characterized in that it is a tray-type paper container.

5. The tray-type paper container according to claim 3 or 4, characterized in that the thickness of the adhesive layer is 2 μm or more and 6 μm or less.

6. At each corner of the blank sheet, there are two portions where the paperboard layer is punched out and the inner synthetic resin film layer exists, and the two portions are separated via the corner plate. The tray-type paper container according to any one of claims 3 to 5, characterized in that.

7. The tray-type paper container according to any one of claims 3 to 6, characterized in that only the inner synthetic resin film layer exists in the portion where the paperboard layer is punched out and the inner synthetic resin film layer exists.

8. The inner synthetic resin film layer is a polyethylene resin film, The tray-type paper container according to any one of claims 3 to 7, characterized in that the adhesive for forming the adhesive layer is a dried product of a polyethylene resin dispersion.

9. The inner synthetic resin film layer is a polypropylene resin film, The tray-type paper container according to any one of claims 3 to 7, characterized in that the adhesive for forming the adhesive layer is a dried product of a polypropylene resin dispersion.

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