JP7593137B2 - Paper containers and paper containers with lids - Google Patents

Description

This disclosure relates to paper containers and paper containers with lids.

Containers for holding food and drink to be taken home (so-called take-out products) or food and drink to be delivered to your home have been known for some time.

In recent years, in order to address the problem of marine pollution and reduce the burden on the environment, there has been a demand to reduce the amount of resin used in such containers, and efforts are being made to reduce the amount of resin and change the materials used in the containers. One such container known is a paper container that comprises a paper container and a molded film laminated on the inner wall of the paper container (see, for example, Patent Document 1). In such a paper container, after the food is filled, the paper container is covered with a lid material.

Special Publication No. 2013-545675

However, with such paper containers, if the adhesive strength between the paper container and the molded film laminated on the paper container becomes weak, there is a risk that the molded film will unintentionally peel off from the paper container. In this case, it may not be possible to peel the lid material off the paper container, and it may be impossible to open the paper container.

In addition, in order to reduce the environmental impact of such paper containers, recycling of the paper used in the paper containers is being promoted. However, in the above-mentioned paper container, if the adhesive strength between the paper container and the molded film laminated on the paper container becomes large, there is a risk that the molded film cannot be peeled off from the paper container. In addition, when the molded film is peeled off from the paper container, there is a risk that the paper container may peel off (part of the paper container may peel off). In this case, it may not be possible to recycle the paper. For this reason, there is a demand for a container that allows consumers to easily peel off the molded film from the paper container after use and allows the paper to be easily recycled.

This disclosure has been made in consideration of these points, and aims to provide a paper container and a paper container with a lid that can improve practicality and recyclability.

A paper container according to one embodiment includes a paper container having a bottom, a number of side sections connected to the bottom via fold lines, and a number of flange pieces connected to each of the side sections via fold lines, and a molded film laminated on the surface of the paper container, the side sections being adjacent to each other without being continuous with each other, the adhesive strength between the flange pieces and the molded film being 1.0 N/15 mm or more, and the adhesive strength between the bottom and the molded film and the adhesive strength between the side sections and the molded film being 0.05 N/15 mm or more and 0.4 N/15 mm or less, respectively.

In one embodiment of the paper container, the adhesive strength between the flange piece and the molded film may be 5.0 N/15 mm or less.

In one embodiment of the paper container, a heat seal layer may be provided on the flange piece.

In one embodiment of the paper container, the weight per unit area of the heat seal layer may be 0.1 g/ ^m2 or more and 10.0 g/m2 or ^less .

A paper container with a lid according to one embodiment is a paper container with a lid comprising the paper container according to the present disclosure and a lid that seals the paper container.

This disclosure makes it possible to improve the practicality and recyclability of paper containers and paper containers with lids.

FIG. 1 is a vertical cross-sectional view showing a paper container with a lid according to the present embodiment. FIG. 2 is a perspective view showing a paper container according to this embodiment. FIG. 3 is a plan view showing the paper container according to the present embodiment. FIG. 4 is a development view showing a blank for producing a paper container according to this embodiment. FIG. 5 is a cross-sectional view showing a method for manufacturing a paper container according to this embodiment. FIG. 6 is a cross-sectional view showing a method for manufacturing a paper container according to this embodiment. FIG. 7 is a cross-sectional view showing a method for manufacturing a paper container according to this embodiment. FIG. 8 is a perspective view showing a first modified example of the paper container according to the present embodiment. FIG. 9 is a development view showing a blank for producing a first modified example of a paper container according to the present embodiment. FIG. 10 is a perspective view showing a second modified example of the paper container according to the present embodiment. FIG. 11 is a development view showing a blank for producing a second modified example of a paper container according to the present embodiment. FIG. 12 is a perspective view showing a third modified example of the paper container according to the present embodiment. FIG. 13 is a development view showing a blank for producing a third modified example of a paper container according to the present embodiment. FIG. 14 is a development view showing another example of a blank for producing the third modified example of the paper container according to the present embodiment. FIG. 15 is a development view showing another example of a blank for producing the third modified example of the paper container according to the present embodiment.

The present embodiment will be described below with reference to the drawings. Figures 1 to 7 are diagrams showing the present embodiment. Each of the figures shown below is a schematic diagram. Therefore, the size and shape of each part are appropriately exaggerated to facilitate understanding. In addition, it is possible to carry out appropriate modifications within the scope of the technical concept. In each of the figures shown below, the same parts are given the same reference numerals, and some detailed explanations may be omitted. In addition, the numerical values such as dimensions of each member and the names of materials described in this specification are examples of embodiments, and are not limited to these, and can be selected and used as appropriate. In this specification, terms that specify shapes and geometric conditions, such as parallel, orthogonal, and vertical, are intended to include substantially the same state in addition to their strict meanings. In this specification, "upper" and "lower" refer to the upper and lower sides of the paper container in an upright state (Figure 1), respectively. In this specification, "surface" refers to the surface facing the contents, or the surface that faces upward when the paper container is upright.

As shown in Fig. 1, a paper container with a lid 1 according to this embodiment comprises a paper container 10 and a lid 50 that seals the paper container 10. Here, the paper container 10 will first be described.

1 to 3, a paper container 10 includes a paper container 20 and a forming film 40 laminated on the surface of the paper container 20. The paper container 20 is produced by assembling blanks 30, which will be described later.

(Paper container)
The paper container 20 has a bottom 21, a plurality of side portions 23 connected to the bottom 21 via fold lines (first fold lines) 22, and a plurality of flange pieces 25 connected to each of the side portions 23 via fold lines (second fold lines) 24.

The bottom 21 has a generally rectangular shape when viewed from above. The bottom 21 may have a polygonal shape, such as an octagonal shape, when viewed from above.

The fold line (first fold line) 22 connecting the bottom 21 and the side 23 may be formed in a perforated shape or a half-cut line. This makes it easier to fold the side 23 relative to the bottom 21. When the fold line 22 is formed in a perforated shape, the molded film 40 is pressed against the paper container 20 in the vicinity of the fold line 22 by sucking air through the suction holes 61 of the cavity side mold 60 described below. This improves the adhesion between the molded film 40 and the paper container 20.

Each side portion 23 extends upward from the bottom portion 21. In the illustrated example, the paper container 20 has four side portions 23, and the side portions 23 are formed in an inverted quadrangular pyramid shape as a whole. However, this is not limited to this, and the side portions 23 may be formed in a polygonal pyramid shape, such as an inverted octagonal pyramid shape as a whole.

The multiple side portions 23 are adjacent to each other without being continuous with each other. In other words, the side portions 23 are adjacent to each other without overlapping each other. This allows the adhesion between the side portions 23 and the molded film 40 to be improved over the entire circumference of the paper container 20. In addition, since the side portions 23 are adjacent to each other without overlapping each other, it is possible to prevent pinholes and the like from occurring in the molded film 40 when the molded film 40 is adhered to the paper container 20. Note that tiny gaps are formed between the side portions 23 to allow air to pass through, and the molded film 40 is configured to be pressed against the paper container 20 by sucking air from the suction holes 61 of the cavity side mold 60 described below.

The fold line (second fold line) 24 connecting the side portion 23 and the flange piece 25 may be formed in a perforated shape, similar to the fold line 22, or may be a half-cut line. This makes it easier to fold the flange piece 25 relative to the side portion 23. When the fold line 24 is formed in a perforated shape, the formed film 40 is pressed against the paper container 20 in the vicinity of the fold line 24 by sucking air through the suction holes 61 of the cavity side mold 60 described below. This improves the adhesion between the formed film 40 and the paper container 20.

Each flange piece 25 protrudes horizontally from the upper end of the side portion 23 toward the side. In the illustrated example, the paper container 20 has four flange pieces 25, and the flange pieces 25 are formed into a ring shape as a whole.

The flange pieces 25 are adjacent to each other without being continuous with each other. That is, the flange pieces 25 are adjacent to each other without overlapping each other. This allows the adhesion between the flange pieces 25 and the molded film 40 to be improved over the entire circumference of the paper container 20. In addition, since the flange pieces 25 are adjacent to each other without overlapping each other, it is possible to suppress the occurrence of pinholes and the like in the molded film 40 when the molded film 40 is adhered to the paper container 20. Furthermore, since the flange pieces 25 are adjacent to each other without overlapping each other, it is possible to improve the adhesion between the molded film 40 and the lid material 50 when sealing the lid material 50 in the region of the molded film 40 of the paper container 10 corresponding to the flange pieces 25. This allows the occurrence of sealing defects of the lid material 50 to be suppressed. In addition, in this specification, "adjacent" includes a case where adjacent members (e.g., flange pieces 25) are in contact with each other without any gaps over the entire circumference, as well as a case that falls under the following (1) or (2).
(1) A first member and another member are adjacent to each other with only a portion of the first member in contact with the other member.
(2) When a first component and another component are adjacent to each other without being in contact with each other, at least a portion of the gap between the first component and the other component is large enough that the molded film 40 (film 40a described below) cannot enter when the molded film 40 is adhered to the first component and the other component.

Next, we will explain the adhesive strength between the paper container 20 and the molded film 40.

The adhesive strength between the bottom 21 and the formed film 40 and the adhesive strength between the side 23 and the formed film 40 may be 0.05 N/15 mm or more and 0.4 N/15 mm or less. By having these adhesive strengths of 0.05 N/15 mm or more, it is possible to prevent the formed film 40 from unintentionally peeling off from the paper container 20. In particular, it is possible to prevent the formed film 40 from unintentionally peeling off from the bottom 21 or side 23 of the paper container 20 when removing the lid material 50 from the paper container 10 of the paper container 1 with lid material. In addition, by having these adhesive strengths of 0.4 N/15 mm or less, the paper container 20 and the formed film 40 can be easily separated when recycling the paper container 20. Note that the adhesive strength between the bottom 21 and the formed film 40 and the adhesive strength between the side 23 and the formed film 40 may be different from each other. For example, the adhesive strength between the side portion 23 and the molded film 40 may be greater than the adhesive strength between the bottom portion 21 and the molded film 40. The adhesive strength can be measured in accordance with JIS Z 0238:1998 by performing a 90° peel test on a sample cut into a strip of 15 mm width using a tensile tester (e.g., Tensilon universal material testing machine: RTC1310A, manufactured by Orientec Co., Ltd.) at a peel speed of 50 mm/min.

The adhesive strength between the flange piece 25 and the molded film 40 may be 1.0 N/15 mm or more. This prevents the molded film 40 from peeling off from the flange piece 25 when removing the lid material 50 from the paper container 10. This prevents the ease of opening the lid material 50 from decreasing.

The adhesive strength between the flange piece 25 and the molded film 40 may be 5.0 N/15 mm or less. This prevents the molded film 40 from becoming difficult to peel off from the paper container 20 when recycling the paper container 20. In this case, the paper container 20 from which the molded film 40 has been peeled off may have peeled off (part of the paper container may peel off).

Here, a heat seal agent may be applied to at least a part of the surface of the paper container 20 (the surface of the blank material 30 described later). This allows the adhesive strength between the paper container 20 and the forming film 40 to be easily adjusted. Therefore, the desired adhesive strength can be easily obtained. In this embodiment, a heat seal layer H is provided on the flange piece 25 (the flange piece panel 35 described later). This heat seal layer H is formed by applying a heat seal agent to the flange piece 25 (the flange piece panel 35 described later). The heat seal agent may be ink. As the heat seal agent, one containing ethylene-vinyl acetate copolymer (EVA), ionomer, polyethylene (PE) or polypropylene (PP) can be used. In addition, as the heat seal agent, vinyl-based, acrylic-based, polyamide-based, polyester-based, polyether-based, polyurethane-based, epoxy-based, chlorinated EVA-based, chlorinated PP-based, vinyl chloride-vinyl acetate-based, polyol-based, polyethyleneimine-based, starch-based, nitrocellulose-based, rubber-based resin, etc. may be included. Furthermore, the heat sealant may be applied onto the flange piece 25 (the flange piece panel 35 described below) by gravure printing, flexographic printing, offset printing, or the like. Note that in FIG. 2 and other figures, the area where the heat seal layer H is provided is shown shaded.

The weight per unit area of the heat seal layer H (i.e., the amount of heat sealant applied to the flange piece 25 (the flange piece panel 35 described later)) may be 0.1 g/m ² or more and 10.0 g/m ² or less. By having the amount of heat sealant applied to the flange piece 25 (the flange piece panel 35 described later) be 0.1 g/m ² or more, the adhesive strength between the flange piece 25 and the molded film 40 can be easily increased to a desired strength. Therefore, when removing the lid material 50 from the paper container 10, the molded film 40 can be prevented from peeling off from the flange piece 25, and the ease of opening the lid material 50 can be prevented from decreasing. In addition, by having the amount of heat sealant applied to the flange piece 25 (the flange piece panel 35 described later) be 10.0 g/m ² or less, the adhesive strength between the flange piece 25 and the molded film 40 can be prevented from becoming too large. Therefore, when recycling the paper container 20, it is possible to prevent the molded film 40 from becoming difficult to peel off from the paper container 20.

(Blank material)
Next, a blank 30 for producing the paper container 20 will be described. As shown in Fig. 4, the blank 30 includes a bottom panel 31, a plurality of side panels 33 connected to the bottom panel 31 via a first fold line 32, and a plurality of flange piece panels 35 connected to each of the side panels 33 via a second fold line 34. In the illustrated example, the blank 30 includes four side panels 33 and four flange piece panels 35. The bottom panel 31, the first fold line 32, the side panel 33, the second fold line 34, and the flange piece panels 35 of the blank 30 correspond to the bottom 21, the fold line (first fold line) 22, the side 23, the fold line (second fold line) 24, and the flange piece 25 of the paper container 20, respectively.

The bottom panel 31, side panel 33, and flange piece panel 35 of the blank 30 are integrally formed. Such a blank 30 can be produced by subjecting the paper material that constitutes the blank 30 to a punching process or the like.

A gap 36 is formed between the side panels 33. In this case, each side panel 33 is formed in a trapezoidal shape. Each side panel 33 has a pair of side edges 33a extending from the bottom panel 31. A gap 36 is formed between the side edges 33a of the side panels 33. As a result, in the paper container 10 described above, the sides 23 do not overlap each other but are adjacent to each other (see Figures 2 and 3). In the illustrated example, in each side panel 33, the pair of side edges 33a extend in a direction away from each other as they move from the first fold line 32 side toward the second fold line 34 side.

Examples of the paper material that can be used to make such blank material 30 include various types of paperboard, coated paper, card paper, ivory paper, milk carton ^base paper, cup base paper, coated cardboard, and other processed papers having a basis weight of approximately 150 g/m2 or more and 600 g/ ^m2 or less.

(Formed film)
Next, the molded film 40 will be described with reference to Figures 1 to 3. This molded film 40 serves to protect the paper container 20. The molded film 40 has a container shape and covers the entire surface of the paper container 20. This prevents the contents filled in the paper container 10 from leaking out of the paper container 10. The molded film 40 is adhered to the paper container 20 by, for example, heat sealing (thermal welding).

Such a molded film 40 may be a film made of a thermoplastic resin having water resistance, sealing properties, and heat fusion properties. For example, various types of polyethylene (PE), polypropylene (PP), polyvinyl chloride, polyethylene terephthalate (PET), ethylene-vinyl acetate copolymer, ionomer, ethylene-acrylic acid copolymer, polyamide, polyvinylidene chloride, polystyrene, saponified ethylene-vinyl acetate copolymer, polycarbonate, polybutene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer (EVOH), and other various thermoplastic resin films can be used alone or laminated. In particular, when it is desired to impart gas barrier properties to the paper container 10, a laminate having a gas barrier material such as ethylene-vinyl alcohol copolymer (EVOH) laminated on the intermediate layer, specifically a laminate having a layer structure such as PE/EVOH/PE, PP/EVOH/PE, or A (amorphous)-PET/EVOH/PE can be used.

The formed film 40 may be made, for example, from a laminate having the following layer configuration:
(Outside) Polyethylene (40 μm) / Ionomer (40 μm) / Polyethylene (40 μm) (Inside)
(Outside) Polypropylene (30 μm) / Adhesive layer (10 μm) / Ionomer (40 μm) / Adhesive layer (10 μm) / Polypropylene (30 μm) (Inside)
(Outside) Polyethylene (20 μm) / Ionomer (30 μm) / Adhesive layer (10 μm) / Ethylene-vinyl alcohol copolymer (10 μm) / Adhesive layer (10 μm) / Ionomer (15 μm) / Ethylene-vinyl acetate copolymer (20 μm) (Inside)

Each of the above layers is formed according to conventional methods, such as dry lamination, extrusion lamination, extrusion coating, or other coating methods.

Lid Material Next, a description will be given of the lid material 50. The lid material 50 is sealed over the entire periphery of the region of the forming film 40 of the paper container 10 that corresponds to the flange piece 25.

Such a lid material 50 can be, for example, a laminate having a layer structure such as PET/sealant, oriented nylon (ONY)/sealant, PET/oriented nylon (ONY)/sealant, PET/PE/sealant, or K-coated oriented nylon (KONY)/PE/sealant. The laminate constituting the lid material 50 can also be, for example, a laminate having a gas barrier material such as ethylene-vinyl alcohol copolymer (EVOH) laminated in the middle layer. The lid material 50 can be, for example, a laminate having a layer structure such as PET/PE/ethylene-vinyl alcohol copolymer (EVOH)/PE/sealant.

The lid material 50 may be made of a laminate having the following layer configuration, for example.
(Outside) Polyethylene terephthalate film with transparent vapor deposition layer (12 μm) / Nylon film (15 μm) / Polyethylene film (40 μm) (Inside)

It is preferable to use a resin material that can exhibit so-called easy peel properties for the laminate that constitutes the lid material 50. In addition, each of the above layers is formed according to a conventional method, such as a dry lamination method, an extrusion lamination method, an extrusion coating method, or another coating method.

In the paper container 1 with a lid material configured as described above, first, the contents are filled into the paper container 10. Next, the lid material 50 is sealed to the area of the molded film 40 of the paper container 10 that corresponds to the flange piece 25. This results in a paper container 1 with a lid material filled with the contents. The paper container 1 with a lid material may be a container for chilled or frozen foods, or may be used as a take-out container. The contents may also be food such as prepared dishes, meat, or dairy products.

Next, the operation of this embodiment having such a configuration will be described. Here, the manufacturing method of the paper container 10 and the manufacturing method of the paper container with lid 1 will be described with reference to Figures 5 to 7.

Manufacturing method of paper container First, a blank material 30 is prepared. At this time, a paper material is prepared, and a heat seal agent is applied to a predetermined position of the paper material. The heat seal agent may be applied by a gravure printing method, a flexographic printing method, an offset printing method, or the like. In this way, a heat seal layer H is provided at a predetermined position of the paper material. Next, the paper material is punched out by a laser or the like to obtain the blank material 30.

Next, as shown in FIG. 5, the blank 30 is attached to the cavity side mold 60. A suction hole 61 is formed in the cavity side mold 60, and the blank 30 is attached to the cavity side mold 60 by sucking air through the suction hole 61. At this time, the side panel 33 of the blank 30 is folded relative to the bottom panel 31 along the first fold line 32. Similarly, the flange piece panel 35 of the blank 30 is folded relative to the side panel 33 along the second fold line 34. This results in a paper container 20 attached to the cavity side mold 60.

Then, the molded film 40 is laminated on the surface of the paper container 20. At this time, first, as shown in FIG. 6, the film 40a constituting the molded film 40 is placed above the paper container 20. Next, the film 40a is heated by the core side mold 62 (see FIG. 7). Then, after the film 40a has been sufficiently heated by the core side mold 62, air is sucked through the suction holes 61. As a result, the film 40a is sucked onto the paper container 20. At this time, the core side mold 62 also presses the film 40a against the paper container 20. As a result, the film 40a is in close contact with the paper container 20.

Then, the film 40a is cut into the desired shape by a cutting mechanism 63 provided on the core side mold 62. This results in a molded film 40 laminated on the paper container 20, as shown in FIG. 7. In this way, the paper container 10 is obtained.

In parallel with the production of the paper container 10, the lid material 50 is prepared. At this time, a predetermined laminate is produced by a dry lamination method or the like. The laminate is then punched into a predetermined shape with a blade or the like to produce the lid material 50.

Next, the paper container 10 is filled with the contents, and the paper container 10 is sealed with the lid material 50. At this time, the paper container 10 is first filled with the contents (not shown). Next, the lid material 50 is placed on the molding film 40 at a position corresponding to the flange piece 25.

Next, the lid material 50 is sealed to the molded film 40 using a sealing hot plate (not shown) or the like. At this time, the air inside the paper container 10 may be replaced with, for example, nitrogen gas.

In this way, a paper container with lid 1 is obtained, which comprises a paper container 10 and a lid 50 that seals the paper container 10.

As described above, according to this embodiment, the adhesive strength between the flange piece 25 and the molded film 40 is 1.0 N/15 mm or more. This prevents the molded film 40 from peeling off from the flange piece 25 when removing the lid material 50 from the paper container 10 of the lid-attached paper container 1. This prevents the ease of opening the lid material 50 from decreasing. In addition, since the ease of opening the lid material 50 can be prevented from decreasing, deformation of the paper container 10 can be prevented when removing the lid material 50 from the paper container 10. This improves the practicality of the lid-attached paper container 1.

In addition, according to this embodiment, the adhesive strength between the bottom 21 and the molded film 40, and the adhesive strength between the side 23 and the molded film 40 are 0.05 N/15 mm or more and 0.4 N/15 mm or less, respectively. This makes it possible to prevent the molded film 40 from unintentionally peeling off from the paper container 20. In particular, when removing the lid material 50 from the paper container 10, it is possible to prevent the molded film 40 from unintentionally peeling off from the bottom 21 or side 23 of the paper container 20. In addition, when recycling the paper container 20, the paper container 20 and the molded film 40 can be easily separated.

In addition, the molded film 40 can be prevented from unintentionally peeling off from the paper container 20, improving the airtightness of the paper container 1 with the lid material. In other words, if the molded film 40 is unintentionally peeled off from the paper container 20, the paper container 20 may not be able to maintain its shape as a container, and the paper container 20 may buckle. In this case, an unintentional force may be applied to the lid material 50 and the molded film 40, and the lid material 50 may be unintentionally removed from the paper container 10. In contrast, in this embodiment, the molded film 40 can be prevented from unintentionally peeling off from the paper container 20, preventing the lid material 50 from being unintentionally removed from the paper container 10. Therefore, the airtightness of the paper container 1 with the lid material can be improved. As a result, the barrier properties of the paper container 1 with the lid material can be improved, and the life of the contents can be extended. This reduces food waste.

In addition, according to this embodiment, the adhesive strength between the flange piece 25 and the molded film 40 is 5.0 N/15 mm or less. This makes it possible to prevent the molded film 40 from becoming difficult to peel off from the paper container 20 when recycling the paper container 20.

Furthermore, according to this embodiment, a heat seal layer H is provided on the flange piece 25. This allows the adhesive strength between the flange piece 25 and the molded film 40 to be easily adjusted. Therefore, the desired adhesive strength can be easily obtained.

Modified examples of the paper container 10 according to the present embodiment will now be described with reference to Figures 8 to 15. In Figures 8 to 15, the same parts as those in the embodiment shown in Figures 1 to 7 are designated by the same reference numerals and detailed description thereof will be omitted.

(First modified example of paper container)
In the above-described embodiment, an example in which the heat seal layer H is provided on the flange piece 25 (flange piece panel 35) has been described, but the present invention is not limited to this. For example, as shown in FIG. 8, the heat seal layer H may be provided along the periphery of the bottom 21 (i.e., the fold line 22). That is, the heat seal agent may be applied to the bottom 21 along the periphery of the bottom 21 (i.e., the fold line 22). In this case, as shown in FIG. 9, in the blank material 30, the heat seal layer H may be provided along the periphery of the bottom panel 31 (i.e., the first fold line 32). That is, in the blank material 30, the heat seal agent may be applied to the bottom panel 31 along the periphery of the bottom panel 31 (i.e., the first fold line 32).

Here, gaps are likely to form between the paper container 20 and the molded film 40 near the periphery of the bottom 21. For this reason, there is a possibility that the molded film 40 may unintentionally peel off from the paper container 20, triggered by the periphery of the bottom 21.

In contrast, by applying a heat sealant to the bottom 21 along the periphery of the bottom 21, the adhesive strength between the paper container 20 and the molded film 40 can be increased near the periphery of the bottom 21. This makes it possible to prevent the molded film 40 from unintentionally peeling off from the paper container 20.

In this case, the amount of heat sealant applied to the bottom 21 (bottom panel 31) may be 0.1 g/m ² or more and 10.0 g/m ² or less. By having the amount of heat sealant applied to the bottom 21 (bottom panel 31) be 0.1 g/m ² or more, the adhesive strength between the bottom 21 and the molded film 40 can be easily increased to a desired strength. Therefore, it is possible to suppress the molded film 40 from being unintentionally peeled off from the paper container 20. In addition, by having the amount of heat sealant applied to the bottom 21 (bottom panel 31) be 10.0 g/m ² or less, it is possible to suppress the adhesive strength between the bottom 21 and the molded film 40 from becoming too large. Therefore, it is possible to suppress the difficulty of peeling off the molded film 40 from the paper container 20 when recycling the paper container 20.

(Second variant of paper container)

Also, as shown in FIG. 10, the heat seal layer H may be provided on the bottom 21 and the side 23 so as to straddle the fold line 22. That is, the heat seal agent may be applied to the bottom 21 and the side 23 so as to straddle the fold line 22. In this case, as shown in FIG. 11, in the blank material 30, the heat seal layer H may be provided on the bottom panel 31 and the side panel 33 so as to straddle the first fold line 32. That is, in the blank material 30, the heat seal agent may be applied on the bottom panel 31 and the side panel 33 so as to straddle the first fold line 32. Even in this case, the adhesive strength between the paper container 20 and the forming film 40 can be increased in the vicinity of the periphery of the bottom 21 (i.e., the fold line 22). Therefore, it is possible to suppress the forming film 40 from being unintentionally peeled off from the paper container 20.

In this case, the amount of heat sealant applied on the bottom 21 (bottom panel 31) and/or the side 23 (side panel 33) may be 0.1 g/m ² or more and 10.0 g/m ² or less. By having the amount of heat sealant applied on the bottom 21 (bottom panel 31) and/or the side 23 (side panel 33) be 0.1 g/m ² or more, the adhesive strength between the bottom 21 and/or the side 23 and the molded film 40 can be easily increased to a desired strength. Therefore, it is possible to prevent the molded film 40 from being unintentionally peeled off from the paper container 20. In addition, by having the amount of heat sealant applied on the bottom 21 (bottom panel 31) and/or the side 23 (side panel 33) be 10.0 g/m ² or less, it is possible to prevent the adhesive strength between the bottom 21 and/or the side 23 and the molded film 40 from becoming too large. This makes it possible to prevent the forming film 40 from becoming difficult to separate from the paper container 20 when recycling the paper container 20 .

(Third variant of paper container)

Furthermore, as shown in FIG. 12, the heat seal layer H may be provided on the bottom 21, the side 23, and the flange piece 25. That is, the heat seal agent may be applied on the bottom 21, the side 23, and the flange piece 25. In the illustrated example, the heat seal agent is applied to the entire surface of the paper container 20. In addition, the weight per unit area of the heat seal layer H provided on the flange piece 25 may be greater than the weight per unit area of the heat seal layer H provided on the side 23. That is, the amount of heat seal agent applied on the flange piece 25 may be greater than the amount of heat seal agent applied on the side 23. Furthermore, the weight per unit area of the heat seal layer H provided on the side 23 may be greater than the weight per unit area of the heat seal layer H provided on the bottom 21. That is, the amount of heat seal agent applied on the side 23 may be greater than the amount of heat seal agent applied on the bottom 21.

In this case, as shown in FIG. 13, in the blank material 30, the heat seal agent may be applied on the bottom panel 31, the side panel 33, and the flange piece panel 35. In the illustrated example, the heat seal agent is applied to the entire surface of the blank material 30. In addition, the weight per unit area of the heat seal layer H provided on the flange piece panel 35 may be greater than the weight per unit area of the heat seal layer H provided on the side panel 33. That is, the amount of heat seal agent applied on the flange piece panel 35 may be greater than the amount of heat seal agent applied on the side panel 33. Furthermore, the weight per unit area of the heat seal layer H provided on the side panel 33 may be greater than the weight per unit area of the heat seal layer H provided on the bottom panel 31. That is, the amount of heat seal agent applied on the side panel 33 may be greater than the amount of heat seal agent applied on the bottom panel 31.

According to this modified example, the adhesive strength between the paper container 20 and the molded film 40 in the paper container 10 can be easily adjusted. Therefore, the desired adhesive strength can be easily obtained.

Here, in order to improve the opening property of the lid material 50, it is preferable to increase the adhesive strength between the flange piece 25 and the molded film 40. On the other hand, in order to improve the recyclability of the paper container 20, it is preferable to reduce the adhesive strength between the side portion 23 and the molded film 40 and the adhesive strength between the bottom portion 21 and the molded film 40. However, if the adhesive strength between the side portion 23 and the molded film 40 and the adhesive strength between the bottom portion 21 and the molded film 40 are reduced, when the lid material 50 is removed from the paper container 10, the molded film 40 may unintentionally peel off from the bottom portion 21 or the side portion 23 of the paper container 20. In particular, if the adhesive strength between the side portion 23 and the molded film 40 is reduced, when the lid material 50 is removed from the paper container 10, the molded film 40 is easily peeled off from the paper container 20, starting from the part of the molded film 40 that is adhered to the side portion 23. Therefore, in order to improve the recyclability of the paper container 20 while improving the openability of the lid material 50, it is preferable to make the adhesive strength between the flange piece 25 and the molded film 40 greater than the adhesive strength between the side portion 23 and the molded film 40, and to make the adhesive strength between the side portion 23 and the molded film 40 greater than the adhesive strength between the bottom portion 21 and the molded film 40 so that the adhesive strength between the side portion 23 and the molded film 40 has a predetermined adhesive strength.

In this modified example, the amount of heat sealant applied to the flange piece 25 is greater than the amount of heat sealant applied to the side portion 23, and the amount of heat sealant applied to the side portion 23 is greater than the amount of heat sealant applied to the bottom portion 21. Therefore, the adhesive strength between the flange piece 25 and the molded film 40 can be greater than the adhesive strength between the side portion 23 and the molded film 40, and the adhesive strength between the side portion 23 and the molded film 40 can be greater than the adhesive strength between the bottom portion 21 and the molded film 40. This makes it possible to prevent the molded film 40 from peeling off from the flange piece 25, side portion 23, and bottom portion 21 of the paper container 20 when removing the lid material 50 from the paper container 10. In addition, when recycling the paper container 20, the paper container 20 and the molded film 40 can be easily separated. Therefore, it is possible to prevent the ease of opening the lid material 50 from decreasing, and it is possible to easily separate the paper container 20 and the molded film 40 when recycling the paper container 20.

As shown in Figs. 14 and 15, the heat sealant may be applied in a predetermined pattern to the entire surface of the blank material 30. For example, as shown in Fig. 14, the heat sealant may be applied to the surface of the blank material 30 so as to present a polka dot pattern. As shown in Fig. 15, the heat sealant may be applied in stripes to the surface of the blank material 30. The pattern shape of the heat sealant is not particularly limited. Although not shown, the heat sealant may be applied to the surface of the blank material 30 so that the areas where the heat sealant is not applied present a polka dot pattern. The heat sealant may be applied to the surface of the blank material 30 so as to present another pattern such as a checkered pattern, or may be applied in a lattice pattern to the surface of the blank material 30. In this case, although not shown, the heat sealant is also applied to the entire surface of the paper container 20 produced from the blank material 30 in a predetermined pattern. The heat sealant may be applied to a portion of the surface of the blank material 30 in a predetermined pattern.

(Fourth modified example of paper container)
In the above embodiment, an example has been described in which the adhesive strength between the paper container 20 and the molded film 40 is adjusted by providing a heat seal layer H (applying a heat seal agent) on the surface of the paper container 20, but the present invention is not limited to this. For example, the adhesive strength may be adjusted by changing the temperature at which the molded film 40 is heated. That is, if it is desired to increase the adhesive strength, the heating temperature of the molded film 40 may be increased. On the other hand, if it is desired to decrease the adhesive strength, the heating temperature of the molded film 40 may be decreased. Even in this case, the adhesive strength between the paper container 20 and the molded film 40 can be easily adjusted. Note that the adhesive strength between the paper container 20 and the molded film 40 may be adjusted by changing the pressure or time when the core side die 62 presses the film 40a against the paper container 20.

Next, we will describe a specific example of the above embodiment.

Example 1
First, a paper container 1 with a lid material shown in Fig. 1 was produced. At this time, a paper material (N Pearl Card (product name), basis weight 260 g/ ^m2 , manufactured by Mitsubishi Paper Mills) was first prepared as the material for the paper container 20. In addition, a film (film for skin packs, manufactured by Sumitomo Bakelite Co., Ltd.) was prepared as the molded film 40. Next, the paper container 10 was produced by laminating the film on the surface of the paper material. At this time, the molded film 40 was heated to 300°C. Furthermore, a film having the following layer structure was produced by a dry lamination method as the lid material 50, and the paper container 10 was sealed with the film.
PET (12 μm) / adhesive / ONY (15 μm) / adhesive / PE (50 μm)

(1) Opening Ease Evaluation Test and Practicality Evaluation Test Next, an opening ease evaluation test and a practicality evaluation test were conducted. In this test, the lid 50 was first removed from the paper container 10 of the prepared lid-attached paper container 1. Then, the ease of removing the lid 50 was evaluated. In addition, deformation of the paper container 10 was observed, and a practicality evaluation was performed.

(2) Adhesive Strength Evaluation Test Next, an adhesive strength evaluation test between the flange pieces 25 and the molded film 40 was performed. The flange pieces 25 to which the molded film 40 was attached were cut into rectangular shapes with a width of 15 mm and a length of 50 mm, and used as test pieces. At this time, three test pieces were prepared for each flange piece 25, totaling 12 test pieces. Next, the adhesive strength between the flange pieces 25 and the molded film 40 was measured by performing a 90° peel test on these test pieces at a peel speed of 50 mm/min using a tensile tester (for example, Tensilon universal material testing machine: RTC1310A, manufactured by Orientec Co., Ltd.). The average value of all the test pieces was taken as the adhesive strength between the flange pieces 25 and the molded film 40.

In addition, an adhesive strength evaluation test was conducted between the side portion 23 and the molded film 40. The test pieces used were the side portion 23 to which the molded film 40 was adhered, cut into a rectangle having a width of 15 mm and a length of 50 mm. In this case, three test pieces were prepared for each side portion 23, for a total of 12 test pieces. Next, the adhesive strength between the side portion 23 and the molded film 40 was measured in the same manner as when the adhesive strength between the flange piece 25 and the molded film 40 was measured. The average value of all the test pieces was then taken as the adhesive strength between the side portion 23 and the molded film 40.

Furthermore, an adhesive strength evaluation test was conducted between the bottom 21 and the molded film 40. The test piece used was a rectangular piece cut from the bottom 21 to which the molded film 40 was adhered, measuring 15 mm in width and 50 mm in length. A total of three test pieces were made. Next, the adhesive strength between the bottom 21 and the molded film 40 was measured in the same manner as in the measurement of the adhesive strength between the flange piece 25 and the molded film 40.

(3) Peelability Evaluation Test Next, a peelability evaluation test was conducted. In this test, the molded film 40 was peeled off from the paper container 20 of the paper container 10. Then, the ease of peeling off the molded film 40 was evaluated.

Example 2
The opening property evaluation test, practicality evaluation test, adhesive strength evaluation test and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film 40 was heated to 320°C when adhering the molded film 40 to the paper container 20.

Example 3
The opening property evaluation test, practicality evaluation test, adhesive strength evaluation test and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film 40 was heated to 350°C when adhering the molded film 40 to the paper container 20.

Example 4
The paper container 20 was made of paper (product name: New Pigeon, manufactured by Oji Materia, basis weight: 260 g/ ^m2 ) and the molded film 40 was heated to 320°C when adhering the molded film 40 to the paper container 20. The same procedures as in Example 1 were carried out to perform the openability evaluation test, the practicality evaluation test, the adhesive strength evaluation test and the peelability evaluation test.

Example 5
The opening property evaluation test, practicality evaluation test, adhesive strength evaluation test and peelability evaluation test were performed in the same manner as in Example 4, except that the molded film 40 was heated to 260°C when adhering the molded film 40 to the paper container 20.

(Comparative Example 1)
The openability evaluation test, practicality evaluation test, adhesive strength evaluation test, and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film was heated to 260°C when adhering the molded film to the paper container.

(Comparative Example 2)
The openability evaluation test, practicality evaluation test, adhesive strength evaluation test, and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film was heated to 280°C when adhering the molded film to the paper container.

(Comparative Example 3)
The openability evaluation test, practicality evaluation test, adhesive strength evaluation test, and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film was heated to 360°C when adhering the molded film to the paper container.

(Comparative Example 4)
The openability evaluation test, practicality evaluation test, adhesive strength evaluation test and peelability evaluation test were conducted in the same manner as in Example 1, except that a paper material (OK Frace (product name), manufactured by Oji Materia, basis weight 260 g ^/m2 ) was used as the material for the paper container and the molded film was heated to 320°C when adhering the molded film to the paper container.

(Comparative Example 5)
The openability evaluation test, practicality evaluation test, adhesive strength evaluation test, and peelability evaluation test were performed in the same manner as in Example 1, except that the molded film was heated to 370°C when adhering the molded film to the paper container.

The above results are shown in Table 1.

In the column for the openability evaluation test in Table 1 above, "○" means that the lid material 50 could be removed from the paper container 10 without the molded film 40 peeling off from the paper container 20. Also, "△" means that a part of the molded film peeled off from the paper container when the lid material was removed from the paper container. Furthermore, "×" means that the molded film peeled off from the paper container, and therefore the lid material could not be removed from the paper container.

In the column for practicality evaluation test in Table 1 above, "○" means that when the lid material 50 was removed from the paper container 10, the paper container 10 was not deformed and the molded film 40 was not peeled off from the paper container 20. "△" means that when the lid material was removed from the paper container, the paper container was not deformed, but part of the molded film was peeled off from the paper container. "×" means that the lid material could not be removed from the paper container because the molded film was peeled off from the paper container, or that the paper container was deformed when the lid material was removed from the paper container.

In the peelability evaluation test column in Table 1 above, "○" means that when the molded film 40 was peeled off from the paper container 20, no peeling (part of the paper container peeled off) occurred on the paper container 20, and the molded film 40 could be easily peeled off from the paper container 20. "△" means that when the molded film was peeled off from the paper container, peeling occurred on the paper container. Furthermore, "×" means that when the molded film was peeled off from the paper container, a great deal of peeling occurred on the paper container.

As a result, as shown in Table 1, in the openability evaluation test, in the paper container with lid according to Comparative Example 1, the molded film peeled off from the paper container, making it impossible to remove the lid from the paper container. In addition, in the paper container with lid according to Comparative Example 2, part of the molded film peeled off from the paper container when the lid was removed from the paper container.

In contrast, in the paper container 1 with a lid according to Examples 1 to 5, the lid 50 could be removed from the paper container 10 without the molded film 40 peeling off from the paper container 20. Therefore, it was found that in the paper container 1 with a lid according to this embodiment, peeling of the molded film 40 from the flange piece 25 can be prevented when removing the lid 50 from the paper container 10, and a decrease in the ease of opening the lid 50 can be prevented.

As shown in Table 1, in the practicality evaluation test, in the paper container with lid according to Comparative Example 1, the molded film peeled off from the paper container, making it impossible to remove the lid from the paper container. In the paper container with lid according to Comparative Example 2, when the lid was removed from the paper container, part of the molded film peeled off from the paper container. Furthermore, in the paper container with lid according to Comparative Example 5, when the lid was removed from the paper container, deformation occurred in the paper container.

In contrast, in the paper container 1 with a lid according to Examples 1 to 5, when the lid 50 was removed from the paper container 10, the paper container 10 was not deformed, and the molded film 40 was not peeled off from the paper container 20. Therefore, it was found that the paper container 1 with a lid according to this embodiment can improve practicality.

As shown in Table 1, in the peelability evaluation test, when the molded film was peeled off from the paper container with the lid material of Comparative Example 3, the paper peeled off from the paper container. Also, when the molded film was peeled off from the paper container of Comparative Example 4 and Comparative Example 5, a large amount of paper peeled off from the paper container.

In contrast, in the paper container 1 with a lid according to Examples 1 to 5, when the molded film 40 was peeled off from the paper container 20, the paper did not peel off from the paper container 20, and the molded film 40 could be easily peeled off from the paper container 20. Therefore, in the paper container 1 with a lid according to this embodiment, the paper container 20 and the molded film 40 can be easily separated when recycling the paper container 20, and it was found that recyclability can be improved.

The present disclosure is not limited to the above-described embodiment and each modified example, and in the implementation stage, the components can be modified to the extent that does not deviate from the gist of the disclosure. In addition, various inventions can be formed by appropriate combinations of the multiple components disclosed in the above-described embodiment and each modified example. Some components may be deleted from all the components shown in the embodiment and each modified example.

REFERENCE SIGNS LIST 10 Paper container 20 Paper container 21 Bottom 22 Fold line 23 Side 24 Fold line 25 Flange piece 40 Forming film H Heat seal layer

Claims (4)

A paper container having a bottom, a plurality of side portions connected to the bottom via fold lines, and a plurality of flange pieces connected to each of the side portions via fold lines;
A formed film laminated on a surface of the paper container,
The side portions are adjacent to each other and are not continuous with each other,
A heat seal layer is provided on the flange piece,
The adhesive strength between the flange piece and the molded film is 1.0 N/15 mm or more;
A paper container, wherein the adhesive strength between the bottom portion and the formed film, and the adhesive strength between the side portion and the formed film are each 0.05 N/15 mm or more and 0.4 N/15 mm or less. The paper container according to claim 1, wherein the adhesive strength between the flange piece and the formed film is 5.0 N/15 mm or less. The paper container according to claim 1 or 2 , wherein the weight per unit area of the heat seal layer is 0.1 g/m2 or ^more and 10.0 g/m2 ^{or less} . The paper container according to any one of claims 1 to 3 ,
A paper container with a lid, comprising a lid that seals the paper container.