Container

Abstract

To provide a vessel excellent in stackability and allowing for suppressing blocking.SOLUTION: A vessel is made up by a composite base material 7 comprising a base material layer 10 of paper and resin layers 11a, 11b laminated over both surfaces of the base material layer 10. A resin layer surface 13 on an inner side of the composite base material 7 has a surface roughness Ra of 0.7 μm or greater and 3.0 μm or smaller, and the resin layer surface 13 on the inner side of the composite base material 7 and a resin layer surface 14 on an outer side thereof have totally a surface roughness Ra of 1.5 μm or greater and 3.5 μm or smaller. The configuration like this provides excellence in stackability and improves the convenience in vessel use thanks to the capability to suppress blocking.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a container, and more particularly to a container obtained by molding a single blank and used as a paper tray or paper cup for storing food, beverages, etc. [Background technology]

[0002] Conventionally, as a lightweight and cost-effective food storage container, there is a plastic container made of a synthetic resin such as polypropylene. However, in recent years, the use of plastic containers has been refrained from due to the microplastics problem, and instead of plastic containers, there is a tendency to prefer the use of containers mainly made of paper.

[0003] Patent Document 1 discloses such a container, which is formed by press molding a single sheet of paperboard base paper (paper blank) with multiple linear stripes extending radially toward the outer periphery. The flange end of the container is formed with a rolled edge.

[0004] However, the container described in Patent Document 1 is formed using a method similar to deep drawing of paper, so if an attempt is made to make the container deeper, there is a risk that the paper will tear during forming, making it difficult to manufacture deep containers.

[0005] Therefore, as an example of a deep container manufactured from a single paper blank, Patent Document 2 proposes folding a blank of a specified shape to form a bottom and sides, and folding and gluing the corners to create a deep shape. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 10-071656 [Patent Document 2] JP 2000-255546 A Summary of the Invention [Problem to be solved by the invention]

[0007] In such containers, since the contents may be frozen foods or the like that contain a lot of moisture, it is preferable to form a resin layer on at least one side of the paperboard base paper that is the inner side in order to impart water resistance and oil resistance. In particular, when the corners are folded and glued as in Patent Document 2, if a resin layer is provided on both sides of the paperboard base paper, the corners can be heat-welded or high-frequency-welded by the resin layer, improving the reliability of the bonding of the corners. In addition, in general, when a resin layer is formed on both sides of the paperboard base paper by extrusion lamination, the surface condition of the cooling roll (chill roll) that cools the resin layer extruded onto the paper during extrusion lamination is reflected in the surface condition of the resin layer, and a glossy finish, a matte finish, or a slightly matte finish (semi-matte finish) can be selected.

[0008] However, in containers such as those in Patent Document 2, resin layers are formed on both sides of the paperboard base paper by extrusion lamination, and when multiple containers obtained are stacked, the surface properties of the resin layers cause blocking (a phenomenon in which when one of the upper containers stacked adjacent to each other is lifted, the other container on the lower side is also lifted), reducing handling efficiency. That is, for example, when a food manufacturer removes a container from a group of stacked containers and places food in it, the stacked containers block each other, making it difficult to remove the individual containers from the group of containers, and reducing productivity when placing food in them.

[0009] As a method for suppressing blocking, in the case of plastic containers, a rib-like convex portion called a stacking boss may be provided on a part of the container. However, in the case of containers formed by folding paper as in Patent Document 2, it is difficult to provide a rib-like convex portion on a part of the container. Also, it is technically difficult to form a rolled edge on the flange end of the container as in the container in Patent Document 1.

[0010] Furthermore, when the containers are stacked, the container group may become bulky depending on the surface properties of the resin layer. In this case, depending on the number of containers stacked, the stacked state may not be maintained and the container group may fall over. In addition, this is not preferable because it requires more space for shipping and storage of the container group.

[0011] The present invention has been made to solve the above-mentioned problems, and has an object to provide a container that has excellent stacking properties and can suppress blocking. [Means for solving the problem]

[0012] In order to achieve the above object, the invention described in claim 1 is a container composed of a composite substrate having a substrate layer made of paper and a resin layer made of a resin laminated on the front and back surfaces of the substrate layer, wherein the surface roughness Ra of at least one surface of the composite substrate is 0.7 μm or more and 3.0 μm or less, the sum of the surface roughness Ra of the one surface and the other surface of the composite substrate is 1.5 μm or more and 3.5 μm or less, and the adhesion when the one surface and the other surface of the composite substrate are welded is 4.0 N / cm or more and 20.0 N / cm or less, and the container has a bottom and a side wall portion rising from the peripheral edge of the bottom, The side wall portion further includes a flat flange extending outward from its rising end portion. Side wall corners The back surface of the flange in In the composite substrate, one side and the other side is melted It is what is worn.

[0013] This structure provides excellent stacking properties, inhibits blocking, prevents peeling at the interface between the resin layers, and improves the stability of container molding. The invention described in claim 2 is a container composed of a composite substrate having a substrate layer made of paper and a resin layer made of a resin laminated on the front and back surfaces of the substrate layer, wherein at least one surface of the composite substrate has a surface roughness Ra of 0.7 μm or more and 3.0 μm or less, and the sum of the surface roughness Ra of the one surface and the other surface of the composite substrate is 1.5 μm or more and 3.5 μm or less, one surface of the resin layer has a matte finish and the other surface has a gloss finish, and the container has a bottom and a side wall portion rising from the periphery of the bottom, The side wall portion further includes a flat flange extending outward from its rising end portion. Side wall corners The back surface of the flange in In the composite substrate, one side and the other side is melted It is what is worn. With this configuration, the stacking property is excellent, blocking can be suppressed, and the stability of the molding of the container is improved. The invention according to claim 3 is a container composed of a composite base material including a base material layer made of paper and resin layers made of resin laminated on the front and back surfaces of the base material layer, wherein the surface roughness Ra of at least one surface of the composite base material is 0.7 μm or more and 3.0 μm or less, the total of the surface roughness Ra of one surface and the other surface of the composite base material is 1.5 μm or more and 3.5 μm or less, and it includes a bottom portion, a side wall portion rising from the periphery of the bottom portion, a corner portion section extending from the corner portion in the blank of the side wall portion, and two joining sections extending from the vicinity of the corner portion section. The side wall portion further includes a flat flange extending outward from its rising end portion, two joining sections are arranged on the back surface of the flange at the corner portion of the side wall portion, and one surface of the flange and the other surface of the joining section are welded. With such a configuration, the stacking property is excellent and blocking can be suppressed. Claim 4 The invention described is as follows: Or claim 3 In the configuration of the described invention, when one surface and the other surface of the composite substrate are welded together, the adhesion is 4.0 N / cm or more and 20.0 N / cm or less. With this configuration, peeling at the interface of the resin layer is prevented. The invention according to claim 5 is the invention according to claim 1 or claim 3, wherein one surface side of the resin layer has a matte finish and the other surface side has a gloss finish.

[0014] Claim 6 The invention described is as follows: 5 In any one of the above-mentioned configurations of the invention, the resin constituting the resin layer is polyethylene terephthalate.

[0015] With this configuration, adhesion between the composite substrates is improved when the composite substrates are welded together. Effect of the Invention

[0024] As described above, the invention described in claim 1 has excellent stacking properties and can suppress blocking, thereby improving the usability of the container. In addition, peeling at the resin layer interface is prevented, improving the reliability of the container. Furthermore, because of favorable adhesion, molding defects of the container can be favorably prevented. The invention described in claim 2 has excellent stacking properties and can suppress blocking, thereby improving the usability of the container. In addition, since the adhesiveness is favorable, molding defects of the container can be favorably prevented. The invention according to claim 3 has excellent stacking property and can suppress blocking, so the usability of the container is improved. Claim 4 The invention described is as follows: Or claim 3 In addition to the effects of the invention described above, peeling at the interface of the resin layer is prevented, improving the reliability of the container.

[0025] Claim 6 The invention described is as follows: 5 In addition to the effects of any one of the above, the strength of the container is improved since the adhesion between the composite substrates is improved when the composite substrates are welded to each other. [Brief description of the drawings]

[0030]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

[0031] FIG. 1 is a perspective view showing the appearance of a container according to a first embodiment of the present invention, and FIG. 2 is an enlarged end view taken along the line II-II shown in FIG.

[0032] With reference to these figures, a container 1 is mainly composed of a bottom 2 and a side wall 3 rising from the peripheral edge of the bottom 2. The side wall 3 also has a flat flange 5 extending outward from the rising end 4 thereof.

[0033] 2, the bottom 2 is composed of a composite substrate 7 including a substrate layer 10 made of paper and resin layers 11a, 11b made of polyethylene terephthalate laminated on the front and back surfaces of the substrate layer 10. The resin layers 11a, 11b are laminated on both sides of the substrate layer 10 by extrusion lamination. The side wall 3 is also composed of the composite substrate 7.

[0034] Here, the surface roughness Ra (arithmetic mean height Ra calculated by JIS B 0601) of the resin layer surface 13 (at least one surface of the composite substrate 7) of the resin layer 11a is configured to be in the range of 0.7 μm or more and 3.0 μm or less. The sum of the surface roughness Ra (total surface roughness of both sides) of the resin layer surface 13 and the resin layer surface 14 (one surface and the other surface of the composite substrate 7) is configured to be in the range of 1.5 μm or more and 3.5 μm or less. By configuring in this way, stacking properties are excellent and blocking can be suppressed, so that the usability of the container is improved. It has been found that when stacking the containers 1, if the total surface roughness of both sides as well as one surface of the composite substrate 7 is within a predetermined numerical range, stacking properties and blocking suppression are favorable.

[0035] Moreover, it is preferable that the surface roughness Ra of at least one surface of the composite substrate 7 is 1.8 μm or more and 2.9 μm or less, and it is preferable that the total surface roughness of both surfaces of the composite substrate 7 is 2.2 μm or more and 3.5 μm or less. By configuring in this way, a container with excellent stacking properties is obtained.

[0036] Next, a method for constructing such a container 1 will be described.

[0037] First, resin layers are laminated on both sides of a paper substrate by extrusion lamination to form a composite substrate 7. Then, the composite substrate 7 is punched out into a predetermined shape to form a blank.

[0038] FIG. 3 is a plan view showing a blank for constructing the container shown in FIG.

[0039] Referring to the same figure, the blank 17 is composed of a bottom blank 18 that contacts the bottom 2 of the container 1 (see Figure 1, etc.), a side wall blank 19 extending outward from the periphery of the bottom blank 18, a lateral tongue piece 20 extending from a portion of the periphery of the side wall blank 19, a corner tongue piece 21 extending from a corner portion of the side wall blank 19, and a joining tongue piece 22 extending from near the corner tongue piece 21 of the side wall blank 19.

[0040] The blank 17 is mountain-folded along mountain fold lines 24 shown by dashed lines in the figure, and is also valley-folded along valley fold lines 25 shown by chain double-dashed lines in the figure, thereby forming a container shape.

[0041] 4 is a plan view showing the surface structure of the container shown in FIG. 1, FIG. 5 is a rear view showing the back structure of the container shown in FIG. 1, and FIG. 6 is an enlarged view of part “A” shown in FIG.

[0042] Referring also to Figures 3 to 6, the bottom blank 18 of blank 17 forms the bottom 2 of the container 1, the side wall blank 19 forms the side wall 3, the side tongue pieces 20 form the side flanges 5a, and the corner tongue pieces 21 form the flanges 5b at the corners of the side wall 3.

[0043] Additionally, the joining tongue pieces 22a, 22b are disposed on the back surface of the flange 5b at the corner portion of the side wall portion 3. Then, one surface (back surface) of the flange 5b, the other surface (front surface) of the joining tongue pieces 22a, 22b, and the other surface (front surface) of the flange 5a are respectively welded by high frequency welding, thereby forming the container 1 having excellent water resistance and oil resistance.

[0044] In addition, when stacking the containers 1, the stacking ability and the suppression of blocking are affected by where and how the containers 1 are joined. One side (front side) and the other side (back side) of the composite substrate 7 of the container 1 are welded by high-frequency welding at the corners, which improves the stability of the container molding and therefore improves reliability.

[0045] Furthermore, by providing a flat flange 5 extending outward from the rising end 4 of the side wall portion 3, the flange can be used as a handle, making it convenient to use when the contents become hot.

[0046] Furthermore, since welding is performed on the reverse side of the flange 5b, the welding area can be made large without impairing the design, thereby improving the reliability of the container.

[0047] In the container according to the embodiment of the present invention, the container has a specific shape, but the shape is not particularly limited. For example, the shape when viewed from above the container opening may be polygonal, circular, or approximately elliptical, but a polygonal shape from a square to an octagon is preferable for ease of molding. The size of the container is also not particularly limited.

[0048] In addition, in the container according to the embodiment of the present invention, the type of paper constituting the base layer is not particularly limited. Pure white roll paper, craft paper, parchment paper, ivory paper, Manila paper, card paper, cup paper, glassine paper, etc. can be used depending on the desired application. In addition, the thickness of the paper is not particularly limited, but is preferably 0.2 mm to 0.5 mm (basis weight 150 g / m 2 ~500g / m 2 By configuring in this way, molding of the container becomes easy and the cost of the container can be reduced.

[0049] Furthermore, in the container according to the embodiment of the present invention, the resin constituting the resin layer is a specific one, but the type of resin is not particularly limited. Examples of the resin include polyester-based resins such as polyethylene terephthalate and polybutylene terephthalate, polyolefin-based resins such as polypropylene, polyethylene, and polymethylpentene, acrylic (methacrylic)-based resins, diene-based resins such as polybutadiene, and thermoplastic resins such as polycarbonate-based resins. In addition, in order to make the paper container more environmentally friendly, biodegradable resins such as polylactic acid (PLA) can also be used. As a preferred type of resin, it is preferable to use polyethylene terephthalate resin as described below, because it has excellent adhesion when the composite substrates are welded together, and the strength of the container is improved.

[0050] Furthermore, when using polyethylene terephthalate resin, the polyethylene terephthalate resin is a copolymerized polyethylene terephthalate resin, and the copolymerized polyethylene terephthalate resin is a copolymerized polyethylene terephthalate resin obtained by copolymerization with isophthalic acid. The copolymerization ratio of isophthalic acid in the copolymerized polyethylene terephthalate resin is preferably 1 mol% or more and less than 10 mol%, and the melting point is preferably 235°C or more and 250°C or less. By configuring in this way, a container with high adhesion between the base material layer and the resin layer and high heat resistance can be obtained, so that molding defects of the container can be prevented, and it is also suitable for use when the content becomes high temperature or when passing through a firing process.

[0051] Furthermore, the polyethylene terephthalate resin in the present invention is preferably a biomass polyethylene terephthalate resin derived from a biological source (derived from biomass resources) with a bio-based carbon content of 5% or more. Polyethylene terephthalate resin is a resin mainly composed of ethylene glycol and terephthalic acid, and is obtained by polycondensing these. Most of them are derived from fossil resources. By using a biomass polyethylene terephthalate resin obtained from a biological source such as sugarcane, the amount of use of fossil resource-derived materials can be reduced, the carbon neutrality can be improved, the sustainability can be improved, and it is useful for environmental protection.

[0052] In the present invention, the bio-based carbon content, which is an index showing the proportion of biologically derived raw materials in the copolymerized polyethylene terephthalate resin, is preferably 5% or more, and more preferably 15% or more. The higher the bio-based carbon content, the lower the proportion of fossil resource-derived raw materials, making the container more environmentally friendly. On the other hand, as the proportion of the bio-based carbon content increases, the cost also increases, so it is more preferable that it is within an appropriate range. The bio-based carbon content can be indicated by the value of the C14 content obtained by a radiocarbon (C14) measurement method in accordance with ISO-16620-2 (equivalent to the ASTM-D6866 standard). That is, since fossil resources contain almost no C14, while biological resources contain a certain proportion of C14 (105.5 pMC), if the content of C14 in the copolymerized polyethylene terephthalate resin is PC14, the bio-based carbon content can be calculated by the following formula.

[0053] Bio-based carbon content (%) = PC14 / 105.5 x 100 Furthermore, in the container according to the embodiment of the present invention, the thickness of the resin layer is not particularly limited, but may be, for example, 10 μm to 50 μm. In particular, a thickness in the range of 20 μm to 30 μm is preferable from the viewpoints of welding stability and ensuring the water resistance and oil resistance of the container.

[0054] Furthermore, in the container according to the embodiment of the present invention, the method of laminating the resin layer on the substrate layer is not particularly limited, and examples thereof include extrusion lamination, dry lamination, wet lamination, and coating of a resin solution. In the present invention, it is preferable to use extrusion lamination, since it is possible to simultaneously form the resin layer and form the resin layer surface having the desired surface roughness. By laminating the resin, it is possible to impart properties such as heat resistance, water resistance, and gas / liquid permeability resistance to the molded container. In addition, an anchor coat layer may be formed on the paper in advance during extrusion lamination. Furthermore, printing may be applied to the surface of the composite substrate. Furthermore, corona treatment may be applied to the paper of the substrate layer.

[0055] Furthermore, in the container according to the embodiment of the present invention, the adhesion when one side and the other side of the composite substrate are welded is preferably 4.0 N / cm or more and 20.0 N / cm or less. By configuring in this way, peeling at the resin layer interface is prevented under normal use conditions as a food storage container, and the reliability of the container is improved. In addition, by being below the above upper limit value, it is also easy to disassemble or dismantle the container to reduce the volume of garbage after use as a container. In addition, the above adhesion is more preferably 5.0 N / cm or more and 20.0 N / cm or less, and even more preferably 8.0 N / cm or more and 20.0 N / cm or less. By configuring in this way, peeling at the resin layer interface is more prevented, and the reliability of the container is further improved.

[0056] Furthermore, the container according to the embodiment of the present invention can be used for various purposes, including but not limited to, storing food, and is particularly suitable as a deep container with increased storage volume.

[0057] Furthermore, although the container according to the embodiment of the present invention is manufactured by a specific manufacturing method, it may be manufactured by other methods.

[0058] Furthermore, in the container according to the embodiment of the present invention, the one surface and the other surface of the composite substrate are welded by high frequency welding, but other welding methods such as ultrasonic welding may also be used.

[0059] Furthermore, in the container according to the embodiment of the present invention, the flange is welded on its rear surface, but the flange may be welded over a wide area including other locations, or may be welded at locations other than the rear surface of the flange.

[0060] Furthermore, although the container according to the embodiment of the present invention is provided with a flange, it is not necessary to provide a flange. EXAMPLES

[0061] The present invention will be described in detail below with reference to examples, although the embodiments of the present invention are not limited to the examples.

[0062] (Preparation of test specimen) First, the basis weight is 260g / m 2 A composite substrate was prepared by preparing a paper substrate and forming a resin layer of polyethylene terephthalate resin on both sides by extrusion lamination. The resin layer had a thickness of 25 μm on both sides. Then, by changing the surface properties (surface roughness) of the cooling roll used during extrusion lamination of the resin, composite substrates were prepared in which a resin layer having a surface roughness Ra of Examples 1 to 6 and Comparative Examples 1 to 4 shown in Table 1 below was formed. That is, in Examples 1 to 3, the resin layer is made glossy on the inner surface and matte on the outer surface, in Examples 4 to 6, the resin layer is made semi-matte on the inner surface and semi-matte on the outer surface, in Comparative Examples 1 to 3, the resin layer is made matte on the inner surface and matte on the outer surface, and in Comparative Example 4, the resin layer is made glossy on the inner surface and glossy on the outer surface.

[0063] The composite substrates of these test specimens (Examples 1 to 6 and Comparative Examples 1 to 4) were cut into blanks having the shape shown in FIG. 3 described above, and while the blanks were folded to maintain the container shape, they were pressed under pressure, and the overlapping portions of the composite substrates at the corners of the container were subjected to high-frequency welding to obtain a container having the shape shown in FIG. 1 described above.

[0064] [Table 1] The surface roughness Ra of each resin layer is expressed in μm, and when both sides are of the same type, the arithmetic average value is given.

[0065] (Stacking test) Fifty containers each of Example 1, Example 4 and Comparative Example 1 were prepared, and the stacking state was observed in a state where 50 of each container were stacked with the container openings facing downward.

[0066] The results are shown in Figure 7. Figure 7 shows the results of the stacking property test.

[0067] Referring to the figure, the stacking height is the highest in Comparative Example 1, followed by Example 4, and the lowest in Example 1.

[0068] (Blocking test) Fifty containers each of Example 1, Example 4, Comparative Example 1, and Comparative Example 4 were prepared, and 50 of each were stacked with the paper container opening facing downward and left for 24 hours. After that, while maintaining the stacked state, the containers were turned over so that the opening faced upward, and the flange part of the top container was pinched with one hand and raised upward to check the blocking state. At this time, the containers that only the top container was lifted without the containers located below being stuck were evaluated as ○ (suitable), and the containers that were lifted while the top container and the containers below it were stuck were evaluated as × (unsuitable).

[0069] The results of the stacking test and the blocking test are shown in Table 2 below.

[0070] [Table 2] Referring to Table 2, it was confirmed that Example 1 had the best stacking property, followed by Example 4. It was also confirmed that Examples 1 and 4 could suppress blocking.

[0071] (Adhesion test) In the above composite substrate, the resin constituting the resin layer was prepared to be polypropylene (PP) (Example 7) or polyethylene terephthalate (PET) (above-mentioned Example 1), and five containers of each were produced using the same method as above.

[0072] For welding, high-frequency welding was performed on the back surface of the flange at the corner of the side wall of the container using a 40 MHz transistor-type high-frequency oscillator with an output of 800 W and a time of 1.5 seconds.

[0073] From each container of the test specimen, as shown as part "B" in Figure 6 above, the welded part on the back surface of the flange (the joining tongue and part of the flange) and the unwelded part on the side wall connected to this were cut out as test pieces, and a tensile testing machine (manufactured by Shimadzu Corporation, product name: Autograph, model number: AGS-X) was used to hold the two ends of the unwelded part and perform a 180° peel test at a tensile speed of 100 mm / min to test the adhesion between one side and the other side of the composite substrate.

[0074] The results are shown in Table 3 below.

[0075] [Table 3] Referring to Table 3, PET (Example 1) had the highest adhesion and provided stable results. Therefore, it was confirmed that PET is suitable as the resin constituting the resin layer in the container of the present invention. [Explanation of symbols]

[0076] 1…Container 2…Bottom 3…Side wall 4...Rising end 5...Flange 7…Composite base material 10...Base material layer 11...Resin layer 13…Resin layer surface 14…Resin layer surface In addition, the same symbols in each figure indicate the same or corresponding parts.

Claims

1. A container made of a composite substrate having a substrate layer made of paper and a resin layer made of a resin laminated on the front and back surfaces of the substrate layer, The surface roughness Ra of at least one surface of the composite substrate is 0.7 μm or more and 3.0 μm or less, The sum of the surface roughness Ra of the one surface and the other surface of the composite substrate is 1.5 μm or more and 3.5 μm or less, The adhesion when the one surface and the other surface of the composite substrate are welded is 4.0 N / cm or more and 20.0 N / cm or less, A bottom portion and a side wall portion rising from a peripheral edge of the bottom portion, The sidewall further includes a flat flange extending outwardly from the upstanding end thereof; A container, wherein the one surface and the other surface of the composite substrate are welded to a rear surface of the flange at a corner portion of the side wall portion.

2. A container made of a composite substrate having a substrate layer made of paper and a resin layer made of a resin laminated on the front and back surfaces of the substrate layer, The surface roughness Ra of at least one surface of the composite substrate is 0.7 μm or more and 3.0 μm or less, The sum of the surface roughness Ra of the one surface and the other surface of the composite substrate is 1.5 μm or more and 3.5 μm or less, the one surface side of the resin layer has a matte finish and the other surface side has a gloss finish, A bottom portion and a side wall portion rising from a peripheral edge of the bottom portion, The sidewall further includes a flat flange extending outwardly from the upstanding end thereof; A container, wherein the one surface and the other surface of the composite substrate are welded to a rear surface of the flange at a corner portion of the side wall portion.

3. A container made of a composite substrate having a substrate layer made of paper and a resin layer made of a resin laminated on the front and back surfaces of the substrate layer, The surface roughness Ra of at least one surface of the composite substrate is 0.7 μm or more and 3.0 μm or less, The sum of the surface roughness Ra of the one surface and the other surface of the composite substrate is 1.5 μm or more and 3.5 μm or less, The blank has a bottom, a side wall rising from a peripheral edge of the bottom, a corner piece extending from a corner of the blank of the side wall, and two joining pieces extending from the vicinity of the corner piece, The sidewall further includes a flat flange extending outwardly from the upstanding end thereof; A container, wherein two of the joining pieces are arranged on the back surface of the flange at the corner portion of the side wall portion, and the one surface of the flange and the other surface of the joining piece are welded to each other.

4. 4. The container according to claim 2, wherein the adhesion between the one surface and the other surface of the composite substrate when they are welded together is 4.0 N / cm or more and 20.0 N / cm or less.

5. A container as described in claim 1 or claim 3, wherein the one side of the resin layer is matte finished and the other side is gloss finished.

6. The container according to claim 1 , wherein the resin constituting the resin layer is polyethylene terephthalate.

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