Paper containers

Abstract

To provide technique for improving the strength of a paper container.SOLUTION: There is provided a paper container formed of a paper base material by drawing molding, and the paper container comprises a bottom face part, a side face part raised from the periphery of the bottom face part, and a flange part extending outward from the side face part, the bottom face part having a bottom raised part which has its surface raised in part in a curved surface shape.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to paper containers. [Background technology]

[0002] Currently, due to environmental concerns and other factors, efforts to eliminate or eliminate plastic are accelerating worldwide. While plastic materials have been primarily used for packaging containers such as food trays, research is being conducted into using paper as a packaging container material instead of plastic materials. For example, Patent Document 1 discloses a paper tray container obtained by molding a laminated sheet having a paper base material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-023026 Summary of the Invention [Problem to be solved by the invention]

[0004] Paper containers have the problem of being weaker than plastic containers. The present disclosure aims to provide a technology for improving the strength of paper containers. [Means for solving the problem]

[0005] That is, the present disclosure provides the following: <1> ~ <6> Regarding. <1> A paper container obtained by drawing a paper base material, A bottom portion; a side surface portion rising from the periphery of the bottom surface portion; a flange portion extending outward from the side surface portion; Equipped with The bottom surface portion has a raised portion that is partially raised so that the surface is curved. Paper container. <2> The surface of the raised bottom portion is a smoothly curved surface. <1> A paper container as described in <3> The surface of the side surface is a smoothly curved surface. <1> or <2> A paper container as described in <4> the bottom surface portion, the side surface portion, and the flange portion each have a long side extending in the same direction and a short side perpendicular to the long side, When viewed from the long side of the side surface portion, the lowest part of the bottom surface portion is linear. <1> from <3> The paper container according to any one of the preceding claims. <5> the bottom surface portion, the side surface portion, and the flange portion each have a long side extending in the same direction and a short side perpendicular to the long side, When the bottom surface portion including the raised bottom portion is cut in the extension direction of the short side, a cross section of the raised bottom portion is arc-shaped. <1> from <4> The paper container according to any one of the preceding claims. <6> The longitudinal and transverse geometric mean value of the fracture elongation of the flange portion is 12.0% or more. <1> from <5> The paper container according to any one of the preceding claims. [Effects of the Invention]

[0006] According to the present disclosure, the strength of paper containers can be improved. [Brief explanation of the drawings]

[0007] [Figure 1] Figure 1(A) is a plan view of a paper container according to the embodiment, Figure 1(B) is a cross-sectional view of the paper container according to the embodiment cut along the short direction, and Figure 1(C) is a cross-sectional view of the paper container according to the embodiment cut along the long direction. DETAILED DESCRIPTION OF THE INVENTION

[0008] In this specification, unless otherwise specified, the expressions "X or more and Y or less" or "X to Y" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints. When a numerical range is described in stages, the upper and lower limits of each numerical range can be combined in any way.

[0009] In this specification, the machine direction refers to the machine direction (MD) of the paper substrate, which is the same as the direction in which the fibers are oriented, and the cross direction refers to the direction perpendicular to the machine direction (CD).

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the configurations of the following embodiments are merely examples, and the present invention is not limited to the configurations of these embodiments.

[0011] <Embodiment> 1(A) to 1(C) are diagrams showing a paper container according to an embodiment. FIG. 1(A) is a plan view of the paper container 1 seen from above, and FIG. 1(B) is a cross-sectional view of the paper container 1 when cut along line AA in FIG. 1(A). FIG. 1(C) is a cross-sectional view of the paper container 1 when cut along line BB in FIG. 1(A). The paper container 1 according to this embodiment is obtained by drawing (deep drawing) a single sheet of paper base material. Since the paper container 1 is manufactured by forming a single sheet of paper base material, the entire paper container is formed as a single unit. As shown in FIG. 1(A), the paper container 1 has a rectangular shape with a longitudinal direction and a lateral direction perpendicular to the longitudinal direction when viewed from above. The paper container 1 is used, for example, as a container for moist foods such as chilled foods.

[0012] 1(A) to 1(C) also show X-axis, Y-axis, and Z-axis, which are perpendicular to each other. The X-axis direction and Y-axis direction correspond to a horizontal direction, and the Z-axis direction indicates a vertical direction perpendicular to the horizontal direction. The following explanation will be made using the directions X, Y, and Z (or horizontal and vertical directions). The paper container 1 has a short side direction in the X-axis direction, a long side direction in the Y-axis direction, and a depth formed by deep drawing in the Z-axis direction.

[0013] As shown in Figures 1(A) to 1(C), paper container 1 has a bottom surface 2 on which food or the like is placed, and side surfaces 3 that rise from the periphery of bottom surface 2. The bottom surface 2 and side surfaces 3 form an opening 4 that corresponds to the inner volume of paper container 1. Bottom surface 2 has paper container corners 5 that are rectangular in shape with four chamfered corners. Side surfaces 3 rise from bottom surface 2 to form, together with bottom surface 2, the opening 4 for accommodating food or the like. A peripheral edge 6 that is the outer periphery of side surfaces 3 has opening corners 7 that are rectangular in shape with four chamfered corners.

[0014] The paper container 1 also has a flange portion 8 that extends outward from the peripheral edge portion 6 of the side portion 3. The flange portion 8 is provided so as to surround the entire periphery of the side portion 3. The outermost periphery of the flange portion 8 forms the outer periphery of the paper container 1 in a plan view. The flange portion 8 has a flat surface that extends approximately parallel to the flat portion of the bottom portion 2, and a step that slopes down toward the bottom portion 2 is formed on the outermost periphery.

[0015] The paper container 1 has a structure in which the bottom portion 2, side portion 3, and flange portion 8 are integrally molded, and each portion is connected to each other.

[0016] Furthermore, the bottom surface 2 of the paper container 1 according to this embodiment has a raised bottom portion 2A, which is a portion raised to form a curved surface. The raised bottom portion 2A has a rectangular shape with chamfered corners, similar to the entire bottom surface 2, so that its center coincides with the center of the raised bottom portion 2A. As shown in Figures 1(B) and (C), the raised bottom portion 2A is formed into a curved surface that is convex vertically upward. The depth of the paper container 1 corresponds to the vertical distance H between the bottom surface 2 excluding the raised bottom portion 2A and the peripheral edge 6 of the side surface portion 3.

[0017] The surface of the raised bottom portion 2A is a smooth curved surface without any corners formed by the intersection of two straight lines. The bottom portion 2 outside the raised bottom portion 2A is also a smooth curved surface. Similarly, the surfaces of the side portions 3 are also smoothly curved. By forming the bottom portion 2 and side portions 3 into smooth curved surfaces, the paper container 1 can eliminate wrinkles and cracks, improving its aesthetics. By forming the bottom portion 2 and side portions 3 into smooth curved surfaces, the paper container 1 can channel and collect oil and moisture from the contents around the raised bottom portion 2A. For example, when food drips, the paper container 1 can channel and collect the drips around the raised bottom portion 2A. Furthermore, by providing the raised bottom portion 2A, the paper container 1 can reduce the contact area between the user's hand and the bottom portion 2 when lifting the bottom portion 2, thereby reducing heat transfer to the hand even when the contents are hot. In this way, the paper container 1 is more convenient.

[0018] Furthermore, by providing the raised bottom portion 2A, the paper container 1 has a large moment of inertia in the longitudinal direction, and the strength against bending in the longitudinal direction is improved. The strength of the paper container 1 can be improved.

[0019] 1(B), when the bottom surface portion 2 including the raised bottom portion 2A is cut in the direction of extension of the short side (X-axis direction), the cross section of the raised bottom portion 2A is an arc-shaped portion that is convex vertically upward. By making the raised bottom portion 2A an arc-shaped portion that is convex vertically upward, the paper container 1 is able to more easily disperse impact when dropped.

[0020] The bottom surface portion 2, the side surface portion 3, and the flange portion 8 each have a long side extending in the Y-axis direction and a short side perpendicular to the X-axis direction. In this embodiment, the bottom surface portion 2, excluding the raised bottom portion 2A, forms the lowest portion, which is formed so as to be parallel to the XY plane. Therefore, when the paper container 1 is viewed from the long side of the side surface portion 3, the lowest portion of the bottom surface portion 2 is linear and extends along the Y-axis. When the lowest portion of the paper container 1 is placed on a horizontal surface, the lowest portion evenly abuts on the horizontal surface, preventing it from wobbling and ensuring stability. The angle of the opening corner portion 7 corresponds to the angle θ formed between the side surface portion 3 and an imaginary plane extending vertically at the peripheral portion 6 of the side surface portion 3.

[0021] The paper container 1 is obtained by drawing a paper base material. The paper container 1 obtained by drawing a paper base material containing pulp has a reduced environmental impact compared to conventional plastic containers. The lower limit of the geometric mean value of the longitudinal and transverse breaking elongation of the paper base material is preferably 12.0% or more, and more preferably 15.0% or more. The upper limit of the geometric mean value of the longitudinal and transverse breaking elongation of the paper base material is not particularly limited, but is usually 20.0% or less from a manufacturing standpoint. The geometric mean value of the length and width is measured in accordance with JIS P 8113:2006.

[0022] By having the breaking elongation of the paper base material within the above range, the formability of the paper container 1 can be further improved, and it becomes easier to prevent breakage and cracking due to drawing, improving the productivity of the paper container 1. In addition, by having the longitudinal and transverse geometric mean values ​​of the paper base material within the above range, it is possible to prevent the occurrence of wrinkles and the like during drawing, and to form the surface into a smooth curved shape. To reduce this, methods include adding a resin layer to the paper layer, subjecting the pulp that makes up the paper layer to high-concentration beating, and performing Clupak treatment when making the paper layer.In addition, the geometric mean values ​​of the length and width of the paper base material used to form the paper container 1 can also be measured by measuring the geometric mean values ​​of the length and width of the portion of the paper container 1 that has not been stretched by drawing (for example, the flange portion 8 shown in Figure 1).

[0023] The paper container 1 according to this embodiment has improved strength. In addition, the paper container 1 has improved productivity and can be formed into a smooth surface. [Explanation of symbols]

[0024] 1. Paper containers 2...Bottom part 2A··Bottom raising part 3...Side part 4. Opening 5 Corner of paper container 6. Periphery 7... Corner of opening 8. Flange

Claims

1. A paper container obtained by drawing a paper base material, A bottom portion; a side surface portion rising from the periphery of the bottom surface portion; a flange portion extending outward from the side surface portion; Equipped with the bottom surface portion has a raised bottom portion that is partially raised so that the center has a curved shape that is most convex upward, the bottom surface portion, the side surface portion, the flange portion, and the raised bottom portion each have a long side extending in the same direction and a short side perpendicular to the long side, the raised portion is formed on a part of the bottom portion so that the center of the raised portion coincides with the center of the bottom portion, When viewed from the long side of the side surface portion, the lowest part of the bottom surface portion is linear. Paper container.

2. The surface of the raised bottom portion is a smoothly curved surface. The paper container according to claim 1.

3. The surface of the side surface is a smoothly curved surface. The paper container according to claim 1.

4. When the bottom surface portion including the raised bottom portion is cut in the extension direction of the short side, a cross section of the raised bottom portion is arc-shaped. The paper container according to any one of claims 1 to 3.

5. The geometric mean value of the longitudinal and transverse breaking elongation of the flange portion is 12.0% or more. The paper container according to any one of claims 1 to 3.

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