JP2023121290A - Paper container and manufacturing method of paper container - Google Patents

Abstract

To provide a paper container capable of enlarging capacity with no wrinkle and step caused by a wrinkle, and a manufacturing method of the paper container.SOLUTION: A paper container 1 is formed of sheets of base material containing a paper base material layer, and comprises: a bottom part 1a; a side wall part 1b rising from the circumference of the bottom part 1a; and a flange part 1c which is provided while connecting to the side wall part 1b on an opening part 1d side of the paper container 1 and is formed in a flange-like shape. Each of base materials of the surfaces of the bottom part 1a, the side wall part 1b, and the flange part 1c is flatly constituted. In a cross section which is orthogonal to the surface of the flange part 1c and cut in a plain face parallel to a normal direction of a wall surface in a cutting position of the side wall part 1b, at least a part of the side wall part 1b has an angle α of 60° or more formed with the flange part 1c.SELECTED DRAWING: Figure 2

Description

TECHNICAL FIELD The present disclosure relates to a paper container and a method for manufacturing the paper container.

The use of paper, which is a recyclable material, has been proposed in order to design containers used for food, daily necessities, and the like in an environmentally friendly manner (see, for example, Patent Document 1).

JP-A-2002-347736

However, the elongation rate of general paper is not high even for paper for paper cups, which is said to be relatively elongating. For this reason, conventionally, molding is performed while wrinkles are formed on the flange portion and the side wall portion, and a step occurs due to the wrinkles on the flange portion and the like after molding. For example, in the above-mentioned Patent Document 1, the strength of the container and the degree of freedom in the shape of the container, such as the depth of the container and the angle of the side wall portion, are obtained by forming creases in the base paper in advance to control wrinkles.

If the container has wrinkles or a step due to the wrinkles, the aesthetic appearance of the container may be impaired, or it may not be possible to display the container properly by means of printing or the like. Moreover, when trying to seal a paper container, if the flange portion has wrinkles or a step due to the wrinkles, it is difficult to completely seal the paper container.
In addition, if the molding is performed to the extent that wrinkles do not occur, a sufficient capacity as a container cannot be obtained.

An object of the present disclosure is to provide a paper container that is free from wrinkles and steps caused by wrinkles and that can increase the capacity, and a method for manufacturing the paper container.

The present disclosure solves the above problems with the following solutions. In order to facilitate understanding, reference numerals corresponding to the embodiments of the present disclosure will be used for description, but the present disclosure is not limited thereto.

The first disclosure is a paper container (1, 1B, 1C) made of one sheet of substrate including a paper substrate layer, comprising a bottom (1a) and side walls ( 1b), and a flange portion (1c) formed in the shape of a brim, which is connected to the side wall portion (1b) on the opening (1d) side of the paper container (1, 1B, 1C), The surfaces of the bottom portion (1a), the side wall portion (1b), and the flange portion (1c) are all formed flat by the base material, are perpendicular to the surface of the flange portion (1c), and , In a cross section taken along a plane parallel to the normal direction of the wall surface at the cutting position of the side wall (1b), at least part of the side wall (1b) forms an angle of 60 with the flange (1c). It is a paper container (1, 1B, 1C) that is above the degree.

A second disclosure is a paper container (1, 1B, 1C) according to the first disclosure, wherein the opening width of the opening (1d) in the cross section, the side wall (1b) and the bottom in the cross section A paper container (1, 1B, 1C) in which the difference in length of the outer surface side of the contour shape from (1a) is 6% or more of the opening width.

A third disclosure is that in the paper container (1, 1B, 1C) according to the first disclosure or the second disclosure, the weight ratio of the paper in the entire paper container (1, 1B, 1C) is It is the largest paper container (1, 1B, 1C) among the materials constituting the container (1, 1B, 1C).

A fourth disclosure is a method for manufacturing a paper container (1, 1B, 1C) according to any one of the first disclosure to the third disclosure, wherein the bottom portion (1a) and the side wall portion (1b) are is performed at least twice using molds having different shapes.

Advantageous Effects of Invention According to the present disclosure, it is possible to provide a paper container and a method for manufacturing a paper container that can increase the capacity without wrinkles or steps caused by wrinkles.

1 is a perspective view showing a first embodiment of a paper container 1 according to the present disclosure; FIG. FIG. 2 is a cross-sectional view of the paper container 1 taken along the arrow AA in FIG. 1; FIG. 3 is a cross-sectional view of a mold used in a molding step cut at a position corresponding to the cross section of FIG. 2; FIG. 3 is a cross-sectional view of the in-process product 50 processed by the pre-forming process, cut at the same position as in FIG. 2 ; FIG. 2 is a diagram summarizing the results of measuring the paper container 1 in Examples and Comparative Examples. It is sectional drawing which cut|disconnected the paper container 1B of a modified form in the same position as FIG. It is a figure which shows the deformation|transformation of the external shape of the flange part 1c.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present disclosure will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a perspective view showing a first embodiment of a paper container 1 according to the present disclosure.
FIG. 2 is a cross-sectional view of the paper container 1 taken along the arrow AA in FIG.
In addition, each figure shown below including FIG. 1 and FIG. 2 is a schematic diagram, and the size and shape of each part may be exaggerated or omitted as appropriate for easy understanding. is shown.
Also, in the following description, specific numerical values, shapes, materials, and the like are shown and described, but these can be changed as appropriate.
In this specification, terms such as plate, sheet, and film are used, and as a general usage, they are used in the order of thickness, plate, sheet, and film. I use it in my book as well. However, since there is no technical meaning in such proper use, these words can be replaced as appropriate.
It should be noted that the specific numerical values defined in the specification and claims should be treated as including a general error range. In other words, the difference of about ±10% is substantially no difference, and the numerical value set in a range slightly exceeding the numerical range of the present disclosure is substantially the disclosure. should be interpreted as within the range.

The paper container 1 of the present embodiment has a bottom portion 1a, a side wall portion 1b, and a flange portion 1c, and is composed of one base material including a paper base material layer. In the following description, the side of the opening 1d of the paper container 1 is the top, and the side of the bottom 1a is the bottom.
Examples of the base material that forms the paper container 1 include the following configurations, but the base material is not limited to these.
(Base material example 1)
As the substrate, a configuration of only a paper substrate layer can be exemplified. In other words, it is a structure that does not include other layers of the paper base layer, and is a base material that is composed only of paper. Examples of thin paper that can be used as the paper base layer include coated paper, high-quality paper, matte paper, and kraft paper. Examples of thick paper include coated board, card paper, ivory, and base paper for cups. It should be noted that other types of paper may be used instead of the paper described above.
Functional paper such as water-resistant paper and oil-resistant paper may be used as the paper base layer.
Further, as the paper base layer, paper mixed with synthetic pulp or the like to impart functionality such as improved strength, elongation, and water resistance may be used. Examples of synthetic pulp include polyolefin hyperbranched fiber SWP (manufactured by Mitsui Chemicals, Inc.).
The basis weight of the paper used for the paper substrate layer is preferably 50 g/m ² or more and 600 g/m ² or less, more preferably 150 g/m ² or more and 300 g/m ² or less.
As the paper base layer, generally used paper may be used, but if paper with high extensibility is used, molding can be easily performed. When using paper with high extensibility, paper with an appropriate elongation rate is appropriately selected according to the shape after molding.

(Base material example 2)
As the substrate, a substrate obtained by coating (laminating) one side or both sides of the paper substrate layer with a heat-sealable resin may be used. For example, the following layer structure in which PE (polyethylene) is laminated can be exemplified. In addition, the layer structure is arranged in order from the upper side (inner side of the container) of the paper container 1 to the lower side (outer side of the container). Also, "/" indicates the boundary of each layer. In addition, in the layer structure examples below, a structure using PE is illustrated, but PP (polypropylene), PET (polyethylene terephthalate), PBT (polybutylene terephthalate), or the like may be used.
(Layer configuration example 1 of base material example 2): PE/paper base layer (Layer configuration example 2 of base material example 2): PE/paper base layer/PE

(Base material example 3)
Furthermore, as the base material, a base material having a structure in which a barrier layer is further added may be used. As the barrier layer, aluminum foil may be used, or EVOH (ethylene-vinyl alcohol copolymer) may be used. When EVOH is used, the base material can be produced by extrusion lamination, bonding of EVOH films, or the like. As a layer structure, the following forms can be illustrated, for example.
(Example of layer structure of base material example 3): Paper base layer/PE/adhesive resin/barrier layer/adhesive resin/PE
Examples of substrates and examples of layer structures are not limited to those illustrated above, and can be changed as appropriate.

In addition, in any form of the base material exemplified above, the ratio of the weight of paper to the entire base material (paper container) is preferably the largest among the materials constituting the base material (paper container). . This is because the ratio of recyclable materials in the base material (paper container) is increased, and the environmental load can be reduced. In addition, in the base material (paper container) of this embodiment, "paper", "resin", and "metal" correspond to the material constituting the base material (paper container).

The bottom portion 1a is provided at the lowest portion of the paper container 1 and has a circular outer shape.
The side wall portion 1b is provided so as to rise from the periphery of the bottom portion 1a, and is inclined in a direction of widening toward the upper opening portion 1d side. In a cross section perpendicular to the plane of the flange portion 1c and parallel to the normal direction of the wall surface at the cutting position of the side wall portion 1b, that is, in the cross section shown in FIG. , and the flange portion 1c is preferably 60 degrees or more. More preferably, the angle α is 65 degrees or more. This is because the closer the angle α is to 90 degrees, the larger the capacity of the paper container 1 can be. A curved surface portion 1e having an arc-shaped cross section may be provided as a part of the side wall portion 1b at the connecting portion between the side wall portion 1b and the base portion rising from the bottom portion 1a.
A body portion of the paper container 1, which is composed of the bottom portion 1a and the side wall portion 1b, has a substantially truncated cone shape.
The flange portion 1c is connected to the side wall portion b on the side of the opening 1d of the paper container 1, and is formed in the shape of a flange extending outward. The flange portion 1c of this embodiment has a substantially square shape with rounded corners when viewed from above.

Here, in a cross section cut along a plane orthogonal to the plane of the flange portion 1c and parallel to the normal direction of the wall surface at the cutting position of the side wall portion 1b, that is, in the cross section shown in FIG. Define as Let L1 be the opening width in the cross section of FIG. Let L2 be the length of the outer surface of the contour shape of the side wall portion 1b and the bottom portion 1a in the cross section of FIG. In FIG. 2, a chain double-dashed line is provided along the contour shape corresponding to the length of L2. Using L1 and L2 shown in FIG. 2, the elongation rate of the paper container 1 after molding preferably satisfies the following relationship.
Elongation rate (%) = (L2-L1) / L1 × 100 ≥ 6 (%)
That is, the difference between the opening width L1 of the opening 1d in the cross section of FIG. 2 and the length L2 of the outer surface side of the contour shape of the side wall portion 1b and the bottom portion 1a in the cross section of FIG. 2 is 6% or more of the opening width L1. is desirable.
This is because when L1 and L2 satisfy the above relationship, the container becomes deeper and the capacity of the container can be increased.

The surfaces of the bottom portion 1a, the side wall portion 1b, and the flange portion 1c are all made flat by a single layer of base material. Here, the phrase "the substrate is a single layer and is flat" refers to a state in which the substrates are not overlapped and do not have wrinkles or steps caused by wrinkles. Further, the curved shape of the side wall portion 1b along the shape of the container shall be interpreted as having a flat surface. Therefore, it does not include a state that appears to be flat at first glance due to additional processing such as crushing wrinkles.

(Production method)
The paper container 1 of the present embodiment can be broadly classified into the following two manufacturing methods (manufacturing methods 1 and 2).

(Manufacturing method 1: molding a blank)
Manufacturing method 1 is a method in which the substrate is supplied to the molding machine as individualized blanks.
(Blank punching process)
First, a step of punching the base material into a blank shape is performed. In this embodiment, it is punched into a substantially square shape with rounded corners in accordance with the outer shape of the flange portion 1c. Before or after this blank punching process, a paper processing process such as lamination or a printing process may be added.
(Blank molding process)
Next, a blank forming process is performed in which the blank punched in the blank punching process is formed into a product shape using a forming die. In this blank forming process, the flange portion 1c is clamped to extend the base material. The blank forming process can be performed by, for example, pressing, pressure forming, or the like.

(Manufacturing method 2: molding in a long state)
Manufacturing method 2 is a method in which a long base material is supplied to a molding machine from a roll around which the base material is wound.
(long molding process)
First, a long forming step is performed in which a base material supplied from a roll to a forming machine in a long state is formed into a product shape by a forming die. In this long forming process, both ends of the rolled paper are clamped to stretch the base material. Further, if necessary, the molding may be performed by clamping the flange portion 1c. The long-length forming process can be performed, for example, by pressing, pressure forming, or the like. Note that a paper processing process such as lamination or a printing process may be performed before this long-length forming process.
(Product punching process)
After the long forming process, a product punching process for punching into a product shape is performed.

Specific features common to the blank forming process and the long forming process (hereinafter both are collectively referred to as the "forming process") will now be described in more detail.
In the molding process of this embodiment, it is possible to produce the shape of the paper container 1 by one molding process. However, in order to form a shape that is deeper and in which the side wall portion 1b stands up (the angle α is larger), in both the blank forming process and the long forming process, a mold having a different shape must be used multiple times. It is desirable to carry out a molding process. Therefore, in the present embodiment, the shape of the paper container 1 is produced not only by one forming process (only the container shape forming process), but also by two forming processes (preforming process and container shape forming process). 1 was fabricated.
FIG. 3 is a cross-sectional view of the mold used in the molding process cut at a position corresponding to the cross-section of FIG. FIG. 3(a) shows a pre-forming mold 100 used in the pre-forming step, and FIG. 3(b) shows a container-shaped forming mold 200 used in the container-shaped forming step. It should be noted that when the molding process is performed only once, that is, when only the container molding process is performed without performing the pre-molding process, it is preferable to use the container shape molding die 200 .

(Pre-molding process)
In the preforming mold 100 shown in FIG. 3(a), the angle β0 of the portion corresponding to the angle α in the paper container 1 is 45 degrees, and the projection height h0 is 15 mm. Further, the preforming mold 100 of this embodiment is a metal mold.
A pre-molding process is performed using the pre-molding tool 100 as described above. The preforming step is performed mainly for the purpose of stretching the base material. Therefore, in the preforming step, the preforming die 100 having an inclined shape with an angle β0=45 degrees smaller than the angle α is used to stretch the paper with as little load as possible. Here, an example of using the preforming mold 100 having an inclined shape with an angle β0=45 degrees illustrated in FIG. Alternatively, a mold having other shapes such as a hemispherical shape and a dome shape may be used.
FIG. 4 is a cross-sectional view of the in-process product 50 that has been processed by the preforming process, cut at the same position as in FIG.
In the in-process product 50, the angle α0 shown in FIG. 4 is preferably the same as or smaller than the angle α of the finished paper container 1 (α0≦α). Further, in the in-process product 50, the depth d0 shown in FIG. 4 is preferably the same as the depth d of the finished paper container 1 or greater than the depth d (d0≧d). In the preforming step, by making the angle α0 smaller than the angle α, the depth d0 can be deepened and the base material can be sufficiently stretched.

(Container shape forming process)
The container-shaped molding die 200 shown in FIG. 3B has an angle β of a portion corresponding to the angle α of the paper container 1 of 85 degrees and a projection height h of 15 mm. Further, the container-shaped mold 200 of this embodiment is a metal mold.
Using the container shape forming mold 200 as described above, the container shape forming step is performed on the in-process product 50 formed by the preforming step, or the base material is directly formed into the container without performing the preforming step. Mold into shape. The container shape forming die 200 is a process for adjusting the shape of the paper container 1 .
When the pre-forming step is performed, the base material is already stretched by the pre-forming step, so the container shape forming step is performed even for a shape with a large angle α that would break in one forming. Molding becomes possible. The angle β of the container-shaped mold 200 is preferably equal to or larger than the angle α.
In this embodiment, both the preforming step and the container shape forming step are performed at room temperature, but the forming may be performed while at least one of the preforming mold 100 and the container shape forming mold 200 is heated. . By heating the mold, it is possible to improve the shape retention after molding.

(Example)
The paper container 1 described above was actually produced, and the results of measuring the dimensions of each part are shown below.
FIG. 5 is a diagram summarizing the results of measurement of the paper container 1 in Examples and Comparative Examples.
Examples 1 to 6 are examples in which a substrate obtained by laminating PE on both sides of a paper substrate layer was used. That is, the layer structure is PE/paper base layer/PE.

In FIG. 5, the "container depth (setting)" represents the depth into which the mold is pushed from the position of the flange portion 1c. In addition, in Examples 2, 4, and 6 in which pre-forming is “yes”, the “measured depth value” is greater than the “container depth (set)” because the shape formed in the pre-forming step is This is due to deformation in the shape of being further pushed in the container shape forming process.
In addition, for the measurement of the side wall angle α in FIG. 5, the contour shape was obtained with a contourer (contour shape measuring machine), a tangent line was drawn at the center of the side wall, and the angle was taken as the measured value. The first measurement point is a measurement point on one side wall of the contour shape, and the second measurement point is a measurement point on the other side wall of the contour shape (measurement point at a position facing the first measurement point).

As shown in FIG. 5, none of the paper containers of the example had wrinkles, and the surfaces of the bottom portion 1a, the side wall portion 1b, and the flange portion 1c all formed a single layer without overlapping the base material. was laid flat. Moreover, the side wall angle α was all 60 degrees or more, and the elongation rate was 6% or more. In particular, under the condition of "preforming", the side wall angle α was 65 degrees or more in some cases, and the elongation rate was 7% or more, and Example 6 was 8.68%. Thus, the paper container 1 of this embodiment can increase the capacity. Further, when a lid member using a base material similar to that used for the paper container 1 was heat-sealed to the flange portion 1c, sufficient sealing strength and sealing performance could be achieved in all the examples.

(deformed form)
Various modifications and changes are possible without being limited to the embodiments described above, and they are also within the scope of the present disclosure.

(1) In the embodiment, the cross-sectional shape of the paper container has been described as an ideal shape as shown in FIG. Not limited to this, for example, the shape formed in the pre-forming step may be partially left.
FIG. 6 is a cross-sectional view of a modified paper container 1B taken at the same position as in FIG.
In the paper container 1B shown in FIG. 6, the approximately 45-degree slant portion 1f formed in the preforming process remains even after the container shape forming process. By intentionally leaving the shape formed in the pre-forming step in this way, the risk of breakage can be avoided and a container with a larger capacity can be produced.

(2) In the embodiment, the main body of the paper container 1 made up of the bottom portion 1a and the side wall portion 1b has been described as an example in which it is configured in a substantially truncated cone shape. However, the shape of the main body of the paper container 1, which is composed of the bottom portion 1a and the side wall portion 1b, may be elliptical, square, or triangular, and can be changed as appropriate.

(3) In the embodiment, the flange portion 1c has an approximately square shape with rounded corners when viewed from above. Not limited to this, the outer shape of the flange portion 1c can be changed as appropriate.
FIG. 7 is a diagram showing a modified form of the outer shape of the flange portion 1c.
Like the flange portion 1c of the paper container 1C shown in FIG. 7, the outer shape of the flange portion 1c may be a circular shape when viewed from above, or a polygonal shape such as a rectangular shape, a triangular shape, or a pentagonal shape. etc.

(4) In the embodiment, an example has been described in which two forming steps, the pre-forming step and the container shape forming step, are performed. For example, the container shape forming step may be performed after performing the preforming step twice or three times, or the preforming step may be performed more times.

1, 1B, 1C Paper container 1a Bottom portion 1b Side wall portion 1c Flange portion 1d Opening portion 1e Curved surface portion 1f Slope portion 50 In-process product 100 Preforming mold 200 Container shape forming mold

Claims (4)

A paper container made of one base material including a paper base layer,
a bottom;
a side wall portion rising from the perimeter of the bottom portion;
a flange portion connected to the side wall portion on the opening side of the paper container and formed in a brim shape;
with
The surface of the bottom portion, the side wall portion, and the flange portion are all formed flat by the base material,
In a cross-section taken along a plane orthogonal to the plane of the flange and parallel to the normal direction of the wall surface at the cutting position of the side wall, at least part of the side wall has an angle formed with the flange. Paper containers that are 60 degrees or more. In the paper container according to claim 1,
A paper container in which the difference between the opening width of the opening in the cross section and the outer length of the contour shape of the side wall and the bottom in the cross section is 6% or more of the opening width. In the paper container according to claim 1 or claim 2,
A paper container in which the weight ratio of paper in the entire paper container is the largest among the materials that make up the paper container. A method for manufacturing a paper container according to any one of claims 1 to 3,
The forming step of forming the shapes of the bottom portion and the side wall portion is performed at least twice using molds having different shapes;
A method for manufacturing a paper container, characterized by:

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