JP7593071B2 - Paper container with curled top - Google Patents

Description

The present invention relates to a paper container. In particular, it relates to a tray-shaped paper container with a curled top that is formed using a blank based on paperboard and can store, for example, frozen foods such as ice cream or powdered foods.

Glass, ceramic, or metal packaging containers have long been used. In the 1960s, technology improved to reduce the permeability of paper, and in the 1970s, paper cartons with even lower permeability were developed. These began to be used for alcoholic beverages and other items, and are now popular on the shelves of supermarkets and convenience stores.

The reasons why paper containers have become so widely used include the following features and conveniences:
- It is lightweight and foldable, reducing transportation costs.
- Various types of printing can be done on the surface, improving the design and making it easy to display information about the contents.
- It is shock resistant and easy to carry.
- Made from materials derived from plants or wood, it has excellent volume reduction and incineration properties when disposed of, making it environmentally friendly.

On the other hand, the quality requirements for paper containers vary widely depending on the contents and application. For example, the following functions are required:
- If the contents are liquid, there will be no leakage.
-Excellent protection against microorganisms and sealing properties.
- It has light-blocking and gas-barrier properties to improve storage stability.
- It has rigidity and toughness to protect the contents from external forces.
And so on.

Paper containers are also used in retail settings such as supermarkets and convenience stores as food packaging materials, for example as paper trays. They come in a variety of forms, but because they are based on paper, they are widely used as an environmentally friendly packaging material in addition to the above-mentioned advantages such as price.

Also, various shapes are possible depending on the contents. For example, in the case of a paper tray, a thermoplastic resin layer is applied to the surface of the paper base material as a blank to impart water resistance, and the thermoplastic resin layer can be sealed to form the three-dimensional shape of the paper container, and a lid is also sealed to seal the entire tray.

Patent Document 1 proposes a blank for a tray container in which side panels are connected to two opposing sides of a rectangular bottom panel via mountain fold lines, and the edges are connected to the outer periphery of the side panels via valley fold lines.

However, paper containers assembled with creases have edges, or flanges, which means that the opening is rectangular or other angular, limiting the development of design possibilities. With the demand for universal design for food containers and other products, there was a demand for paper containers with flanges that provide a stable seal even when the container is in a soft arc or round shape that is gentle on the hands and has no sharp angles.

On the other hand, paper cups are a common paper container in which a flange that can be sealed to the top is curled by extending the side part of the container. However, because the bottom part and the cylindrical body part are crimped together to form the container, there are areas on the outside of the bottom that will overheat when heated in a microwave oven, potentially causing smoke or fire, making them unsuitable for microwave heating.

Patent No. 3687396

The present invention was made in consideration of such circumstances, and aims to provide a paper container with a curled top that is microwave-safe, has a curved surface, and is equipped with a sealable flange.

As a means for solving the above problem, the invention described in claim 1 is:
A paper container comprising a blank made of paperboard having a resin layer formed on at least one side thereof,
A paper container consists of a bottom, side panels, and a flange.
The bottom surface is a substantially octagon having a rectangular shape and has four corners.
The side panels surround the bottom and form the sides of the paper container.
The flange is continuous with the upper end of the side plate and surrounds the periphery of the paper container.
Around each of the four corners, there are provided eight wedge-shaped regions, each of which is made of only the resin layer and has no paperboard, in two locations each ;
Among the periphery of the bottom surface, a pair of sides corresponding to the long sides of the approximate rectangular shape are curved outwardly,
The boundary between the side panel connected to the set of edges and the flange connected to the side panel, and the portion of the outer periphery of the blank formed by the flange, are curved outwardly,
The blank has a curved outer periphery that bulges 0.7 mm to 1.0 mm at the center of the longitudinal side and is smaller than the bulge of the curved periphery of the bottom surface;
This is a paper container with a top curl, characterized in that the flange of the paper container is curled.

The invention described in claim 2 is as follows:
The paper container with a top curl described in claim 1 is characterized in that the resin layer formed on one side of the blank is made of one or more of polyethylene-based resin, polypropylene-based resin, polyethylene terephthalate-based resin, polybutylene terephthalate-based resin, and polymethylpentene-based resin.

The present invention makes it possible to provide a paper container with a curled top that is microwave-safe, has a curved surface, and is equipped with a sealable flange.

A paper container made of a blank made of paperboard with a resin layer formed on at least one side can be made to have sealability. This makes it possible to seal the paper container by sealing a lid material having a sealant layer.

The paper container is made up of a bottom, side panels, and a flange. The bottom is roughly rectangular with four corners, and the side panels rise up and surround the bottom, forming the sides of the paper container. This means that the paper container is made up of a single part, and there is no risk of the paper container overheating even when heated in a microwave oven.

The flange continues from the upper end of the side panel and surrounds the periphery of the paper container, making it possible to seal a lid or the like at this point and hermetically seal the paper container.

The blank is roughly rectangular, with eight wedge-shaped areas at each of the four corners that are made of only the resin layer and no paperboard, and the adjacent side panels can be sealed together at these parts to create a three-dimensional side wall, forming a roughly rectangular tray-type paper container. This sealing can be done, for example, by heat sealing.

In the blank,
At least one pair of opposing sides of the boundary between the bottom surface and the side panel of the approximately rectangular bottom surface is a curved line protruding outward,
Similarly, at least one pair of opposing sides of the boundary between the top side of the side panel and the flange are also curved outward,
Similarly, at least one pair of opposing edges of the periphery of the blank are also curved outwardly,
The curve of the outer periphery of the blank bulges by 0.7 mm to 1.0 mm at the center of its longitudinal side, so that a paper container made from this blank can be formed into a stable shape, has no sharp corners, and is a container with an arc-shaped form that is gentle on the hand.

In addition to the curved side panels, the flanges of the paper container are curled, meaning that the paper container has no sharp corners and an arc-shaped form that is gentle on the hands.

Further, according to the present invention,
It is possible to provide a paper container with a top curl that has: - Dimensional stability of the top curl flange - No cracks or wrinkles in the top curl flange - Stable sealing with the lid material - Excellent suitability for curling molding.

In particular, according to the invention described in claim 2, the resin layer formed on the blank is made of one or more of polyethylene resin, polypropylene resin, polyethylene terephthalate resin, polybutylene terephthalate resin, and polymethylpentene resin, so that the blank has sealing suitability, particularly heat sealing suitability, and is also effective in improving the water resistance of the paper container.

It is particularly effective in improving productivity when assembling paper containers by heat sealing, and is also effective in making sealing with a lid easy and stable.

FIG. 1 is a schematic plan view illustrating a blank constituting one embodiment of a paper container with a top curl according to the present invention. FIG. 2 is a schematic partial cross-sectional view for explaining the top curl portion of a top curled paper container according to the present invention. FIG. 3 is a schematic perspective view for explaining one embodiment of a paper container with a top curl according to the present invention. FIG. 4 is a schematic perspective view illustrating how a lid is sealed and then opened in one embodiment of a paper container with a top curl according to the present invention.

The present invention will be described in more detail below with reference to Figures 1 to 4. However, the present invention is not limited to the examples shown here. The present invention is defined by the claims.

Figure 1 is a schematic plan view illustrating a blank that constitutes one embodiment of a paper container with a top curl according to the present invention.

The present invention is a paper container with a top curl, which is made of a blank (5) made of paperboard with a resin layer formed on at least one side.

The blank (5) is roughly rectangular, with no paperboard at the four corners, and has eight wedge-shaped areas (4) made of only the resin layer, two at each corner.

Due to the presence of this wedge-shaped region (4) of only the resin layer, the blank (5) can be assembled into a three-dimensional paper container by connecting the side panels (2) on both sides and standing it up from the bottom surface (1). The connection between the side panels (2) on both sides can be done, for example, by sealing, particularly by heat sealing.

The paper container is composed of a bottom surface (1), side panels (2), and a flange (3). The bottom surface (1) is roughly rectangular with four corners, and the side panels (2) rise up and surround the bottom surface (1), forming the sides of the paper container.

The flange (3) is continuous with the upper end of the side panel (2) and surrounds the periphery of the paper container, and the present invention is characterized in that the flange (3) is curled. In this case, curling is a process in which the flange (3) is curled by rolling in the edge portion through a process such as pressing.

This curling technique allows the shape of the top of the paper container to be curved, making it possible to achieve a design that is also pleasing. For example, in the case of a tray-shaped paper container, the opening can be rounded rather than rectangular, with no sharp corners, making it an arc-shaped opening that is gentle on the hands, and it is also possible to create a paper container with a flange that provides a stable, airtight seal.

Therefore, with the growing demand for universal design of food containers and other items, this product can meet that demand.

The curled flange (3) can be sealed with a paper container using a lid material with a resin layer that acts as a sealant. Sealing with the lid material and the resulting sealing of the paper container will be described later.

The paper container with a top curl according to the present invention is characterized in that at least one pair of opposing sides (10) of the boundary between the bottom surface (1) and the side panel (2) of the approximately rectangular bottom surface (1) of the blank (5) is curved outwardly. The bulge of this curve is shown as bulge (b) in Figure 1.

Similarly, at least one pair of opposing edges (11) at the boundary between the top side of the side panel (2) of the paper container and the flange (3) are also curved outward.

Similarly, at least one pair of opposing edges (12) on the outer periphery of the flange (3) are also characterized by outwardly protruding curves.

The curve of the outer periphery of the flange (3) is characterized by a bulge of 0.7 mm to 1.0 mm at the center of the longitudinal side. This bulge of the curve is shown as bulge (c) in Figure 1.

Figure 2 is a schematic partial cross-sectional view to explain the top curl portion of a paper container with a top curl according to the present invention.

As mentioned above, the flange (3) is continuous with the upper end of the side panel (2) and surrounds the periphery of the paper container, and the present invention is characterized in that the flange (3) is curled. In this case, curling is a process in which the flange (3) is curled by rolling in the edge portion through a process such as pressing.

The cross section of the curl of the curled flange (3) is initially cylindrical, but it can be made flatter by applying force from above and below in the direction of the arrows in Figure 2.

By having a resin layer (7) on the surface of the blank (5), it is possible to provide sealing properties with the lid material. The resin layer (7) is provided on at least one side of the blank (5).

The flange (3) can be sealed by overlapping the resin layers of the flange (3) and the lid material so that they face each other, and then fusing them together by heat sealing using heat and pressure, for example, to hermetically seal the paper container.

In the present invention, the resin layer formed on the blank can be one or more of polyethylene-based resin, polypropylene-based resin, polyethylene terephthalate-based resin, polybutylene terephthalate-based resin, and polymethylpentene-based resin.

The use of these resins is effective in improving sealing properties and seal strength.

Figure 3 is a schematic perspective view illustrating one embodiment of a paper container with a top curl according to the present invention.

The blank (5) shown in Figure 1 can be used to make a paper container (10) with a top curl as shown in Figure 3.

As shown in FIG. 3, the paper container with a curled top (10) according to the present invention can be a paper container (10) that has no sharp corners and has an arc-shaped form that is gentle on the hands.

Furthermore, since the flange (3) with a top curl surrounds the periphery of the top of the paper container (10), the lid material having a sealant can be sealed to hermetically seal the paper container (10) with a top curl.

In addition, this paper container (10) has a resin layer (7) on at least one side of the blank (5), which allows the blank (5) to be assembled into a three-dimensional paper container (10), and when the resin layer (7) is provided on the inside of the paper container (10), it is possible to impart water resistance to the paper container (10).

Figure 4 is a schematic perspective view illustrating how the lid is sealed and then opened in one embodiment of a paper container with a top curl according to the present invention.

As described above, the paper container (10) can be hermetically sealed by sealing the lid material (6) to the flange (3) of the paper container (10).

As shown in FIG. 4, the sealed paper container (10) can be opened by pulling and peeling off the seal between the flange (3) and the lid material (6) in the direction of the arrow.

In the present invention, the resin layer (7) formed on the blank (5) can be one or more of polyethylene-based resin, polypropylene-based resin, polyethylene terephthalate-based resin, polybutylene terephthalate-based resin, and polymethylpentene-based resin.

These resins are thermoplastic resins and have excellent heat sealing and other sealing properties as sealants, and also have a certain level of sealing strength, making it possible for the sealed paper container (10) to have resistance to external forces, for example.

Specific examples of polyethylene-based resins and polypropylene-based resins that can be used include ethylene-based resins such as low-density polyethylene resin (LDPE), medium-density polyethylene resin (MDPE), linear low-density polyethylene resin (LLDPE), ethylene-vinyl acetate copolymer (EVA), ethylene-α-olefin copolymer, and ethylene-methacrylic acid resin copolymer.

In addition, blend resins of polyethylene and polybutene, and polypropylene-based resins such as homopolypropylene resin (PP), propylene-ethylene random copolymer, propylene-ethylene block copolymer, and propylene-α-olefin copolymer can be used.

To form a thermoplastic resin layer, a film of molten resin can be formed using an extruder or the like, and the layer can be formed on the paper substrate. Alternatively, a material that has already been formed into a film can be laminated to form a layer on the surface of the paper substrate.

In this way, the present invention makes it possible to provide a paper container (10) with a curled top that is microwave-safe, has a curved surface, and is equipped with a sealable flange.

The present invention will be explained in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the examples shown here. The present invention is defined by the claims.

Blanks of different dimensions were prepared to create paper containers with a top curl, and the paper containers were evaluated.

The evaluation items are as follows:
- Dimensional stability of the top curl flange - No cracks or wrinkles in the top curl flange - Sealing stability with the lid material - Suitability for curling molding.

The evaluation was made on a three-level scale of ◯, △, and ×, and a rating of ◯ for all evaluation items was judged to be a pass.
Moreover, any item evaluated as △ or × was determined as a failure.

The shape and dimensions of the blank shall be as shown in Figure 1, and the symbols shall conform to this.

That is, at least one pair of opposing edges (10) at the boundary between the bottom surface (1) and the side panel (2) is a curved line protruding outward, and the bulge of this curve is shown as bulge (b) in FIG.
The bulge of the curve on the outer periphery of the flange (3) is shown as bulge (c) in FIG.

Example 1
b = 5 mm and c = 0.7 mm.
In the present invention, in the blank, at least one pair of opposing sides of the boundary between the bottom surface and the side panel of the approximately rectangular bottom surface is a curved line protruding outward,
Similarly, at least one pair of opposing sides of the boundary between the top side of the side panel and the flange are also curved outward,
Similarly, at least one pair of opposing edges of the periphery of the blank are also curved outwardly,
The blank outer periphery curve has a bulge of 0.7 mm to 1.0 mm at the center of the longitudinal side.
In this example, both b and c are within the range defined by the present invention.

Example 2
b = 7 mm and c = 0.7 mm.
In this example, both b and c are within the range defined by the present invention.

Example 3
b = 9 mm and c = 0.7 mm.
In this example, both b and c are within the range defined by the present invention.

Example 4
b = 5 mm and c = 1.0 mm.
In this example, both b and c are within the range defined by the present invention.

Example 5
b = 7 mm and c = 1.0 mm.
In this example, both b and c are within the range defined by the present invention.

Example 6
b = 9 mm and c = 1.0 mm.
In this example, both b and c are within the range defined by the present invention.

<Comparative Example 1>
b = 0 mm and c = 0 mm.
In the present invention, in the blank, at least one pair of opposing sides of the boundary between the bottom surface and the side panel of the approximately rectangular bottom surface is a curved line protruding outward,
Similarly, at least one pair of opposing sides of the boundary between the top side of the side panel and the flange are also curved outward,
Similarly, at least one pair of opposing edges of the periphery of the blank are also curved outwardly,
The blank outer periphery curve has a bulge of 0.7 mm to 1.0 mm at the center of the longitudinal side.
In this example, both b and c deviate from the scope of the present invention.

<Comparative Example 2>
b = 5 mm and c = 0 mm.
In this example, c deviates from what is defined in the present invention.

<Comparative Example 3>
b = 7 mm and c = 0 mm.
In this example, c deviates from what is defined in the present invention.

<Comparative Example 4>
b = 9 mm and c = 0 mm.
In this example, c deviates from what is defined in the present invention.

<Comparative Example 5>
The dimensions were set as follows: b = 0 mm and c = 0.7 mm.
In this example, b deviates from what is defined in the present invention.

<Comparative Example 6>
b = 0 mm and c = 1.0 mm.
In this example, b deviates from what is defined in the present invention.

<Comparative Example 7>
b = 9 mm and c = 1.2 mm.
In this example, c deviates from what is defined in the present invention.

The evaluation results are shown in Table 1.

As is clear from the results shown in Table 1, the paper containers with top curl according to the present invention in Examples 1 to 6 received a passing rating in all evaluation items. This directly indicates that the present invention is effective in achieving the objectives and evaluation items of the present invention.

In contrast, Comparative Examples 1 to 7, which deviate from the scope of the present invention, were evaluated as △ or lower in all or some of the evaluation items. Therefore, all of the Comparative Examples were judged to be unsatisfactory. This indirectly indicates that the present invention is effective in achieving the objectives and evaluation items of the present invention.

In this way, it was verified that the present invention can provide a paper container with a curled top that is microwave-safe, has a curved surface, and is equipped with a sealable flange.

1: bottom surface 2: side panel 3: flange 4: wedge-shaped area of resin layer only 5: blank 6: lid material 7: resin layer 10: paper container

Claims (2)

A paper container comprising a blank made of paperboard having a resin layer formed on at least one side thereof,
A paper container consists of a bottom, side panels, and a flange.
The bottom surface is a substantially octagon having a rectangular shape and has four corners.
The side panels surround the bottom and form the sides of the paper container.
The flange is continuous with the upper end of the side plate and surrounds the periphery of the paper container.
Around each of the four corners, there are provided eight wedge-shaped regions, each of which is made of only the resin layer and has no paperboard, in two locations each ;
Among the periphery of the bottom surface, a pair of sides corresponding to the long sides of the approximate rectangular shape are curved outwardly,
The boundary between the side panel connected to the set of edges and the flange connected to the side panel, and the portion of the outer periphery of the blank formed by the flange, are curved outwardly,
The blank has a curved outer periphery that bulges 0.7 mm to 1.0 mm at the center of the longitudinal side and is smaller than the bulge of the curved periphery of the bottom surface;
A paper container with a top curl, characterized in that the flange of the paper container is curled. The paper container with a curled top according to claim 1, characterized in that the resin layer formed on the blank is made of one or more of polyethylene-based resin, polypropylene-based resin, polyethylene terephthalate-based resin, polybutylene terephthalate-based resin, and polymethylpentene-based resin.