WO2022085089A1 - Manufacturing method for frozen food packaging container - Google Patents

Abstract

The present invention provides a manufacturing method for a frozen food packaging container in which both airtight sealability and ease of opening a lid member are achieved. This manufacturing method for a frozen food packaging container including a container and a lid member comprises a sealing step in which the container and the lid member are joined by heating. At the sealing step, heat-sealing is performed multiple times at predetermined positions in the same pattern over the entire periphery of the outer edge portion of the container, whereby the container and the lid member are joined by heating.

Description

Manufacturing method of packaging container for frozen food

The present invention relates to a method for manufacturing a packaged container for frozen foods having a container and a lid material, and more particularly to a method for manufacturing a packaged container for frozen foods, which achieves both sealability and openability of the lid material.

Currently, a packaging container having a container for storing various foods or beverages and a lid material for sealing the container so as to block the outside air is used. The container is made of plastic or the like, and has various shapes such as a cup shape or a tray shape.
In the packaging container, for example, after storing food or the like in the container, the container is covered with a lid material, and the container and the lid material are heat-sealed and sealed. Various methods for manufacturing packaging containers have been proposed.

The method for sealing a container in Patent Document 1 is a method for sealing a container in which a lid material is heat-bonded to a ring-shaped flange portion of a container body to seal the container. While it is composed of a sealing step in which at least two sealing portions are overlapped by a sealing head provided with a convex portion, at least one sealing step of these at least two sealing steps is performed on the inner and outer peripheral edges of the annular convex portion. It consists of a sealing process using a sealing head equipped with a part. In Patent Document 1, in order to facilitate the opening of the lid material, a portion that is not heat-sealed at all is formed at the corner portion of the outer peripheral edge portion of the flange portion, and the opening can be started from this portion.

In Patent Document 2, when the lid is heat-sealed on the upper end surface of the mouth edge portion of the molded container, the lid is placed on the upper end surface, and the entire circumference of the outer peripheral edge of the lid is formed from the upper surface of the lid along the upper end surface portion. A partial lid double sealing method is described in which heat seals at a relatively low temperature and then heat seals a part of the outer peripheral edge of the lid again at a temperature higher than the temperature at the time of the first heat seal.

Japanese Patent No. 4135334 Special Fair 7-098530 Gazette

As a packaging container, in the distribution process, storage process, sales process, etc., the lid material does not peel off and the contents do not leak to the outside of the container, and high sealing performance is required to improve the storage stability of the contents. There is. On the other hand, for the convenience of taking out the stored food or the like, the lid material is required to have an openability that can be easily peeled off.
When the contents of the packaging container are frozen foods, in a low temperature environment of -18 ° C or less, after storing the frozen foods in the container, seal the lid material and the container, and then again in a low temperature environment of -18 ° C or less. It will be saved. In addition, the low temperature environment is maintained even in the distribution process, and each packaging container is heated by a microwave oven.
As described above, in the case of frozen food, the temperature changes greatly because the frozen food is heated using a microwave oven from a low temperature state of -18 ° C or lower. Packaging containers for frozen foods are required to have a sealing property that can withstand low temperature conditions and large temperature changes.

However, as described above, in Patent Document 1, in order to facilitate the opening of the lid material, a portion that is not heat-sealed at all is formed at the corner of the outer peripheral edge portion of the flange portion, and the opening of the lid material can be started from this portion. It is done like this. From this, there is a possibility that the sealing property with a low temperature state and a large temperature change is not sufficient.
Further, Patent Document 2 partially seals twice, and there is a portion where the seal is once. In one seal, if foreign matter is mixed in the seal portion or air bubbles are generated in the seal portion, there is a possibility that the sealing property with a low temperature state and a large temperature change is not sufficient. As described above, at present, there is no packaging container for frozen foods that achieves both sealability and openability of the lid material.

An object of the present invention is to provide a method for manufacturing a packaging container for frozen foods, which achieves both sealability and openability of a lid material.

In order to achieve the above object, one aspect of the present invention is a method for manufacturing a packaged container for frozen foods having a container and a lid material, which comprises a sealing step of heat-bonding the container and the lid material. In the sealing process, a method for manufacturing a packaged container for frozen foods, in which the container and the lid material are heat-bonded by performing heat sealing multiple times at predetermined positions in the same pattern over the entire circumference of the outer edge of the container. Is to provide.

The container has an opening and has a flange overhanging on the opposite side of the opening along the outer edge of the opening, and the sealing process preferably heat-bonds the lid to the flange of the container. ..
In the sealing step, it is preferable to carry out heat bonding twice.
It is preferable that a continuous linear sealing portion is formed on the entire circumference of the outer edge portion of the container by the sealing step.
A heater is used in the sealing step, and the heater preferably has a curved surface in contact with the lid material, and the radius of the curved surface is smaller than the width of the sealing portion formed in the sealing step.
The sealing portion preferably has a protruding portion that protrudes outward at the outer edge portion.

According to the present invention, a packaging container for frozen foods can be obtained in which both the sealing property and the opening property of the lid material are compatible.

It is a graph explaining the openability of the lid material of the packaging container for frozen foods of this invention. It is a graph which shows the seal strength which shows the sealing property at each position of the packaging container for frozen foods of this invention. It is a schematic diagram which shows the position which measured the seal strength which shows the sealing property of the package container for frozen foods of this invention. It is a schematic perspective view which shows an example of the manufacturing method of the packaging container for frozen foods of embodiment of this invention. It is a schematic perspective view which shows an example of the packaging container for frozen foods of embodiment of this invention. It is a schematic diagram which enlarges and shows a part of an example of the seal part of the packaging container for frozen foods of embodiment of this invention. It is a schematic diagram explaining an example of the manufacturing method of the packaging container for frozen foods of embodiment of this invention. It is a schematic enlarged view explaining an example of the manufacturing method of the packaging container for frozen foods of embodiment of this invention. It is a schematic perspective view which shows the other example of the container of the packaging container for frozen foods of embodiment of this invention. It is a graph which shows the seal strength which shows the sealing property at each position of the package container for frozen foods of Example 1. FIG.

Hereinafter, the method for producing the packaged container for frozen foods of the present invention will be described in detail based on the preferred embodiment shown in the attached drawings.
Hereinafter, an example of the method for producing a packaged container for frozen foods of the present invention will be described, but the figures described below are exemplary for explaining the present invention, and the present invention is limited to the figures shown below. It is not something that will be done.

As described above, a packaging container for frozen foods is desired, which has both a sealing property and an opening property of a lid material. Regarding the packaging container for frozen foods manufactured by heat-bonding the container and the lid material, the openability of the lid material, that is, whether the lid material can be opened with a small force was examined. Specifically, the openability of the lid material was evaluated when the number of heat seals was one and when the number of heat seals was two. The fact that the heat seal is performed twice means that the heat seal is performed twice at the same position (predetermined position) in the same pattern.
Here, FIG. 1 is a graph illustrating the openability of the lid material of the packaging container for frozen foods of the present invention.
As shown in FIG. 1, when the heat seal is performed once (see reference numeral α), the seal strength increases when the temperature of the heat seal is high up to 190 ° C. On the other hand, when the heat seal is performed twice (see reference numeral β), the seal temperature of the heat seal is 160 ° C. or higher, and the seal strength becomes substantially constant. The seal strength is the seal strength at the outwardly protruding portion 11a (see FIG. 3), which will be described later.
As described above, it was found that the sealing strength does not increase above a certain temperature when the sealing temperature is higher than a certain temperature by setting the number of heat sealings a plurality of times at the time of heat bonding. That is, it was found that by setting the number of heat seals to a plurality of times, the force required to open the lid material can be reduced even if the heat seal seal temperature is high.

In the measurement of the seal strength shown in FIG. 1, a polypropylene container was used as the container. The size of the container was 151 mm × 205.5 mm × 42.0 mm (height). A laminated film of nylon / nylon / polyethylene / sealant layer was used as the lid material.
For the heat seal, a heater having a width of 5 mm and a tip radius of 4 mm was used. The sealing time was 0.9 seconds. Further, at the time of heat sealing, the pressing force of the seal bar was set to 250 kgf (2.45 kN). The second heat seal was performed before the temperature of the container and the lid material by the first heat seal returned to room temperature.
The seal strength indicating openability is the strength when the lid material is peeled off from the outside of the container, and was measured based on JIS S0021-2: 2018 (packaging-accessible design-openability).

Regarding the packaging container for frozen foods produced by heat-bonding the container and the lid material, the sealing property, that is, the force required to peel the lid material from the inside of the container was examined. Specifically, the sealing strength indicating the sealing property at each position of the packaged container for frozen food was evaluated when the number of heat seals was 1 and when the heat seal was 2 times.
FIG. 2 is a graph showing the sealing strength indicating the sealing property of the frozen food packaging container of the present invention at each position, and FIG. 3 is a position where the sealing strength indicating the sealing property of the frozen food packaging container of the present invention is measured. It is a schematic diagram which shows.
As shown in FIG. 2, it has been found that at each position A to D of the packaged container for frozen food, the sealing temperature is 160 ° C. or higher, and the sealing strength indicating the sealing property of the container becomes substantially constant. Moreover, the sealing strength is sufficient to maintain the sealing property of the container. As a result, the storage stability of the frozen food stored in the container is ensured.
As described above, by performing the heat sealing a plurality of times at the time of heat joining, it is possible to achieve both the sealing property and the opening property of the lid material in the package container for frozen foods.

The seal portion 11 is shown in FIG. The seal portion 11 is a continuous linear trace formed by heat bonding. As shown in FIG. 3, the package container 10 for frozen food has a rectangular shape in a plan view. Position A is the long side portion 10a of the frozen food packaging container 10, and position B is the short side portion 10b of the frozen food packaging container 10. The position C is the corner portion 10c of the package container 10 for frozen foods. The position D is a diagonal corner portion 10d of the position C of the frozen food packaging container 10, and the seal portion 11 has a protruding portion 11a protruding outward.
The sealing strength indicating the sealing property is the strength when the lid material is peeled off from the inside of the container at each position A to D, and was measured based on JIS Z 0238: 1998.
Hereinafter, a method for manufacturing a packaged container for frozen foods and a packaged container for frozen foods will be specifically described.

(Packaging container for frozen foods)
FIG. 4 is a schematic perspective view showing an example of a method for manufacturing a packaged container for frozen food according to the embodiment of the present invention, and FIG. 5 is a schematic perspective view showing an example of the packaged container for frozen food according to the embodiment of the present invention. Is. FIG. 6 is a schematic view showing an enlarged part of an example of a sealed portion of a packaged container for frozen foods according to an embodiment of the present invention. In FIGS. 4 to 6, the same components shown in FIGS. 3 are designated by the same reference numerals, and detailed description thereof will be omitted.
The packaged container 10 for frozen foods shown in FIG. 4 has a container 12 and a lid material 14.
The container 12 has a bottom surface portion 20b and a side surface portion 20c continuously provided on the peripheral edge of the bottom surface portion 20b. In the container 12, the side surface portion 20c forms an opening portion 20a facing the bottom surface portion 20b. For example, the side surface portion 20c is composed of a slope. The side surface portion 20c extends from the bottom surface portion 20b toward the opening portion 20a, and the opening portion 20a has a larger area than the bottom surface portion 20b. The side surface portion 20c is not limited to being composed of a slope, and may be composed of a surface perpendicular to the bottom surface portion 20b. The container body 20 is composed of the bottom surface portion 20b and the side surface portion 20c. A space is formed by the bottom surface portion 20b and the side surface portion 20c, and this space is the storage portion 20e. That is, the internal space of the container body 20 is the storage portion 20e.

The container 12 has an opening 20a and has a flange portion 22 overhanging on the opposite side of the opening 20a along the outer edge of the opening 20a. The container body 20 and the flange portion 22 are integrated. The flange portion 22 is, for example, a flat plate, and the surface 22a is a flat surface. The lid material 14 is joined to the flange portion 22. The outer edge of the opening 20a of the container 12 is the same as the outer edge 20d of the container 12.
The contents 16 are stored in the storage portion 20e of the container 12. The content 16 is a frozen food. As the frozen food, it is preferable that the frozen food packaging container 10 is heated by a microwave oven. The frozen food may remain solid after heating, may be liquid, or may be a mixture of solid and liquid. The frozen food is not particularly limited, and examples thereof include noodles such as udon, buckwheat, and pasta, hamburger steak, shumai, and soup. Further, the frozen food may be not only packaged for each meal, but may be, for example, packaged only for prepared foods or packaged for a plurality of meals at the same time.

The lid material 14 closes the opening 20a of the container 12, shields the inside of the container 12 from the outside air, and seals the container 12. The lid material 14 is composed of, for example, a film-shaped member.
In the frozen food packaging container 10, for example, when the frozen food is heated by a microwave oven, the lid material 14 is opened to a predetermined position in order to discharge the steam generated by the heating from the container 12, and the de-steaming port is opened. May be formed.

(Manufacturing method of packaging containers for frozen foods)
In the method for manufacturing a packaged container for frozen foods, the contents 16 are stored in the storage portion 20e of the container 12 through the opening 20a of the container 12.
Next, the lid material 14 is positioned and covered with respect to the flange portion 22 from above the opening 20a of the container 12.
The front surface 22a of the flange portion 22 and the back surface 14b of the lid material 14 are in contact with each other.
Next, a sealing step of heat-bonding the container 12 and the lid material 14 is carried out.

In the sealing step, heat sealing is performed a plurality of times at predetermined positions over the entire circumference of the outer edge portion 20d of the container 12, and the container 12 and the lid material 14 are heat-bonded. As a result, it is possible to obtain a packaging container for frozen foods that has both sealability and openability of the lid material.
Performing heat sealing multiple times at a predetermined position means performing heat sealing at the same position (predetermined position) with the same pattern at each heat sealing, and is formed by each heat sealing. It means that the seal marks to be made match. Matching the seal marks includes a positional error during heat sealing, and includes other than perfect matching of the seal marks.
By the sealing step, as shown in FIG. 5, one continuous linear sealing portion 11 is formed on the entire circumference of the outer edge portion 20d of the container 12. In the sealing step, for example, in the flange portion 22, the lid material 14 is heat-bonded to the surface 22a which is a flat surface of the flange portion 22.

As shown in FIG. 6, the sealing portion 11 preferably has a protruding portion 11a protruding toward the outside of the container 12. By providing the protruding portion 11a, a force for opening the lid material 14 is easily applied to the tip of the protruding portion 11a at the time of opening. Therefore, when the lid material 14 is opened, the lid material 14 can be opened with a smaller force. Even when the projecting portion 11a is provided, the sealing property of the lid material 14 is maintained.
The protruding portion 11a is not particularly limited as long as it has a shape that protrudes toward the outside of the container 12. For example, the protruding portion 11a can be V-shaped, U-shaped, or W-shaped so as to protrude toward the outside of the container 12.

<Seal process>
As described above, heat sealing is used in the sealing process. A known method can be used for heat sealing. For the heat seal, for example, a heater is used.
Here, FIG. 7 is a schematic diagram illustrating an example of a method for manufacturing a packaged container for frozen foods according to the embodiment of the present invention, and FIG. 8 is an example of a method for manufacturing a packaged container for frozen foods according to the embodiment of the present invention. It is a schematic enlarged view to explain. In FIGS. 7 and 8, the same components shown in FIGS. 4 to 6 are designated by the same reference numerals, and detailed description thereof will be omitted.
The sealing step is carried out, for example, by using the seal bar 30 and the receiving member 34, as shown in FIG. The seal bar 30 is provided with a heater 32 that forms the seal portion 11 including the protrusion 11a shown in FIG. The heater 32 has a curved surface 32a, and the curved surface 32a is in contact with the lid member 14. Further, the heater 32 has the same pattern shape as the shape of the seal portion 11 shown in FIG. 5 in a plan view. With this configuration, if the heater 32 is pressed against the lid material 14 at a predetermined position, the heater 32 is heat-sealed at the same position in the same pattern, and even if the heat-sealing is performed a plurality of times, one sealing portion 11 is provided. It is formed. The plan view is to view the lid material 14 from a direction perpendicular to the surface 14a.
The receiving member 34 is a flat plate-shaped member and has an opening 34a into which the container body 20 of the container 12 is fitted. When the container 12 is fitted into the opening 34a of the receiving member 34, the receiving member 34 supports the back surface 22b of the flange portion 22.
For example, in the sealing step, the container 12 is fitted into the opening 34a of the receiving member 34, and the back surface 22b of the flange portion 22 is supported by the receiving member 34.

Next, the back surface 14b of the lid material 14 is brought into contact with the front surface 22a of the flange portion 22. In this state, the curved surface 32a of the heater 32 held at the sealing temperature is pressed against a predetermined position on the surface 14a of the lid material 14 to perform heat sealing. After a lapse of a predetermined time, the curved surface 32a of the heater 32 is separated from the lid material 14.
Next, the curved surface 32a of the heater 32 held at the sealing temperature is pressed again at a predetermined position on the surface 14a of the lid material 14 to perform heat sealing. As a result, as shown in FIG. 5, the seal portion 11 is formed on the entire circumference of the outer edge portion 20d of the container 12.

As described above, in the sealing process, heat sealing is performed a plurality of times at predetermined positions, but all heat sealing is performed by pressing the heater 32 to the same position and having the same shape of the heater. .. The multiple heat seals may be performed at the same position without changing the position of the container, or may be performed at different positions of the container. That is, the heat seal may be performed a plurality of times with the container 12 fitted in one receiving member 34. A plurality of receiving members 34 may be prepared, and the receiving member 34 may be changed for each heat seal. Heat sealing may be performed.
Further, as described above, in the sealing process, the heat sealing is performed a plurality of times at predetermined positions to maintain the sealing property of the content 16, and the distribution process and storage process of the frozen food packaging container 10 are performed. In addition, damage such as peeling of the lid material during the sales process can be suppressed. In addition, when the lid material 14 is peeled off, it can be peeled off with a small force.

In the sealing process, the upper limit of heat sealing performed multiple times is not particularly limited. However, if the number of heat seals is large, the sealing process takes time, so it is preferable that the number of heat seals is small. Therefore, it is preferable to carry out the heat seal twice. If the heat seal is performed twice, the sealing property of the lid material 14 can be maintained and the opening property of the lid material 14 can be compatible, and the lid material 14 can be peeled off with a small force.

In the sealing process, a heater 32 having a curved surface 32a is used, and by pressing the curved surface 32a against the surface 14a of the lid material 14 at the time of heat sealing, the lowermost end of the curved surface 32a first contacts and then the lowermost end. The surroundings are pressed. Therefore, even if there is a contaminated material between the lid material 14 and the flange portion 22, the contaminated material can be pushed out to the surroundings so that the lid material 14 and the flange portion 22 are brought into close contact with each other for sealing. .. For this reason, the heater 32 preferably has a curved surface 32a. It is desirable that the diameter of the curved surface 32a of the heater 32 is larger than the width of the heater 32 and smaller than three times the width of the heater 32.
The width th of the heater 32 (see FIG. 8) is preferably 3 to 10 mm. When the width of the heater 32 is 3 to 10 mm, the sealing strength is sufficient, the sealing strength does not become too high, and the opening property does not deteriorate. Further, even if there is a contaminated material between the lid material 14 and the flange portion 22, the contaminated material can be pushed out to the surroundings.
Further, as shown in FIG. 8, the radius r of the curved surface 32a of the heater 32 may be smaller than the width d of the seal portion 11. This makes it possible to suppress variations in the heat seal.
The seal width of the seal portion is determined by the width of the heater 32, the radius of the curved surface of the heater, the width of the flange portion 22, and the like, and is about 3 to 10 mm.
In the sealing process, heat sealing is performed a plurality of times, and each heat sealing is performed, for example, at the same sealing temperature. The same sealing temperature means that the set temperature at the time of heat sealing is the same, and includes a temperature error of a device such as a heater.

(container)
The container 12 stores the contents 16 as described above. Further, the container 12 can also serve as tableware. That is, the package container 10 for frozen food may be heated in a microwave oven and then used as tableware with the lid material 14 removed.
<Container shape>
The shape of the container 12 is not particularly limited, and is appropriately determined according to the shape of the content 16 and the shape after thawing, and even those having a design that can be used as tableware as described above. good. The size of the container 12 is appropriately determined depending on the type, amount, and the like of the contents 16 to be accommodated.
The container body 20 of the container 12 is, for example, cup-shaped or tray-shaped. The shape of the opening 20a is also not particularly limited, and examples thereof include a square shape, a rectangular shape, a circular shape, and an elliptical shape in a plan view. The shape of the outer edge of the flange portion 22 may be similar to the shape of the opening portion 20a. Further, depending on the design or the like, the shape of the outer edge of the flange portion may be different from the shape of the opening 20a.

Here, FIG. 9 is a schematic perspective view showing another example of the container of the packaging container for frozen foods according to the embodiment of the present invention. In the container 12 shown in FIG. 9, the same components as the container 12 shown in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.
In the container 12, the number of the container main body 20 is not limited to one shown in FIG. 4, and may be a plurality. As the container 12, for example, the outer edges of the flange portions 22 of the container body 20 shown in FIG. 4 may be connected to each other to have a plurality of container bodies 20. Further, as in the container 12a shown in FIG. 9, there may be a configuration in which four container main bodies 20 are provided. In the container 12a, a sealing portion 11 (see FIG. 5) is formed on the surface 22a of the flange portion 22 so as to surround the periphery of the opening 20a.

Further, the plurality of container main bodies 20 is not limited to the four shown in FIG. 9, and if the number of container main bodies 20 is 2 or more, the number can be set according to the application or the like.
When there are a plurality of container bodies 20 in the container 12, the sizes of the container bodies 20 may be the same or different depending on the intended use. Further, the size of the opening of the container body 20 may be the same or different depending on the intended use. When there are a plurality of container main bodies 20, the arrangement of the container main bodies 20 is not particularly limited, and for example, they may be arranged side by side.

When there are a plurality of container main bodies 20, the seal portion is formed over the entire circumference of the outer edge portion of the container, and the opening portion of each container main body 20 is formed in addition to the outer edge portion of the container, for example, as described above. A seal portion may be formed around the circumference of 20a. Further, even when there are a plurality of container main bodies 20, a seal portion may be formed only on the outer edge portion of the container without forming a seal portion around each of the openings 20a of the plurality of container main bodies 20. The sealing portion may have a protruding portion 11a (see FIG. 5). The protrusions 11a may be provided for each container body 20, and one protrusion 11a may be provided for each container 12, and the number of protrusions 11a is not particularly limited.
Further, when there are a plurality of container main bodies 20, each container main body 20 may be configured to be separable from each other by providing a cut-off portion (not shown) at the boundary portion 25 (see FIG. 9) of each container main body 20, for example. .. The cut-off portion is formed, for example, at the boundary portion of each container body 20 by perforation processing for intermittent cutting.

<Material of container>
As the material constituting the container, a plastic material having a heat-sealing property, which is usually used for manufacturing a packaging container, can be used.
Examples of the heat-sealing plastic material include known low-density polyethylene, linear low-density polyethylene, medium-density polyethylene, high-density polyethylene, polypropylene, propylene-ethylene copolymer, and ethylene-vinyl acetate copolymer. Examples thereof include olefin resins such as olefin resins graft-modified with polyethylene-based unsaturated carboxylic acids or their anhydrides; polyamides or copolyamide resins having a relatively low melting point or low softening point; polyester to copolyester resins; polycarbonate resins.

Further, the member used for the container 12 is preferably a member having high water resistance and high flexibility. Further, it is more preferable that microwaves are easily transmitted because heating by a microwave oven can be efficiently performed. Further, it is more preferable that the material is made of a material having a low thermal conductivity because it is suppressed that the temperature becomes too high when the packaging container is taken out from the microwave oven after heating. Examples of the member satisfying the above conditions include polypropylene-based resin, polyethylene-based resin, mixed resin of polypropylene-based resin and polyethylene-based resin, polyethylene terephthalate resin, polystyrene-based resin, and polylactic acid-based resin.

The container 12 can also be made of a laminated body. A suitable layer structure of the laminated body is, for example, a laminated body of biaxially stretched polypropylene and unstretched polypropylene (CPP) in order from the inside of the container.

(Cover material)
As described above, the lid material 14 shields the inside of the container 12 from the outside air and seals the container 12. The lid material 14 is a film-like member, and is composed of, for example, a heat-sealable film.
The lid material 14 is not particularly limited as long as the portion in contact with the container 12 can be heat-sealed, and even if it is composed of a single member, it is composed of a member having a multi-layered structure. You may. Further, similarly to the container 12, it is more preferable that the lid material 14 easily transmits microwaves because heating by a microwave oven can be efficiently performed.

<Material of lid material>
Examples of the material of the lid material include polyester resin, polyamide resin, polyethylene resin, polyethylene terephthalate resin, polypropylene resin, polystyrene resin, polylactic resin, polyvinyl chloride resin, and polyvinylidene chloride resin. Alternatively, a polycarbonate resin is used.
Further, the lid material may have a laminated structure, and examples thereof include nylon / nylon / polyethylene in order from the surface side (outside) of the lid material. The lid material may be provided with a sealant layer on the back surface side (inside) which is the container side. The sealant layer is composed of, for example, one containing polypropylene.

The present invention is basically configured as described above. Although the method for producing a packaged container for frozen foods of the present invention has been described in detail above, the present invention is not limited to the above-described embodiment, and various improvements or changes have been made without departing from the gist of the present invention. Of course, it is also good.

Hereinafter, the features of the present invention will be described in more detail with reference to examples. The materials, reagents, amounts of substances and their ratios, operations and the like shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following examples.
In this example, the seal strength at each position of the packaging container of Example 1 was measured. The results are shown in FIG.

In Example 1, a container having a laminated structure of biaxially stretched polypropylene and unstretched polypropylene (CPP) was used as the container. A nylon / nylon / polyethylene / sealant layer laminated film (manufactured by Towa Sangyo Co., Ltd.) was used as the lid material.
In Example 1, the size of the container was 151 mm × 205.5 mm × 42.0 mm (height).

(Heat joining conditions)
In Example 1, a heater having a width of 5 mm and a tip radius of 4 mm was used for the heating joint. The number of heat seals was set to 2, the seal time was set to 0.9 seconds, and the pressing force of the seal bar was set to 250 kgf (2.45 kN) during heat seal. In addition, the second heat seal was performed before the temperature of the container and the lid material by the first heat seal returned to room temperature.
The sealing temperature was 140 ° C., 150 ° C., 160 ° C., 170 ° C., 180 ° C., 190 ° C., 195 ° C.
The measurement positions of the seal strength were the positions A to D shown in FIG.
The seal strength was measured based on JIS Z 0238: 1998 (“Test method for heat-sealed flexible packaging bag and semi-rigid container”).

In Example 1 shown in FIG. 10, it was found that the sealing strength became substantially constant and the sealing property was obtained at a sealing temperature of 160 ° C. or higher.
For Example 1, the seal strength indicating openability was measured. The seal strength indicating openability was measured by peeling the lid material from the protruding portion 11a (see FIG. 3) of the seal portion 11 and measuring it based on JIS S0021-2: 2018.
In Example 1, the seal strength was in the range of 15 to 20 N at a seal temperature of 170 ° C. to 190 ° C., and the seal strength was not too high, and good openability results were obtained. From this, in Example 1, both the sealing property and the opening property of the lid material were compatible.

10 Packaging container for frozen foods 10a Long side part 10b Short side part 10c, 10d Square part 11 Seal part 11a Protruding part 12 Container 14 Cover material 14a, 22a Surface 14b, 22b Back side 16 Contents 20 Container body 20a Opening 20b Bottom part 20c Side part 20d Outer edge part 20e Storage part 22 Flange part 25 Boundary part 30 Seal bar 32 Heater 32a Curved surface 34 Receiving member 34a Opening part r Radius

Claims (6)

1. A method for manufacturing a packaging container for frozen foods having a container and a lid material.
   It has a sealing step of heat-bonding the container and the lid material.
   In the sealing step, the container is heat-sealed a plurality of times at predetermined positions in the same pattern over the entire circumference of the outer edge of the container, and the container and the lid material are heat-bonded. Manufacturing method.
2. The container has an opening and has a flange portion overhanging on the opposite side of the opening along the outer edge of the opening.
   The method for manufacturing a packaged container for frozen foods according to claim 1, wherein the sealing step heat-bonds the lid material to the flange portion of the container.
3. The method for manufacturing a packaged container for frozen foods according to claim 1 or 2, wherein the sealing step is performed twice by the heat bonding.
4. The method for manufacturing a packaged container for frozen foods according to any one of claims 1 to 3, wherein a continuous linear sealed portion is formed on the entire circumference of the outer edge portion of the container by the sealing step.
5. A heater is used in the sealing process.
   The frozen food according to any one of claims 1 to 4, wherein the heater has a curved surface in contact with the lid material, and the radius of the curved surface is smaller than the width of the sealing portion formed in the sealing step. Manufacturing method of packaging container.
6. The method for manufacturing a packaged container for frozen foods according to claim 4 or 5, wherein the sealed portion has a protruding portion protruding outward at the outer edge portion.

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