JP6928422B2 - Packaging container, manufacturing method and usage of packaging container - Google Patents

Description

The present invention relates to, for example, a packaging container for foods sold at supermarkets and convenience stores, and more particularly, to a packaging container sealed with a lid material for a top seal having low gas permeability such as oxygen and easy to open. Is.

Conventionally, packaging containers (PSP containers) made by molding polystyrene paper (PSP) into a desired shape have been widely used for foods sold at supermarkets and convenience stores, for example. In the specifications of such packaging containers, attention was paid to the design including the handle on the surface, the oil resistance of the part in contact with food, and the easy recyclability for tray recovery. These properties can be imparted by heat laminating a laminate film on polystyrene paper (PSP). Furthermore, the peel strength between the laminating film and the base material was not emphasized because it was designed to be sealed with a molded lid material or wrap packaging.

On the other hand, an idea of heat-bonding a polypropylene film layer to a expanded polystyrene sheet layer without performing a dry laminating process has been proposed (see, for example, Patent Document 1). Specifically, an adhesive layer is applied to the expanded polystyrene sheet layer with a gravure roll, and the polypropylene film layer is heat-bonded to the expanded polystyrene sheet layer via the adhesive layer.

Japanese Unexamined Patent Publication No. 2006-137044

However, the above-mentioned idea is not configured to prevent the permeation of gas such as oxygen entering the container. That is, gas permeates into the container not only from the outside of the polystyrene foam base material but also from the outside of the molded lid material and wrap packaging. Therefore, the storage period (best-by date) of the food is shortened due to the oxidation by the oxygen gas existing in the container. In addition, in order to extend the storage period (expiration date) of food, attempts have been made to replace the air in the container with a gas other than oxygen (for example, nitrogen gas, carbon dioxide gas, or a mixed gas thereof). Such gas also permeates out of the container and does not have a sufficient storage period (expiration date).

For foods for external sale in recent years, reducing the amount of waste and reducing the profit margin by discounting the selling price have become issues, so it is necessary to extend the expiration date (extend the shelf life) and reduce the cost associated with packaging. Has been done. In view of this point, it is important to review not only the container body but also the lid material.

Here, in the container body, a method of attaching a laminate film having a barrier layer that suppresses gas permeation such as oxygen to a base material made of polystyrene foam is effective. However, the addition of the barrier layer not only increases the thickness of the entire laminated film, but also may reduce the peel strength of the laminated film with respect to the substrate.

Further, the molded lid material is not suitable for a long storage period because not only the manufacturing cost is high but also the airtightness is poor. Further, in the case of wrap packaging, the wrap fee is relatively high in order to cover the entire container to ensure airtightness. Therefore, in order to solve the problem of the conventional lid material, for example, it is preferable to utilize a thin top seal that closes the opening of the container body.

However, assuming vibration during distribution of the product or unexpected drop, it is necessary to bond the top seal with a strength that does not easily peel off. On the other hand, if the peeling strength of the top seal is increased too much, the laminated film adhering to the base material will be peeled off, and the contents such as food will remain wrapped in the top seal and the laminated film (bag shape). There is a risk of inducing a phenomenon of peeling (bagging phenomenon). That is, the top seal does not peel off from between the lid material and the laminated film at the time of opening, but peels off from between the laminated film and the base material.

Therefore, an object of the present invention is to provide a packaging container having a peeling strength of a laminated film that does not increase in thickness and does not hinder the opening of the top seal lid material.

In order to solve the above problems, the packaging container according to the present invention is made of a polystyrene foam, and extends outward from the bottom, the side portion that stands up from the outer periphery of the bottom portion, and the upper end of the side portion. A packaging container for a gas barrier having a base material having a flange portion and a coextruded laminated film having a gas barrier layer laminated on the base material and adhering to a lid material for a top seal . Ri der peel strength 1.5 N / 15 mm or more defined by JISK6854 between said substrate and said co-extruded laminated film, the coextruded multilayer film is from the outside with respect to the substrate, the first thermoplastic The resin layer, the adhesive layer, the gas barrier layer, the adhesive layer, and the second thermoplastic resin layer are laminated in this order, and the second thermoplastic resin layer is made of polypropylene or polyethylene. An adhesive is interposed between the base material and the second thermoplastic resin layer, and the thickness of the flange portion is thinner than the thickness of the bottom portion or the side portion .

Further, it is desirable that the thickness of the coextruded laminated film is 20 μm or more and less than 60 μm.

Another packaging container according to the present invention is made of a polystyrene foam and has a bottom portion, a side portion that stands up from the outer periphery of the bottom portion, and a flange portion that extends outward from the upper end of the side portion. A packaging container for a gas barrier and having a coextruded laminated film laminated on the base material and having a gas barrier layer, which is laminated on the base material and adheres to a lid material for a top seal. The peel strength specified by JISK6854 between the co-extruded laminated films is 1.5 N / 15 mm or more, and the co-extruded laminated film has the first thermoplastic resin layer and the adhesive layer from the outside with respect to the base material. The gas barrier layer, the adhesive layer, and the second thermoplastic resin layer are laminated in this order, and the second thermoplastic resin layer is made of polypropylene or polyethylene, and the base material and the above. An adhesive is interposed between the second thermoplastic resin layer and the coextruded laminated film has a thickness of 30 μm or more and less than 50 μm.

Further, it is desirable that the thickness of the flange portion is thinner than the thickness of the bottom portion or the side portion.

Further, as a method for manufacturing a packaging container described above, a step of heating the raw material sheet before molding of the base material and the coextruded laminated film to obtain a sheet after secondary foaming and the sheet after secondary foaming are used. It is desirable that the inside of the double-sided vacuum forming mold satisfies the following conditions, including a step of obtaining a desired molded sheet by double-sided vacuum forming.
In-mold clearance of the flange part-thickness of the sheet after secondary foaming = 0

Further, as another method for manufacturing the packaging container described above, a step of heating the raw material sheet before molding of the base material and the coextruded laminated film to obtain a sheet after secondary foaming, and a step of obtaining a sheet after secondary foaming, and after secondary foaming. It is desirable that a step of obtaining a desired molded sheet by single-sided vacuum forming in which the sheet is evacuated from the base material side is provided, and the inside of the single-sided vacuum forming mold satisfies the following conditions.
In-mold clearance of the flange part-thickness of the sheet after secondary foaming> 0

Further, as a method of using the packaging container described above, a step of filling the base material with food and a step of attaching the lid material to the flange portion of the base material containing the food via the coextruded laminated film. It is desirable to include a step of adhering the flange portion and the lid material via the coextruded laminated film to seal the base material.

Here, the "gas barrier layer" refers to a layer that suppresses the permeation of gases that affect the quality of food, such as oxygen, nitrogen, carbon dioxide, and water vapor in the air, from the outside of the base material. The "co-extruded laminated film" extrudes two or more resins (for example, a first thermoplastic resin layer, an adhesive resin layer, a gas barrier layer, an adhesive resin layer, and a second thermoplastic resin layer) together from a slit. It means a laminated film produced by the coextrusion method. Hereinafter, a film obtained by applying an adhesive to a "coextruded laminated film" is also simply referred to as a "laminated film".

The "first thermoplastic resin layer" can be heat-bonded to the top seal lid material and has easy-opening property (easy peeling property) as required. For example, polypropylene (PP) or polyethylene (PE). However, not only when these are used alone, but also when a plurality of types are used in combination, polypropylene: polyethylene may be 90:10 to 10:90, and 80:20 to 20:80. It may be 70:30 to 30:70. It is preferable that polystyrene (PS) is not contained, and the content thereof may be, for example, 1% by mass or less.

The "gas barrier layer" is not particularly limited as long as the permeability of a gas such as oxygen gas, water vapor gas, or carbon dioxide gas is low. Specifically, the oxygen permeability according to JIS K 7126 is 1000 ml / m ^{2 with a thickness of 25 μm.} Any resin that is 24 hr · MPa (75% RH at 20 ° C.) or less and can be co-extruded may be used, and examples thereof include ethylene-vinyl alcohol copolymer (EVOH) and polyamide (PA).

The "second thermoplastic resin layer" is to be adhered to a predetermined adhesive to be adhered to the above-mentioned base material made of polystyrene (PS), and for example, polypropylene (PP) or polyethylene (PE) is applicable. The polypropylene: polyethylene may be 90:10 to 10:90, 80:20 to 20:80, 70: It may be 30 to 30:70. It is preferable that polystyrene (PS) is not contained, and the content thereof may be, for example, 1% by mass or less.

The "adhesive resin" is not particularly limited as long as the first thermoplastic resin layer or the second thermoplastic resin layer can be bonded to the gas barrier layer, but may be, for example, an olefin-based adhesive resin.

The "raw sheet" and the "post-secondary foamed sheet" mean the state before molding of the base material to which the coextruded laminated film is adhered, and the "molded sheet" means the state after the secondary foaming. It means the state after molding of the sheet (the above-mentioned base material). The “in-mold clearance” means a space created when the male-side mold and the female-side mold for molding the base material are in mesh with each other.

According to the present invention, when the peel strength defined by JISK6854 between the base material and the coextruded laminated film having the gas barrier layer is 1.5 N / 15 mm or more, the bagging phenomenon is less likely to occur and the package is easy to open (easy to open). It is possible to realize a packaging container that can be sealed with a peelable lid material and has low gas permeability such as oxygen. That is, the peeling strength of the adhesive portion between the base material and the coextruded laminated film is higher than the peel strength of the adhesive portion between the lid material that seals the base material and the coextruded laminated film, so that the bagging phenomenon occurs. The lid material can be easily opened without doing so. Further, by forming a thin film gas barrier layer having a desired gas permeability into a laminated film by a coextrusion method, the coextruded laminated film as a whole is thin, so that a peel strength of 1.5 N / 15 mm or more can be obtained. It can be secured, and it is possible to prevent not only the bagging phenomenon but also the peeling between the layers. Therefore, it is possible to provide a packaging container having a peeling strength of a laminated film that does not increase in thickness and does not easily hinder the opening of the top seal lid material.

Further, as a method of using the packaging container, by adhering a top seal lid material to the flange portion and sealing the inside of the base material, food can be easily packaged in a short time, and wrap packaging or molding is performed. Since the airtightness is higher than when the lid is used, the storage period of food can be extended.

It is a front view of the packaging container. It is a partially enlarged sectional view of a packaging container. It is a figure explaining the molding method of the packaging container. It is a figure which supplements the explanation of the test result of Example 1 and Example 2. It is a figure which supplements the explanation of the test result of Example 3 and Example 4. It is a figure which supplements the explanation of the test result of Example 5 and Example 6. It is a figure which supplements the explanation of the test result of Example 7 and Example 8. It is a conceptual diagram of the method of evaluating the rigidity of a packaging container.

Hereinafter, the structure and manufacturing method of the packaging container according to the embodiment of the present invention will be described with reference to FIGS. 1 to 3. Note that FIG. 2 is an enlarged cross-sectional view taken along the line XX of FIG.

The packaging container according to the embodiment of the present invention is made of polystyrene foam, and has a bottom portion 11, a side portion 12 rising from the outer periphery of the bottom portion, and a flange portion extending outward from the upper end of the side portion. A base material 1 having 13 and a coextruded laminated film 2 laminated on the base material and having a gas barrier layer 23 are provided, and is defined by JIS K6854 between the adhered base material and the coextruded laminated film. The peel strength is 1.5 N / 15 mm or more, or 2.0 N / 15 mm or more, and it is desirable that the upper 4.0 N / 15 mm or more is assumed assuming violent vibration during distribution and unexpected drop. Here, the polystyrene foam may contain a resin such as polyphenylene ether (PPE) or methacrylic acid, and the content thereof may be less than 30% by mass and 70% by mass or more of polystyrene. good. Further, the polystyrene foam preferably contains 75% by mass or more of polystyrene, and more preferably 85% by mass or more.

Further, in order to suppress a decrease in peel strength, it is desirable that the thickness of the coextruded laminated film 2 is 20 μm or more and less than 60 μm, and 30 μm or more and less than 50 μm assuming violent vibration during distribution or unexpected drop. ..

Further, the coextruded laminated film 2 has a first thermoplastic resin layer 21, an adhesive resin layer 22, a gas barrier layer 23, an adhesive resin layer 22, and a second from the outside with respect to the base material 1. The thermoplastic resin layer 24 is laminated in this order.

Further, the thickness of the flange portion 13 may be thinner than the thickness of the bottom portion 11 or the side portion 12. According to such a configuration, the mechanical strength of the entire container can be increased while maintaining the peel strength between the base material of the flange portion 13 and the coextruded laminated film.

Here, the surface of the flange portion 13 shown in FIG. 1 is flat and is smoothly connected to the upper end of the side portion 2. The coextruded laminated film 2 is attached to the inside of the bottom portion 11 and the side portion 12 of the base material 1 and the outside (surface) of the flange portion 13 via a predetermined adhesive.
The base material 1 is made by shaping a polystyrene foam sheet material (secondary foamed sheet) into a predetermined shape with a mold, and the shape and size thereof do not matter. The bottom portion 11 and the side portion 12 may have, for example, a rectangular shape, a circular shape, or an elliptical shape, or may have a flat shape, an uneven shape, or a curved surface. There may be, for example, a partition, a step or a mound on the bottom 11. The lid material 3 may be any material as long as it can seal the opening formed at the inner edge of the flange portion 13.

Further, the coextruded laminated film 2 shown in FIG. 2 has two or more resins (for example, a first thermoplastic resin layer 21, an adhesive resin layer 22, a gas barrier layer 23, an adhesive resin layer 22, and a second thermoplastic). It is manufactured by a coextrusion method in which the resin layer 24) is extruded together from the slit. There is no limit to the thickness of the resin or material to be laminated.

Here, the first thermoplastic resin layer 21 can be thermally pressure-bonded to the top seal lid material 3 and has easy-opening property (easy peeling property) as required. For example, polypropylene (PP) or polyethylene (polyethylene (PP) or polyethylene) ( PE) is applicable, but it is not limited to the case where these are used alone, but also the case where a plurality of types are used in combination, and polypropylene: polyethylene may be 90:10 to 10:90, and 80:20 to 20: It may be 80, or it may be 70:30 to 30:70. It is preferable that polystyrene (PS) is not contained, and the content thereof may be, for example, 1% by mass or less.

The gas barrier layer 23 is not particularly limited as long as the permeability of a gas such as oxygen gas, steam gas, or carbon dioxide gas is low. Specifically, the oxygen permeability according to JIS K 7126 is 1000 ml / m ^{2 with a thickness of 25 μm.} Any resin that is 24 hr · MPa (75% RH at 20 ° C.) or less and can be co-extruded may be used, and examples thereof include ethylene-vinyl alcohol copolymer (EVOH) and polyamide (PA).

The second thermoplastic resin layer 24 adheres to a predetermined adhesive to be bonded to the base material 1 made of polystyrene (PS). For example, polypropylene (PP) or polyethylene (PE) is applicable, but these are used alone. Including the case where a plurality of types are used in combination, the polypropylene: polyethylene may be 90:10 to 10:90, 80:20 to 20:80, or 70:30. It may be ~ 30: 70. It is preferable that polystyrene (PS) is not contained, and the content thereof may be, for example, 1% by mass or less.

The adhesive resin layer 22 is not particularly limited as long as the first thermoplastic resin layer 21 or the second thermoplastic resin layer 24 and the gas barrier layer 23 can be adhered to each other. good.

Further, the method for manufacturing a packaging container according to an embodiment of the present invention includes a step of heating a raw fabric sheet before molding of a base material 1 and a coextruded laminated film 2 to obtain a sheet after secondary foaming, and a secondary step of obtaining a sheet after secondary foaming. It is desirable that the foamed sheet is provided with a step of obtaining a desired molded sheet by double-sided vacuum forming, and that the inside of the double-sided vacuum forming mold satisfies the following conditions.
In-mold clearance of flange part-thickness of sheet after secondary foaming = 0

Further, in the above manufacturing method, it is desirable that the inside of the double-sided vacuum forming mold satisfies the following conditions.
In-mold clearance at the side and bottom-thickness of the sheet after secondary foaming> 0
According to such a configuration, the thickness of the flange portion 13 can be made thinner than the thickness of the bottom portion 11 or the side portion 12, and as a result, the peel strength between the base material of the flange portion and the coextruded laminated film can be maintained. , The mechanical strength of the entire container can be increased.

Further, another method for manufacturing a packaging container according to an embodiment of the present invention includes a step of heating a raw sheet before molding of the base material 1 and the coextruded laminated film 2 to obtain a sheet after secondary foaming. It is desirable that a step of obtaining a desired molded sheet by single-sided vacuum forming in which the sheet after secondary foaming is evacuated from the base material side is provided, and the inside of the single-sided vacuum forming mold satisfies the following conditions.
In-mold clearance of flange part-thickness of sheet after secondary foaming> 0

Here, the container body P shown in FIG. 1 is a post-secondary foamed sheet obtained by heating the corresponding raw sheet before molding the base material 1 and the laminate film 2, for example, the mold shown in FIG. 3 (a). It is obtained by inserting into and vacuum forming. The mold is a space corresponding to the bottom portion 11, the side portion 12, and the flange portion 13 constituting the base material 1 (hereinafter referred to as “in-mold clearance”), and each of the in-mold clearances has a predetermined dimension.

Then, as shown in FIG. 3B, when the in-mold clearance is, for example, a bottom portion of 3.0 μm, a side portion of 3.0 μm, a flange portion of 4.0 μm, and a secondary foamed sheet thickness of 3.0 μm, the following The relational expression of the difference between the clearance in the mold and the thickness of the sheet after the secondary foaming is established.
Flange> 0 Side / bottom = 0
That is, since the in-mold clearance of the flange portion is 4.0 μm and the sheet thickness after secondary foaming is 3.0 μm, the in-mold clearance of the flange portion before molding is a space where 1.0 μm of resin does not exist, that is, Excess space is created (flange portion> 0). On the other hand, since the side / bottom is 3.0 μm and the sheet thickness after secondary foaming is 3.0 μm, there is no excess space in the mold clearance of the side / bottom before molding (side / bottom =). 0) That is, the in-mold clearance is filled with resin.

Further, as shown in FIG. 3C, the dimensions of the container body after molding differ depending on the vacuum forming of the secondary foamed sheet inserted into the mold. That is, in the case of single-sided vacuum forming, the material is molded by attracting from the lower side of the sheet after secondary foaming (the base material 1 side in FIG. 1) in a vacuum state. Therefore, the dimensions of the molded sheet do not change. On the other hand, in the case of double-sided vacuum forming, after secondary foaming, the sheet is attracted and molded in a vacuum state from both the upper and lower sides. Therefore, in the molded sheet, the portion corresponding to the flange portion foams upward, and the thickness becomes equivalent to the in-mold clearance of 4.0 μm of the flange portion.

Further, the method of using the packaging container in one embodiment of the present invention includes a step of filling the base material 1 with food, a step of attaching the lid material 3 to the flange portion 13 of the base material containing the food, and the flange. It is desirable to include a step of adhering the portion and the lid material to seal the base material.

Examples of the layer structure of the lid material for the top seal include polyamide (PA), an adhesive resin layer, a gas barrier layer, an adhesive resin layer, and a sealant layer (thermoplastic resin) from the non-food contact side. If necessary, the sealant layer may be easily opened. The adhesive resin layer is an olefin-based adhesive resin. Examples of the gas barrier layer include ethylene-vinyl alcohol copolymer (EVOH) and polyamide (PA).

Here, the outline of the peel strength test (test standard, testing machine, test piece, test status) of the laminated film common to the examples and the comparative examples will be described.
≪Test standard≫
Peeling strength test specified in JIS K 6854-2 << Testing machine >>
Fuji Impulse Seal Peeling Tester << Testing Machine Setting >>
Distance between chucks: 25 mm
Peeling speed: 200 mm / min
≪Test piece≫
Of the container body P shown in FIG. 1, a part (15 mm width) of the flange portion 13 (15 mm width) of the base material 1 to which the laminate film 2 is attached is cut from a part of the side portion 12. Of these, a crack was made from the back in the width direction of the polystyrene foam portion on the side opposite to the part of the cut flange portion 13, and the laminate film 2 was partially peeled off toward a part of the flange portion 13 and at the same time. The polystyrene foam portion on the opposite side of the flange portion 13 is peeled off from the laminate film. The product thus obtained is used as a test piece.
When the flange portion 13 has a rectangular shape, the laminated film attached to the base material 1 is cut from a part of the four corners where it is easy to peel off by using a packaging container. The base material, which is the original form of the test piece, is molded by the method described above.
≪Test status≫
A polystyrene foam portion opposite to a part of the flange portion 13 of the test piece is sandwiched between one chuck of the testing machine, and the peeled laminate film 2 is sandwiched between the other chucks.
After that, when the operation of the testing machine is started, the laminate film 2 is pulled as the gap between the chucks is automatically expanded, and when the laminate film is peeled from a part of the polystyrene foam of the flange portion 13, the test is completed.

In this way, the peel strength test of the laminated film (and the evaluation of the rigidity and design of the container body) was performed using the test pieces collected from the base materials having different molding methods.

Here, the test conditions of Examples 1 to 8 are listed below.
≪Base material≫
Material: Polystyrene paper (PSP)
≪Laminated film≫
Manufacturing method: Coextrusion method Thickness: 40 μm
Layer structure: (toward the substrate) a mixture of polypropylene (PP) and polyethylene (PE), olefin-based adhesive resin, ethylene-vinyl alcohol copolymer (EVOH), olefin-based adhesive resin, polypropylene (PP), glue

On the other hand, the test conditions of Comparative Example 1 are listed below.
≪Base material≫
Material: Polystyrene paper (PSP)
≪Laminated film≫
Manufacturing method: Dry laminating method Thickness: 40 μm
Layer structure: (towards the substrate) a mixture of polypropylene (PP) and polyethylene (PE), polyurethane-based adhesive resin, ethylene-vinyl alcohol copolymer (EVOH), adhesive

Table 1 below shows the test results of Examples 1 to 8 and Comparative Example 1 conducted based on the outline of the peel strength test and the test conditions described above.

Hereinafter, the test results of Examples 1 to 8 and Comparative Example 1 will be described based on the above-mentioned method for molding the base material. The unit of peel strength is N / 15 mm (1 kgf / 15 mm width = 9.8 N / 15 mm).

Example 1 and Example 2
As shown in FIG. 4A, in the method of molding the base material from which the test pieces used in Example 1 and Example 2 were collected, the following relational expression of the difference between the in-mold clearance and the thickness of the sheet after secondary foaming was obtained. To establish.
Flange> 0 Side / bottom = 0
At this time, as shown in FIGS. 4 (b) and 4 (c), the peel strength of the laminated film was 4.6 N / 15 mm in Example 1 (during single-sided vacuum forming) and in Example 2 (during double-sided vacuum forming). It was 2.9 N / 15 mm.
The rigidity (waist strength) of the base material is 4.8 N in both Example 1 (during single-sided vacuum forming) and Example 2 (during double-sided vacuum forming), and the design of the base material is Example 1 (single-sided vacuum forming). There was no particular problem in (during molding), and it was good in Example 2 (during double-sided vacuum forming). Here, the rigidity of the base material was measured by the method shown in FIG. 8 at a head speed of 50 mm / min using "Autograph AGS-500S" manufactured by Shimadzu Corporation. In addition, the design was judged to be "good" if the shape of the ribs and the like was clearly visible, and "bad" if the shape was floating.

Example 3 and Example 4
As shown in FIG. 5A, in the method of molding the base material from which the test pieces used in Examples 3 and 4 were collected, the following relational expression of the difference between the in-mold clearance and the sheet thickness after secondary foaming was obtained. To establish.
Flange> 0 Side / bottom> 0
At this time, as shown in FIGS. 5 (b) and 5 (c), the peel strength of the laminated film was 4.6 N / 15 mm in Example 3 (during single-sided vacuum forming) and in Example 4 (during double-sided vacuum forming). It was 2.9 N / 15 mm.
The rigidity of the base material was 4.8 N in Example 3 (during single-sided vacuum forming) and 6.5 N in Example 4 (during double-sided vacuum forming), and the design of the base material was in Example 3 (single-sided vacuum forming). (Time) was defective, and Example 4 (during double-sided vacuum forming) was good.

Example 5 and Example 6
As shown in FIG. 6A, in the method of molding the base material from which the test pieces used in Example 5 and Example 6 were collected, the following relational expression of the difference between the in-mold clearance and the sheet thickness after secondary foaming was obtained. To establish.
Flange = 0 Side / bottom = 0
At this time, as shown in FIGS. 6 (b) and 6 (c), the peel strength of the laminated film was 4.9 N / 15 mm in both Example 5 (during single-sided vacuum forming) and Example 6 (during double-sided vacuum forming). Met.
The rigidity of the base material is 4.8 N in both Example 5 (during single-sided vacuum forming) and Example 6 (during double-sided vacuum forming), and the design of the base material is that of Example 5 (during single-sided vacuum forming). Example 6 (at the time of double-sided vacuum forming) Both were good.

Example 7 and Example 8
As shown in FIG. 7A, in the method of molding the base material from which the test pieces used in Examples 7 and 8 were collected, the following relational expression of the difference between the in-mold clearance and the sheet thickness after secondary foaming was obtained. To establish.
Flange = 0 Side / bottom> 0
At this time, as shown in FIGS. 7 (b) and 7 (c), the peel strength of the laminated film was 4.9 N / 15 mm in both Example 7 (during single-sided vacuum forming) and Example 8 (during double-sided vacuum forming). Met.
The rigidity of the base material was 4.8 N in Example 7 (during single-sided vacuum forming), 6.5 N in Example 8 (during double-sided vacuum forming), and the design of the base material was in Example 7 (single-sided vacuum forming). Time) and Example 8 (during double-sided vacuum forming) were both good.

Comparative Example 1
In the method of molding the base material from which the test piece used in Comparative Example 1 was collected, the following relational expression of the difference between the in-mold clearance and the thickness of the sheet after secondary foaming is established.
Flange = 0 Side / bottom> 0
At this time, the peel strength of the laminated film was 1.3 N / 15 mm at the time of double-sided vacuum forming.
The rigidity of the base material was 6.3 N during double-sided vacuum forming, and the design of the base material was good during double-sided vacuum forming.

Next, the test results of Examples 8 to 10 are shown in Table 2.
The test results (peeling strength) of Example 8 are the same as those listed in Table 1. Further, among the test conditions of Examples 9 and 10, the thickness of the laminated film is 50 μm in Example 9 and 60 μm in Example 10, and other test conditions and the method of molding the base material are the same as those in Example 8 described above. Is.

Example 9 and Example 10
At this time, the peel strength of the laminated film was 4.2 N / 15 mm in Example 9 and 2.1 N / 15 mm in Example 10.

Next, the test results of Examples 8 and 11 and Comparative Example 1 are shown in Table 3.
The test results (peeling strength) of Example 8 and Comparative Example 1 are the same as those listed in Table 1. Further, among the test conditions of Example 11, the layer structure of the laminate film is a mixture of polypropylene (PP) and polyethylene (PE) (toward the base material), an olefin-based adhesive resin, and an ethylene-vinyl alcohol copolymer. (EVOH), an olefin-based adhesive resin, and polyethylene (PE), and other test conditions and a method for molding a base material are the same as those in Example 8 described above.

Example 11
At this time, the peel strength of the laminated film was 4.6 N / 15 mm in Example 11.

As described above, from the test results of Examples 1 to 8 and Comparative Example 1 (see Table 1), the peel strength of the laminate film having the ethylene-vinyl alcohol copolymer (gas barrier layer) produced by the coextrusion method is 2 It was confirmed that it was 0.0 N / 15 mm or more.

Further, from the test results of Examples 8 to 10 (see Table 2), it was confirmed that the thickness of the laminated film for ensuring the above-mentioned peel strength is preferably 40 μm to 60 μm.

Further, from the test results of Examples 8 and 11 and Comparative Example 1 (see Table 3), the layer structure of the laminate film for ensuring the peel strength described above is a mixture of polypropylene and polyethylene (first) toward the base material. Thermoplastic resin), olefin-based adhesive resin, polyethylene-vinyl alcohol copolymer (gas barrier layer), olefin-based adhesive resin, polypropylene (second thermoplastic resin), as well as the second thermoplastic resin , It was confirmed that polyethylene may be used.

Further, from the test results of Example 8 (see Table 1), the thickness of the flange portion of the container body from which the test piece was collected is thinner than the thickness of the side portion and the bottom portion, that is, the clearance in the mold and the thickness of the sheet after secondary foaming. Since the flange part does not (cannot) foam due to the base material made of the molded sheet in double-sided vacuum that satisfies the relationship of "flange part = 0 side part / bottom part> 0", it sticks to this flange part. It was confirmed that the peel strength of the laminated film could be secured at a high level (4.9 N / 15 mm), which was desirable.

Further, from the structure in which the thickness of the flange portion does not change, the difference between the in-mold clearance of the flange portion and the thickness of the sheet after secondary foaming is "flange portion = 0" from the test results of Examples 6 and 8 (see Table 1). From the test results of Examples 1 and 3 (see Table 1), the difference between the in-mold clearance of the flange portion and the thickness of the sheet after secondary foaming is "flange portion>". It was confirmed that it is desirable to use a base material made of a molded sheet formed by single-sided vacuum forming that satisfies the relationship of "0".

Here, an embodiment of how to use the packaging container will be described. First, at a manufacturing factory or a retail store, food (for example, meat) is packed in the same container as in Example 1. After the food is packed in a container, gas replacement is performed. For attaching the lid material, for example, "Eco-wrap GLS-L" manufactured by Okura Industrial Co., Ltd. is used, and the lid material is attached to the flange portion of the container containing the food. After the lid material is attached, the flange portion and the lid material are adhered and sealed by thermocompression bonding using "SN-2S (N2N)" manufactured by Shinwa Machinery Co., Ltd. Cut the lid along the outer circumference of the container. The expiration date of the food packaged in this way could be extended.

Therefore, when the peel strength specified by JISK6854 between the laminated films laminated by the coextrusion method having the base material and the gas barrier layer is 1.5 N / 15 mm or more, the bagging phenomenon is less likely to occur and the opening is easy (easy). It is possible to realize a packaging container that can be sealed with a peelable lid material and has low gas permeability such as oxygen. That is, since the peeling strength of the adhesive portion between the base material and the laminated film is higher than the peeling strength of the adhesive portion between the lid material and the laminated film that seals the base material, the lid material is easily opened without the bagging phenomenon. can do. Further, by forming a thin film gas barrier layer having a desired gas permeability into a laminated film by a coextrusion method, the laminated film as a whole is thin, so that a peel strength of 1.5 N / 15 mm or more can be secured. This makes it difficult for not only the bagging phenomenon but also the peeling between layers to occur.

Furthermore, by adhering the top seal lid material to the flange of the base material and sealing it, food can be easily wrapped in a short time, and the airtightness is higher than when using wrap packaging or molded lid material. Therefore, the storage period of food can be extended.

The packaging container in the present invention can be used in an industry related to external sales of foods in general, including, for example, lunch boxes, prepared foods, fresh foods, meats, and vegetables.

1 Base material 11 Bottom 12 Side 13 Flange 2 Co-extruded laminated film (laminated film)

Claims (4)

A base material made of polystyrene foam and having a bottom portion, a side portion rising from the outer circumference of the bottom portion, and a flange portion extending outward from the upper end of the side portion.
A packaging container for a gas barrier and having a coextruded laminated film having a gas barrier layer, which is laminated on the base material and adheres to a top seal lid material.
The peel strength specified by JISK6854 between the bonded base material and the coextruded laminated film is 1.5 N / 15 mm or more.
In the coextruded laminated film, the first thermoplastic resin layer, the adhesive layer, the gas barrier layer, the adhesive layer, and the second thermoplastic resin layer are arranged in this order from the outside with respect to the base material. It is laminated with
The second thermoplastic resin layer is made of polypropylene or polyethylene and is made of polypropylene or polyethylene.
An adhesive is interposed between the base material and the second thermoplastic resin layer,
A packaging container characterized in that the thickness of the flange portion is thinner than the thickness of the bottom portion or the side portion. A base material made of polystyrene foam and having a bottom portion, a side portion rising from the outer circumference of the bottom portion, and a flange portion extending outward from the upper end of the side portion.
A packaging container for a gas barrier and having a coextruded laminated film having a gas barrier layer, which is laminated on the base material and adheres to a top seal lid material.
The peel strength specified by JISK6854 between the bonded base material and the coextruded laminated film is 1.5 N / 15 mm or more.
In the coextruded laminated film, the first thermoplastic resin layer, the adhesive layer, the gas barrier layer, the adhesive layer, and the second thermoplastic resin layer are arranged in this order from the outside with respect to the base material. It is laminated with
The second thermoplastic resin layer is made of polypropylene or polyethylene and is made of polypropylene or polyethylene.
An adhesive is interposed between the base material and the second thermoplastic resin layer,
A packaging container having a thickness of the coextruded laminated film of 30 μm or more and less than 50 μm. The packaging container according to claim 1, wherein the coextruded laminated film has a thickness of 30 μm or more and less than 50 μm. The process of filling the base material with food and
A step of attaching the lid material to the flange portion of the base material containing the food via the coextruded laminated film, and
The packaging according to any one of claims 1 to 3, further comprising a step of adhering the flange portion and the lid material via the coextruded laminated film to seal the base material. How to use the container.

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