JP7410112B2 - packaging container - Google Patents

Description

The present invention relates to a packaging container made of a polystyrene resin foam sheet and a top sealing lid material.

BACKGROUND ART Packaging containers made from polystyrene resin foam sheets by vacuum thermoforming, pressure air thermoforming, etc. are widely used in supermarkets, convenience stores, etc. as food packaging containers for selling boxed lunches and side dishes.

Regarding such packaging containers, in recent years, there has been a social demand to reduce the amount of plastic containers used from the perspective of reducing environmental impact, and there is also a growing need to extend the expiration date of food and reduce food loss. In addition, packaging containers of the type that use a so-called top-seal lid material and heat-seal the lid material to the flange of the container body after storing the food in the container body are widely used because they can maintain the freshness of the stored food at a high level. It is becoming more and more common.

However, although such top-seal packaging containers can keep food fresh and reduce the amount of plastic used, it is difficult to achieve uniform sealing strength on the flange surface around the entire circumference of the container body, and This sometimes resulted in areas lacking in strength. Therefore, there was a problem in that the seal could be opened from the weakened part when transporting the sealed product or when the product was dropped. On the other hand, when the overall seal strength is increased, it becomes extremely difficult to open the package, and there are problems such as the contents scattering when the package is opened with force.

Therefore, as a conventional method for achieving uniform and appropriate sealing strength in top-seal packaging containers, for example, Patent Document 1 discloses a method of providing a flat, wide flange with a width of 4 mm or more over the entire circumference of the opening of the container body. discloses a packaging container with improved uniformity of seal strength during sealing.

However, although the uniformity of the seal strength described in Patent Document 1 can be improved to some extent, the so-called impact resistance is not sufficient in that the bag is easily torn by external impact such as dropping. In particular, when used as a container for frozen foods, the impact resistance in a frozen environment (for example, -30°C) is poor.

Patent No. 6908969

Therefore, the problem to be solved by the present invention is that a packaging container made of a polystyrene resin foam container and a top seal lid material has excellent impact resistance, and can be easily peeled off even in a frozen environment (-30°C). To provide a packaging container with excellent cold resistance and impact resistance, which does not cause any damage.

As a result of intensive studies to solve the above problems, the present inventors have developed a foam base material made of styrene resin and having a flange, and a thermoplastic non-foam film on the inner surface that accommodates the contents of the foam base material. The present invention was completed based on the discovery that the cold and impact resistance could be dramatically improved by using a container body laminated with a laminated container body and using a multilayer film having a cohesive release layer or an interlayer release layer as the lid material. I ended up doing it.

That is, the present invention is a packaging container composed of a polystyrene foam (A) and a top sealing lid material (B),
The polystyrene foam (A) has a shape including a bottom, a side wall extending upward from the outer edge of the bottom, and a flange extending outward from the upper end of the side wall, and has a polystyrene foam base. The foam base material has a structure in which a thermoplastic non-foamed film is laminated on the inner surface that accommodates the contents of the foam base material, and the top seal lid material (B) is made of the polystyrene foam. The present invention relates to a packaging container characterized in that it is a multilayer film having a cohesive release layer or an interlayer release layer on the side that is sealed to the flange surface of the container.

According to the present invention, a packaging container made of a polystyrene resin foam container and a lid material for a top seal has excellent impact resistance, and is particularly cold and impact resistant and does not easily peel off even in a frozen environment (-30°C). It is possible to provide packaging containers with excellent properties.

FIG. 1 is a perspective view of a polystyrene foam (A) used in the present invention. FIG. 2 is an end view schematically showing the AA' end face of the polystyrene foam (A) used in the present invention. FIG. 3 is an enlarged end view of the flange portion of the polystyrene foam (A) used in the present invention. FIG. 4 is a plan view of the polystyrene foam (A) used in the present invention. FIG. 5 is an enlarged cross-sectional view schematically showing the cross-sectional structure of the top seal lid material (B) used in the present invention.

<Polystyrene foam (A)>
The polystyrene foam (A) used in the present invention has a shape including a bottom, a side wall extending upward from the outer edge of the bottom, and a flange extending outward from the upper end of the side wall. It has a structure in which a foamed base material and a thermoplastic non-foamed film are laminated on the inner surface of the foamed base material that accommodates the contents. Here, the shape of the bottom in plan view may be rectangular, circular, or elliptical, but is preferably rectangular with rounded corners as shown in FIG. The side wall portion extending upward from the bottom periphery may stand up vertically, but is preferably formed so as to expand upward (for example, the bottom portion 2 in FIG. 2). In addition, the flange extending outward from the upper end of the side wall (for example, flange 4 in FIGS. 2 and 3) extends horizontally, which facilitates heat sealing and improves the uniformity of the sealing strength. It is preferable from the point of view that it becomes useful. Further, the flange may have a curved shape that bulges upward, or may be flat over the entire circumference. Among these, a flat one is preferable in terms of uniformity of seal strength and better cold and impact resistance, and the end of the flange is a thin part with a reduced thickness (for example, a thin part in FIGS. 2 and 3). 5), it is preferable that the top film is not heat-sealed to the thin part and a clearance is formed between the thin part and the film, from the viewpoint that the top film can be easily peeled off.

The polystyrene foam (A) has a structure in which a polystyrene foam base material and a thermoplastic non-foamed film are laminated on the inner surface of the foam base material that accommodates the contents.

Here, the polystyrene foam base material is a foam molded product made of a styrene resin composition, and examples of the styrene resin composition include styrene homopolymer (GPPS), high impact polystyrene (HIPS), Resin compositions containing hyperbranched polystyrene, styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid ester copolymer, styrene homopolymer (GPPS) and polyphenylene ether as essential components, or these Examples include mixtures of.

Among these, resin compositions containing styrene and (meth)acrylic acid ester copolymers and resin compositions containing styrene homopolymer (GPPS) and polyphenylene ether as essential components are preferred from the viewpoint of excellent heat resistance. The amount of (meth)acrylic ester in the resin composition containing styrene and (meth)acrylic ester copolymer is preferably in the range of 1 to 30% by mass. The content of polyphenylene ether in the resin composition containing polyphenylene ether as an essential component is preferably in the range of 1 to 40% by mass.

Among these, resin compositions containing styrene homopolymer (GPPS) and polyphenylene ether as essential components are particularly preferable from the viewpoint of more remarkable heat resistance, and particularly, in addition to styrene homopolymer (GPPS) and polyphenylene ether, The resin composition containing HIPS is preferable because it exhibits excellent impact resistance even under extremely low temperature conditions of -30°C, such as when used for frozen foods. Here, in the case of a resin composition containing styrene homopolymer (GPPS), HIPS, and polyphenylene ether as essential components, it is preferable to contain polyphenylene ether in a proportion of 1 to 40% by mass.

The foaming ratio of the polystyrene foam base material is preferably in the range of 2 to 40 times, and especially in the case of a highly foamed sheet that requires high heat resistance, the foaming ratio of the polystyrene resin foam sheet layer is 10 to 40 times. It is preferable.

Next, examples of the thermoplastic non-foamed film on the inner surface that accommodates the contents of the foamed base material include a styrene resin film, an olefin resin film, and a gas barrier film. These can be used as a single layer film or as a multilayer film of two or more types,
for example,
Film structure 1: A structure in which a styrene resin film is thermally laminated onto a foam base material;
Film structure 2: A structure in which an olefin resin film is laminated onto a foam base material via an adhesive;
Film structure 3: a structure in which a styrene resin film is laminated on an olefin resin film via a dry lamination adhesive, and the styrene resin film side is thermally laminated to a foam base material;
Film structure 4: The second olefin resin layer of the laminated film obtained by coextruding the first olefin resin, the resin constituting the gas barrier layer, and the second olefin resin is formed into a foam via an adhesive. Structure laminated on base material; Film structure 5: second olefin resin layer side of a laminated film obtained by coextruding the first olefin resin, the resin constituting the gas barrier layer, and the second olefin resin Another example is a structure in which a styrene resin film is laminated via a dry lamination adhesive, and the surface of the styrene resin film is thermally laminated to a foam base material.

Among these, when the foam base material is a foam of styrene homopolymer, the above-mentioned film structure 1: a structure in which a styrene resin film is thermally laminated alone to the foam base material is a molded product. In addition to the smoothness of the surface, it is preferable because the foamed molded product can be easily collected and recycled into food trays again.

In addition, when the inside of the top film is replaced with an inert gas or the like when top-sealing the top film, it is preferable to provide a gas barrier layer. In that case, film structure 4: the first olefin resin and the gas barrier layer are formed A structure in which a second olefin resin layer of a laminated film obtained by coextruding a resin and a second olefin resin is laminated on a foam base material via an adhesive; Film structure 5: first olefin A styrene resin film is laminated via a dry lamination adhesive on the second olefin resin layer side of the laminated film obtained by coextruding the resin constituting the gas barrier layer and the second olefin resin. , a structure in which the surface of the styrene resin film is thermally laminated to a foam base material is preferred.

In addition, when the foam base material is a mixed resin containing styrene homopolymer (GPPS) and polyphenylene ether as essential components,
Film structure 2: a structure in which an olefin resin film is laminated onto a foam base material via an adhesive;
Film structure 3: a structure in which a styrene resin film is laminated on an olefin resin film via a dry lamination adhesive, and the styrene resin film side is thermally laminated to a foam base material;
Film structure 4: The second olefin resin layer of the laminated film obtained by coextruding the first olefin resin, the resin constituting the gas barrier layer, and the second olefin resin is formed into a foam via an adhesive. Structure laminated on base material;
Film structure 5: Dry styrene resin film on the second olefin resin layer side of the laminated film obtained by coextruding the first olefin resin, the resin constituting the gas barrier layer, and the second olefin resin. A structure in which the styrene resin film surface is laminated via a lamination adhesive and thermally laminated to a foam base material is preferable because the molded product surface has good gloss and oil resistance, and
Film structure 3 in which an olefin resin film or a coextruded film containing the same is laminated on a foam base material via a styrene resin film, since it can exhibit excellent impact resistance even in a frozen environment, and the film Structure 5 is particularly preferred.

Here, as the polystyrene resin constituting the polystyrene resin film, styrene homopolymer (GPPS), high impact polystyrene (HIPS), hyperbranched polystyrene, syndiotactic polystyrene (SPS), styrene-acrylonitrile copolymer Coalescence, styrene-butadiene-acrylonitrile copolymer, styrene-acrylic acid copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-methacrylic acid copolymer, styrene-methyl methacrylate Examples include copolymers, styrene-ethyl methacrylate copolymers, styrene-maleic anhydride copolymers, and styrene-α-methylstyrene copolymers. Here, in particular, when a polystyrene resin film is thermally laminated to a foam base material, unstretched styrene homopolymer (GPPS) has good fusion properties and lowers the fusion temperature. Biaxially oriented polystyrene is preferable because it allows for better moldability, and when the polystyrene resin film is located on the surface of the molded product, it provides better surface gloss.

Next, as the olefin resin constituting the olefin resin film, polyethylene, polypropylene, a propylene-ethylene random copolymer with an ethylene polymerization amount of 5% by mass or less, or a propylene homopolymer and an ethylene polymerization amount of 5% by mass or less are used. % or less of a propylene-ethylene random copolymer. Among these, polyethylene and polypropylene are preferable, and particularly when an olefin resin film is located on the surface layer, polypropylene is preferable from the viewpoint of oil resistance and heat resistance. In addition, non-stretched polypropylene is particularly preferred since it has excellent shapeability into containers.

The gas barrier layer may be any material as long as it has low permeability to inert gases, oxygen, water vapor, etc., and examples thereof include ethylene-vinyl alcohol copolymer and polyamide.

The thickness of the layer composed of these thermoplastic non-foamed films is, for example,
In the case of the film structure 1, the thickness of the styrene resin film layer is preferably in the range of 5 to 100 μm from the viewpoint of good surface smoothness and gloss. In the case of the film structure 2, the thickness of the olefin resin film layer is preferably in the range of 5 to 100 μm from the viewpoint of good surface smoothness and gloss.

In the case of the film structure 3, the thickness of the olefin resin film layer is preferably in the range of 15 to 100 μm. That is, by setting the thickness to 15 μm or more, a container with excellent oil resistance can be obtained. Further, by setting the thickness to 100 μm or less, good adhesion can be obtained. Particularly, from the standpoint of achieving an excellent balance of performance, a range of 20 to 50 μm is preferred. On the other hand, the thickness of the polystyrene resin film layer is preferably in the range of 10 to 40 μm, particularly in the range of 10 to 17 μm, from the standpoint of achieving an excellent balance between adhesion to the substrate and surface smoothness.

In the case of Film Structure 4 and Film Structure 5, the thickness of the first olefin resin film layer is preferably in the range of 20 to 150 μm in terms of the total thickness of the coextruded film layer. In addition, in the case of film structure 5, the thickness of the styrene resin film layer is in the range of 10 to 40 μm, particularly in the range of 10 to 17 μm, which provides an excellent balance between adhesion to the base material and surface smoothness. preferred.

Further, as the dry laminating adhesive used when forming the film structure 3 and the film structure 5, urethane-based, acrylic-based, or epoxy-based dry laminating adhesives can be mentioned, but from the viewpoint of adhesive strength etc., urethane type adhesives are preferred. The thickness or coating amount of the dry lamination adhesive layer is not particularly limited, but the thickness is in the range of 1 to 8 μm, and the coating amount is 0.5 to 5 g/m ² , particularly 1 to 3 g/m ² It is preferable that it is in the range of .

As described above, the polystyrene foam (A) detailed above has a shape having a bottom, a side wall extending upward from the outer edge of the bottom, and a flange extending outward from the upper end of the side wall. The flange of the polystyrene foam (A) may have a flat shape or a curved shape that bulges upward. Among these, it is preferable that the flange has a flat structure, as shown in flange 4 in Fig. 3. Specifically, a flat structure with a width of 3.5 to 10 mm is desirable for uniformity of sealing strength, cold resistance and impact resistance. This is preferable because it provides good results.

Further, it is preferable that the flange thickness is 4 mm or less from the viewpoint of smoothness of the flange surface and productivity, and it is preferable that the outer peripheral end of the flange has a thin wall part as shown in the thin wall part 5 in FIG. . The thin part has a structure in which it is not heat-sealed to the top sealing lid material, so that it has good unsealability. In addition, a fine unevenness is formed on the upper surface of the thin part over part or all of the outer circumference of the end, which prevents injuries caused by workers and handlers coming into contact with the flange. , is preferable because safety is maintained well.

Moreover, it is desirable that the flange surface be in a smooth state, and specifically, it is preferable that the surface roughness (Ra) is 3 μm or less. Here, the surface roughness (Ra) refers to the arithmetic mean roughness over a reference length. For example, the inner surface of the bottom of a molded container is measured using a Keyence laser microscope (VK- X200series) at a magnification of 1000 times, the evaluation length is 2000 μm, the cutoff λs is 2.5 μm, and the cutoff λc is 0.25 mm.

The polystyrene foam (A) is a composite sheet made by laminating a polystyrene foam sheet and a single-layer thermoplastic non-foamed film or a multilayer film containing the same (hereinafter abbreviated as "non-foamed film"). It can be obtained through step 1 of forming the composite sheet, followed by step 2 of shaping the obtained composite sheet into a predetermined shape to form a molded body.

The means for laminating the polystyrene foam sheet and the non-foamed film in step 1 include thermal lamination, dry lamination, or extrusion lamination in which polystyrene resin is foamed and extruded to form a sheet and then laminated. There are several methods. Next, step 2 is a step of thermoforming the composite sheet obtained in step 1 into a desired container shape. The molding method may be a conventional method, for example, vacuum pressure air thermoforming.
Regarding the temperature conditions for vacuum pressure air thermoforming in step 2, it is preferable that the heater temperature is in the range of 200 to 300°C.

In the polystyrene foam (A) thus obtained, the foaming ratio of the base foam is preferably in the range of 2 to 40 times. At this time, the foaming ratio of the polystyrene foam sheet is in the range of 3 to 20 times. In the case of a highly foamed sheet that particularly requires high heat resistance, the foaming ratio of the base foam of the polystyrene resin foam (A) should be 10 to 40 times, and the foaming ratio of the polystyrene foam sheet should be in the range of 5 to 20 times. is preferred.

Furthermore, the basis weight of the polystyrene resin foam sheet is preferably 90 to 400 g/m ² , more preferably 100 to 350 g/m ² .

The thickness of the polystyrene resin foam sheet (i) is preferably in the range of 0.5 to 4 mm, more preferably in the range of 1 to 3 mm.

In the present invention, the polystyrene foam (A) can be applied to various food trays, cups, etc., and can be used as a highly foamed deep-drawn container with excellent heat insulation properties. As for the specific shape of the deep-drawn container, for example, it is preferable that the surface area of the entire container is 2 to 4 times the opening width of the container opening. In addition, in the end view of the container in FIG. 2, the depth is 0.5 to 1.5 times the linear distance between the thin wall portions 5, and the developed length (total length of the inner surface including the flange portion in the end view of the container in FIG. 2) is preferably 1.5 to 4 times.

One embodiment of such polystyrene foam (A) will be described based on the drawings. This embodiment is represented by the container body 1 in FIG. 1, and the corners are rounded in plan view. It is a foamed molded product having a square bottom 2, a side wall 3 extending upward from the outer edge of the bottom 2, and a flange 4 extending outward from the upper end of the side wall. Here, the bottom part 2 has a raised bottom part 6 in the center in order to improve thermal conductivity when heating in a microwave oven. The upper surface of the flange 4 is a smooth surface, and the upper part of the flange 4 forms a flat portion with a width of 3.5 mm or more, preferably 4 mm or more. Furthermore, it has a skirt portion extending outward and downward from its outer end, and a thin wall portion 5 extending outward from the lower end of the skirt. Further, from the viewpoint of safety such as prevention of cuts during handling, it is preferable that the upper surface of the thin portion 5 has a wavy uneven shape when viewed from the end surface side.

<Top seal lid material (B)>
Next, the top sealing lid material (B) is a multilayer film having a cohesive release layer or an interlayer release layer on the side of the polystyrene foam that is sealed to the flange surface. Specifically, it is sufficient that the base film (for example, the base film b1 in FIG. 5) has an agglomerated release layer or an interlayer release layer (for example, the base film b3 in FIG. 5), and at least two layers may be used. Any multilayer structure as described above may be used, but it may have a cohesive release layer or an interlayer release layer on the support film (for example, the base film b2 in FIG. 5), and the cohesive release layer or interlayer release layer of the support film. It is preferably a multilayer film in which a base film is laminated on the opposite side via a laminate layer if necessary.

Here, various styrene resins, nylon resins, and polyester resins can be used as the base film, but nylon resins and polyester resins are particularly preferred from the viewpoint of rigidity. The thickness of the base film is, for example, in the range of 5 to 20 μm.

As the support film, a resin material having high affinity with the cohesive release layer or the interlayer release layer can be appropriately selected, and examples thereof include polyethylene, high-density polyethylene, polypropylene, propylene block copolymer, and the like. The thickness of such a support film is preferably in the range of 20 to 60 μm when used as one layer, and 20 to 60 μm in total when used as two layers.

The cohesive release layer may be a mixture of two or more resin materials that can undergo cohesive failure during peeling, and the two or more resin materials preferably have a sea-island structure with low compatibility with each other. . Specifically, component (i): propylene/α-olefin random copolymer component (ii): a mixture of low density polyethylene,
Component (i): polypropylene or polybutene,
Component (ii): Mixture of ethylene vinyl acetate copolymer, low density polyethylene (LDPE), linear low density polyethylene (LLDPE), or ionomer Component (i): Propylene/ethylene random copolymer component (ii) : Medium density polyethylene,
Component (iii): mixture of ethylene methacrylic acid copolymer,
Examples include. In addition, in each of the above mixtures, the composition ratio of component (i)/component (ii) on a mass basis is in the range of 60/40 to 90/10, and that component (i)/component (ii) /Component (iii) is preferably in the range of 50/45/5 to 85/10/5 from the viewpoint of good adhesive strength in a frozen environment.

Next, as the interlayer peeling layer, for example, a multilayer film of two or more layers of two types with low affinity may be mentioned, and the type of thermoplastic non-foamed film laminated on the inner surface of the polystyrene foam (A), It can be appropriately selected depending on the type of support film. For example, when the thermoplastic non-foamed film is polyethylene, the support film has a two-layer structure of a polypropylene layer and the delamination layer is a polyethylene layer; the support film has a three-layer structure of a polypropylene layer/polypropylene layer and the delamination layer is a polyethylene layer; When the thermoplastic non-foamed film is polypropylene, it has a three-layer structure: the support film is a polypropylene layer/polyethylene layer, and the delamination layer is a polypropylene layer; the support film is made of linear low-density polyethylene (LLDPE), and the delamination layer is made of polypropylene. Examples include a two-layer structure of a polypropylene layer; a three-layer structure in which the support film is linear low density polyethylene (LLDPE)/linear low density polyethylene (LLDPE), and the interlayer peeling layer is a polypropylene layer.

The thickness of the interlayer peeling layer is preferably in the range of 1 to 10 μm.

The polystyrene foam (A) detailed above and the top seal lid material (B) can be used in any combination, but as the polystyrene foam (A), styrene homopolymer (GPPS) and polyphenylene ether as a polystyrene foam base material, film structure 3 (a styrene resin film is laminated on an olefin resin film via a dry lamination adhesive, and the styrene resin film side is a foam base material). (for example, the layered structure shown in Figure 3), and using a multilayer film with a cohesive release layer as the top sealing lid material (B) improves cold and impact resistance. Preferred because of its superiority.

As a method for heat-sealing the top sealing lid material (B) to the polystyrene foam (A), for example, after storing food in the polystyrene foam (A), the top sealing lid material (B) is coagulated and peeled. It is obtained by covering the foam (A) so that the layer or thin interlayer side is in contact with the foam (A) and heat-sealing it by pressing a hot plate from above the flange.

Here, the sealing width when heat sealing is not particularly limited, but can be appropriately selected according to the size of the flange upper surface of the polystyrene foam (A). For example, in the case of a flat shape, the range is 3.5 to 10 mm.

The temperature conditions for heat sealing can be appropriately selected from 100 to 200° C. to provide the desired sealing strength. In other words, in food packaging applications, where a desired seal strength is required depending on the application, the higher the seal temperature, the stronger the seal strength. Can be set. In the present invention, it is possible to exhibit excellent impact resistance (bag breakage resistance) at a desired seal strength level, and in particular, to exhibit remarkable performance such as excellent cold and impact resistance in a frozen environment. can.

From the viewpoint of adjusting the seal strength, the top seal lid material (B) having a cohesive release layer is particularly preferable because the seal strength follows changes in seal temperature and the degree of freedom in design is increased.

Further, the contents are not particularly limited, but as mentioned above, frozen foods are particularly preferred because they have the ability to exhibit excellent impact resistance in a frozen environment.

The present invention will be described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Example 1
[Manufacture of laminated foam sheet]
An unstretched polypropylene resin film (CPP film, manufactured by Suntox Co., Ltd., product name "KL-12", thickness 25 μm, peak melting temperature 164°C) was coated with a urethane-based dry laminating adhesive ("TOMOFLEX" manufactured by Toyo Morton). ) was applied at 2 g/m ² , and a polystyrene resin film (GPPS: 85% by mass + HIPS: 15% by mass, thickness 15 μm) was laminated thereto by dry lamination to obtain a multilayer film.
Next, the above multilayer film was coated with a heat-resistant polystyrene resin foam sheet (manufactured by Sekisui Plastics Co., Ltd., product name "Eslen Sheet", basis weight 110 g/m2, thickness 1 7 mm), the polystyrene resin film layer side of the multilayer film faced the heat-resistant polystyrene resin foam sheet, and the multilayer film was pasted between opposing thermal laminating rolls set at a temperature of 185°C.

[Manufacture of molded containers]
The above laminated sheet was molded into the shape of the container body 1 shown in FIG. 1 using a vacuum pressure air thermoforming machine. Specifically, the polypropylene resin film layer is on the inner surface of the container, the opening is a rectangle with a length of 200 mm and a width of 150 mm, the bottom is a rectangle with a length of 150 mm and a width of 100 mm, a depth of 70 mm, and an unfolded length. A tray-shaped molded container was obtained by shaping with a container-shaped mold having a length of 220 mm and a width of 170 mm. The surface roughness (Ra) of the flange surface of the obtained molded container was 1.9 μm.

[Top film sticker]
After storing 130 g of food sample in the obtained molded container, "CMPS017C" (thickness 30 μm) manufactured by Mitsui Chemicals Tohcello Co., Ltd. was laminated with PET film (thickness 12 μm), and "CMPS017C" was placed in the molded container. A container with a lid for evaluation was obtained by adjusting the temperature conditions so that the sealing strength was 7N/24mm and 12N/24mm in the temperature range of 110°C to 120°C.

[Cold resistance and impact resistance test]
The container with a lid for evaluation was placed on an evaluation stand, and a blank molded container was placed on top of the top film, which was fixed from above with a jig shaped to follow the bottom surface of the blank molded container.
A weight was dropped from a height of 80 cm in an environment of -30°C to check for peeling of the top film. Here, a 600 g weight was used for the seal strength of 7 N/24 mm, and an 800 g weight was used for the seal strength of 12 N/24 mm.
After the weight was dropped, no peeling occurred in any of the containers with lids for evaluation.

Example 2
An attempt was made to create a container with a lid for evaluation in the same manner as in Example 1, except that a delamination type top film ("DIFAREN E3311T" manufactured by DIC Corporation) laminated with a PET film was used as the top film.
Although we were able to obtain a container with a lid for evaluation with a seal strength of 12 N/24 mm, it was difficult to adjust the sealing temperature to obtain the specified seal strength, and it was difficult to manufacture a container with a lid for evaluation with a seal strength of 7 N/24 mm. I couldn't.
A cold resistance and impact resistance test was conducted on a container with a lid for evaluation having a seal strength of 12 N/24 mm in the same manner as in Example 1, and as a result, no peeling occurred.

Comparative example 1
The sealing strengths were 7N/24mm and 12N/2 in the same manner as in Example 1, except that an interfacial release type top film ("CMPS 008C" manufactured by Mitsui Chemicals Tohcello Co., Ltd.) laminated to a PET film was used as the top film. A 24 mm container with a lid for evaluation was obtained.
When a cold resistance and impact resistance test was conducted in the same manner as in Example 1, the top film of each container with a lid for evaluation peeled off when the weight was dropped.

1... Container body 2... Bottom part 3... Side face 4... Flange 5... Thin wall part 6... Upper bottom part a1... Foam base material a2... Styrene resin film a3 ... Olefin resin film b1 ... Base film b2 ... Support film b3 ... Cohesive release layer or interlayer release layer

Claims (5)

A packaging container composed of a polystyrene foam (A) and a top sealing lid material (B),
The polystyrene foam (A) has a shape including a bottom, a side wall extending upward from the outer edge of the bottom, and a flange extending outward from the upper end of the side wall, and has a polystyrene foam base. It has a structure in which a thermoplastic non-foamed film is laminated on the inner surface of the foam base material that accommodates the contents of the foam base material,
The foam base material constituting the polystyrene foam (A) is a foam of a resin composition containing a styrene homopolymer, a polyphenylene ether resin, and high impact polystyrene (HIPS),
The flange of the polystyrene foam (A) has a surface roughness Ra of 3 μm or less on the upper surface of the flange, and
A packaging container characterized in that the top sealing lid material (B) is a multilayer film having a cohesive release layer on the side that is sealed to the flange surface of the polystyrene foam. A claim in which the thermoplastic non-foamed film layer present on the inner surface of the polystyrene foam (A) is a single layer of a styrene resin film layer or an olefin resin film layer or a multilayer including at least one layer thereof. The packaging container according to item 1. The packaging container according to claim 1 or 2, wherein the flange of the polystyrene foam (A) has a flat shape or a curved shape that bulges upward. According to any one of claims 1 to 2, the foam base material constituting the polystyrene foam (A) is a foam molded product of a polystyrene resin containing a styrene and (meth)acrylic acid ester copolymer. packaging container. According to any one of claims 1 to 4, wherein the top sealing lid material (B) has a cohesive release layer on one or two layers of base film selected from polyolefin resins and polyester resins. Packaging container as described.

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