JPH0694160B2 - Insulation container manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a heat insulating container.

[0002]

2. Description of the Related Art Generally, in a container which requires a high heat insulating property such as a container for instant noodles, a method of forming a heat insulating layer inside the container is adopted.
The one described in Japanese Patent No. 60221 is known.

As shown in FIG. 4, a container 10 is formed in three layers, and a polyvinylidene chloride layer 12 is bonded to the outside of a film 11 made of unstretched polypropylene, high impact polystyrene, or polyethylene through a binder. Further, the expanded polystyrene sheet layer 13 is laminated on the outer side of the expanded polystyrene sheet layer 13 via a binder.

Since the expanded polystyrene sheet layer 13 contains innumerable air bubbles, it has a heat insulating effect and keeps the heat of the contained items. In addition to the above-mentioned one, there is one in which an outer container and an inner container are independently formed and an air layer is formed between them by combining them.

On the other hand, as a heat molding method, a synthetic resin sheet is set in a mold having a container-shaped cavity, the synthetic resin sheet is heated, and the synthetic resin sheet is adhered to the inner wall of the cavity to produce a container. It has been known. As a means for bringing the synthetic resin sheet into close contact with the inner wall of the cavity, a vacuum molding method in which the inside of the cavity is evacuated to suck the synthetic resin sheet, and pressurized air is inserted into the cavity to press the synthetic resin sheet side against the inner wall of the cavity A molding method is known in which a male mold is inserted into a cavity and a synthetic resin sheet is pressed by the male mold toward the inner wall of the cavity.

[0006]

However, in the former case described above, since the expanded polystyrene sheet layer 13 is the main heat insulation layer, the heat insulation performance is higher than that of the air insulation layer. Is low, and there is a risk that heat retention will not be sufficient.

Moreover, the three-layer structure has a drawback that the manufacturing is complicated and the weight becomes heavy. On the other hand, the latter one is excellent in heat retaining effect because it uses air as a heat insulating layer, but since the outer and inner containers are formed independently and they are combined in a later step,
There is a drawback that the number of manufacturing processes increases.

The present invention has been made in view of the above matters, and an object of the present invention is to provide a method for manufacturing a lightweight heat-insulating container having an excellent heat insulating effect by utilizing the conventional heat molding method.

[0009]

The present invention adopts the following means in order to solve the above technical problems. That is, the method of the present invention is a thermoforming method for producing a container by setting a synthetic resin sheet in a mold having a cavity, heating the synthetic resin sheet, and closely contacting the synthetic resin sheet with the inner wall of the cavity. A first synthetic resin sheet for forming an outer container and a second synthetic resin sheet for forming the inner container, the second synthetic resin having a larger heat shrinkage after heating and cooling than the first synthetic resin sheet. A sheet is prepared, and the both sheets are peelably bonded to each other to form an integrated sheet, and the integrated sheet is set in a mold having a container-shaped cavity. Make it adhere to the inner wall,
By molding the container so that the first synthetic resin sheet is on the outer side of the container and then cooling, the second synthetic resin sheet shrinks more than the first synthetic resin sheet,
This is a method for producing a container in which an inner container is peeled from an outer container and a hollow layer as the heat insulating layer is formed between the inner container and the inner container.

[0010]

In the present invention, two synthetic resin sheets having different heat shrinkage rates are stacked and the container is manufactured by heat molding. that time,
When the sheet having a large heat shrinkage is placed inside, the inner sheet shrinks more than the outer sheet during molding, so that the container having the hollow layer as the heat insulating layer between them can be instantly molded.

Here, as means for bringing the two integrated synthetic resin sheets into close contact with the inner wall of the cavity, a vacuum forming method in which the inside of the cavity is evacuated to suck the integrated sheet from the first synthetic resin sheet side, the cavity Pressurized air is inserted into the inside of the cavity, and the compressed sheet is pressed against the inner wall of the cavity from the second synthetic resin sheet side. A male mold is inserted into the cavity, and the integral sheet is inserted from the second synthetic resin sheet side. An embossing molding method in which a mold presses against the inner wall of the cavity can be used.

As the sheet for forming the heat insulating container, for example, polypropylene having a heat shrinkage of 0.01 to 0.025 (cm / cm) is used as the second synthetic resin sheet for forming the inner container 1, and the outer container 2 is used. A sheet formed of polystyrene having a heat shrinkage ratio of 0.002 to 0.006 (cm / cm) can be used as the first synthetic resin sheet to be formed.

Subsequently, this sheet is releasably adhered and molded into a container in the heated state as described above, and then cooled. Here, since polypropylene has a contraction rate about 5 times larger than that of polystyrene, only the inner container 1 contracts greatly and the adhesion is peeled off, and the hollow layer 3 is formed between both containers 1 and 2.

Since the two sheets to form the inner container 1 and the outer container 2 are weakly adhered to each other to form an integrated sheet, and the integrated sheet is thermoformed into a container shape, the inner container 1 and the outer container are formed. The molding process is halved compared to the case where 2 and 2 are molded separately.

Subsequently, the molded container is cooled to shrink the inner container more than the outer container to form the hollow layer 3. As described above, the container is easy to manufacture, and excellent heat insulating property is obtained by the hollow layer formed by heat shrinkage of the inner container 1 after molding.

[0016]

Embodiments of the present invention will be described with reference to FIGS. The heat insulating container is composed of an inner container 1 made of polypropylene and an outer container 2 made of polystyrene, and a hollow layer 3 is formed between the both containers 1 and 2.

When manufacturing this heat-insulating container, first, a polypropylene sheet and a polystyrene sheet are weakly adhered with an adhesive 4 to form an integrated sheet.
When molding a container, use this integrated sheet at 200 ℃
While heating it to about 260 ° C, it is sandwiched between the molds 5 and 6, and then pressed to form the desired shape.

After that, the container-shaped sheet is removed from the molds 5 and 6 and cooled. The heat shrinkage rate of polypropylene is 0.01 to 0.025 (cm / cm), that of polystyrene is
Since it is 0.002 to 0.006 (cm / cm), the inner container 1 has a larger shrinkage ratio than the outer container 2, and the adhesion between the both containers 1 and 2 is peeled off to form the hollow layer 3.

As described above, the container can be manufactured by one-time molding and has good productivity. Further, since the hollow layer 3 is automatically formed by cooling after thermoforming, a general molding is performed. The equipment can be used as it is to manufacture an insulated container.

Although polypropylene and polystyrene are used as the material of the container in the above embodiments, it goes without saying that other materials can be used as long as they have different heat shrinkage rates after heating.

[0021]

According to the present invention, since the shrinkage rate of the inner container after heat-cooling is set to be larger than that of the outer container, both are preliminarily adhered and heated to be molded into a desired shape. A hollow layer can be formed between the two just by cooling.

For this reason, not only the heat insulating effect is excellent, but also the pre-polymerized sheet can be manufactured by molding only once, so that the process can be greatly simplified and the manufacturing can be performed at low cost. can do.

[Brief description of drawings]

FIG. 1 is a cross-sectional view at the time of heat molding showing an embodiment of the present invention,

FIG. 2 is a sectional view after cooling showing an embodiment of the present invention.

FIG. 3 is a sectional view of a manufacturing apparatus showing an embodiment of the present invention.

FIG. 4 is a sectional view showing a conventional heat insulating container.

[Explanation of symbols]

 1 inner container, 2 outer container, 3 hollow layer, 5, 6 mold.

Claims (1)

[Claims] 1. A thermoforming method for manufacturing a container by setting a synthetic resin sheet in a mold having a cavity, heating the synthetic resin sheet, and bringing the synthetic resin sheet into close contact with the inner wall of the cavity, wherein the outer container is Prepare a first synthetic resin sheet to be formed and a second synthetic resin sheet that is to form the inner container and has a greater heat shrinkage rate after heating and cooling than the first synthetic resin sheet. Then, the two sheets are releasably adhered to each other to form an integrated sheet, and the integrated sheet is set in a mold having a container-shaped cavity, and the integrated sheet is adhered to the inner wall of the cavity with the integrated sheet in a heated state. Then, the container is molded so that the first synthetic resin sheet is on the outside of the container and then cooled.
Of the synthetic resin sheet of claim 1 shrinks more than the first synthetic resin sheet, so that the inner container is stuffed from the outer container to form a hollow layer as the heat insulating layer therebetween. Method.